Fenofibrate induces liver enlargement in aging mice via activating the PPARα-YAP signaling pathway.

Fenofibrate is a clinically prescribed drug for treating hypertriglyceridemia, which is also a classic peroxisome proliferator-activated receptor α (PPARα) agonist. We previously reported that fenofibrate induced liver enlargement in adult mice partially through activation of the yes-associated protein (YAP) signaling pathway. However, the effects of fenofibrate on liver enlargement and the YAP signaling pathway in aging mice remain unclear. In this study, D-galactose-induced aging mice, naturally aging mice, and senescence-accelerated mice P8 (SAMP8) were used to investigate the effects of aging on fenofibrate-induced liver enlargement and YAP signaling activation. The results showed that fenofibrate-induced liver enlargement in aging mice was consistent with that of adult mice. The effects of fenofibrate on hepatocyte enlargement around the central vein (CV) area and hepatocyte proliferation around the portal vein (PV) area were comparable between adult and aging mice. There was no significant difference in the upregulation of PPARα downstream proteins between the two groups following fenofibrate treatment. Fenofibrate treatment also increased the expression of proliferation-related proteins and activated the YAP signaling pathway to a similar degree in both groups. In summary, these results demonstrate that the fenofibrate-induced liver enlargement and activation of the YAP pathway are consistent between adult and aging mice, indicating that the effects of fenofibrate on promoting liver enlargement and its activation of the PPARα and YAP pathway were independent of aging. These findings offer a new perspective for the clinical use of fenofibrate in elderly patients and provide a new insight for the role of PPARα in liver enlargement.