Pituitary responsiveness to luteinizing hormone-releasing hormone in prepubertal and postpubertal male ferrets.
The pituitary response to three different doses of exogenously administered LHRH was examined in prepubertal (9-wk-old) and postpubertal (32-wk-old) male ferrets. The doses of 5, 10, and 15 ng LHRH/kg body weight tested in this study produced dose-related increases in circulating LH concentrations in both pre- and postpubertal groups. In addition, a significant effect of age on LH response was observed, with the prepubertal animals demonstrating significantly greater serum LH values in response to the two higher doses than the postpubertal males. Prepubertal ferrets also exhibited a significant increase in endogenous LH pulse amplitude in sampling periods following exogenous administration of LHRH compared to baseline pulse amplitudes in periods prior to the LHRH infusions. These results suggest that the low frequency of endogenous LH pulses previously observed in prepubertal ferrets is not due to unresponsiveness of the pituitary gland to LHRH. Thus, suppression of the hypothalamo-hypophyseal axis observed in the prepubertal ferret is probably mediated at the level of the hypothalamus.
Department of Psychology, Michigan State University, East Lansing 48824-1117.
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Berglund
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Sisk
D000375:Aging / Q000502:physiology; D000818:Animals; D002335:Carnivora / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005289:Ferrets / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D012741:Sexual Maturation / Q000502:physiology*; D013737:Testis / Q000033:anatomy & histology
D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone