Document Detail


Retrogradely labelled neurosecretory neurones of the rat hypothalamic arcuate nucleus express Fos protein following systemic injection of GH-releasing peptide-6.
MedLine Citation:
PMID:  8958794     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Previously, we demonstrated that the synthetic hexapeptide GH-releasing peptide (GHRP-6) activates a subpopulation of arcuate neurones, as reflected by increased electrical activation and by the detection of Fos protein in cell nuclei. Here we set out to determine (1) what proportion of the cells activated by GHRP-6 are neurosecretory neurones and (2) whether the cells activated by GHRP-6 contain tyrosine hydroxylase (TH; a marker of dopaminergic cells in this region) or beta-endorphin. In the first study, adult male rats were injected i.v. with the retrograde tracer, Fluorogold, to detect cells which project outside the blood-brain barrier (and are therefore likely to be neurosecretory neurones). Three days later the conscious rats were injected i.v. with 50 micrograms GHRP-6 and the brains processed for the immunocytochemical detection of Fos protein. Between 68% and 82% of the arcuate neurones expressing Fos protein following GHRP-6 injection were retrogradely labelled with Fluorogold. In the second study, conscious male rats, bearing a chronically implanted jugular catheter, were killed 90 min following an i.v. injection of 50 micrograms GHRP-6 and the brains were processed for the double immunocytochemical detection of Fos protein and either TH or beta-endorphin. Less than 7% (mean +/- S.E.M. = 6.7 +/- 2.6% nuclei/section per rat) of the arcuate neurones expressing Fos protein following GHRP-6 injection were TH-containing cells. Of 143 beta-endorphin-containing arcuate cells detected only four cells were identified as containing Fos protein. Thus, the majority of arcuate neurones activated by GHRP-6 (1) project outside the blood-brain barrier (and are therefore likely to be neuro-secretory neurones) and (2) were not identified as TH- or beta-endorphin-containing cells.
Authors:
S L Dickson; O Doutrelant-Viltart; R E Dyball; G Leng
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of endocrinology     Volume:  151     ISSN:  0022-0795     ISO Abbreviation:  J. Endocrinol.     Publication Date:  1996 Nov 
Date Detail:
Created Date:  1997-01-02     Completed Date:  1997-01-02     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0375363     Medline TA:  J Endocrinol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  323-31     Citation Subset:  IM    
Affiliation:
Laboratory of Neuroendocrinology, Babraham Institute, Cambridge, UK.
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MeSH Terms
Descriptor/Qualifier:
Animals
Arcuate Nucleus / chemistry,  metabolism*
Growth Hormone-Releasing Hormone*
Immunohistochemistry
Male
Neurons / chemistry,  metabolism
Neurosecretory Systems / drug effects,  metabolism*
Oligopeptides / pharmacology*
Proto-Oncogene Proteins c-fos / metabolism*
Rats
Rats, Wistar
Tyrosine 3-Monooxygenase / analysis
beta-Endorphin / analysis
Chemical
Reg. No./Substance:
0/Oligopeptides; 0/Proto-Oncogene Proteins c-fos; 60617-12-1/beta-Endorphin; 87616-84-0/growth hormone releasing hexapeptide; 9034-39-3/Growth Hormone-Releasing Hormone; EC 1.14.16.2/Tyrosine 3-Monooxygenase

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