| Pituitary-dependent hormonal regulation of galaninergic neurons in the rat hypothalamus. | |
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MedLine Citation:
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PMID: 7529898 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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To investigate whether pituitary-dependent hormones may regulate galanin (GAL) content, synthesis and distribution in the hypothalamus, female hypophysectomized Wistar rats were treated for 2 weeks with subcutaneous injections of thyroxine (T4, 2 x 1 microgram), bovine growth hormone (GH, 2 x 125 micrograms), cortisol (C, 50 micrograms), subcutaneous implants of beta-estradiol (E2, 5-mm implant, dilution 1:1), or with the combinations [T4+GH], [T4+GH+C+E2] or [T4+GH+C+E2 + rat PRL, 2 x 125 micrograms] (doses/100 g BW/day). Concentrations of GAL in the hypothalamus were measured by radioimmunoassay (RIA) and GAL mRNA abundance was quantified by Northern blot (6 rats/group); 2 rats/group were used for immunohistochemistry. Hypophysectomy caused decreases of hypothalamic GAL peptide and mRNA concentrations (by 70 and 50%, respectively; p < 0.05 vs. intact rats). GAL immunoreactivity disappeared in the median eminence (ME), but increased in the neurohypophyseal magnocellular neurons of hypophysectomized rats. Substitution with T4, GH, [T4+GH], C or E2 had no significant effect on total hypothalamic GAL peptide and GAL mRNA concentrations. A treatment combining [T4+GH+C+E2] increased hypothalamic GAL (1.9 +/- 0.1 vs. 1.2 +/- 0.1 ng/mg protein in untreated hypophysectomized rats; p < 0.01) and GAL mRNA concentrations (127 +/- 19 vs. 59 +/- 2 densitometric units in untreated rats, p < 0.001). Addition of PRL to this combined treatment had no further effect. Treatment with T4, GH, [T4+GH] or E2 enhanced GAL labeling in the ME of hypophysectomized rats. The effect of estrogens was restricted to the GnRH-rich lateral regions of the ME. The combined treatment with [T4+GH+C+E2] restored the ME GAL immunoreactivity to levels observed in intact rats. In contrast, the increased GAL labeling observed in magnocellular neurons after hypophysectomy was not influenced by any hormonal treatment. In conclusion, hypophysectomy leads to marked reductions of hypothalamic GAL and GAL mRNA concentrations, and of GAL immunoreactivity in the ME. These reductions are prevented in part by a combined hormonal treatment associating T4, GH, C and E2, but not by any hormone given alone. This suggests specific pituitary hormone-dependent regulation of the hypophysiotropic GAL neurons. In contrast, the increased GAL labeling in magnocellular neurons of hypophysectomized rats persists despite hormonal treatment and likely represents a lesional effect on the neurohypophyseal GAL system. |
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Authors:
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P L Selvais; E Adam; I M Colin; J Z Kasa-Vubu; J F Denef; D M Maiter |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Neuroendocrinology Volume: 60 ISSN: 0028-3835 ISO Abbreviation: Neuroendocrinology Publication Date: 1994 Oct |
Date Detail:
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Created Date: 1995-02-16 Completed Date: 1995-02-16 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0035665 Medline TA: Neuroendocrinology Country: SWITZERLAND |
Other Details:
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Languages: eng Pagination: 368-77 Citation Subset: IM |
Affiliation:
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Unité de Diabétologie et Nutrition, Université de Louvain, Bruxelles, Belgique. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Blotting, Northern Female Galanin Hypophysectomy Hypothalamus / cytology, metabolism, physiology* Immunohistochemistry Neurons / metabolism, physiology* Neuropeptides / metabolism, physiology* Peptides / metabolism, physiology* Pituitary Gland / physiology* Pituitary Hormones / physiology* RNA, Messenger / biosynthesis Radioimmunoassay Rats Rats, Wistar |
| Grant Support | |
ID/Acronym/Agency:
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ST 32 DK 07245-14/ST/OHS HRSA HHS |
| Chemical | |
Reg. No./Substance:
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0/Neuropeptides; 0/Peptides; 0/Pituitary Hormones; 0/RNA, Messenger; 88813-36-9/Galanin |
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