Characterization and localization of nitric oxide synthase isoforms in theBB/WOR diabetic rat

Purpose: Erectile dysfunction is a common pathological development in indiv iduals with diabetes mellitus. Nitric oxide synthase (NOS) is essential for regulation of normal penile erection and NOS protein activity has been sho wn to be altered with diabetes. Several different isoforms and subtypes of NOS exist. However, little is known about how the distribution and abundanc e of these isoforms are altered with diabetes. We characterized the distrib ution and abundance of NOS isoforms and explored how they are altered with diabetes and result in erectile failure. Materials and Methods: In situ hybridization and quantitative reverse trans criptase-polymerase chain reaction were done to measure the abundance and d istribution of NOS-Ia, NOS-Ib, NOS-Ic, NOS-II and NOS-III in control and di abetic (BB/WOR) rats. Protein was localized by immunohistochemical analysis and alterations in protein abundance With diabetes Were examined by Wester n blot analysis. Results: NOS-I, NOS-II and NOS-III were observed in the endothelium lining the cavernous spaces and in the epithelium of the urethra. NOS-I protein wa s also present in the nerves of control and diabetic penes. We observed an increase in NOS-II expression around the dorsal nerves of diabetic penes, a decrease in NOS-III expression in diabetic pelvic ganglia and a decrease i n NOS-Ib expression in the diabetic penis. NOS-I protein abundance was sign ificantly decreased in diabetic pelvic ganglia. Conclusions: To our knowledge this is the first report of regional differen ces in the distribution of NOS-III in the urethra and altered NOS-Ib gene e xpression with diabetes.