Two subtypes of enteric non-opioid sigma receptors in guinea-pig cholinergic motor neurons.
In the longitudinal muscle-myenteric plexus preparation (LMMP) of the guinea-pig ileum, the non-opioid sigma receptors agonists, 1,3-di-ortho-tolylguanidine (DTG) and (+)N-allyl-N-normetazocine [(+)SKF 10,047], had opposite effects on nerve-mediated cholinergic contractions caused by electrical field stimulation. DTG (0.1-10 microM) inhibited and (+)SKF 10,047 (0.1-10 microM) markedly enhanced these contractile responses. Both effects were evaluated in the presence (0.5 or 1 microM) of the putative antagonists at central sigma sites: haloperidol, rimcazole, BMY 14802 and dextromethorphan. Haloperidol and dextromethorphan were ineffective. Rimcazole antagonized the effect of both DTG and (+)SKF 10.047. BMY 14802 antagonized the (+)SKF 10.047-mediated excitatory response only. These results suggest that two sigma receptor subtypes are present in enteric cholinergic motor neurons innervating the longitudinal coat. Rimcazole and BMY 14802 may provide useful tools for the characterization of peripheral non-opioid sigma receptors.
Department of Internal Medicine and Therapeutics, University of Pavia, Italy.
T
T
Coccini
L G
LG
Costa
L
L
Manzo
S M
SM
Candura
N
N
Iapadre
B
B
Balestra
M
M
Tonini
D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology; D014150:Antipsychotic Agents / Q000494:pharmacology; D002227:Carbazoles / Q000494:pharmacology; D003915:Dextromethorphan / Q000494:pharmacology; D004558:Electric Stimulation; D006146:Guanidines / Q000494:pharmacology; D006168:Guinea Pigs; D006220:Haloperidol / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009046:Motor Neurons / Q000187:drug effects*; D009197:Myenteric Plexus / Q000187:drug effects; D010275:Parasympathetic Nervous System / Q000166:cytology / Q000187:drug effects*; D010620:Phenazocine / Q000031:analogs & derivatives / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D011957:Receptors, Opioid / Q000187:drug effects*; D017480:Receptors, sigma
D014151:Anti-Anxiety Agents; D014150:Antipsychotic Agents; D002227:Carbazoles; D006146:Guanidines; D011743:Pyrimidines; D011957:Receptors, Opioid; D017480:Receptors, sigma; C050408:alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazine butanol; D003915:Dextromethorphan; C012134:SK&F 10047; C034931:rimcazole; D010620:Phenazocine; D006220:Haloperidol; C050232:1,3-ditolylguanidine