[Analysis of central mechanisms involved in gastric mucosal integrity].

Beta-endorphin, deltorphin II, [D-Ala2, Phe4, Gly5-ol-enkephalin (DAGO) as well as endomorphin-1 and endomorphin-2 injected intracerebroventricularly (i.c.v.) induced gastroprotective action. It has been raised that endogenous opioids may have a central role in maintaining gastric mucosal integrity. Therefore we aimed to study the role of endogenous opioid system in the gastroprotective action induced by activation of alpha 2-adrenoceptors, nociceptin- and cannabinoid-receptors. Our results suggest that the non-selective opioid receptor antagonist naloxone (27 nmol i.c.v.) and the delta-opioid receptor antagonist naltrindole (5 nmol i.c.v.) abolished the mucosal protective effect of alpha 2-adrenoceptor agonists clonidine (470 pmol i.c.v.) and rilmenidine (45 pmol i.c.v.), nociceptin (1 nmol i.c.v.) and the cannabinoid receptor agonist anandamide (110 nmol i.c.v.). Based on our findings it can be raised that opioid system besides its well known regulatory functions might be involved in maintenance of gastric mucosal integrity.