Duodenal ulcer induced by MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine).

Experiments in rats revealed that the parkinsonian drug 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) given in multiple daily doses either per os (p.o.) or subcutaneously (s.c.) induced in a dose-dependent manner solitary or double ("kissing") duodenal ulcers in the rat. MPTP also diminished cerebral concentrations of DOPAC and the duodenal ulcers were prevented by pretreatment with dopamine agonists (e.g., bromocriptine, lergotrile) or monoamine oxidase inhibitors (e.g., pargyline, 1-deprenyl). High doses of MPTP also caused gastric erosions and motility changes resembling parkinsonism (e.g., akinesia, rigidity, forward bending of trunk). This chemical decreased gastric secretion of acid and pepsin, as well as pancreatic bicarbonate, trypsin and amylase. Thus, MPTP causes duodenal ulcers that are possibly associated with impaired defense in the duodenal bulb (e.g., decreased availability of duodenal and pancreatic bicarbonate).