Autoradiographic localization of nitric oxide synthase binding sites in normal and diabetic rat corpus cavernosum.

Abstract

To investigate density and distribution of nitric oxide synthase (NOS) binding sites in rat cavernosal tissue, and to assess any changes brought about by the onset of diabetes mellitus. Hyperglycaemic non-ketonuric diabetes mellitus was induced in 5 rats using streptozotocin. The penises were excised from these rats 2 months after the administration of streptozotocin and stored at -70 degrees C. Longitudinal serial sections (6 microns) were cut in a cryostat and thaw mounted onto gelantinized microscope slides. Low- and high-resolution autoradiography was performed using a radioligand for NOS. Densitometric analysis was performed on the autoradiographs and the results compared with those obtained from 5 age-matched no-diabetic rats. NOS binding was primarily localized to the endothelium lining the cavernosal lacunar spaces. Significantly increased binding of NOS was seen in the diabetic cavernosal tissue 2 months after induction of diabetes mellitus. NOS binding is present on the endothelium of the rat corpus cavernosum and is increased in diabetic rats 2 months after streptozotocin administration. This increase in NOS binding may be part of the endothelial dysfunction which is reported in the corpus cavernosum of diabetic patients or rats.