| The effects of melatonin and hypothyroidism on estradiol and gonadotropin levels in female Syrian hamsters. | |
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MedLine Citation:
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PMID: 3109508 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Since melatonin injections administered near the end of the daily photoperiod influence both gonadal and thyroid hormones in the female hamster, the present study was designed to compare the effects of melatonin and hypothyroidism on the reproductive system and to determine whether thyroid status influenced the action of melatonin on the regulation of the hormones of reproduction. The effects of daily melatonin injections were determined in control hamsters, in hamsters rendered hypothyroid with thiourea, and in hypothyroid hamsters receiving thyroxin (T4) hormone replacement. As previously reported, melatonin injections disrupted estrous cyclicity, disrupted the normal pattern of gonadotropin secretion, and resulted in atrophy of the uterus and vagina. These changes coincided with depressed serum and pituitary prolactin (PRL), and depressed levels of estradiol. The effects of melatonin on uterus, vagina, ovary, and on gonadotropin levels were not prevented by T4 replacement, with the exception of a melatonin-induced increase in serum follicle-stimulating hormone (FSH). This suggested that the cessation of estrous cyclicity was not primarily a result of thyroid deficiency. Hypothyroidism, however, like melatonin, resulted in a reduced number of developing and mature follicles and corpora lutea in the ovaries, and in reduced uterine weight. It also produced follicular atresia, reduced the circulating levels of estradiol, and resulted in reduced incidence of estrus smears. T4 replacement, for 2 weeks, prevented the decline in mature follicles and corpora lutea, reduced the extent of follicular atresia, increased circulating levels of estradiol, and increased uterine weight. PRL and luteinizing hormone (LH) data also provided evidence for antagonistic effects of melatonin and T4 in female hamsters. These data raise the question whether melatonin-induced changes in circulating levels of T4 play a role in the seasonal cycles of reproductive competence in the female hamster. |
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Authors:
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J Vriend; F D Bertalanffy; T A Ralcewicz |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Biology of reproduction Volume: 36 ISSN: 0006-3363 ISO Abbreviation: Biol. Reprod. Publication Date: 1987 Apr |
Date Detail:
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Created Date: 1987-07-24 Completed Date: 1987-07-24 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0207224 Medline TA: Biol Reprod Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 719-28 Citation Subset: IM |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Cricetinae Estradiol / metabolism* Female Gonadotropins, Pituitary / metabolism* Hypothyroidism / chemically induced, metabolism*, pathology Luteinizing Hormone / metabolism Melatonin / pharmacology* Mesocricetus Ovary / drug effects, pathology Pituitary Gland / drug effects, metabolism Prolactin / metabolism Thiourea Thyroid Hormones / metabolism |
| Chemical | |
Reg. No./Substance:
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0/Gonadotropins, Pituitary; 0/Thyroid Hormones; 50-28-2/Estradiol; 62-56-6/Thiourea; 73-31-4/Melatonin; 9002-62-4/Prolactin; 9002-67-9/Luteinizing Hormone |
| Comments/Corrections | |
Erratum In:
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Biol Reprod 1987 Aug;37(1):following 256 Biol Reprod 1987 Oct;37(3):following 747 |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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