A quantitative study of the effects of anaesthesia and stress of operation on gastric secretion in rats

Morphine reduces vagal-stimulated gastric acid secretion through a central action

The influence of morphine on gastric acid secretion stimulated by 2-deoxy-D-glucose or electrical vagal stimulation was studied in anaesthetised rats with perfused stomachs. It was found that changes in gastric acid output induced by electrical vagal stimulation were not noticeably affected, whereas those evoked by 2-deoxy-D-glucose were significantly suppressed by morphine pretreatment. The depressant effect of the opiate on the acid secretion stimulated by 2-deoxy-D-glucose was abolished by naloxone pretreatment. It is suggested that morphine inhibits vagal-stimulated gastric acid secretion in rats by acting predominantly on opioid receptors in the central nervous system.

Acute gastric ulcer formation in response to electrical vagal stimulation in rats

Intermittent electrical stimulation of the left cervical vagus increased intragastric pressure and induced a 100% incidence of haemorrhagic ulcers in the glandular mucosa of rat stomachs. Atropine pretreatment of sub-diaphragmatic vagotomy prevented these effects. The findings substantiate the idea that stress-induced glandular ulcers result from vagal-mediated increased gastric contractions.