DARK-CYCLE VIDEO SURVEILLANCE OF SEXUAL PERFORMANCES OF NORMAL AND DIABETIC RATS

Clinically, a 59% prevalence of impotence was reported among diabetic male patients. Neurological, vascular, endocrinologic and psychologica l factors are probably involved. Previous reports with the rat model f ound deterioration of sexual behavior and reproductive function caused by streptozotocin (STZ)-induced diabetes. The purpose of the present study was to develop the dark-cycle video recording methodology for th e observation of rat sexual activities and to study the effect of STZ- induced diabetes on sexual performances of the rat. Adult male Wistar rats were rendered diabetic with intraperitoneal injection of STZ (60 mg/kg body weight). In the 4th week a diabetic rat or a control rat wa s caged with an adult ovariectomized female rat during the dark cycle. The female had been brought into behavioral estrus with intramuscular injection of 0.1 mg estradiol benzoate 3 days before and 1.0 mg proge sterone 3 h before testing. Infrared-light-illuminated video recording was performed to evaluate the sexual performances. The mounting laten cy and frequency, intromission latency and frequency, the hit rate as well as the post-ejaculatory period of the diabetic rats were signific antly deteriorated when compared with the controls (p < 0.05). However , the ejaculatory latency showed no significant difference between the two groups (p > 0.05). In conclusion, it has been demonstrated that w ith this methodology, behavioral studies on nocturnal animals like the rat can be carried out conveniently. It was shown that the sexual aro usal mechanism and copulation-ejaculatory mechanism were both depresse d in STZ-induced diabetic rats. The same study model can be used for f urther pathophysiological and pharmacological researches on the sexual behaviors of diabetic rats.