Macroautophagy Involved in Testosterone Synthesis in Leydig Cells of Male Dairy Goats (Capra Hircus)

Abstract Background Testosterone is an important steroid hormone that is indispensable for male sexual development and the reproductive system. Leydig cells (LCs), where autophagy extremely active, reside in the testicular interstitium and are the major sites of testosterone production. However, the ultrastructural characteristics and the functional role of autophagy in LCs of livestock remain unknown. This study was to investigate the role of autophagy in LCs testosterone synthesis of dairy goats at juvenile, pubertal, and adult stages. Results In the present study, morphological results showed that the steroidogenic activity and ultrastructure of the LCs were altered with increasing age. Serum luteinizing hormone and testosterone levels were significantly elevated with sexual maturation. Organelles involved in testosterone synthesis, e.g., smooth endoplasmic reticulum, mitochondria, and lipid droplets, were abundantly distributed within the cytoplasm of LCs in adult testes. However, further studies demonstrated that selective autophagy (including lipophagy and mitophagy) did not participate in the synthesis of testosterone in LCs. In contrast, the autophagy activity was enhanced in the testes at puberty and adulthood compared to that at the juvenile stage. Moreover, a number of different autophagosomes, including phagophores and autolysosomes, were observed within the cytoplasm of LCs. Conclusions Together, our results reveal that macroautophagy is involved in testosterone synthesis mainly through degrading mitochondria and endoplasmic reticulum in the LCs of dairy goats.