The Importance Of The Resting Zone In The Epiphyseal Growth Plate (Important)

Me: My collaborator in the project found a very interesting article that shows just how critical the resting zone is in the development of the growth plate itself which I had discovered previously in my searching. I wanted to bring to light the discovery because it shows just which elements in the growth mechanism are the most critical, which must be either preserved or regenerated for longitudinal increase to occur.

Note: As always I am using PubMed and reading just the abstract. The Full Text for the article is either not available or I just didn’t want to expend the energy to do a massive search to find the full article.

1st paper: This article shows just how important the resting zone is to the overall entire growth plate. if you remove the proliferative and hypertrophic zones, apparently adolescent rabbit growth place of the distal ulnar can regrow back in most cases within just 1 week. If you take the growth plates and put them sideways next to the proliferative layer, the chondrocytes in the proliferative layer starts to align themselves in alignment with the resting zone chondrocytes. This also stops the ability of the chondrocytes in the proliferative layer from turning hypertrophic. this suggest the resting zone might have some form of orientation growht factor involved.

2nd paper: This article shows that researchers have been hypothesizing that the real cause of growth plate senescence if because the chondrocytes in the resting zone have a finite proliferative capacity that is gradually depleted. With the rabbits, they saw that the proliferation rate and the chondrocyte density in resting zones decreased with age. Gluccocorticoids and dexamethasone treatment decreased the proliferative rate of the chondrocytes which helped conserve their proliferative capacity for later. They slowed the senescence of growth plates and slowed the depletion of the number of chondrocytes in the resting zone. They also foun that estradiol cypionate treatment slowed resting zone chondrocyte proliferation

The Implications (READ THIS!): The first article shows how important the resting zone is to the overall growth plate. As long as you have the resting zone, you can create all of the rest of layers. The 2nd article make me understand at a still superficial level that apparently the puberty we go through is just estrogen telling the resting zone chondorcytes to proliferate faster, which means rate of loss>rate of growth. as long as that happens, the proliferation and subsequent hypertrophy and apoptosis is the explanation behind the jump in rate of growth or height increase we see in kids going through puberty and the growth spurts. However, the growth spurts do come at a cost, especially the growth spurt associated with puberty. The estrogen has pushed the rate of loss over a limit where the rate of growth is not enough to stave off the loss of the number of chondrocytes seen in the resting zone.

If we remember the cases seen of the 3 men who had mutations in their estrogen receptors, we remember that for 2 of the men, they still had open growth plates with cartilage even in their 30s. This shows that as long as estrogen doesn’t come along to accelerate the rate of decrease in the number of chondrocytes in the resitng zone, the rate of proliferation thus rate of increase of chondrocytes in the resting zone is probably (and i am making a big leap of faith here) self-sustaining, which will not ever drop the number of chondrocytes around. What we could do then to create growth spurts but never loss all of the chondrocytes is to create a way to inhibit and promote estrogen release alternatively where the loss of chondrocytes can be made up for by inhibiting estrogen affects afterwards. 

A device can be build that can specifically block estrogen ligands from reaching their receptors on the growth plate in a pulsing, sinusoidal fashion to use the feedback mechanism of the two rates themselves to cause multiple growth spurts throughout an adolescent’s growth and development!

source link HERE. and from source link 2 HERE. both are PubMed Articles.

Endocrinology. 2002 May;143(5):1851-7.

The role of the resting zone in growth plate chondrogenesis.

Abad V, Meyers JL, Weise M, Gafni RI, Barnes KM, Nilsson O, Bacher JD, Baron J.

Source

Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Building 10, Room 10N262, 10 Center Drive MSC 1862, Bethesda, MD 20892, USA.

Abstract

In mammals, growth of long bones occurs at the growth plate, a cartilage structure that contains three principal layers: the resting, proliferative, and hypertrophic zones. The function of the resting zone is not well understood. We removed the proliferative and hypertrophic zones from the rabbit distal ulnar growth plate in vivo, leaving only the resting zone. Within 1 wk, a complete proliferative and hypertrophic zone often regenerated. Next, we manipulated growth plates in vivo to place resting zone cartilage ectopically alongside the proliferative columns. Ectopic resting zone cartilage induced a 90-degree shift in the orientation of nearby proliferative zone chondrocytes and seemed to inhibit their hypertrophic differentiation. Our findings suggest that resting zone cartilage makes important contributions to endochondral bone formation at the growth plate: 1) it contains stem-like cells that give rise to clones of proliferative chondrocytes; 2) it produces a growth plate-orienting factor, a morphogen, that directs the alignment of the proliferative clones into columns parallel to the long axis of the bone; and 3) it may also produce a morphogen that inhibits terminal differentiation of nearby proliferative zone chondrocytes and thus may be partially responsible for the organization of the growth plate into distinct zones of proliferation and hypertrophy.

PMID: 11956168         [PubMed – indexed for MEDLINE] 

J Endocrinol. 2006 Apr;189(1):27-36.

Depletion of resting zone chondrocytes during growth plate senescence.

Schrier L, Ferns SP, Barnes KM, Emons JA, Newman EI, Nilsson O, Baron J.

Source

Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, CRC, Room 1-3330, 10 Center Drive, MSC 1103, Bethesda, Maryland 20892, USA.

Abstract

With age, the growth plate undergoes senescent changes that cause linear bone growth to slow and finally cease. Based on previous indirect evidence, we hypothesized that this senescent decline occurs because growth plate stem-like cells, located in the resting zone, have a finite proliferative capacity that is gradually depleted. Consistent with this hypothesis, we found that the proliferation rate in rabbit resting zone chondrocytes (assessed by continuous 5-bromo-2′-deoxy-uridine labeling) decreases with age, as does the number of resting zone chondrocytes per area of growth plate. Glucocorticoid excess slows growth plate senescence. To explain this effect, we hypothesized that glucocorticoid inhibits resting zone chondrocyte proliferation, thus conserving their proliferative capacity. Consistent with this hypothesis, we found that dexamethasone treatment decreased the proliferation rate of rabbit resting zone chondrocytes and slowed the numerical depletion of these cells. Estrogen is known to accelerate growth plate senescence. However, we found that estradiol cypionate treatment slowed resting zone chondrocyte proliferation. Our findings support the hypotheses that growth plate senescence is caused by qualitative and quantitative depletion of stem-like cells in the resting zone and that growth-inhibiting conditions, such as glucocorticoid excess, slow senescence by slowing resting zone chondrocyte proliferation and slowing the numerical depletion of these cells, thereby conserving the proliferative capacity of the growth plate. We speculate that estrogen might accelerate senescence by a proliferation-independent mechanism, or by increasing the loss of proliferative capacity per cell cycle.

