A neurotoxin, 6-hydroxydopamine (6-OHDA) has been widely used to create animal model for Parkinson's disease (PD). The present study was undertaken to examine whether depletion of brain dopamine (DA) stores with 6-OHDA can make alteration in the activities of the testicular steroidogenesis in adult rats. Young adult male rats (3 months old) were received a single dose of 6-OHDA (200 in 10 /animal) by intracerebroventricular (icv) injection, and sacrificed after two weeks. The mRNA levels of steroidogenesis-related enzymes were measured by qRT-PCRs. Serum testosterone levels were measured by radioimmunoassay. Single icv infusion of 6-OHDA significantly decreased the mRNA levels of CYP11A1 (control:6-OHDA group= AU, p<0.05), CYP17 (control:6-OHDA group= AU, p<0.05). There were no changes in the mRNA levels of -HSD (control:6-OHDA group= AU) and -HSD (control: 6-OHDA group= AU), though the levels tended to be decreased in the 6-OHDA treated group. Administration of 6-OHDA decreased significantly the mRNA level of StAR when compared to the level of saline-injected control animals (control:6-OHDA group= AU, p<0.05). Treatment with single dose of 6-OHDA remarkably lowered serum testosterone levels compared to the levels of control group (control:6-OHDA group=, p<0.05). Taken together with our previous study, the present study demonstrated that the activities of hypothalamus-pituitary-testis hormonal axis could be negatively affected by blockade of brain DA biosynthesis, and suggested the reduced reproductive potential might be resulted in the animals. More precise information on the testicular steroidogenic activities in PD patients and PD-like animals should be required prior to the generalization of the sex steroid hormone therapy to meet the highest standards for safety and efficacy.

Some organotin compounds such as butyltins and phenyltins are known to induce impo-sex in various marine animals and are considered to be endocrine disruptors. In this study, the effect of organotins on follicular steroidogenesis in amphibians was examined using ovarian follicles of Rana dybowskii and Rana catesbeiana. Isolated follicles were cultured for 6 or 18 h in the presence and absence of frog pituitary homogenate (FPH) or various steroid precursors, and the levels of product steroids in the culture media oassay. Among the butyltin compounds, tributyltin (TBT) strongly and dose-dependently inhibited the FPH-induced synthesis of pregnenolone () and progesterone () by the follicles. TBT also strongly suppressed the conversion of cholesterol to and partially suppressed the conversion of to . A high concentration of dibutyltin (DBT) also inhibited steroidogenesis by the follicles while monobutyltin and tetrabutyltin had negligible effects. The toxic effect of TBT or DBT was irreversible and a short time of exposure (30 min) was enough to suppress steroidogenesis. All the phenyltin compounds significantly inhibited FPH-induced synthesis by the follicles. The effective dose of 50% inhibition by diphenyltin was and those of monophenyltin and triphenyltin were and , respectively. However, none of the phenyltin compounds significantly suppressed the conversion of to -hydroxyprogesterone (-OHP) (by -hydroxylase), -OHP to androstenedione (AD) (by lyase), or AD to testosterone by the follicles. Taken together, the data show that among the steroidogenic enzymes, P450scc in the follicles is the most sensitive to organotin compounds and that an amphibian follicle culture system can be a useful screening model for endocrine disruptors.