Testosterone-dependence of oxidative stress in Sprague-Dawley rats fed a high salt diet

Abstract

Background: One of the mechanisms by which high salt diet (HSD) induces hypertension is by increasing the generation of reactive oxygen species (ROS). Salt sensitivity exhibits sex difference which is higher in males when compared with females. Likewise, sex disparity in oxidative stress has also been suggested. However, the role of the sex steroids in these sex differences is not clear. Therefore, experiments were designed to assess the role of testosterone on the oxidative status of male rats fed a high salt diet.

Methods: Weanling male Sprague-Dawley rats were either sham-operated or orchidectomised under (90mg/kg bodyweight ketamine and 10mg/kg bodyweight xylazine i.p) anesthesia, with or without testosterone replacement (10mg/kg sustanon 250® i.m) once in 3 weeks. They were placed on a diet with normal 0.3% or high 8% NaCl content for 6 weeks. Blood pressure (BP) was measured via arterial cannulation. Levels of lipid peroxidation (LP), superoxide dismutase (SOD), bilirubin and testosterone were measured in the serum.

Results: Orchidectomy attenuated the BP elevating effect of a high salt diet, but concomitant replacement of testosterone in orchdectomised rats restored the BP values towards that observed in sham-orchidectomised animal. Orchidectomy abolished while testosterone replacement re-established the significant increase (p<0.001) in LP of the HSD group when compared with the control. High salt diet significantly reduced (p<0.01) the serum levels of SOD. Orchidectomy prevented the reduction in SOD level effect of a high salt diet but testosterone replacement re-established it. Findings from this study show that orchidectomy reduced oxidative stress in male Sprague-Dawley rats fed a high salt diet suggesting a role for testosterone in ROS generating effect of a high salt diet.

Keywords: Bilirubin, Hypertension, Lipid peroxidation, Orchidectomy, Oxidative stress, Super oxide dismutase, Testosterone