Combined Gene and Protein Expression of Hormone-Sensitive Lipase and Adipose Triglyceride Lipase, Mitochondrial Content, and Adipocyte Size in Subcutaneous and Visceral Adipose Tissue of Morbidly Obese Men

Aims: Lipotoxicity in obesity might be a failure of adipocytes to respond sufficiently adequate to persistent energy surplus. To evaluate the role of lipolytic enzymes or mitochondria in lipotoxicity, we studied expression levels of genes and proteins involved in lipolysis and mitochondrial DNA (mtDNA) content. Methods: As differences in lipid metabolism between men and women are extremely complex, we recruited only men (lean and morbidly obese) and collected subcutaneous and visceral adipose tissue during abdominal surgery for real-time PCR gene expression, protein expression, and microscopic study. Results: Although mRNA levels of hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) were increased in visceral adipose tissue of morbidly obese men, this was not paralleled by alterations in protein expression and phosphorylation of HSL and ATGL. mtDNA content of visceral adipose tissue was increased in morbidly obese men as compared to lean controls (p < 0.013). Positive correlations were observed between visceral adipocyte size and serum triacylglycerol (r = 0.6, p < 0.007) as well as between visceral adipocyte size and CRP (r = 0.6, p < 0.009) in analyses performed separately in obese men. Conclusion: Lipotoxicity of morbidly obese men might be related to the quantitative impact of the visceral fat depot rather than to important dysregulation of involved lipolytic enzymes or adipocyte mitochondria.