Document Detail

Mu opioid receptors in rat ventral medulla: effects of endomorphin-1 on phrenic nerve activity.
MedLine Citation:
PMID:  14609508     Owner:  NLM     Status:  MEDLINE    
Anatomical and in vitro studies suggest that mu opioid receptors (MOR) on pre-Bötzinger complex neurons are responsible for opioid induced respiratory depression (Grey et al., Science 286 (1999) 1566). However, mu opioid agonists injected in vivo, in other regions of the ventral respiratory group (VRG), produce respiratory depression, suggesting that opioids are widely distributed in the VRG. We therefore re-examined the distribution of the MOR in the ventral medulla and found MOR-immunoreactive neurons and terminals in all subdivisions of the VRG. Furthermore, we determined, in rats, the effects of a MOR agonist (endomorphin-1, 10 mM, 60 nl, unilateral), microinjected into different subdivisions of the VRG, on phrenic nerve activity. Endomorphin-1 produced changes in phrenic nerve frequency and amplitude, throughout the VRG. Unexpectedly, endomorphin-1 microinjected into the Bötzinger and pre-Bötzinger complexes consistently increased phrenic nerve frequency. These results support the widespread distribution of MOR in the VRG and also indicate that endomorphin-1, a postulated endogenous ligand, may differentially regulate respiration.
Tina Lonergan; Ann K Goodchild; Macdonald J Christie; Paul M Pilowsky
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Respiratory physiology & neurobiology     Volume:  138     ISSN:  1569-9048     ISO Abbreviation:  Respir Physiol Neurobiol     Publication Date:  2003 Nov 
Date Detail:
Created Date:  2003-11-11     Completed Date:  2004-01-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  101140022     Medline TA:  Respir Physiol Neurobiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  165-78     Citation Subset:  IM    
Department of Pharmacology, University of Sydney, Camperdown, NSW 2006, Australia.
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MeSH Terms
Action Potentials / drug effects
Analgesics, Opioid / pharmacology*
Blood Pressure / drug effects
Immunohistochemistry / methods
Medulla Oblongata / anatomy & histology,  drug effects*,  metabolism
Oligopeptides / pharmacology*
Phrenic Nerve / drug effects*,  physiology
Rats, Sprague-Dawley
Receptors, Opioid, mu / metabolism*
Time Factors
Reg. No./Substance:
0/Analgesics, Opioid; 0/Oligopeptides; 0/Receptors, Opioid, mu; 0/endomorphin 1

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