Abstract
Male sexual debility affects patients' confidence and damages the relationship between the couples and thus affects the stability of the family. This study aimed to investigate the effects of oligopeptides isolated from ginseng and oyster (GOPs and OOPs), separately and in combination, on sexual function in male mice. In the first experiment, male mice were randomly divided into five groups: vehicle control group; whey protein (125.0 mg kg(-1)) group; and GOPs 62.5, 125.0, and 250.0 mg kg(-1) groups. In the second experiment, male mice were randomly divided into five groups: vehicle control group, whey protein (160.0 mg kg(-1)) group, and OOPs 80.0, 160.0, and 320.0 mg kg(-1) groups. In the third experiment, male mice were randomly divided into six groups: vehicle control group, whey protein (222.5 mg kg(-1)) group, and GOPs + OOPs 62.5 + 160.0, 62.5 + 320.0, and 125.0 + 160.0, 125.0 + 320.0 mg kg(-1) groups. Test substances were given by gavage once a day for 30 days. The sexual behavior parameters, serum nitric oxide (NO), testosterone, cyclic guanosine monophosphate (cGMP), and phosphodiesterase-5 (PDE5) concentrations were detected. We found that GOPs at 250.0 mg kg(-1) improved male sexual behavior, NO, and testosterone content, whereas GOPs at 62.5 and 125.0 mg kg(-1) and OOPs at 80.0, 160, and 320 mg kg(-1) did not have significant effects. The combination of 62.5 mg kg(-1) GOPs + 160.0 mg kg(-1) OOPs and the combination of 125.0 mg kg(-1) GOPs + 320.0 mg kg(-1) OOPs improved male sexual behavior, serum NO, testosterone, and cGMP contents and decreased PDE5 content. The combination of 62.5 mg kg(-1) GOPs and 160.0 mg kg(-1) OOPs had the best effects among four combined groups. These results suggested that GOPs in combination with OOPs had the synergistic effects of enhancing male sexual function, probably via elevating serum testosterone, NO, and corpus cavernosum cGMP level and decreasing the corpus cavernosum PDE5 level. GOPs and OOPs could be novel natural agents for improving male sexual function.