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Department of Tissue Physiology, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
1 Laboratory of Veterinary Physiology, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
2 Laboratory of Animal Science, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
3 Department of Basic Veterinary Science, The United Graduate School of Veterinary Science, Gifu University, Gifu 501-1193, Japan
4 Air Pollutants Health Effect Team, National Institute of Environmental Studies, Ibaraki 305-0053, Japan
5 Ecological Effect Research Team, National Institute of Environmental Studies, Ibaraki 305-0053, Japan
(Requests for offprints should be addressed to K Taya; Email: taya{at}cc.tuat.ac.jp)
To elucidate changing patterns of inhibin/activin subunit mRNAs in the ovary of the golden hamster (Mesocricetus auratus) during the oestrous cycle, inhibin/activin subunit cDNAs of this species were cloned and ribonuclease protection assay and in situ hybridization were carried out. Inhibin
-subunit mRNA was localized in granulosa cells of primary, secondary, tertiary and atretic follicles throughout the 4-day oestrous cycle. It was also expressed in luteal cells on days 1 (oestrus), 2 (metoestrus) and 3 (dioestrus). ßA-subunit mRNA was localized in granulosa cells of large secondary (>200 µm) and tertiary follicles throughout the oestrous cycle. ßB-subunit mRNA was confined to granulosa cells of large secondary and tertiary follicles. Both
- and ßA-subunit mRNAs were also found in ovarian interstitial cells and theca interna cells of tertiary and atretic follicles in the evening of day 4 (pro-oestrus). A striking increase in ßA-subunit mRNA levels was also observed during the preovulatory period. The expression pattern of ßA-subunit mRNA during the preovulatory period is unique and not found in other species. An i.v. injection of anti-luteinizing hormone-releasing hormone (LHRH) serum before the LH surge abolished the expression of
- and ßA-subunit mRNAs in ovarian interstitial cells and theca interna cells. The treatment also abolished the preovulatory increase in ßA-subunit mRNA. Furthermore, administration of human chorionic gonadotrophin (hCG), which followed the injection of anti-LHRH serum, restored the expression patterns of
- and ßA-subunit mRNAs. The present study revealed that the golden hamster showed a unique expression pattern of ßA-subunit mRNA in response to the LH surge.
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