The influence of dopamine agonists and antagonists on indomethacin lesions in stomach and small intestine in rats.

Dopamine agents (saline in control groups) were coadministered with indomethacin by either single or repeated application. The ulcerogenic effect (erosions and/or ulcers) of repeated given indomethacin on gastric mucosa differed clearly from that on intestinal mucosa. The effect on intestinal mucosa was markedly greater than after a single dose. The effects of dopamine agents appeared to be more consistent. Domperidone and haloperidol, given as single or repeated doses, strongly aggravated both the gastric and intestinal lesions. Bromocriptine and amantadine had a protective effect. The adverse effects of both dopamine antagonists (increased after repeated administration) were strongly inhibited by the simultaneous administration of either bromocriptine or amantadine. The involvement of the dopamine system (central or peripheral) in the mechanisms that maintain gastric (probably related to cytoprotection also) and intestinal mucosa integrity is therefore suggested.