Oxidative alterations induced by d-aspartic acid in prepubertal rat testis in vitro: A mechanistic study

The objective of the present study was to investigate the oxidative induction response following in vitro treatment with d-aspartic acid (DA) in prepubertal rat testis (homogenates, explants, and cell suspensions). In all three preparations, DA enhanced (P < 0.001) lipid peroxidation, manifest as increased reactive oxygen species (ROS) and malondialdehyde (MDA). Further, DA-induced oxidative induction was potentiated (P < 0.001) in the presence of iron (5 μM) and 3-amino triazole and mercaptosuccinate (P < 0.001), known inhibitors of the peroxide metabolizing enzymes, catalase and glutathione peroxidase, respectively. Testis homogenates exposed to l-arginine (LA) per se had reduced (P < 0.001) endogenous levels of ROS and MDA; furthermore, pre-incubation with l-arginine markedly suppressed (P < 0.001) DA-induced oxidative induction, suggesting an antagonistic action, perhaps due to LA-derived nitric oxide. In conclusion, DA caused significant oxidative induction in prepubertal rat testis, but this action was abrogated by l-arginine. The relevance of this phenomenon in vivo merits further study, as both of these molecules have specific physiological functions in the testis.