PLACE, N.J.; DREA, C.M.; HOLEKAMP, K.E.; WELDELE, M.L.; COSCIA, E.M.; GLICKMAN, S.E.: Sex differences and effects of prenatal anti-androgens on LH secretion in spotted hyenas

Sex differences in the secretion of luteinizing hormone (LH) have been attributed to the hormonal milieu to which mammals are exposed during gestation. Additionally, prenatal treatment with androgens can alter LH secretion patterns of female offspring. However, female spotted hyenas, renowned for their highly masculinized external genitalia, are naturally exposed to high levels of testosterone (T) in utero. To determine how, and if, LH secretion patterns of spotted hyenas are affected by prenatal exposure to T, we treated pregnant animals with anti-androgens. Later, as adults, both anti-androgen treated (AA) and control (C) males and females underwent an LHRH challenge test. Patterns of LH secretion were sexually dimorphic in untreated hyenas; females had higher baseline LH levels and showed higher and more sustained LH levels after injection of LHRH. Prenatal treatment with anti-androgens had no effect on baseline levels of LH, but it did significantly alter the response to LHRH. Peak LH levels of AA-males were higher than control males, and similar to control females. Control females, AA-females, and AA-males had similar LH secretion patterns up until 30 min after the LHRH injection. Thereafter the patterns diverged; LH levels rapidly declined in AA-males, plateaued and then slowly declined in C-females, and continued to rise in AA-females. Thus, prenatal anti-androgens partially feminized LH secretion in males (higher peak), and further modified the secretion pattern in females (later peak). These findings suggest the hypothalamic-pituitary unit in female spotted hyenas is partially masculinized by the high androgen levels that normally occur during development