CONICET | Buscador de Institutos y Recursos Humanos

It has become increasingly evident that disturbances of the hypothalamic-pituitary-testicular axis account for only a small percentage of male infertility cases (Bartlett et al., 1989). A number of factors have been associated to testicular paracrine regulation but their physiological significance must be examined. In the last decades, the major topics on testicular research have been focused on regulation of steroidogenesis. Particularly, the fine tunning exerted by local substances at the cellular level has been taking into account. In the last years, it has been described the presence and influence of neurotransmitters (N-T) on the gonadal activity at the different stages of sexual development. In addition to the well established actions of different N-T and neuropeptides in the vertebrate central and peripheral nervous systems (Gershon et al., 1977), recent data indicate that significant levels of these compounds are also found in many non neural tissues including sexual organs (Verbeuren, 1989; Zhu et al., 1995). Our studies have demonstrated for the first time a cross talk between N-T, hormones and factors at the testicular level. In this context, we have found that the serotoninergic and melatonergic inhibition of cAMP and testosterone production is exerted though specific receptors (5-HT2 and Mel1a, respectively) localized on Leydig cells by cross-interaction with the testicular CRH /CRH-R1 system (Frungieri et al., 2002, 2005). Nevertheless, more studies are required before the biological relevance of our results and, consequently the role of local action of 5-HT, melatonin and CRH in the hamster testis can be placed in its proper perspective. We have also identified the expression of all components of those systems in human testes (Frungieri et al., 2005) but whether their role in the seasonal breeder golden hamster can be extended to non seasonal reproductive mammalian species including man remains to be clarified.