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Volume 57, Number 4 >

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)

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Please use this identifier to cite or link to this item:http://doi.org/10.14943/jjvr.57.4.185

Title: 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)
Authors: Iibuchi, Ruriko Browse this author
Kamine, Akari Browse this author
Shimozuru, Michito Browse this author
Nio-Kobayashi, Junko Browse this author
Watanabe, Gen Browse this author
Taya, Kazuyoshi Browse this author
Tsubota, Toshio Browse this author
Keywords: follicle-stimulating hormone
gonadotropin receptor
inhibin
Japanese black bear
luteinizing hormone
Issue Date: Feb-2010
Publisher: Graduate School of Veterinary Medicine, Hokkaido University
Journal Title: Japanese Journal of Veterinary Research
Volume: 57
Issue: 4
Start Page: 185
End Page: 196
Abstract: 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.
Type: bulletin (article)
URI: http://hdl.handle.net/2115/42745
Appears in Collections:Japanese Journal of Veterinary Research > Volume 57, Number 4

Submitter: 獣医学部図書室

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