Changes in lipid metabolism in the visceral rather than the subcutaneous adipose tissue depot attenuate metabolic disturbances in obesity-resistant mice fed a high-fat diet

Obesity is characterized by an enlargement of white adipose tissue caused by caloric excess. The depot-specific adaptation of white adipose tissue in individuals resistant to obesity despite a high-calorie diet is crucial for understanding the pathogenesis of obesity and related metabolic disorders. Our aim was to characterize the metabolic and morphological state of obesity resistance and to investigate depot-specific changes in signaling pathways in epididymal visceral (eVAT) and inguinal subcutaneous (iSAT) white adipose tissue of C57BL/6J male mice on a high-fat diet (60 kcal% fats). After 14 weeks, the mice were categorized as obese (at least 30% higher body mass compared to the control group) or obesity-resistant (weight gain below 30%). Biochemical and morphological parameters, as well as histology, and signaling pathways involved in lipid metabolism, inflammation, and insulin sensitivity were investigated in eVAT and iSAT. The results showed unaltered body, total VAT and iSAT mass in obesity-resistant mice despite increased caloric intake. Leptin levels and glucose homeostasis were improved in these animals compared to the obese mice. In both eVAT and iSAT of the obesity-resistant mice, adipocyte size and lipolytic capacity were retained at control levels, while compared to the obese mice, preserved capacity for adipogenesis, improved local insulin sensitivity and the absence of inflammation were observed only in the eVAT. In conclusion, metabolic adaptation of eVAT rather than iSAT may have a substantial impact on the maintenance of the obesity-resistant phenotype with fewer metabolic complications, which could contribute to the improvement of existing obesity therapies.