: Melatonin (MT) is an indoleamine primarily produced by the pineal gland in a light-dark-dependent manner; however, it is also locally synthesized in the testis, where it influences male reproductive physiology upon interaction with its receptors (MT1/MT2), the binding started the bio-signaling inside the cells mediated by MT. This review outlines the intratesticular effects of MT, addressing seasonal and non-seasonal mammals. In rodents, Leydig, Sertoli, and germ cells contain enzymatic machinery to produce MT, with MT1/MT2 signaling influencing androgen production through cAMP-dependent and independent pathways and interacting with local Corticotropin-Releasing Hormone (CRH), serotoninergic, and catecholaminergic systems to regulate steroidogenesis and testicular plasticity. In non-seasonal species, Sertoli cells express MT1/MT2 and react to melatonin through alterations in proliferation, expression of spermatogenesis-related genes, and restructuring of glycolytic and acetate metabolism, thus modifying energetic support to germ cells. In seasonal breeders like rams and roe deer, MT1/MT2, N-acetyltransferase (AANAT), and acetylserotonin O-methyltransferase (ASMT) are found in testicular cells, spermatozoa, and the epididymis. Exogenous MT treatments are linked to advancements in the breeding season, increased testicular size and enhanced testosterone secretion in rams. MT1/MT2 were reported in spermatozoa from several seasonal and non-seasonal mammalian species and MT frequently was detected in seminal plasma, where they are involved in motility, capacitation, cryotolerance, and antioxidant protection. Therefore, suggesting that MT serves as a conserved but diversified intratesticular signal that integrates photoperiodic, metabolic, and cytoprotective regulation of male fertility.
Melatonin testicular synthesis and its role in reproductive physiology in seasonal and non-seasonal breeders
Cesauri, Mattia;Fanelli, Diana;Elmi, Alberto
2026-01-01
Abstract
: Melatonin (MT) is an indoleamine primarily produced by the pineal gland in a light-dark-dependent manner; however, it is also locally synthesized in the testis, where it influences male reproductive physiology upon interaction with its receptors (MT1/MT2), the binding started the bio-signaling inside the cells mediated by MT. This review outlines the intratesticular effects of MT, addressing seasonal and non-seasonal mammals. In rodents, Leydig, Sertoli, and germ cells contain enzymatic machinery to produce MT, with MT1/MT2 signaling influencing androgen production through cAMP-dependent and independent pathways and interacting with local Corticotropin-Releasing Hormone (CRH), serotoninergic, and catecholaminergic systems to regulate steroidogenesis and testicular plasticity. In non-seasonal species, Sertoli cells express MT1/MT2 and react to melatonin through alterations in proliferation, expression of spermatogenesis-related genes, and restructuring of glycolytic and acetate metabolism, thus modifying energetic support to germ cells. In seasonal breeders like rams and roe deer, MT1/MT2, N-acetyltransferase (AANAT), and acetylserotonin O-methyltransferase (ASMT) are found in testicular cells, spermatozoa, and the epididymis. Exogenous MT treatments are linked to advancements in the breeding season, increased testicular size and enhanced testosterone secretion in rams. MT1/MT2 were reported in spermatozoa from several seasonal and non-seasonal mammalian species and MT frequently was detected in seminal plasma, where they are involved in motility, capacitation, cryotolerance, and antioxidant protection. Therefore, suggesting that MT serves as a conserved but diversified intratesticular signal that integrates photoperiodic, metabolic, and cytoprotective regulation of male fertility.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
