RESUMO
OBJECTIVE: To investigate the expression characteristics of neuronal nitric oxide synthase (nNOS) in the corpus cavernosum of diabetic erectile dysfunction (ED). METHODS: Fifty rabbits underwent single intravenous injection of alloxan (100 mg/kg). Blood glucose, system arterial pressure (SAP), and intracavemosal pressure (ICP) were measured 15, 30, and 45 days later. The rabbits with the blood glucose >10 mmol/L were used as diabetic models and those with the ICP lower than the normal control group by more than 25% were used as diabetic ED models. RT-PCR, immunohistochemistry, and Western-blotting were used to detect the expression of nNOS in the corpus cavemosum. RESULTS: Seven days after the alloxan injection the blood glucose levels of 35 rabbits (70%) were > 10 mmol/L. 40% rabbits (14/35) were were used as diabetic ED models. Compared with control group, the ICP 15, 30, and 45 days after alloxan injection were considerately decreased in diabetic ED rabbits (all P < 0.01), and there was no significant difference in SAP between the two groups (all P > 0.05). The relative values of nNOS mRNA expression 15, 30, and 45 days after alloxan injection of diabetic ED rabbits were 0.670 +/- 0.030, 0.451 +/- 0.012, and 0.206 +/- 0.023 respectively,all significantly lower than those of the control group (0.817 +/- 0.010, 0.814 +/- 0.020, and 0.802 +/- 0.007 respectively, all P < 0.05). Western blotting showed that the relative values of nNOS 15, 30, and 45 days after alloxan injection of the ED rabbits were 0.713 +/- 0.014, 0.424 +/- 0.007, and 0.337 +/- 0.009 respectively, all significantly lower than those of the control group (0.797 +/- 0.015, 0.706 +/- 0.020, and 0. 750 +/- 0.022 respectively, all P < 0.05). CONCLUSION: Decreased expression of nNOS in corpus cavernosum is one of possible pathway of diabetic ED.