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Androgens exert opposite effects on body mass of heavy and light meadow voles
J Dark1, C S Whaling, I Zucker
1Department of Psychology, University of California, Berkeley 94720.
Abstract:
The influence of gonadal hormones on body mass of adult male meadow voles varied systematically as a function of the animals' baseline body weight; heavier voles decreased and lighter voles increased their body mass after castration. Testosterone replacement reversed the effects of castration; changes in body mass during hormone treatment were negatively correlated with changes observed after castration. Body mass of intact males was not correlated with plasma testosterone titers. Individual differences in body mass of male voles appear to reflect variations among animals in substrate responsiveness to hormones rather than differences in circulating hormone levels.