EFFECTS OF AUTONOMIC NERVOUS-SYSTEM ON GASTRIC DAMAGE BY ETHANOL IN THE RAT

To study whether or not the autonomic nervous system influences the defense mechanisms of the gastric mucosa, groups of Sprague-Dawley rats were given stimulants and inhibitors of the different components of the vagus and celiac nerves before administration of absolute or 70% w/v ethanol. The effects of vagotomy and sympathectomy on "adaptive cytoprotection" were studied, as were the effects of blocking the muscarinic receptors and stimulation of β-adrenergic receptors. We found that: (1) cholinomimetic agents and norepinephrine make the damage caused by 70% ethanol worse; (2) atropine is the only agent that fully protects against absolute ethanol; (3) vagotomy and sympathectomy abolish the effects of atropine and adaptive cytoprotection; and (4) β-adrenergic stimulation replaces conditions that allow adaptive cytoprotection and the protection by anticholinergics. These results suggest that two different reflexes are triggered by ethanol: when low concentrations are given, the β-adrenergic-mediated effect is prevalent, with protection of the mucosa; when high concentrations are given, the cholinergic- mediated effect is prevalent with damage of the mucosa.