Mechanisms regulating steroid hormone receptor gene expression in the ovine uterus : effects of trophoblast interferon tau /
This research was conducted to determine the cellular and
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1995.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=742746241&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | This research was conducted to determine the cellular and molecular mechanism(s) whereby ovine interferon tau (IFNR) regulates steroid hormone receptor gene expression in the endometrium. Results from the first study indicated that uterine estrogen receptor (ER) and progesterone receptor (PR) gene expression is regulated in a tissue and cell-type specific manner during the estrous cycle and early pregnancy. In both cyclic and pregnant ewes, PR gene expression decreased to low levels in all endometrial cell types and was undetectable in the luminal and superficial glandular epithelium during late diestrus. In pregnant ewes, the conceptus blocked increases in ER gene expression that occurred in the endometrial epithelium of cyclic ewes undergoing luteolysis. Results from the second study indicated that intrauterine injections of IFNR into cyclic ewes suppressed increases in endometrial ER MRNA, ER protein, OTR density and oxytocin-induced prostaglandin F. (PGF.) release which occurred in control ewes undergoing luteolysis. Results from the third study indicated that IFNR does not stabilize or prevent autologous down-regulation of PR MRNA or protein expression in the endometrial epithelium of ovariectomized ewes continously exposed to progesterone. However, IFNR does suppress increases in endometrial ER MRNA and protein expression which occurred in control ewes receiving progesterone alone or progesterone plus estrogen. Results from the fourth study indicated that IFNR prevented estrogen-induced luteolysis in cyclic ewes by suppressing increases in ER MRNA expression in the endometrial epithelium. Results from the fifth study indicated that progesterone affects estrogen-induced increases in ER, PR and OTR expression in the PR-positive deep glandular epithelium and stroma, whereas IFNT regulates estrogen-induced increases in expression of those hormone receptors in the PR-negative luminal and superficial glandular epithelium. Finally, results of the sixth study indicated that IFNT suppresses increases in transcription of the endometrial ER and OTR genes, but has no effect on transcription of the PR or 28S RRNA genes. Collectively, these studies demonstrate that the antiluteolytic action of IFNT is to suppress ER gene expression through a negative-acting transcriptional mechanism to prevent estrogen-induced increases in OTR gene transcription. This sequence of events, initiated by IFNT from the conceptus, would prevent OTR formation in the endometrial epithelium, production of luteolytic pulses of PGF, and ensure maintenance of the corpus luteum and successful maternal recognition of pregnancy. |
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| Item Description: | Vita. "Major Subject: Physiology of Reproduction". |
| Physical Description: | xiii, 271 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |