title: Effects of morphine and naloxone on stress ulcer formation and gastric acid secretion.
abstract: The effect of both acute and chronic morphine and naloxone on restraint-stress gastric ulcer formation and on basal gastric acid secretion were examined in the conscious rat. Acute morphine administration produced a dose-related decrease in stress ulceration and basal gastric acid secretion. Acute naloxone treatment resulted in a dose-related increase in stress ulcer formation and markedly augmented gastric acid secretion. Naloxone (4.0 mg/kg) antagonized the ulcer-reducing effects at all doses of morphine tested (4.0-32.0 mg/kg). Morphine-dependent rats, restrained during spontaneous or naloxone-precipitated withdrawal, exhibited the most severe ulceration. However, only those subjected to naloxone-precipitated withdrawal produced a significant increase in gastric acid output. Chronic treatment with naloxone or with chronic naloxone followed by morphine (16.0 mg/kg) resulted in augmented stress ulcer formation relative to all acutely treated groups. Both chronic naloxone-treated groups exhibited markedly enhanced gastric secretion. These data suggest that central and/or peripheral opiate receptors can modulate both basal and stress-perturbed gastric function.
mesh_terms: D000818:Animals; D005744:Gastric Acid / Q000378:metabolism*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012149:Restraint, Physical; D013276:Stomach Ulcer / Q000209:etiology / Q000517:prevention & control*; D013315:Stress, Psychological / Q000150:complications*; D013997:Time Factors
chemical_list: D009270:Naloxone; D009020:Morphine