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A Review of Growth Hormone in Aging

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#1 reason

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Posted 18 May 2018 - 10:15 AM

The author of this open access review of the study of growth hormone in aging is one of the eminent experts in this part of the field, noted for work on various loss of function mutant mice, lacking either functional growth hormone or functional growth hormone receptor genes. The current record for mouse longevity is held by a growth hormone knockout variant: these mice wouldn't survive in the wild, as they are small and vulnerable to cold, but they live 60-70% longer than their unmodified peers in the laboratory.

It is well documented that circulating levels of GH decline with age in various mammalian species, including humans, domestic dogs, and laboratory rodents. Yet in laboratory mice, disruption of growth hormone (GH) signaling leads to a remarkable extension of longevity. These findings were hard to interpret and were originally received with some skepticism because they implied that normal actions of a hormone have significant 'costs' in terms of longevity, and that a gross defect in the functioning of the endocrine system can have striking benefits for healthy survival. However, the evidence that absence of GH signaling extends longevity of mice is strong, reproducible, and now generally accepted.

Several aspects of the findings in GH-deficient and GH-resistant mice deserve particular emphasis. First, the significant extension of longevity in these animals is reproducible and not limited to a particular laboratory, diet, or genetic background. Second, lifespan is extended in both females and males. Third, extension of longevity is associated with a similarly striking extension of healthspan. Fourth, the magnitude of the increase in longevity exceeds the effects of most genetic, pharmacological, or dietary interventions that have anti-aging effects in mice.

A recent study examined longevity of mice lacking both GH and functional GH receptors. While these tiny 'double mutants' were remarkably long-lived compared to their normal siblings, they did not live significantly longer than mice lacking only GH or only GH receptors. In females, survival curves of GH-deficient Ames dwarf, GH-resistant GHRKO, and 'double mutant' (df/KO) animals were nearly identical.

The importance of GH signaling in the control of murine lifespan is further emphasized by the evidence that disruption of signaling events 'downstream' from GH and its receptor also extends longevity. Early findings of extended longevity of female mice heterozygous for the deletion of IGF-1 receptor were confirmed and extended in further studies. Major increase of longevity was seen in mice in which amount of bioavailable IGF-1 was reduced at the tissue level by germline or adult disruption of the gene coding for pregnancy associated plasma protein A, an enzyme degrading IGF-1 binding protein. Significant and reproducible extension of longevity was also produced by pharmacological suppression of the activity of mechanistic target of rapamycin, a kinase regulated by GH and IGF1.

Importantly, conclusions concerning pro-aging effects of normal or elevated GH based on studies in mutant, gene knockout, transgenic, or drug treated mice appear to apply to genetically normal mice and to other mammalian species. Multiple studies reported negative association of adult body size (a strongly GH- and IGF-1-dependent trait) with longevity in comparisons of different mouse strains, selected lines, and individual animals.

Link: https://doi.org/10.5534/wjmh.180018

View the full article at FightAging

#2 Rocket

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Posted 20 May 2018 - 02:11 AM

Healthy, youthful GH like the level of a normal 30yo maintained throughout life would mean a better immune system from preventing the thymus from shrinking, and would help prevent other organs from shrinking and would allow the body to heal and recover from injury and exercise.

I am growing weary of the concerted effort by the establishment to throw mud on, and besmirch one of the best things people can do to alleviate many effects of aging through healthy supplementation with HGH.

There is an undeniable downward plot of health and vitality that correlates very well with the decline in HGH with age.

If the same scientists who point to graphs to prove global warming looked at the graph of HGH with health and vitality, HGH supplementation would be mandated by the nanny state governments.

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#3 Mind

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Posted 20 May 2018 - 10:48 AM

I think the way to look at this is that "growth" creates damage and metabolic waste. That is why supplementing with HGH does not rejuvenate. It probably helps bodily systems (damaged by aging) function at a higher level late in life, but it does not reverse aging-related damage (as far as I am aware). Does it help? Many people claim it makes them feel good, which is great.


The GH knock-out mice grow just the minimum to survive. Seems like they are in more of a "stasis". Minimal growth and activity, but not accumulating much damage along the way.


Ideally, we would want to rejuvenate (remain vital and active), and not be vulnerable/static like the GH knockout mice. But don't knock the research. It is valuable to know how different signalling and biological processes affect health and the rate of aging.

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