Resveratrol reverses diabetes-related decrement in sildenafil-induced relaxation of corpus cavernosum in aged rats

Background The aim of this study was to investigate the effect of resveratrol (RVT) on sildenafil-induced relaxations of isolated corpus cavernosum in non-diabetic and diabetic aged rats. Methods A total of 13 male aged rats (72–80 weeks old) were randomized into two groups including non-diabetic aged rats and diabetic aged rats. Diabetes was induced in aged rats by streptozotocin (single i.p. dose of 45 mg/kg body weight) administration. At the end of the 12th week, corpus cavernosum strips of rats were suspended in an organ bath system. The corpus cavernosum relaxation was evaluated by sildenafil in the presence or absence of RVT (10 −4 M) for 45 min. Results Induction of diabetes resulted in significant inhibition of sildenafil-induced corpus cavernosum relaxation in aged rats. The diminished relaxation in response to sildenafil was significantly improved by acute RVT incubation in both non-diabetic and diabetic aged rats; however, the magnitude of potentiation induced by RVT was more pronounced in diabetic aged rats. The potentiating effect of RVT was significantly inhibited by L-NG-nitroarginine methyl ester (L-NAME, 10 −4 M, for 30 min) incubation in both groups. After the L-NAME incubation, the relaxation response of corporal tissues evoked by sildenafil was found to be similar in diabetic and non-diabetic aged rats. Conclusions RVT improves sildenafil-induced relaxations of corpus cavernosum in both diabetic and non-diabetic aged rats probably by potentiating the activity of NOS, and this effect seems to be more manifest in diabetic aged group.