Longevity
Liver growth hormone signalling shapes ageing pace in mice, study finds
By Life and Health Today Staff, . Life and Health Today.
Mice whose liver cells were stripped of the growth hormone receptor, a protein that picks up signals from growth hormone and relays them into the cell, aged faster on almost every measure the researchers tracked, according to a study published in Aging Cell in October 2026. The same paper also appeared on PubMed under its longevity research feed.
Growth hormone is produced by the pituitary gland and acts on tissues throughout the body. The receptor for it, known as GHR, is particularly dense in the liver, where it helps regulate metabolism. The researchers created mice in which only the liver's copies of GHR were deleted, leaving the receptor intact everywhere else.
Compared with normal mice, those animals showed shortened lifespans, increased cellular senescence (a state in which cells stop dividing and begin releasing inflammatory signals), reduced ability to handle metabolic stress, signs of cognitive decline, weaker bone mineralisation, and higher levels of what the authors called inflammaging, a term for the low-grade chronic inflammation associated with ageing. The study also reported that these mice developed worse liver disease both as they aged naturally and when fed a high-fat diet.
The paper describes a specific molecular sequence behind these effects. When the liver cannot receive growth hormone signals, growth hormone itself accumulates in the bloodstream. That elevated circulating hormone then acts on fat tissue, driving the release of fatty acids. Those fatty acids travel to the liver, where a protein called CD36 pulls them in. Inside the liver cell, the loss of GHR also suppresses a signalling molecule called STAT5b while raising levels of a different regulator called PPARgamma. PPARgamma then moves into the cell nucleus and switches on two genes: one coding for CD36, which draws in more fat, and one coding for an enzyme called PDK4, which interferes with how the cell's mitochondria, the structures that generate energy, process fuel. The result, according to the paper, is a self-reinforcing loop: disrupted fat metabolism damages mitochondria, and damaged mitochondria worsen fat metabolism, accelerating the ageing process in the liver and, the authors argue, contributing to broader systemic ageing.
The researchers then tested whether blocking PDK4 pharmacologically, meaning with a drug compound rather than genetic manipulation, could interrupt that loop in living mice. According to the paper, it did: inhibiting PDK4 in vivo, that is, in the animals rather than in cells in a dish, reduced the age-related damage caused by the GHR deletion.
The authors describe hepatic GHR signalling as "a promising therapeutic target for age-related liver disorders," a phrase that belongs to the paper's own framing and should be read at that level. Promising, in the language of research, means the hypothesis is worth pursuing, not that a treatment is near.
What this study does not establish is considerable. Every finding here is in genetically engineered mice. The molecular pathway described may operate differently in humans, or may be one of several overlapping mechanisms that matter less in isolation than the mouse model suggests. The PDK4 inhibition result is encouraging as a proof of concept, but a compound that works in mice frequently fails when tested in people, and no human trial of PDK4 inhibition for liver ageing appears in this paper. The study also does not address whether people with naturally lower hepatic GHR activity age faster, or whether boosting GHR signalling in the liver would slow ageing in humans, questions that would require a different kind of study entirely.
The open question is whether the PDK4 pathway identified here holds up in human liver tissue and, eventually, in a clinical trial. That work, if it happens, is years away. What this paper contributes is a mechanistic map of one route by which liver metabolism and systemic ageing may be connected, and a candidate target within it. Whether that map leads anywhere useful for people will depend on research that has not yet been done.