Lordosis-enhancing medial preoptic area lesions do not alter hypothalamic estrogen receptor- or progestin receptor-immunoreactivity in prepubertal female guinea pigs.
Female guinea pigs rarely display adult-typical lordosis responses to ovarian steroid hormones until 40-50 days of age. Behavioral hyporesponsiveness in prepubertal females may be due, in part, to deficiencies in hypothalamic estrogen receptors and/or estradiol-induced progestin receptors. This study was designed to test the hypothesis that bilateral medial preoptic area (MPOA) lesions, which enhance the display of progesterone-facilitated lordosis in juvenile females, increase levels of hypothalamic estrogen receptors and/or estradiol-induced progestin receptors. Hartley guinea pigs were ovariectomized at 11-12 days of age and at 14-15 days of age received bilateral electrolytic or sham lesions aimed at the MPOA. At approximately 3 weeks of age, lesioned and sham-lesioned animals were either tested for the display of progesterone-facilitated lordosis or perfused, and their hypothalamic tissue processed for estrogen receptor- or estradiol-induced progestin receptor-immunostaining. Although a significantly higher percentage of MPOA-lesioned than sham-lesioned guinea pigs displayed progesterone-facilitated lordosis (85.7% vs. 5. 8%, respectively, p<0.05), there were no significant lesion-related differences in the number or staining intensity of cells containing estrogen receptor- or estradiol-induced progestin receptor-immunoreactivity in the ventrolateral hypothalamus or arcuate nucleus. These data do not support the hypothesis that the enhanced display of progesterone-facilitated lordosis in prepubertal guinea pigs following MPOA lesions is due to increased hypothalamic concentrations of estrogen receptors or estradiol-induced progestin receptors.
Olster
D H
DH
Psychology Department, University of California, Santa Barbara, CA 93106, USA. olster@psych.ucsb.edu
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000737:chemistry / Q000502:physiology; D003429:Cross Reactions; D003714:Denervation; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D007150:Immunohistochemistry; D010052:Ovariectomy; D011187:Posture / Q000502:physiology*; D011301:Preoptic Area / Q000737:chemistry / Q000502:physiology*; D011960:Receptors, Estrogen / Q000032:analysis* / Q000276:immunology; D011980:Receptors, Progesterone / Q000032:analysis* / Q000276:immunology; D012726:Sexual Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D012741:Sexual Maturation / Q000502:physiology
D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C074283:estradiol 3-benzoate; D004958:Estradiol