High-fat diet feeding induces a depot-dependent response on the pro-inflammatory state and mitochondrial function of gonadal white adipose tissue

Abstract

Obesity has been related to a chronic pro-inflammatory state affecting white adipose tissue (WAT), which has a great impact on carbohydrate, lipid and energy metabolism. In turn, the dysregulation of adipokine secretion derived from the accumulation of excess lipids in adipocytes further contributes to the development of insulin resistance and can be associated with mitochondrial dysfunction. The aim of the present study was to determine whether sexual dimorphism found in the systemic insulin sensitivity profile is related to sex differences in a high-fat diet (HFD) response of gonadal WAT at mitochondrial function and inflammatory profile levels. Wistar rats (10 weeks old) of both sexes were fed a control pelleted diet (3 % (w/w) fat;n8 for each sex) or a HFD (24 % (w/w) fat;n8 for each sex). Serum insulin sensitivity markers, mRNA expression levels of inflammatory factors and the protein content of insulin and adiponectin signalling pathways were analysed, as well as the levels of the main markers of mitochondrial biogenesis, antioxidant defence and oxidative damage. In the present study, the periovarian depot exhibits a greater expandability capacity, along with a lower hypoxic and pro-inflammatory state, without signs of mitochondrial dysfunction or changes in its dynamics. In contrast, epididymal fat has a much more pronounced pro-inflammatory, hypoxic and insulin-resistant profile accompanied by changes in mitochondrial dynamics, probably associated with HFD-induced mitochondrial dysfunction. Thus, this explains the worse serum insulin sensitivity profile of male rats.