Ablating the growth hormone receptor (Ghr) in 12-month-old mice — equivalent to roughly midlife — extended lifespan in both sexes without stunting body size. Male knockouts showed improved insulin sensitivity and preserved neuromuscular performance and bone microarchitecture despite increased adiposity. Single-nucleus RNA sequencing of liver tissue revealed reduced B-cell populations in both sexes and a striking transcriptional shift in male hepatocytes toward feminized gene expression patterns, driven by impaired pulsatile GH-STAT5 signaling.
The field has long known that congenital GH/IGF-1 disruption — as in Ames dwarf or liver-specific IGF-1 knockout mice — dramatically extends lifespan, but those models raise developmental confounders. This study's tamoxifen-inducible midlife intervention is a meaningful methodological step forward, demonstrating the pathway remains therapeutically actionable well into adulthood. The hepatic sex-dimorphism finding is particularly intriguing: feminization of male liver gene expression has been associated with altered drug metabolism and metabolic disease risk in other contexts, raising questions about translational trade-offs that the abstract does not address. The improved metabolic and musculoskeletal outcomes in males despite adiposity gain suggest that GH suppression's benefits are not purely metabolic in origin. As a mouse study, causal extrapolation to humans is premature, and no pharmacological GH antagonist mimetic was tested. Still, this is more than incremental — it meaningfully narrows the therapeutic window question for GH-axis targeting as a genuine gerotherapeutic strategy.