PMID:   16614378          [PubMed – indexed for MEDLINE] 

Beating And Eliminating The Grow Taller Scams And Bullshit On The Internet

I have been very patient with the numerous numbers of grow taller scams and bullshit on the internet but I have recently been loosing the tolerance for these types of sites.

When I was first starting out on the website, I had to accept the idea that the internet which is a sort of Wild West where almost anything goes and swindlers and sales people try to sell everything under the sun to get people like us to open our wallets and pull out our credit cards. I accepted it and I was sort of happy that I would be able to build a sort of brand and place where real height increase and grow taller research and information could be found. One of the first things I did on the website was to create a section which lists all of the fake, non useful, sleazy websites and webpages out there who are trying to trick me. I worked on it for 3-4 days finding nearly a hundred websites. I went through as many google ranking webpages as possible to find all of the fake stuff.

Most of it were affiliate websites and links to the scam Grow Taller 4 Idiots or the (Company will not be named) program. There were a lot of grow taller supplements out there too which made me realize that most people wanted a easy solution to their problem which doesn’t exist. I slowly wrote out the product reviews trying to make the internet a better place and blasted all of the grow taller supplements showing how none of them work.

However, now I am tired. I am very tired of the crap I am finding on the internet. The frustration has been building and I don’t know how much I can take. It is becoming harder and harder to find real useful information for the website since the fake grow taller websites have been using all the SEO and internet marketing tricks to rank higher on Google than the useful website which must be out there. If I type in the phrases “height increase” or “grow taller” I don’t see my website on the front  page, or any of the resulting pages. My website is ranked somewhere in the lower end and for any of the genuine people who want to grow taller, they never find my website. It is a loss/loss situation for everyone, except maybe the people who are plugging the Grow Taller 4 Idiots programs.

I want to beat and eliminate all of the webpages that do nothing but make my life and the research 10X harder than it already is. Why can’t Google realize that for this specific niche on the internet, nearly 95% of all of the website are just fake sales pages which do nothing but annoy people and give no real value? They should be trying to remove those websites and stop all the people playing the internet marketing game in backlinking.

How many times do I have to read a fake sales page tell me that I should drink milk, get more sleep, and do some stretching? I am dealing with bullshit after bullshit everyday in searching through the internet space. I want to be ranked higher, get more traffic, and help more people. I want to be at least on the 1st page of google rankings when a person types in the phrase “how do i grow taller” at least.

 

Why Guanyl Cyclase And Natriuretic Peptides Are Important For Height Increase

I had previously wrote about the invention using Guanyl Cyclase through a vector injection in gene therapy to increase in height apparently twice HERE and HERE. Tyler in a post on June 18 this year wrote about the exact same thing HERE. That was more than a month before I started on this website.

It is quite clear that we have been scouring through the internet to try to find everything under the sun to push this endeavor and search for a possible noninvasive way to increase the height of people who have already reach physical maturity. So far I would say that we are doing a rather good job and at this rate, we probably could cover everything that is on the internet. One day we will have to regularly contact real doctors, specialists, and surgeons to be able to get answers.

So the question I wanted to answer in this post is why is guanyl cyclase and natriuretic peptides important for possible height increase and growing taller. I’ll just assume that you know the basics of the growth process with knowledge on the hormones and growth plate function.

You have these peptides known as natriuretic peptides which are ligands. There is 3 types in a specific family. You have the ANP aka atrial natriuretic peptide , the brain natriuretic peptide aka BNP, and the C-type natriuretic peptide aka CNP. The effect of the types of natriuretic peptides of ANP and CNP which are ligands for the receptors GC-A and GC-B. When the 3 types of ligands were tested on a culture of mice tibias simulating the longitudinal growth process in bones. It showed that CNP produced more cGMP than ANP which resulted in longer bones. closer look at the cells showed an increase in the height of the proliferative and hypertropic layers in the mouse tibias with CNP.   To mimic the binding of the CNP and GC-B, the experimenters used similar compounds. The conclusion of the study showed that the CNP/GC-B pathway is very significant in the endochondral ossification process.

Let’s look at this specific article found from PubMed. Source Link HERE.

J Biol Chem. 1998 May 8;273(19):11695-700.

Natriuretic peptide regulation of endochondral ossification. Evidence for possible roles of the C-type natriuretic peptide/guanylyl cyclase-B pathway.

Yasoda A, Ogawa Y, Suda M, Tamura N, Mori K, Sakuma Y, Chusho H, Shiota K, Tanaka K, Nakao K.

Source

Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606, Japan.

Abstract

The natriuretic peptide family consists of three structurally related endogenous ligands: atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). The biological actions of natriuretic peptides are thought to be mediated through the activation of two guanylyl cyclase (GC)-coupled receptor subtypes (GC-A and GC-B). In this study, we examined the effects of ANP and CNP, which are endogenous ligands for GC-A and GC-B, respectively, on bone growth using an organ culture of fetal mouse tibias, an in vitro model of endochondral ossification. CNP increased the cGMP production much more potently than ANP, thereby resulting in an increase in the total longitudinal bone length. Histological examination revealed an increase in the height of the proliferative and hypertrophic chondrocyte zones in fetal mouse tibias treated with CNP. The natriuretic peptide stimulation of bone growth, which was mimicked by 8-bromo-cGMP, was inhibited by HS-142-1, a non-peptide GC-coupled natriuretic peptide receptor antagonist. The spontaneous increase in the total longitudinal bone growth and cGMP production was also inhibited significantly by HS-142-1. CNP mRNA was expressed abundantly in fetal mouse tibias, where no significant amounts of ANP and BNP mRNAs were detected. A considerable amount of GC-B mRNA was present in fetal mouse tibias. This study suggests the physiologic significance of the CNP/GC-B pathway in the process of endochondral ossification.

