Longevity
Blocking growth hormone receptors in middle-aged mice extended lifespan by under 10%
By Life and Health Today Staff, . Life and Health Today.
Researchers reported that switching off the growth hormone receptor in mice at 12 months of age, roughly the midpoint of a typical laboratory mouse lifespan, extended lifespan in both sexes, according to a study covered by Fight Aging!, a newsletter focused on longevity research. The life extension was less than 10% and was smaller in female mice than in male mice.
Growth hormone is a signalling molecule that drives cell growth and metabolism. The growth hormone receptor is the protein on cell surfaces that receives that signal. Knocking it out, as this study did using a tamoxifen-inducible model that allows researchers to switch off a gene in adult animals, creates what the researchers called "GH resistance": circulating levels of growth hormone rose while levels of insulin-like growth factor 1, a downstream messenger, fell.
Male mice with the receptor disabled showed improved insulin sensitivity and were protected against age-related decline in neuromuscular performance and bone structure, the study reported. Both sexes showed changes in liver cell gene activity, including a shift in male liver cells toward patterns of gene expression more typical of females, which the researchers linked to disrupted pulsatile growth hormone signalling.
The finding sits within a long-running line of research. As Fight Aging! noted, the longest-lived laboratory mice on record are strains engineered in the 1990s with lifelong mutations that disable growth hormone metabolism, and those animals live up to 70% longer than unmodified mice. A study published roughly five years ago showed that disrupting growth hormone metabolism starting at six months of age, earlier in adulthood, also extended lifespan. The new work pushes the intervention later, to 12 months, and finds a similar, modest effect in males but a worse one in females.
The open question the research does not settle is whether any of this translates to people. Fight Aging! points directly to a reason for scepticism: Laron syndrome, the closest human equivalent, is an inherited condition in which the growth hormone receptor does not function normally. People with Laron syndrome may have a lower incidence of some age-related conditions, but, according to Fight Aging!, do not appear to live meaningfully longer than the general population. The newsletter's commentary argues that this pattern, large effects in short-lived mice and no clear lifespan benefit in the analogous human condition, is one of the most consistent lessons from three decades of research into calorie restriction and growth hormone metabolism, and that it argues against investing heavily in human therapies built on this mechanism.
The study authors reached a different conclusion in their abstract, describing the growth hormone and insulin-like growth factor 1 axis as "a promising target for gerotherapeutic interventions" on the basis that midlife suppression was sufficient to reshape liver gene programmes and extend healthy lifespan in mice. That framing and Fight Aging!'s sceptical reading of the same evidence represent a genuine disagreement about what the mouse data implies for human medicine.
What this study does not show is any effect in people. It is entirely preclinical work, conducted in mice, and no human trial of midlife growth hormone receptor suppression is described in the reports available. The study also used single-nucleus RNA sequencing of liver tissue, a technique that reads gene activity in individual cells, to characterise the molecular changes, but the reports do not describe whether those molecular changes are themselves responsible for the lifespan extension or are a parallel effect of the same intervention.
What would begin to settle the human question is evidence from people with Laron syndrome followed over full lifespans, or a controlled trial of growth hormone axis suppression in older adults with lifespan or healthspan as the measured outcome. Neither is described in these reports. Anyone weighing whether this line of research is relevant to their own health would need to discuss it with a clinician who knows their individual history.
Source: https://www.fightaging.org/archives/2026/09/fight-aging-newsletter-september-21st-2026/