| Sex steroid effects on the development and functioning of the growth hormone axis. | |
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MedLine Citation:
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PMID: 8818398 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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1. The secretory pattern of growth hormone (GH) is sexually dimorphic in the adult rat. However, this difference between the sexes does not become apparent until after the onset of puberty, suggesting that pubertal sex steroids play an important role in the manifestation of this phenomenon. 2. We have addressed the question as to whether there exists a sexual dimorphism in the hypothalamic neuropeptides that regulate GH release from the anterior pituitary, i.e., somatostatin (SS) and growth hormone-releasing hormone (GHRH). In addition, we have investigated whether the developmental changes in the GH secretory pattern are correlated with changes in these neuropeptides. The effect of testosterone treatment on SS and GHRH neurons during both the neonatal period and adulthood have also been studied. 3. We have found that the synthetic capacity, as reflected in relative messenger RNA (mRNA) levels, of both SS and GHRH neurons changes throughout development in both male and female rats. These mRNA levels are sexually dimorphic at certain times during maturation and can be modulated by changes in testosterone levels, suggesting that sex steroid modulation of these two neuropeptide systems could at least partially account for the sexual dimorphism seen in the adult GH secretory pattern. 4. The neonatal steroid environment has also been suggested to be involved in the generation of the final adult GH secretory pattern, although the mechanisms underlying this effect are even less well understood. In support of the hypothesis that the neonatal steroid environment plays an important role in organizing the GH axis, we have found that the number of GHRH neurons in the adult brain, as well as their sensitivity to adult steroids, is modulated by neonatal testosterone treatment. The number of SS neurons in the periventricular and paraventricular nuclei were not modulated by neonatal steroids; however, the synthetic capacity of these neurons does appear to be influenced by the neonatal steroid environment. 5. These studies suggest that both the neonatal and adult sex steroid environments influence the adult GH secretory pattern by modulating GHRH and SS neurons. |
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Authors:
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J A Chowen; L M García-Segura; S González-Parra; J Argente |
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Publication Detail:
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Type: Journal Article; Review |
Journal Detail:
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Title: Cellular and molecular neurobiology Volume: 16 ISSN: 0272-4340 ISO Abbreviation: Cell. Mol. Neurobiol. Publication Date: 1996 Jun |
Date Detail:
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Created Date: 1996-12-31 Completed Date: 1996-12-31 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8200709 Medline TA: Cell Mol Neurobiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 297-310 Citation Subset: IM |
Affiliation:
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Instituto Cajal, C.S.I.C, Madrid, Spain. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Animals, Newborn Castration Cells, Cultured Estradiol / pharmacology* Female Growth Hormone-Releasing Hormone / secretion* Hypothalamo-Hypophyseal System / drug effects*, growth & development, secretion Male Neurons / drug effects RNA, Messenger / biosynthesis, genetics Rats Sex Characteristics* Sexual Maturation Somatostatin / secretion* Testosterone / pharmacology* |
| Chemical | |
Reg. No./Substance:
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0/RNA, Messenger; 50-28-2/Estradiol; 51110-01-1/Somatostatin; 58-22-0/Testosterone; 9034-39-3/Growth Hormone-Releasing Hormone |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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