PMID: 9565590           [PubMed – indexed for MEDLINE] 

 

Increase Height And Grow Taller Using cGMP

Me: I have written two related posts linking the ligand CNP with the receptor NPR2 resulting in increased cGMP production resulting in height increase. The study linked HERE which I have already analyzed the abstract. The link with Guanyl Cyclase B is that it acts as a catalyst for it. For most biological catalysts, they are not minerals or metals but proteins being enzymes. So…

CNP + NPR2 (+ GC-B as catalyst) –> increased levels of cGMP

It seems that elevated levels of cGMP in growth plates lead to the elongation of long bones. It is kind of sad that I have to quote HeightQuest again because of the research that has already been previously done on the link between cGMP and possible height increase HERE.

one critical formula to take away from the post again is 

GTP (+ GC-B as catalyst) –> cGMP

It seems that test subjects (mice) which are bred with the mutation in their genes which causes higher CNP and GC-B expression leads to all of the resting zone, the proliferation , and the hypertropy layer being increased in thickness. 

cGMP stands for Cyclic Guanosine Monophosphate. From the wikipedia article on cGMP HERE… (As always the most important points are highlighted)

…is a cyclic nucleotide derived from guanosine triphosphate (GTP). cGMP acts as a second messenger much like cyclic AMP. Its most likely mechanism of action is activation of intracellular protein kinases in response to the binding of membrane-impermeable peptide hormones to the external cell surface.[1]

Synthesis

Guanylate cyclase (GC) catalyzes cGMP synthesis. This enzyme converts GTP to cGMP. In turn, peptide hormones such as the atrial natriuretic factor activate membrane-bound GC, while soluble GC is typically activated by nitric oxide to stimulate cGMP synthesis.

Effects

cGMP is a common regulator of ion channel conductance, glycogenolysis, and cellular apoptosis. It also relaxes smooth muscle tissues. In blood vessels, relaxation of vascular smooth muscles lead to vasodilation and increased blood flow.

cGMP is a secondary messenger in phototransduction in the eye. In the photoreceptors of the mammalian eye, the presence of light activates phosphodiesterase, which degrades cGMP. The sodium ion channels in photoreceptors are cGMP-gated, so degradation of cGMP causes sodium channels to close, which leads to the hyperpolarization of the photoreceptor’s plasma membrane and ultimately to visual information being sent to the brain.[2] GMP and a number of its derivatives also have an umami taste.[3]

cGMP is also seen to mediate the switching on of the attraction of apical dendrites of pyramidal cells in cortical layer V towards semaphorin-3A (Sema3a).[4]Whereas the axons of pyramidal cells are repelled by Sema3a, the apical dendrites are attracted to it. The attraction is mediated by the increased levels of soluble guanylate cyclase (SGC) that are present in the apical dendrites. SGC generates cGMP, leading to a sequence of chemical activations that result in the attraction towards Sema3a. The absence of SGC in the axon causes the repulsion from Sema3a. This strategy ensures the structural polarization of pyramidal neurons and takes place in embryonic development.

cGMP, like cAMP, gets synthesized when olfactory receptors receive odorous input. cGMP is produced slowly and has a more sustained life than cAMP, which has implicated it in long-term cellular responses to odor stimulation, such as long-term potentiation cGMP in the olfactory is synthesized by both membrane guanylyl cylcase (mGC) as well as soluble guanylyl cyclase (sGC). Studies have found that cGMP synthesis in the olfactory is due to sGC activation by nitric oxide, a neurotransmitter. cGMP also requires increased intracellular levels of cAMP and the link between the two second messengers appears to be due to rising intracellular calcium levels.[5]

Degradation

Numerous cyclic nucleotide phosphodiesterases (PDE) can degrade cGMP by hydrolyzing cGMP into 5′-GMP. PDE 5, -6 and -9 are cGMP-specific while PDE1, -2, -3, -10 and -11 can hydrolyse both cAMP and cGMP.

Phosphodiesterase inhibitors prevent the degradation of cGMP, thereby enhancing and/or prolonging its effects. For example, Sildenafil (Viagra) and similar drugs enhance the vasodilatory effects of cGMP within the corpus cavernosum by inhibiting PDE 5 (or PDE V). This is used as a treatment for erectile dysfunction. However, the drug can inhibit PDE6 in retina (albeit with less affinity than PDE5). This has been shown to result in loss of visual sensitivity but is unlikely to impair common visual tasks, except under conditions of reduced visibility when objects are already near visual threshold.[6] This effect is largely avoided by other PDE5 inhibitors, such as tadalafil.[7]

Protein kinase activation

cGMP is involved in the regulation of some protein-dependent kinases. For example, PKG (protein kinase G) is a dimer consisting of one catalytic and one regulatory unit, with the regulatory units blocking theactive sites of the catalytic units.

cGMP binds to sites on the regulatory units of PKG and activates the catalytic units, enabling them to phosphorylate their substrates. Unlike with the activation of some other protein kinases, notably PKA, the PKG is activated but the catalytic and regulatory units do not disassociate.

What Are Growth Hormone Secretagogues?

Me: It seems the hypothalamic-pituitary pathway system not only releases growth hormones (GH) but also growth hormone secretagogues (GHS). The human body releases growth hormones throughout life, which decreases to a lower rate later in life. At the same time the growth hormone is being released, the growth hormone inhibiting somatostatin is also released at the same time. It would appear that as time moves forward and we grow older, the rate of somatostatin release increase, until it overtakes the rate of GH release. remember that the release of GH by the pituitary is controlled by growth hormone releasing hormone and somatostatin in the hypothalamus.

