title: Suppressive effect of neonatal treatment with a phytoestrogen, coumestrol, on lordosis and estrous cycle in female rats.
abstract: The neural control systems for the ovulatory cycle and lordosis behavior are sexually differentiated by estrogen during the perinatal period in rats. In the present study, the effects of a single neonatal injection with the phytoestrogen, coumestrol, on female reproductive functions were investigated. Female rats were injected subcutaneously with 1 or 3mg coumestrol (CM1, CM3), 1mg genistein (GS1), 1mg estradiol (E2), or oil at day 5 after birth (birth day=day 1) and an estrous cycle check and lordosis behavior test were performed. As a result, vaginal opening was advanced in CM1-, CM3- or E2-treated females. A vaginal smear check indicated that oil- or GS1-treated females showed a constant 4- or 5-day estrous cycle, whereas CM1-, CM3- or E2-treated rats showed a persistent or prolonged estrus. Ovariectomy was performed in all females at 60 days of age. The ovary weights in the CM1-, CM3- or E2-treated groups were lower than those in the oil- and GS1-treated groups and no corpora lutea were found in any rats of these three groups, except for two E2-treated rats. Behavioral tests were carried out after implantation of E2-tubes. All rats in the CM1-, GS1-treated groups showed a high lordosis quotient (LQ), being comparable to that in the oil-treated females. On the other hand, LQs in the CM3, E2 or male groups were lower than that in the control female group. These results suggest that a single neonatal injection of 3 mg coumestrol was effective in suppressing the functions of ovulation-inducing mechanisms and the induction of lordosis, but 1mg coumestrol was effective in only the estrous cycle of female rats.
authors.affiliation: Laboratory of Neuroendocrinology, Faculty of Human Sciences, Waseda University, 2-579-15, Mikajima, Tokorozawa, Saitama 359-1192, Japan.
authors.forename: Tom
authors.initials: T
authors.lastname: Kouki
authors.forename: Miho
authors.initials: M
authors.lastname: Okamoto
authors.forename: Shizuko
authors.initials: S
authors.lastname: Wada
authors.forename: Miki
authors.initials: M
authors.lastname: Kishitake
authors.forename: Korehito
authors.initials: K
authors.lastname: Yamanouchi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D001835:Body Weight / Q000187:drug effects; D003277:Contraceptives, Oral, Combined; D003375:Coumestrol / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology; D030762:Estrous Cycle / Q000187:drug effects*; D005040:Ethynodiol Diacetate; D005260:Female; D008297:Male; D008656:Mestranol; D009929:Organ Size / Q000187:drug effects; D010052:Ovariectomy / Q000379:methods; D048789:Phytoestrogens / Q000494:pharmacology*; D011187:Posture; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D013997:Time Factors; D014621:Vagina / Q000187:drug effects / Q000502:physiology
chemical_list: D003277:Contraceptives, Oral, Combined; D048789:Phytoestrogens; D004958:Estradiol; D005040:Ethynodiol Diacetate; C018467:Bisecurin I; D008656:Mestranol; D003375:Coumestrol