Effects of Testosterone on Renal Function in Salt-Loaded Rats

Introduction: The objective of this study is to investigate the effects of androgen on renal sodium excretion and renal functional in sodium-loaded rats. Methods: Sixty male Wistar rats aged 8 weeks were used, of which 48 underwent orchiectomy and the other 12 underwent a sham procedure. The 48 orchiectomized rats were randomly divided into 4 groups (12/group): castrated rats (Cas), testosterone-supplemented castrated rats (TC), flutamide (androgen receptor blocker)-treated castrated rats (FC) and flutamide-treated testosterone-supplemented castrated rats (FTC). The 12 sham-operated rats served as controls. All 60 rats were fed with 8% NaCl chow for 8 weeks. Systemic blood pressure (BP) was recorded at 0, 4 and 8 weeks. Sodium excretion, microalbuminuria and creatinine clearance were calculated before and at the end of the experiment. Circulating levels of testosterone and angiotensin II and plasma renin activity were measured by radioimmunological method at the end of the experiment. Results: BP of controls and TC was higher at 8 weeks than at baseline; BP of Cas, FC or FTC was lower than that of controls. Plasma renin activity and angiotensin concentrations were lower in Cas, FC and FTC (groups with testosterone absent or blocked) than in controls and TC (groups with testosterone intact). Cas, FC and FTC displayed less microalbuminuria, higher sodium excretion and higher creatinine clearance than control and TC. Conclusions: In salt-loaded rats, testosterone seems to activate the renin-angiotensin system, resulting in sodium retention, higher BP and renal injury.