Apoptotic germ cells regulate Sertoli cell lipid storage and fatty acid oxidation

The presence of lipid droplets (LD) and the utilization of fatty acids (FA) as a source of energy are Sertoli cell (SC) putative characteristics. It is well known that SC can phagocyte and degrade apoptotic germ cells (AGC) resulting in increasing lipid content and ATP levels. A relationship between the regulation of lipid storage and of lipid oxidation in SC might be envisaged. The aim of this study was to analyze whether AGC and FA are able to simultaneously regulate molecular mechanisms involved in lipid storage and FA oxidation in SC. The experimental model utilized in this study consisted in SC cultures obtained from 20-day-old rats that were co-cultured with AGC or treated with palmitic acid (PA, 500μM) for 24 and 48 hours. AGC and PA increase LD, triacylglycerol (TAG) content, and mRNA levels of Plin1, Plin2, Plin3 (proteins involved in TAG storage). Simultaneously, AGC and PA rise the extent of FA oxidation and mRNA levels of Cpt1, Lcad (proteins involved in FA degradation). PPARs are transcription factors which participate in lipid metabolism regulation. Results show that AGC and PA treatment increase PPAR transcriptional activity in SC. Additionally, the presence of a PPARg antagonist decreases the up-regulation of LD content and Plin1 expression. Similarly, the presence of a PPARb/d antagonist reduces the increase in FA oxidation and Cpt1 mRNA levels. Altogether these results suggest that AGC and FA, which probably generates PPARs ligands, regulate lipid storage and fatty acid utilization, contributing to the energy homeostasis in the seminiferous tubules.