title: Secretion of inhibin during the estrous cycle in the female Asian elephant (Elephas maximus).
abstract: To define the source of circulating inhibin in female Asian elephants, the immunolocalizations of the inhibin α, β(A) and β(B) subunits, 3β-hydroxysteroid dehydrogenase (3β-HSD), aromatase cytochrome P450 (P450arom) and cytochrome 17α-hydroxylase P450 (P450 c17) were investigated. Concentrations of immunoreactive (ir-) inhibin, progesterone and follicle-stimulating hormone (FSH) during the estrous cycle were measured by radioimmunoassay. Inhibin immunoreactivity in follicular fluid and homogenate of corpora lutea was also measured. Immunolocalizations of inhibin subunits, 3β-HSD, P450arom and P450c17 were detected in the granulosa cells of antral follicles and luteal cells. The follicular fluid contained high levels of ir-inhibin and bioactive inhibin. The homogenate of corpora lutea also contained ir-inhibin. Serum ir-inhibin remained at low levels during the early non-luteal phase, began to increase from the late non-luteal phase and continued to increase during the early luteal phase. Serum ir-inhibin showed maximal levels in the middle of the luteal phase and gradually decreased to baseline three weeks prior to progesterone decline. The serum ir-inhibin levels were positively correlated with progesterone throughout the estrous cycle. On the other hand, ir-inhibin was negatively correlated with FSH during the late non-luteal and early luteal phases. These findings strongly suggest that the corpus luteum is one of the sources of inhibin as well as granulosa cells in the Asian elephant.
authors.affiliation: Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Japan.
authors.forename: Saroch
authors.initials: S
authors.lastname: Kaewmanee
authors.forename: Gen
authors.initials: G
authors.lastname: Watanabe
authors.forename: Miori
authors.initials: M
authors.lastname: Kishimoto
authors.forename: Wan Zhu
authors.initials: WZ
authors.lastname: Jin
authors.forename: Yuki
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nagaoka
authors.forename: Etsuo
authors.initials: E
authors.lastname: Narushima
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Komiya
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Taya
mesh_terms: D000818:Animals; D004606:Elephants / Q000502:physiology*; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D007150:Immunohistochemistry; D007265:Inhibins / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D011374:Progesterone / Q000097:blood / Q000378:metabolism; D021122:Protein Subunits / Q000276:immunology; D011863:Radioimmunoassay / Q000662:veterinary; D013997:Time Factors
chemical_list: D021122:Protein Subunits; D011374:Progesterone; D007265:Inhibins; D005640:Follicle Stimulating Hormone