Amelioratory effects of testosterone propionate supplement on behavioral, biochemical and morphological parameters in aged rats.

Testosterone has been shown to affect motor behavior and nigrostriatal dopaminergic (NSDA) system in young and adult male rats. However, it is not known whether exogenous testosterone intervention to aged male rats can ameliorate age-related motor impairment. Thus, in the present study, the open field motor behavior and adhesive tape removal motor performance as well as the expression of tyrosine hydroxylase (TH) and dopamine transporter (DAT) of NSDA system were examined in aged male rats following chronic subcutaneous injections of testosterone propionate (TP). Aged rats showed significantly reduced open field motor behavior and adhesive tape removal motor performance compared to adult rats. Chronic TP supplement significantly ameliorated the age-related motor deficits. The expression of TH and DAT of NSDA system was significantly enhanced in TP-treated aged rats revealed by RT-PCR, Western blot and immunohistochemistry analysis respectively. The results imply that chronic TP treatment may favorably improve the declined motor behavior and motor performance with aging. Testosterone propionate supplement that facilitated NSDA system may influence the maintenance of motor behavior and performance in aged rats.