Heat stress affects the metabolism of lipids of epididymal epithelial cells

Abstract

Frequent exposures of testes to hyperthermia are known to result in germ cell death, and, although not lethal to Sertoli cells, we previously showed that such exposures damage them structurally and functionally. Here we studied the consequences of heat stress on the epididymis by assessing its effects on epithelial cells from its three regions (caput, corpus, and cauda) in primary culture. All of them had abundant lipid droplets (LD) rich in triacylglycerols (TAG), similar in size and numbers in vivo and in culture. Temperature-treated (a 15 min exposure once a day to 43ºC for 5 days) and control cells were incubated for 1 h with [3H]20:4 on the 5th day. In the three regions, TAG were faintly labeled, most of the fatty acid being taken up by phospholipids. Caput-derived cells exhibited the highest rate of lipid labeling. Due to heat exposures, caput and corpus cells showed a significant increase in the label from [3H]20:4 in diacylglycerols (DAG), concomitant with a decrease in the label in phosphatidylinositol (PI), phospatidylethanolamine phosphatidylglycerol (PE-PG), and little change in phosphatidylcholine (PC). Quite the opposite occurred in cells from cauda: the label in DAG decreased, while that in PI, PE-PG and PC increased. Our results suggest that epididymal cells are differentially susceptible to short but periodical exposures to mild hyperthermia.