Testosterone up-regulates vacuolar ATPase expression and functional activities in vas deferens of orchidectomized rats

Hormonal control of vas deferens fluid volume and aquaporin expression in rats

Precise regulation of vas deferens fluid volume which is important for sperm survival might be influenced by testosterone. In order to investigate changes in vas deferens fluid volume and aquoporins (AQP) isoforms expression under testosterone influence, orchidectomized Sprague-Dawley rats were given 125 and 250 µg/kg/day testosterone with or without flutamide, an androgen receptor blocker or finasteride, a 5alpha-reductase inhibitor for seven consecutive days. Following treatment completion, vas deferens was perfused and changes in the fluid secretion rate and osmolality were determined in the presence of acetazolamide. Rats were then sacrificed and vas deferens was harvested for histology, tissue expression and distribution analyses of AQP-1, AQP-2, AQP-5, AQP-7 and AQP-9 proteins by Western blotting and immunohistochemistry, respectively. Our findings indicate that testosterone causes vas deferens fluid secretion rate to increase, which was antagonized by acetazolamide. Fluid osmolality increased following testosterone treatment and further increased when acetazolamide was given. Co-administration of flutamide or finasteride with testosterone causing both fluid secretion rate and osmolality to decrease. Histology revealed increased size of vas deferens lumen with increased thickness of vas deferens stroma. Expression of AQP-1, AQP-2 and AQP-9 were detected in vas deferens but not AQP-5 and AQP-7, and the levels of these proteins were increased by testosterone treatment mainly at the apical membrane of vas deferens epithelium. In conclusion, increased in vas deferens fluid secretion rate under testosterone influence mediated via the up-regulation of AQP-1, 2 and 9 might be important for vas deferens fluid homeostasis in order to ensure normal male fertility.

Testosterone enhances expression and functional activity of epithelial sodium channel (ENaC), cystic fibrosis transmembrane regulator (CFTR) and sodium hydrogen exchanger (NHE) in vas deferens of sex-steroid deficient male rats

Effects of testosterone on expression and functional activity of ENaC, CFTR and NHE in vas deferens were investigated.

METHODS

Orchidectomized, adult male rats were given 125 and 250 μg/kg/day testosterone subcutaneously, with or without flutamide and finasteride for seven consecutive days. At the end of the treatment, rats were anesthetized and vas deferens were perfused. Changes in vas deferens fluid secretion rate, pH, HCO₃^-, Cl^- and Na⁺ concentrations were recorded in the presence of amiloride and Cftr inh-172. Rats were then sacrificed and vas deferens were harvested and subjected for molecular biological analysis.

RESULTS

Testosterone treatment caused the fluid pH and HCO₃^- concentrations to decrease but secretion rate, Cl^- and Na⁺ concentrations to increase, where upon amiloride administration, the pH and HCO₃^- concentration increased but Cl^- and Na⁺ concentrations further increased. In testosterone-treated rats, administration of Cftr inh-172 caused all fluid parameters to decrease. In testosterone-treated rats co-administered with flutamide or finasteride, pH and HCO₃^- concentration increased but fluid secretion rate, Cl^- and Na⁺ concentrations decreased and these parameters were not affected by amiloride or Cftr inh-172 administration. Under testosterone influence, CFTR and γ-ENaC were highly expressed at the apical membrane while NHE-1 and 4 were highly expressed at the basolateral membrane of vas deferens epithelium. Meanwhile, NHE-2 and 3 were highly expressed at the apical membrane.

CONCLUSIONS

Differential expression of ENaC, CFTR and NHE in vas deferens under testosterone influence indicated the important role of these transporters in creating optimal fluid microenvironment that is essential for preserving male fertility.