CAVERNOSAL NERVE-STIMULATION IN THE RAT REVERSES CASTRATION-INDUCED DECREASE IN PENILE NOS ACTIVITY

Castration in the rat reduces both tile erectile response and penile n itric oxide synthase (NOS) activity, and these effects are prevented b g androgen administration. In this study we determined that the decrea se of penile NOS in the castrated rat is due to NOS enzyme inhibition rather than to a reduction of its content and that this inhibition may be reversed. Adult rats were either castrated or left intact, and, af ter 1 wk, electrical field stimulation (EFS) was applied to the cavern osal nerve and the penises were excised either at the peak of erection or after detumescence. Penile NOS activity in the non-EFS castrates d ecreased by 70% as compared with the intact non-EFS-treated controls, but neuronal NOS content remained unaffected despite changes in region al distribution. NOS activity in the castrated penis was restored to n ormal values by EFS at the peak of stimulation, and then decreased on detumescence. This was in contrast to the intact controls in which EFS did not stimulate penile NOS activity. These data indicate that andro gen depletion in the rat reduces penile NOS activity rather than NOS c ontent and that this enzyme inhibition is reversed by cavernosal nerve stimulation.