Abstract: The main function of Leydig cells (LCs) is to synthesize and secrete testosterone. In Leydig cells, steroidogenic acute regulatory protein (StAR) located on the outer mitochondrial membrane with cholesterol as raw material promotes the transport of cholesterol to the inner mitochondrial membrane, and pregnenolone is produced under the catalysis of cholesterol side chain cleavage cytochrome (P450scc) in the inner mitochondrial membrane, then hydroxyl steroid dehydrogenase 3 through smooth endoplasmic reticulum β-hydroxysteroid dehydrogenase(3β-HSD) and transporter protein (TSPO) to synthesize testosterone. Therefore, the synthesis and secretion of testosterone by Leydig cells are closely related to mitochondria. The integrity of mitochondrial structure and function directly affects the biosynthesis of testosterone, and StAR and P450scc located on mitochondria are the key regulatory factors of testosterone synthesis. Testosterone can promote the development and maturation of male reproductive organs and maintain their function. It is of great significance to promote protein synthesis (such as protein synthesis in muscle, bone and reproductive organs). In recent years, promoting testosterone synthesis by maintaining mitochondrial structural integrity and improving mitochondrial oxidative damage and mitochondrial biogenesis has become a research hotspot of testosterone synthesis mechanism, which has attracted extensive attention of scholars at home and abroad. In this review, the molecular mechanism of testosterone synthesis in Leydig cells and the important factors affecting testosterone synthesis were introduced, the effects of mitochondrial structure, mitochondrial oxidative damage, mitochondrial regulated cell death and mitochondrial biogenesis on testosterone synthesis in Leydig cells were reviewed, the relationship between mitochondria and testosterone synthesis was expounded. It can provide a basis for improving the structure and function of mitochondria in Leydig cells and promoting testosterone synthesis, and it is of great significance to deeply understand the regulation of testosterone synthesis and improve the reproductive performance in male animals.

Key words: Leydig cells; testosterone synthesis; mitochondria