Abstract: OBJECTIVE: To determine whether the central nervous system is involved in the effect of Chinese herbal medicine on sexual function recovery in orchidectomized rats.METHODS: Orchidectomized rats were administered intragastrically with a decoction of "kidneynourishing" Chinese herbal medicine once per day for 28 days. Accessory genital organ weight, plasma testosterone, and mating behavior were investigated. The expression of c-Fos and neuronal nitric oxide synthase(n NOS) in neuronal cells in the nucleus accumbens(NAc) was analyzed by immunohistochemistry.RESULTS: There was a decrease in accessory genital organ weight, plasma testosterone, and sexual behavior, as well as a low number of c-Fos-positive cells and a large n NOS-positive cell area in orchidectomized rats. Administration of the herbal medicine increased accessory genital organ weight, testosterone level, mating behavior, and c-Fos-positive cell number, while it decreased the n NOS-positive cell area in orchidectomized rats.CONCLUSION: An increase of plasma testosterone after administration of "kidney-nourishing" herbal medicine might contribute to the elevated sexual function and activity in orchidectomized rats. In addition, a central nervous system mechanism, such as the functional alteration of NAc, might be involved.

Key words: Medicine, Chinese traditional, Reinforcing kidney, Orchidectomy, Sexual function, physiological, Nucleus accumbens, c-Fos, Nitric oxide synthase type Ⅰ