DIABETES-MELLITUS INCREASES NITRIC-OXIDE SYNTHASE IN PENISES BUT NOT IN MAJOR PELVIC GANGLIA OF RATS

Objective To determine the effect of diabetes mellitus (DM) on erectil e function and evaluate the levels of nitric oxide synthetase (NOS) ac tivity in streptozotocin-induced diabetic rats., Materials and methods Rats were studied at 9 weeks and 14 weeks after the induction of DM b y streptozotocin and compared with untreated control rats, Erectile po tency was assessed physiologically by testing and recording mating beh aviour. NOS activity was assayed in penile tissues and major pelvic ga nglia (MPG) by conversion of [H-3] L-arginine to [H-3] citrulline. His tological, ultrastructural and immunohisto-chemical studies of penile tissues were performed in similar groups of rats. Results Diabetes mel litus adversely and significantly degraded all parameters of mating be haviour, thus indicating defective erectile potency, However, NOS acti vities in penile tissues from both groups of diabetic rats were signif icantly higher than those in controls (P<0.01). In MPG, NOS activities were not significantly different between diabetic and control rats (P >0.05), Histological, ultrastructural and immunohistochemical studies of penile tissues revealed no significant differences between control and diabetic rats, indicating an intact effector organ (smooth muscles ) in rats with up, to 14 weeks of DM. Conclusion The impotence frequen tly observed in diabetic subjects would suggest that despite the incre ase in NOS activity in the penis, the pharmacological action of nitric oxide is impaired.