Sex differences in the effect of high-fat diet feeding on rat white adipose tissue mitochondrial function and insulin sensitivity.

Obesity-induced mitochondrial dysfunction in white adipose tissue (WAT) leads to a dysregulation of adipokine secretion, which is involved in insulin resistance development. Taking into account the sex differences previously found both in mitochondrial function and for the insulin sensitivity profile in different tissues, the aim of this study was to investigate whether a sex-dependent effect of a long-term high-fat diet (HFD) feeding exists on WAT mitochondrial function. Indeed, HFD effects on the levels of the key components of the insulin and adiponectin signaling pathways, and the consequences of these effects on the systemic profile of insulin sensitivity were also studied. Wistar rats of both sexes were fed a standard diet or an HFD. Serum markers of insulin sensitivity, protein, and mRNA levels of the main elements of the insulin and adiponectin signaling pathways, and the markers of mitochondrial function and biogenesis, were measured. Our results indicate that different physiological strategies are adopted by male and female rats in response to HFD. In this regard, HFD induced mitochondrial proliferation in males and mitochondrial differentiation in females, as well as a greater retroperitoneal WAT expandability capacity, which allows them to preserve a better insulin sensitivity profile than male rats for both control and HFD groups. Moreover, female WAT showed a decrease in adiponectin and insulin signaling pathway element levels. This sexual dimorphism suggests that there are different strategies for retroperitoneal WAT to maintain the energetic and metabolic homeostasis in response to HFD feeding.