The synthetic type of GH we could take after reaching physical maturity would have to be in injection form. However, this method is not in the pulsating fashion that GH is supposed to act in the body. Naturally, the hypothalamic-pituitary system releases GH in a pulsation way into the body. The secretagogues are peptides made of 6 amino acids linked together. These GHS can be taken orally without the stomach digesting the peptide and breaking it up effectively destroying it.

It seems that GHS like MK-677 in experiments have mixed results. The link says that the authors think GHS works because it mimics ghrelin towards the body’s GH receptors. If I was asked whether GHS can be used to increase height, I would say it could work for people who are of short stature due to low growth hormones in the system but probably little else. THe IGF-1 level was shown to increase from GHS intake from the first study below. 

From the website Iron Man Magazine, a well written article on GHS.

From the website on The Journal Of Endocrinology & Metabolism

Effects of an Oral Growth Hormone Secretagogue in Older Adults

  1. Heidi K. White, Charles D. Petrie, William Landschulz, David MacLean, Ann Taylor,Kenneth Lyles, Jeanne Y. Wei, Andrew R. Hoffman, Roberto Salvatori, Mark P. Ettinger,Miriam C. Morey, Marc R. Blackman, George R. Merriam and for the Capromorelin Study Group

–Author Affiliations


  1. Duke University School of Medicine and Geriatric Research Education and Clinical Center (GRECC), Durham Veterans Affairs (VA) Medical Center (H.K.W., K.L., M.C.M.), Durham, North Carolina 27710; Pfizer Global Research and Development (C.D.P.), Groton, Connecticut 06340; Endocrine Clinical Research (W.L.), Eli Lilly and Co., Indianapolis, Indiana 46285; Brown University Medical School (D.M.), Providence, Rhode Island 02912; Novartis (A.T.), Cambridge, Massachusetts 02139; GRECC, Central Arkansas Veterans Affairs (VA) Healthcare System, and University of Arkansas for Medical Sciences (J.Y.W.), Little Rock, Arkansas 72205; VA Palo Alto Health Care System and Stanford University (A.R.H.), Palo Alto, California 94304; The Johns Hopkins University School of Medicine (R.S.), Baltimore, Maryland 21205; Radiant Research and the Regional Osteoporosis Center (M.P.E.), Stuart, Florida 34996; Washington DC VA Medical Center (M.R.B.), Washington, D.C. 20422; and VA Puget Sound Health Care System and University of Washington School of Medicine (G.R.M.), Seattle and Tacoma, Washington 98493
  1. Address all correspondence and requests for reprints to: Heidi K. White, M.D., M.H.S., Duke University School of Medicine, Box 3003, Durham, North Carolina 27710. E-mail:White031@mc.duke.edu.

Abstract

Context: GH secretion declines with age, possibly contributing to reduced muscle mass, strength, and function. GH secretagogues (GHS) may increase muscle mass and physical performance.

Objectives/Design: We conducted a randomized, double-masked, placebo-controlled, multicenter study to investigate the hormonal, body composition, and physical performance effects and the safety of the orally active GHS capromorelin in older adults with mild functional limitation.

Intervention/Participants: A total of 395 men and women aged 65–84 yr were randomized for an intended 2 yr of treatment to four dosing groups (10 mg three times/week, 3 mg twice a day, 10 mg each night, and 10 mg twice a day) or placebo. Although the study was terminated early according to predetermined treatment effect criteria, 315 subjects completed 6 months of treatment, and 284 completed 12 months.

Results: A sustained dose-related rise in IGF-I concentrations occurred in all active treatment groups. Each capromorelin dose prompted a rise in peak nocturnal GH, which was greatest with the least frequent dosing. At 6 months, body weight increased 1.4 kg in subjects receiving capromorelin and decreased 0.2 kg in those receiving placebo (P = 0.006). Lean body mass increased 1.4 vs. 0.3 kg (P = 0.001), and tandem walk improved by 0.9 sec (P = 0.02) in the pooled treatment vs. placebo groups. By 12 months, stair climb also improved (P = 0.04). Adverse events included fatigue, insomnia, and small increases in fasting glucose, glycosylated hemoglobin, and indices of insulin resistance.

Conclusions: In healthy older adults at risk for functional decline, administration of the oral GHS capromorelin may improve body composition and physical function.

From the Dr. Lam website article on Growth Hormones And Growth Hormone Secretagogues located HERE…

B. Amino Acid Secretagogues

A secretagogue (pronounced se-cre’-ta-gog) is a natural polyamino acid chain that is postulated to initiate the pituitary gland to release growth hormone. It is the precursor to hGH. While hGH causes the body to act as if the pituitary has released growth hormone, a secretagogue actually causes the release of it. Hence a secretagogue causes the bodies own natural processes to produce growth hormones. Secretagogues do not act as growth hormones at all as they stimulate the pituitary gland to secrete growth hormone.

Interestingly, the inconvenience of hGH injections first led to the discovery of Secretagogues. For years, it was believed that the pituitary gland, which produces growth hormones, dries up as a natural effect of aging. Science has recently discovered that growth hormones reside in the pituitary gland, which stops the release due to aging. Scientists then discovered that certain combinations of amino acids could actually spur the pituitary gland to release the growth hormones. Experiments soon led to the right combinations.

Natural secretagogue is the most practical approach because there are no side effects. In comparison with hGH, their potency and efficacy are low. Since these are orally taken, they can be a first line approach for those who may not choose hGH injections.

This category of hGH products uses amino acids as “secretagogues,” which stimulate the pituitary gland to produce hGH. Other proprietary agents are usually part of the powder/tablet mix, which provide each product with a presumed marketing advantage. Studies show that certain amino acid combinations such as L-lysine, L-arginine, L-ornithine and L-glutamine can stimulate pituitary hGH. While this is theoretically plausible and positive clinical results have been widely reported, published double blind controlled studies that show evidence that these other proprietary factors provide additional pituitary hGH secretion is still incomplete at best. Most studies reveal at least two grams of amino acids are needed to have any effect on pituitary hGH stimulation.

