Molecular Mechanisms and Signaling Pathways Involved in the Nutritional Support of Spermatogenesis by Sertoli Cells.

Sertoli cells play a central role in spermatogenesis. They maintain the blood-testis barrier, an essential feature of seminiferous tubules which creates the proper environment for the occurrence of the spermatogenesis. However, this confinement renders germ cells almost exclusively dependent on Sertoli cells' nursing function and support. Throughout spermatogenesis, differentiating sperm cells become more specialized, and their biochemical machinery is insufficient to meet their metabolic demands. Although the needs are not the same at all differentiation stages, Sertoli cells are able to satisfy their needs. In order to maintain the seminiferous tubule energetic homeostasis, Sertoli cells react in response to several metabolic stimuli, through signaling cascades. The AMP-activated kinase, sensitive to the global energetic status; the hypoxia-inducible factors, sensitive to oxygen concentration; and the peroxisome proliferator-activated receptors, sensitive to fatty acid availability, are pathways already described in Sertoli cells. These cells' metabolism also reflects the whole-body metabolic dynamics. Metabolic diseases, including obesity and type II diabetes mellitus, induce changes that, both directly and indirectly, affect Sertoli cell function and, ultimately, (dys)function in male reproductive health. Insulin resistance, increased estrogen synthesis, vascular disease, and pubic fat accumulation are examples of metabolic-related conditions that affect male fertility potential. On the other hand, malnutrition can also induce negative effects on male sexual function. In this chapter, we review the molecular mechanisms associated with the nutritional state and male sexual (dys)function and the central role played by the Sertoli cells.