Clonidine injected intracerebroventricularly (i.c.v.) (0.47 nmol/rat) exerted gastric mucosal protective effect against acidified ethanol. Evidence was obtained that the gastroprotective effect of clonidine was blocked by i.c.v. injected α2-adrenoceptor antagonists yohimbine (non-subtype selective antagonist), prazosin and 2-[2-(4-(O-methoxyphenyl)piperazin-1-yl)ethyl]-4,4-dimethyl-1,3-(2H,4H)-isoquinolindione (ARC-239) (representative α(2B/2C)-adrenoceptor blocking agents) and opioid receptor antagonists naloxone (a non-selective, moderately μ-opioid receptor preferring antagonist), naltrindole and naltriben δ-opioid receptor antagonists). The centrally injected naltrindole (0.5 nmol/rat) antagonised also the gastroprotective effect of clonidine - but not that of the δ-agonist [D-Ala2, D-Leu5]enkephalin - administered peripherally. The results suggest that central α(2B/2C)-adrenoceptor subtypes and opioid - particularly δ - receptors are likely to be involved in the gastric mucosal protective effect of clonidine. Copyright (C) 2000 Elsevier Science B.V.
- Opioid receptor
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