Glutamine

Glutamine is the most abundant amino acid in the body and causes GH secretion. It is a conditional amino acid as the body may not be able to synthesize it under stressful conditions. Traditionally it has been used to strengthen the immune system. The standard anti-aging intake is 50 mg to 1 gm twice daily.

Glutamine is a neurotransmitter in the brain. It is essential for proper brain functions, immune functions, kidneys, pancreas, bladder, and liver functions.

Glutamine becomes one of our body’s most powerful antioxidants in high quantities. Many people, especially those in weight training, add this amino acid due to its benefit in muscle metabolism. Supplementation of two to three gm/day is quite common. For those who plan to take extra doses, it is best to divide the doses throughout the day with up to four servings daily.

Two grams of glutamine was shown to cause a four fold increase in Growth Hormone levels.

Lysine

Lysine is an essential amino acid, which affects bone formation, height, and genital function. It also boosts the effects of arginine. The recommended dosage is one gram on an empty stomach one hour before bedtime and before exercise.

Ornithine

Ornithine is a non-essential amino acid. It is used to potentate the effect of Arginine. The suggested dosage is one gram at bedtime. Doses of more than two to five grams have been known to cause diarrhea.

C. Oral Peptide Secretagogues

hGH is a hormone made up of a long chain of amino acids. Only a portion of the long chain of amino acids makes up the active ingredient. Researchers have been able to identify and extract these active peptides, which are usually five to ten amino acids linked together in a chain. These are then stabilized and formulated into a power or tablet effervescent form. The oral tablets are dissolved in water to be taken before bedtime on an empty stomach. This is to stimulate the release of hGH from the anterior pituitary, which peaks during the early phase of sleep. The effervescent form is best to draw the peptide away from the gastric juice closer to the mucous for better absorption. Gastric juices are highly acidic. Peptides are proteins that are easily denatured when exposed to an acidic environment. Extraction of the peptide is a tedious process. Peptides are not stable enough to maintain its activity in an aqueous environment. Thus, the peptide is formulated in the oral tablet format. Secretagogues using peptides are abundant in the marketplace. They are sold as a natural nutritional supplement and no FDA approval is required. However, some unscrupulous operators simply use ground bovine pituitary gland and pass them off as secretagogues. The consumer is often faced with the arduous task of identifying which is the real secretagogue.

Secretagogues can also work at multiple sites leading to growth hormone release. For example, a secretagogue targeted towards the hypothalamus would stimulate the hypothalamus to release Growth Hormone Releasing Factor (GHRF) that in turn stimulates the pituitary gland to release growth hormone. An oral peptide pituitary secretagogue, on the other hand, stimulates the pituitary gland directly to effect the release of growth hormone.

An effective secretagogue could easily raise IGF-1 levels, although the result is not as significant as growth hormone injections. Clinically many users have reported better sleep, increased alertness during the day, and less joint pain.

IGF-1 levels may not be the best indicator of how effective a secretagogue is for the GH receptor sites may be damaged. A low IGF-1 level does not mean that the body’s growth hormone level has not increased. It may simply mean that that the level is not accurately measured, or that there is a defective receptor site. If your IGF-1 does not increase, do not be despair. Talk to your health care practitioner. How you feel is just as important and sometimes even more important than laboratory studies alone.

D. Growth Factors

Growth factors (GF) are small protein chains, commonly known as polypeptides, which bind to cell surface receptor sites and exert actions directly on the target cells. This is generally done through cellular proliferation and or differentiation.

Some GFs exert generalized effect, while others are cell and action specific. There are many different classes of GFs. Some common ones include: Insulin-like Growth Factor (IGF-1) that is responsible for much of Growth Hormones (GH) action in the body; Interleukins (IL); Fibroblast Growth Factors (FGF); Transforming Growth Factor (TGF); Tumor Necrosis Factor (TNF); Epidermal Growth Factor (EGF); and Transforming Growth Factors-b (TGFs-b).

GFs come from a wide variety of sources. Epithelial Growth Factors (EGF) comes from sub maxillary gland, and FGF comes from a wide range of cells. A unique family of growth factors that is secreted primarily by leukocytes (white blood cells) is called cytokines. When such cytokines are secreted by lymphocytes, they are called lymphokines. Many of the lymphokines are also known as interleukins (ILs). Not only are interleukins secreted by leukocytes, they are also able to affect the cellular responses of leukocytes.

What Do Growth Factors Do? 

Different GFs have different jobs to do. Generally, all of them work at the cellular level to:

Repair damaged cells

Enhance cellular proliferation

Maintain optimum function of the target organ

Rejuvenate aging tissues

While hormones generally are more specific and sometimes work through other mediations elicited from its simulation of intermediate organs, GFs often act directly on the target tissue and have a wide range of effects. Its action is mostly stimulatory. It can also work synergistically with other GFs or hormones to elicit a biological effect. Growth hormone, for example, exerts its effect in the body via Insulin-like Growth Factor (IGF-1). In other words, it is the IGF-1 that actually carries out the function of growth hormone and not growth hormone itself.

The Connection Between mTOR, Rapamycin, Leucine And Height

Me: Throughout the other boards I have come across on the occasional thread which talks about the possibility of using mTor or Leucine to increase height.

Now as I have shown in previous posts, there is a link between tall stature and increased chance for cancer and faster aging rate. It seems that what makes you taller, makes it more likely that you develop cancer and age faster.

With mTor it has been shown in studies to possibly increase the rate of aging in people and also increase the chance for cancer. So using sort of a reverse causality type of logic, (which is not really logic but correlation) I would guess that Leucine and mTor might have some connection with height and might contribute to growth somehow.

Analysis: From the first article I found, we learn that mTor Stands for mammalian target of rapamycin (didn’t know that) which is a nutrient sensing protein kinase that regulates numerous cellular processes. In an experimental chondrogenic cell line, rapamycin seems to regulate and inhibit proteoglycan accumulation and collagen X exprsesion. This would suggest that the overall affect of Rapamycin is to inhibit the creation of chondrocytes. It decreases the amount of Ihh, which regulates chondrocyte differentiation If you added more ihh into the culture, it reverses the effect of mTor. The researchers concluded that if you can control and manipulate the mTOR signalling, you can control at least part of the mechanism causing chondrocyte differentiation, thus also longitudinal growth. 

