Orchidectomy attenuates impaired endothelial effects of a high salt diet in sprague-dawley rats

Abstract

The effect of sex hormones on vascular reactivity is considered to be one of the underlying factors contributing to gender differences in cardiovascular function and disease. For this study, experiments were designed to investigate the role of androgens in salt-induced hypertension by assessment of the relaxation response of isolated aortic rings to acetylcholine (ACh) and sodium nitroprusside (SNP) in the presence or absence of L-nitro arginine methyl ester (L-NAME) in Sprague-Dawley rats that were either orchidectomised or sham-operated with or without testosterone replacement, and were placed on a normal (0.3% NaCl) or high (8% NaCl) salt diet for 6 weeks. The results indicate a statistically significant (P < 0.001) increase in the mean arterial blood pressure (MABP) of rats on a high-salt diet, when compared with control or orchidectomised rats. Orchidectomy elicited a reduction in MABP (P < 0.01), while testosterone replacement normalized MABP to values seen in intact rats on a high-salt diet. A high-salt diet reduced the relaxation response to ACh both in the presence and absence of endothelial nitric oxide synthase (eNOS) inhibition with L-NAME. Bilateral orchidectomy attenuated the impaired endothelial function induced by a high-salt diet in the rats, but this was reversed by the concomitant administration of testosterone, suggesting a role for androgens in enhancing long-term vascular smooth-muscle tone, and hence maintenance of high blood pressure in salt-induced hypertension.