Document Detail

Immunoblotting technique to study release of melanophore-stimulating hormone from individual melanotrope cells of the intermediate lobe of Xenopus laevis.
MedLine Citation:
PMID:  1333944     Owner:  NLM     Status:  MEDLINE    
The melanotrope cells in the pars intermedia in the pituitary of Xenopus laevis synthesize and release the melanophore-stimulating hormone (alpha MSH), a small peptide that causes skin darkening during the process of background adaptation. Evidence has been found for a heterogeneity in biosynthetic activity of the melanotrope cells. In the present study two questions were addressed: (1) does the melanotrope cell population also show heterogeneous alpha MSH-release, and (2) can this heterogeneity be changed by extracellular messengers? Since dopamine is known to inhibit alpha MSH-release, this messenger is used to study the regulation of the heterogeneity. To quantify alpha MSH-release from individual cells, a cell blotting procedure has been developed for the binding and relative quantification of the small alpha MSH peptide. The immunoblotting procedure involves binding of the cells to a carrier slide and binding of released alpha MSH to a nitrocellulose filter. After immunostaining, the amount of alpha MSH per cell was quantitated by image analysis. Untreated melanotrope cells reveal a distinct variability in alpha MSH-release, some cells showing low secretory activity, whereas others are strongly secreting, indicating heterogeneity of alpha MSH-release. Dopamine treatment strongly inhibits alpha MSH-release from individual cells, resulting in a clearly less pronounced melanotrope cell heterogeneity. The effect of dopamine appears to be dose-dependent as a low dopamine concentration has only a moderate effect on the alpha MSH-release. It is proposed that dopamine is a physiological regulator of the degree of melanotrope cell heterogeneity in alpha MSH-release.
E P de Rijk; M Terlou; P M Cruijsen; B G Jenks; E W Roubos
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Cytometry     Volume:  13     ISSN:  0196-4763     ISO Abbreviation:  Cytometry     Publication Date:  1992  
Date Detail:
Created Date:  1993-01-13     Completed Date:  1993-01-13     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8102328     Medline TA:  Cytometry     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  863-71     Citation Subset:  IM    
Department of Animal Physiology, University of Nijmegen, The Netherlands.
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MeSH Terms
Dopamine / pharmacology,  physiology
Image Processing, Computer-Assisted / instrumentation
Immunoblotting / methods*
Pituitary Gland / cytology,  drug effects,  secretion*
Xenopus laevis / physiology*
alpha-MSH / secretion*
Reg. No./Substance:

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