In the 2nd article the researchers found that if you inactivate TOR or its substrate s6 kinase you cause cells to be smaller in size and also die. This shows that the TOR pathway controls cell growth. They did a homogolous recombination of the deletion of the C-terminal six amino acids of mTOR, which are essential for kinase activity, resulted in reduced cell size and proliferation arrest in embryonic stem cells. mTOR controls cell size and proliferation at least in mouse stem cells. mTOR can make cells produce chemicals such as cyclins that trigger cell growth.

In the 3rd article, the writer states from the beginning, ” Amino acids, in particular leucine, have been shown to regulate cell growth, proliferation, and differentiation through the mammalian target of rapamycin (mTOR), a nutrient-sensing protein kinase”…plus “we hypothesized that leucine restriction, acting through mTOR, would inhibit growth plate chondrocyte proliferation and differentiation. The effect of leucine restriction was compared with that of the specific mTOR inhibitor, rapamycin. Leucine restriction produced a dose-dependent inhibition of fetal rat metatarsal explant growth. This was accounted by reduced cell proliferation and hypertrophy but not apoptosis. mTOR activity, as reflected by ribosomal protein S6 phosphorylation, was only partially inhibited by leucine restriction, whereas rapamycin abolished S6 phosphorylation. In chondrogenic ATDC5 cells, leucine restriction inhibited cell number, proteoglycan accumulation, and collagen X expression despite minimal inhibition of mTOR“

So we can say that leucine can influence mTOR which influences chondrogenesis which influeneces longitudinal growth. Rapamycin also influences mTOR but negatively. increases in leusin increase mTOR which increase chondrogenesis. increase in rapamycin leads to reduced mTOR which reduces chondrogenesis. If you see a decrease in chondrogenesis from leucin restriction you get clumping of proteoglycans and increased production of collagen X. The issues is that leucin and rapamycin both have a small effect on the overall genes.

I did a very quick search on Google for any evidence and this is what i found…

From link HERE

Dev Dyn. 2008 Mar;237(3):702-12.

mTOR signaling contributes to chondrocyte differentiation.

Phornphutkul C, Wu KY, Auyeung V, Chen Q, Gruppuso PA.

Source

Department of Pediatrics, Division of Pediatric Endocrinology and Metabolism, Rhode Island Hospital and Brown University, Providence, Rhode Island 02903, USA. chanika_phornphutkul@brown.edu

Abstract

The mammalian Target Of Rapamycin (mTOR) is a nutrient-sensing protein kinase that regulates numerous cellular processes. Fetal rat metatarsal explants were used as a physiological model to study the effect of mTOR inhibition on chondrogenesis. Insulin significantly enhanced their growth. Rapamycin significantly diminished this response to insulin through a selective effect on the hypertrophic zone. Cell proliferation (bromodeoxyuridine incorporation) was unaffected by rapamycin. Similar observations were made when rapamycin was injected to embryonic day (E) 19 fetal rats in situ. In the ATDC5 chondrogenic cell line, rapamycin inhibited proteoglycan accumulation and collagen X expression. Rapamycin decreased content of Indian Hedgehog (Ihh), a regulator of chondrocyte differentiation. Addition of Ihh to culture medium reversed the effect of rapamycin. We conclude that modulation of mTOR signaling contributes to chondrocyte differentiation, perhaps through its ability to regulate Ihh. Our findings support the hypothesis that nutrients, acting through mTOR, directly influence chondrocyte differentiation and long bone growth.

Me: It seems that mTOR may be one of the things that regulates Ihh.

From link HERE

mTOR Is Essential for Growth and Proliferation in Early Mouse Embryos and Embryonic Stem Cells

  1. Mirei Murakami1,2, Tomoko Ichisaka1,2, Mitsuyo Maeda3, Noriko Oshiro2,4,Kenta Hara2,5, Frank Edenhofer6, Hiroshi Kiyama3, Kazuyoshi Yonezawa2,4,* and Shinya Yamanaka1,2,*

+Author Affiliations

  • 1Research and Education Center for Genetic Information, Nara Institute of Science and Technology
  • 2CREST, Japan Science and Technology Agency, Nara 630-0192
  • 3Department of Anatomy and Neurobiology, Osaka City University Medical School, Osaka 545-8585
  • 4Biosignal Research Institute, Kobe University, Hyogo 657-8501
  • 5Fourth Department of Internal Medicine, Kobe University School of Medicine, Hyogo 650-0017, Japan
  • 6Institute of Reconstructive Neurobiology, University of Bonn Medical Center, D-53105 Bonn, Germany

ABSTRACT

TOR is a serine-threonine kinase that was originally identified as a target of rapamycin in Saccharomyces cerevisiae and then found to be highly conserved among eukaryotes. In Drosophila melanogaster, inactivation of TOR or its substrate, S6 kinase, results in reduced cell size and embryonic lethality, indicating a critical role for the TOR pathway in cell growth control. However, the in vivo functions of mammalian TOR (mTOR) remain unclear. In this study, we disrupted the kinase domain of mouse mTOR by homologous recombination. While heterozygous mutant mice were normal and fertile, homozygous mutant embryos died shortly after implantation due to impaired cell proliferation in both embryonic and extraembryonic compartments. Homozygous blastocysts looked normal, but their inner cell mass and trophoblast failed to proliferate in vitro. Deletion of the C-terminal six amino acids of mTOR, which are essential for kinase activity, resulted in reduced cell size and proliferation arrest in embryonic stem cells. These data show that mTOR controls both cell size and proliferation in early mouse embryos and embryonic stem cells.

Me: So mTOR in general controls cell size and proliferation in stem cells and embryos. That sounds pretty important in longitudinal growth to me.

