Document Detail


In vitro characterization of the effects of endomorphin 1 and 2, endogenous ligands for mu-opioid receptors, on mouse colonic motility.
MedLine Citation:
PMID:  17274956     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effects of endomorphin 1 (EM1) and 2 (EM2) in colonic motility remain unknown. We investigated the effects and mechanisms of these endomorphins (EMs) on the colonic motility in vitro by applying various neural blocking agents and various opioid receptor antagonists. EMs (10(-9) to 10(-6)M) displayed significant stimulatory effects on the basal tonus or spontaneous activity of mouse colon but not of stomach and small intestine. It is noteworthy that the contractile actions of EMs varied slightly among different regions of colonic longitudinal muscle layers, whereas the contractile responses induced by EMs were significantly different among different regions of circular muscle layers. EMs-induced longitudinal or circular muscle contractions were not significantly affected by atropine, N(G)-nitro-l-arginine methyl ester, phentolamine, propranolol and methysergide. Tetrodotoxin, indomethacin and naloxone completely abolished the EMs-induced colonic contractions. Surprisingly, EMs (10(-7)M)-induced longitudinal muscle contractions were significantly attenuated by nor-binaltorphimine (3x10(-6)M). By contrast, pretreatment with naltrindole (10(-6)M) did not significantly affect EMs-induced longitudinal or circular muscle contractions. Interestingly, the circular muscle contractions in response to EM2 (10(-7)M) were not fully blocked by beta-funaltrexamine (6x10(-6)M). Naloxonazine (10(-6)M) almost fully antagonized the EMs-induced longitudinal or circular muscle contractions, and these effects could be only partially reversed by extensive washing. All the results indicated that the mechanisms and sites of actions of EMs were region-specific. Furthermore, these findings showed that the activation of multiple subtypes of opioid receptors, possibly including mu(1) (naloxonazine-sensitive), mu(2) and even other forms of muORs (beta-FNA-insensitive), was required for EMs-induced mouse colonic motility.
Authors:
Ye Yu; Yun Cui; Xiang Wang; Lu-hao Lai; Chang-Lin Wang; Ying-zhe Fan; Jing Liu; Rui Wang
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-01-10
Journal Detail:
Title:  Biochemical pharmacology     Volume:  73     ISSN:  0006-2952     ISO Abbreviation:  Biochem. Pharmacol.     Publication Date:  2007 May 
Date Detail:
Created Date:  2007-03-27     Completed Date:  2007-05-17     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0101032     Medline TA:  Biochem Pharmacol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1384-93     Citation Subset:  IM    
Affiliation:
Institute of Biochemistry and Molecular Biology, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, China.
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MeSH Terms
Descriptor/Qualifier:
Analgesics, Opioid / pharmacology
Animals
Colon / cytology
Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / pharmacology
Gastrointestinal Motility / drug effects*
Intestine, Small / cytology
Mice
Morphine / pharmacology
Muscle Contraction / drug effects
Muscle, Smooth / drug effects*,  physiology
Oligopeptides / pharmacology*
Receptors, Opioid, mu / drug effects,  physiology*
Stomach / cytology
Chemical
Reg. No./Substance:
0/Analgesics, Opioid; 0/Oligopeptides; 0/Receptors, Opioid, mu; 0/endomorphin 1; 100929-53-1/Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; 57-27-2/Morphine

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