Sex steroids and renal protein excretion in mice: the importance of testosterone

Abstract

Sex steroids are involved in the renoprotection in females. Our purpose was to determine the effect of estrogen and testosterone on protein excretion (PE, mg/day) in female and male mice. Two studies were conducted: one with normal and ovariectomized (ovx) females and one with normal and castrated (cast) males (3 groups each study, n=4). Female groups were normal, ovx+vehicle, and ovx+17β‐estradiol (sc injection, 5μg/day). Pellets were implanted in males. Normal and cast groups were given placebo (P) pellets and another cast group was given 35mg pellets of testosterone proprionate (T). Mice (25–30 days old) were placed in metabolic cages for 25 days and consumed 40% casein. In females, no differences in PE occurred between the three groups. In males, average PE was: normal+P = 18.1 ± 2.9*, cast+P = 5.1 ± 1.0, and cast+T = 20.9 ± 3.27* (*− p<.0001 to cast+P). On day 25, kidney weight‐to‐body weight (kw/bw) did not differ in females. In males, kw/bw differed in the profile: cast+T > normal+P > cast+P, and that for cast+P did not differ from females. Results suggest that the absence of testosterone rather than the presence of estrogen accounts for the renoprotection in females.