From link HERE

mTOR inhibitors

mTOR is a kinase protein. It can make cells produce chemicals such as cyclins that trigger cell growth. It may also trigger cells to produce proteins which trigger the development of new blood vessels that cancers need in order to grow. In some types of cancer mTOR is switched on, which makes the cancer cells grow and produce new blood vessels. mTOR inhibitors are a new type of cancer growth blocker being used to try to stop the growth of some cancers. mTOR inhibitors include temsirolimus (Torisel), everolimus (Afinitor) and deforolimus.

As for Leucine, from link HERE

Leucine restriction inhibits chondrocyte proliferation and differentiation through mechanisms both dependent and independent of mTOR signaling

  1. Mimi S. Kim1,*, Ke Ying Wu1,*, Valerie Auyeung2, Qian Chen2,Philip A. Gruppuso2, and Chanika Phornphutkul1

+Author Affiliations

  1. Division of Pediatric Endocrinology and Metabolism, Departments of 1Pediatrics and 2Orthopaedic Surgery, Rhode Island Hospital/Warren Alpert School of Medicine of Brown University, Providence, Rhode Island
  1. Address for reprint requests and other correspondence: C. Phornphutkul, Division of Pediatric Endocrinology and Metabolism, Rhode Island Hospital, 593 Eddy St., Providence, RI 02903 (e-mail: Chanika_Phornphutkul@brown.edu)
  • Submitted 19 December 2008.
  • Accepted in final form15 April 2009.

Abstract

Linear growth in children is sensitive to nutritional status. Amino acids, in particular leucine, have been shown to regulate cell growth, proliferation, and differentiation through the mammalian target of rapamycin (mTOR), a nutrient-sensing protein kinase. Having recently demonstrated a role for mTOR in chondrogenesis, we hypothesized that leucine restriction, acting through mTOR, would inhibit growth plate chondrocyte proliferation and differentiation. The effect of leucine restriction was compared with that of the specific mTOR inhibitor, rapamycin. Leucine restriction produced a dose-dependent inhibition of fetal rat metatarsal explant growth. This was accounted by reduced cell proliferation and hypertrophy but not apoptosis. mTOR activity, as reflected by ribosomal protein S6 phosphorylation, was only partially inhibited by leucine restriction, whereas rapamycin abolished S6 phosphorylation. In chondrogenic ATDC5 cells, leucine restriction inhibited cell number, proteoglycan accumulation, and collagen X expression despite minimal inhibition of mTOR. Microarray analysis demonstrated that the effect of leucine restriction on ATDC5 cell gene expression differed from that of rapamycin. Out of 1,571 genes affected by leucine restriction and 535 genes affected by rapamycin, only 176 genes were affected by both. These findings indicate that the decreased chondrocyte growth and differentiation associated with leucine restriction is only partly attributable to inhibition of mTOR signaling. Thus nutrient restriction appears to directly modulate bone growth through unidentified mTOR-independent mechanisms in addition to the well-characterized mTOR nutrient-sensing pathway.

UNDERNUTRITION IS A WELL-DOCUMENTED cause of poor linear growth, whereas obesity produces accelerated linear growth in children. Primary causes of undernutrition are complex. They can range from inadequate availability of calories to inadequate specific nutrients, such as protein or amino acids. Despite the many causes and forms of undernutrition, one universal outcome is poor long bone growth, which can be presumed to be an effect on endochondral bone elongation (1, 6). Over the last several decades, the mechanisms by which nutritional status affects bone growth have focused on indirect effects via changes in insulin-like growth factor I (IGF-I) biological effect (3, 7). Impaired IGF-I production in undernutrition is in part associated with impaired hepatic growth hormone (GH) sensitivity, which is associated with decreased hepatic GH receptor expression, hepatic IGF-I mRNA, and circulating IGF-I levels (31). Similarly, overnutrition is associated with upregulation of the GH/IGF-I axis (23).

The effect of IGF-I on chondrocyte growth and differentiation within the growth plate has been well documented (14, 24). We and others have demonstrated that IGF-I has an important role in chondrocyte proliferation and differentiation (25, 28). In addition to the effects of IGF-I on chondrocytes, we have demonstrated that insulin at physiological concentration has a direct effect on chondrocyte differentiation (27), thus providing for another mechanism by which nutritional status can modulate bone growth.

In recent years, mechanisms by which nutrients exert a direct effect on cell growth and function have been elucidated (17). Although restriction of essential amino acids has been viewed as limiting because of their requirement as substrates for protein synthesis, essential amino acids also act as signaling factors in several regulatory pathways (15,16). Perhaps the most well-characterized signaling pathway regulated by amino acids has at its center the mammalian target of rapamycin (mTOR) (17). mTOR is a nutrient-sensing kinase that integrates input from amino acids, growth factors, and the energy status of the cell (15). It acts as a central controller of translation, controlling ribosomal biogenesis and global protein synthesis (4). The TOR protein is highly conserved from yeast to mammals (5). Rapamycin, a widely used immunosuppressive agent, directly inhibits mTOR activity and has been key to understanding the role of mTOR in cell regulation (22, 35).

We have recently demonstrated the effect of rapamycin on chondrocyte growth and differentiation in ATDC5 cells (26), fetal rat metatarsal explants (26), and the rabbit growth plate (unpublished observation). mTOR inhibition with rapamycin results in significantly decreased chondrocyte differentiation, a modest decrease in chondrocyte proliferation, and decreased total bone growth in physiological systems.

Leucine is the most potent nutrient regulator of mTOR signaling (29, 30). We therefore hypothesized that leucine availability would have a direct effect on chondrocyte growth and differentiation, resulting in decreased longitudinal bone growth when restricted. We further hypothesized that the effect of leucine restriction would be a direct result of mTOR inhibition, although mTOR-independent pathways have been described. One of these involves the mammalian general control nonderepressible 2 (GCN2) kinase (32). GCN2 is a stress kinase that is activated by amino acid starvation to modulate protein synthesis. GCN2 phosphorylates the α-subunit of the eukaryotic initiation factor (eIF2). The response that allows organisms to tolerate amino acid deprivation in states of malnutrition and starvation involves repression of protein synthesis and upregulation of amino acid biosynthesis and transport (10) with a net effect of decreased cell growth.

