INVOLVEMENT OF DA1AND DA2RECEPTORS IN THE GASTROPROTECTIVE ACTIVITY OF AMYLIN IN THE RAT

Peripheral administration of amylin (40 μg kg−1) exerts gastroprotective effects in the reserpine-induced gastric lesions in the rat. This activity is decreased by pretreatment (30 min before) with (−)-sulpiride (0.1 mg kg−1s.c.) or domperidone (0.1–2.5 mg kg−1per os), dopamine DA2antagonists. Pretreatment with SCH 23390 (0.5–4 mg kg−1s.c.), a DA1antagonist, at the maximal dose used, also significantly decreased the gastroprotective activity of the peptide. Amylin does not exert any gastroprotective effect in indomethacin-pretreated rats (7.5 mg kg−1s.c., 30 min before), as well as in the aspirin-induced ulcer test (200 mg kg−1per osat the time of amylin administration). Our data confirm that the gastroprotective effect of amylin in reserpine-induced gastric lesions involves, at least in part, the dopaminergic transmission, interfering with both the DA1and DA2receptor subtypes.