Reviewing the Implication of Aldehyde Dehydrogenases in Male Reproduction: Prospects for New Therapeutic Approaches

The World Health Organization (WHO) defines infertility as the inability of a couple to conceive after at least 12 months of regular, unprotected sexual intercourse. The male factor appears to be contributing, solely or in combination with other causes, to approximately 50% of all infertility cases. Several etiological factors of male infertility have been identified; however, the exact molecular mechanisms underlying sperm dysfunction are not yet fully understood. Aldehyde dehydrogenases (ALDHs) are multifaceted metabolic enzymes that catalyze the detoxification of several aldehydes, thus acting as antioxidants, while they regulate additional homeostatic functions by contributing to retinoic acid (RA) synthesis. Consequently, they have been identified as crucial factors in various pathogenetic mechanisms. ALDHs hold physiological roles in the testis through supporting the Sertoli cell function, the steroidogenesis in Leydig cells, and the maintenance of sperm integrity. Current evidence supports that dysregulation of specific ALDHs isoforms could be associated with disrupted testicular cell function, including oxidative imbalance and altered RA synthesis. These irregularities could interfere with germ cell development and, subsequently, contribute to decline in reproductive function. In this paper, we are reviewing the role of ALDHs in male reproduction and how their dysregulation could be implicated in male infertility. Unraveling the mechanisms underlying the association of ALDHs with male reproductive function could hold clinical interest regarding the development of novel approaches for enhancing male fertility.