title: Endocrine mechanisms responsible for different follicular development during the estrous cycle in Hatano high- and low-avoidance rats.
abstract: Hatano high- and low-avoidance rats (HAA and LAA strains, respectively) were selected and bred according to the avoidance rate in a shuttle-box task. Although they have clear strain differences in ovarian function, their endocrine mechanisms still remain to be clarified. Differences in female reproductive endocrinology between the strains were investigated by means of measuring the plasma concentration of reproductive hormones during the estrous cycle. LAA rats showed approximately threefold lower basal and surge levels of LH, a more than fourfold lower level of FSH surges and higher levels of inhibin A and inhibin B during the estrous cycle compared with the levels seen in HAA rats. The concentration of estradiol-17β in the proestrous stage was significantly lower in LAA rats than in HAA rats. Additionally, LH and FSH secretions from primary cultured anterior pituitary cells with or without in vitro GnRH stimulation were lower in the cells derived from LAA rats and, in terms of FSH secretion, were unresponsive to GnRH in contrast to cells derived from HAA rats. Although an increased number of preantral follicles in diestrus were observed in LAA rats, number of hCG-induced ovulation was lower in LAA rats. LAA rats may have much more follicle growth during the early stage of folliculogenesis, but most follicles might not grow into mature follicles. These results strongly suggest that the strain difference in ovarian function of these two Hatano rats is due to the difference in the regulation of hypothalamo-hypophyseal system for gonadotropins secretion.
authors.affiliation: Primate Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Sukanya
authors.initials: S
authors.lastname: Jaroenporn
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Horii
authors.forename: Sayaka
authors.initials: S
authors.lastname: Akieda-Asai
authors.forename: KaiMing
authors.initials: K
authors.lastname: Wang
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nagaoka
authors.forename: Ryo
authors.initials: R
authors.lastname: Ohta
authors.forename: Mariko
authors.initials: M
authors.lastname: Shirota
authors.forename: Gen
authors.initials: G
authors.lastname: Watanabe
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Taya
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004958:Estradiol; D030762:Estrous Cycle / Q000097:blood / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000502:physiology; D007265:Inhibins / Q000097:blood; D007986:Luteinizing Hormone / Q000097:blood; D006080:Ovarian Follicle / Q000187:drug effects / Q000502:physiology*; D010060:Ovulation / Q000187:drug effects / Q000502:physiology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D006063:Chorionic Gonadotropin; C422362:inhibin A; C422364:inhibin B; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone