(291) The Effect of Administration and Discontinuation of Finasteride in Male Rats

It has been suggested that 5AR (5-alpha reductase) inhibitors may have negative effects on psychosexual activity, but there is still debate. We aimed to observe the effect of 5AR type 2 inhibition on brain tissue by using finasteride. 14 weeks old, eight male rats were assigned to each group (group 1 as the control group, group 2 as the finasteride group, and group 3 as the finasteride withdrawal group). Each rat was isolated and acclimatized in a single cage, then mated for 2 days. Rats in group 2 and 3 were administrated with finasteride for 4 weeks, then rats in group 2 were sacrificed whereas rats in group 3 were sacrificed 4 weeks thereafter. Before sacrifice, they were exposed to female bedding at least for 2 days. RT-PCR, western blot, and immunohistochemistry were performed for brain tissue evaluation where the target genes/proteins were 5AR (type 2) and c-Fos. Dihydrotestosterone (ng/dl) and dihydrotestosterone to testosterone ratio (%) plunged after 1 month administration of finasteride (group 2), and they were ameliorated after discontinuation of the drug (group 3) (Figure 1). These results were parallel to those from the western blot and immunohistochemistry (Figure 2 and 3). On the contraty, RT-PCR showed elevation of each gene (5AR and c-Fos) expression (Figure 2). Finasteride exerted an influence on brain tissue including hippocampus and ventromedial preoptic area via 5AR-2 inhibition, resulting in decrease of c-Fos protein activation. However, the negative impact of finasteride on rat brain in regard with c-Fos activation may fall away in a month cessation of the drug. No.