Naloxone and restraint stress: effects on gastric mucosal injury and gastric function

Contradictory findings have been reported from previous investigations of the effects of opiate receptor blockade on stress-related gastric injury. We performed two studies of the effects of naloxone on gastric mucosal injury and gastric function in cold restraint stress. In the first, naloxone had a linear, dose-dependent effect, reducing mucosal injury both parenterally and enterally. Gastric acidity was not related to the dose of naloxone, or to the amount or extent of mucosal injury. Gastric residual volume, by contrast, was related to both naloxone dose and gastric mucosal injury. In the second study we investigated the effect of gastric distention by enteral vehicle in the restraint model, and the interaction of the vehicle with the effects of naloxone. Periodic distention of the stomach with enteral vehicle did not alter the drug's effects on mucosal injury or on gastric residual volume. Because cold restraint stress produces harmful gastric contractions, naloxone is likely to be protective by altering gastric motility.