Document Detail

Effects of hypophysectomy and dexamethasone treatment on plasma beta-endorphin and pain threshold during pregnancy.
MedLine Citation:
PMID:  2959351     Owner:  NLM     Status:  MEDLINE    
During pregnancy, rats and humans show an increase in pain threshold that is mediated by an endorphin system. In order to determine whether plasma beta-endorphin and/or other factors of pituitary origin are involved in pregnancy-induced analgesia in the rat, the effects of hypophysectomy (day 12 of pregnancy) or pharmacological suppression of pituitary function via dexamethasone administration (day 14-21 of pregnancy) were investigated. Hypophysectomy did not affect either the magnitude of the increase or the pattern of change in pain threshold despite the resulting decrease in stress-induced plasma beta-endorphin concentrations. However, the observed effect of the surgical and/or postsurgical procedure on pain threshold confounded unequivocal interpretation of these results. Pharmacological suppression of pituitary function with dexamethasone (2 micrograms/ml), a non-invasive procedure, also produced a significant decrease in resting plasma beta-endorphin levels. As was observed for surgical removal of the pituitary gland, this treatment did not produce a significant alteration in the magnitude of the increase in jump threshold. Furthermore, no correlation was found between plasma beta-endorphin concentrations and jump threshold values on day 21 of pregnancy. These results indicate that the pituitary gland does not play an essential role in the maintenance of opioid analgesia during pregnancy. It is suggested that pregnancy-induced analgesia depends on central rather than peripheral opioid systems.
S A Baron; A R Gintzler
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Brain research     Volume:  418     ISSN:  0006-8993     ISO Abbreviation:  Brain Res.     Publication Date:  1987 Aug 
Date Detail:
Created Date:  1987-12-09     Completed Date:  1987-12-09     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0045503     Medline TA:  Brain Res     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  138-45     Citation Subset:  IM    
Department of Biochemistry and Psychiatry, State University of New York, Brooklyn 11203.
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MeSH Terms
Dexamethasone / pharmacology*
Pain / metabolism*,  physiopathology
Pain Measurement
Pituitary Gland / drug effects,  metabolism*
Pregnancy, Animal / drug effects,  metabolism*
Rats, Inbred Strains
Stress, Physiological / blood
beta-Endorphin / blood*
Grant Support
Reg. No./Substance:
50-02-2/Dexamethasone; 60617-12-1/beta-Endorphin

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