Based on our hypothesis and well-defined mechanisms that control chondrocyte growth and differentiation, we have performed studies using embryonic day 19 (E19) fetal rat metatarsal explants. The benefit of this model is the intact bone maintains its cell-cell and cell-matrix interaction. We have also used the ATDC5 chondrogenic cell line to extend our observations to an in vitro model. Last, using microarray analysis, we have explored other potential mechanisms accounting for the effect of leucine restriction on chondrocyte growth and differentiation.

DISCUSSION

The present studies were aimed at characterizing the effect of restricting a key nutrient, leucine, on two models of bone growth: metatarsal explants and growth and a chondrogenic cell line. Amino acids, particularly the branched-chain amino acids, regulate protein synthesis beyond the level of their own availability as the substrate for peptide-chain elongation (15, 17). They do so by functioning as signaling molecules. Leucine appears to be the most potent of the branched-chain amino acids in this regard, having a potent effect on signaling via two important signaling kinases, mTOR and GCN2 (8, 10,32, 33).

The mTOR signaling pathway has been shown to mediate the effects of leucine on mRNA translation initiation. We recently demonstrated the important role of mTOR in the regulation of chondrocyte growth and differentiation (26). Our previous findings provided for a mechanism whereby nutrients, acting through mTOR, can directly modify linear growth. In the present study, we performed analogous experiments comparing the effect of leucine restriction in the fetal metatarsal explant model as well as ATDC5 cells.

The present studies were undertaken to test the hypothesis that leucine restriction would exert its effects on bone growth through its ability to signal via mTOR. Using the more physiological bone explant model, we confirmed that leucine affected growth in a dose-dependent manner. The observed growth inhibition was associated with decreased chondrocyte proliferation as measured by decreased BrdU incorporation. Decreased chondrocyte proliferation presumably results in fewer chondrocytes that are available to differentiate and become hypertrophic cells, consistent with the decreased hypertrophic zone height that we observed.

Chondrocytes that differentiate into prehypertrophic and hypertrophic chondrocytes undergo a 4- to 10-fold increase in cytoplasmic volume, making distal hypertrophic cells a significant component of longitudinal bone growth. In rapidly growing bones, ∼10% of bone length is contributed by proliferating cells, a one-third by matrix synthesis throughout the growth plate, and nearly two-thirds by the contribution of hypertrophic cells (34).

Although leucine restriction appears to have an effect on chondrocyte proliferation and differentiation, we did not observe an increase in apoptosis as assessed by TUNEL staining. Premature cell death can result in reduced bone growth, as observed in humans with skeletal dysplasia (12) and in mice with disruption of genes important to chondrogenesis, including those encoding filamin B, matrilin-3, or components of the β-catenin signaling pathway (11, 21). Our results indicate that the effect of leucine restriction occurs during the early phase of the chondrocyte growth and differentiation process, not as a result of increased apoptosis.

Because mTOR is a signaling target for leucine, we examined the effect of leucine restriction on mTOR signaling in metatarsals by assessing the phosphorylation state of ribosomal protein S6. We observed only a modest decrease in phospho-S6 staining in the explants grown in 0.02 mM leucine. This was in sharp contrast to rapamycin, which abolished phospho-S6 staining. This raised the possibility that leucine response was mediated through a mechanism other than one involving modulation of mTOR activity.

Using the ATDC5 chondrogenic cell line, we extended our observations in an attempt to support or refute conclusions drawn from the metatarsal explant studies. Leucine restriction decreased chondrocyte differentiation as measured by accumulation of proteoglycan and expression of collagen X. Total cell mass measured by Neutral Red accumulation was also decreased. Again, markers of mTOR activity, S6 phosphorylation and the pattern of 4E-BP1 phosphorylation, were modestly inhibited under conditions of leucine restriction relative to the marked effect of rapamycin. The expression of Ihh, a key contributor to chondrocyte proliferation and differentiation (9, 18, 20), was also decreased under conditions of leucine restriction. We previously demonstrated that mTOR inhibition may directly regulate Ihh expression (26).

In an effort to identify an mTOR-independent pathway to account for the effects of leucine restriction, we examined the regulation of GCN2 in the ATDC5 cell line. The GCN2 pathway is activated by the accumulation of uncharged tRNAs during amino acid starvation as shown in myoblasts (10). This leads to the phosphorylation of eIF2α, resulting in inhibition of translation initiation of cellular proteins and a global reduction in protein synthesis (10, 13). We observed only a modest increase in the phosphorylation of eIF2α under conditions of leucine restriction.

Microarray analysis of the effects of leucine restriction vs. rapamycin on gene expression in ATDC5 cells revealed that only a small proportion of genes was affected by both leucine restriction and rapamycin. These genes, which numbered 176, accounted for 11.2% of the genes that were affected in leucine restriction. The large effect of leucine restriction relative to rapamycin (1,571 vs. 535 genes) may indicate that leucine restriction has a broader effect on chondrocyte growth and differentiation than does targeted inhibition of mTOR. Using very stringent criteria for significance, gene ontology and pathway analysis further supported marked differences in the effects of the two conditions.

In summary, our studies show that leucine restriction affects proliferation and differentiation in the ATDC5 chondrogenic cell line. Results using the fetal metatarsal explant model are consistent with the ATDC5 studies. Our findings support the conclusion that both mTOR and GCN2 signaling may contribute to the effect of leucine restriction on chondrocyte proliferation and differentiation and, therefore, on long bone growth. However, our studies are also consistent with the possibility that the effects of leucine restriction are mediated by pathways that are independent of effects on these two signaling kinases. We are left to conclude that the mechanism by which leucine restriction inhibits chondrogenesis and attenuates linear bone growth is complex, likely involving modulation of multiple pathways that may involve mTOR and GCN2, but that may also be independent of both of these well-characterized pathways.