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Changes in plasma gonadotropins inhibin and testosterone concentrations and testicular gonadotropin receptor mRNA expression during testicular active, regressive and recrudescent phase in the captive Japanese black bear (Ursus thibetanus japonicus)
2010
Iibuchi, R., Hokkaido Univ., Sapporo (Japan) | Kamine, A. | Shimozuru, M. | Nio Kobayashi, J. | Watanabe, G. | Taya, K. | Tsubota, T.
Male Japanese black bears (Ursus thibetanus japonicus) have an explicit reproductive cycle. The objective of this study was to clarify the variation of plasma testosterone, FSH, inhibin, LH levels and testicular gonadotropin receptor mRNA expression of male bears associated with their testicular activity. Notably, this study investigated peripheral FSH concentration and localization of gonadotropin receptor mRNAs for the first time in male bears. Blood and testicular tissue samples were taken from captive, mature, male Japanese black bears during testicular active, regressive and recrudescent phases. Plasma hormone concentrations were measured by immunoassays, and gonadotropin receptor mRNA expression in the testis was investigated by in situ hybridization technique and also by real-time PCR. There were significant variations in plasma testosterone and inhibin concentrations. Changes in FSH concentration preceded these hormones with a similar tendency. Hormones started to increase during denning, and achieved the highest values at the end of the recrudescent phase for FSH and in the active phase for testosterone and inhibin. These changes in hormone concentrations were accompanied by testicular growth. In situ hybridization analysis revealed that FSH and LH receptor mRNA was possibly expressed in Sertoli cells and Leydig cells, respectively, as they are in other mammals. However, neither plasma LH concentration nor testicular gonadotropin receptor mRNA expression level varied significantly among the sampling months. These results suggest that FSH, inhibin and testosterone have roles in testicular activity in male bears. This study provides important endocrine information for comprehending seasonal reproductivity in male Japanese black bears.
Afficher plus [+] Moins [-]Timing of sequential changes in chromosome configurations during the 1st meiotic division of pig oocytes cultured in vitro
1990
Ocampo, M.B. (Hokkaido Univ., Sapporo (Japan). Faculty of Veterinary Medicine) | Ocampo, L.T.C. | Kanagawa, H.
Relationship between serum total cholesterol level and the number of transferable embryos in relation to milk yield in superovulated cows
1987
Kweon, O.K. (Hokkaido Univ., Sapporo (Japan). Faculty of Veterinary Medicine) | Kanagawa, H. | Yamashina, H.
Effects of LH-RH analogue on the ovulation rate and embryo quality in heifers superovulated with PMSG and PGF2alpha
1984
Takahashi, Y. | Kanagawa, H. (Hokkaido Univ., Sapporo (Japan). Faculty of Veterinary Medicine)
