Diazepam and muscimol blockade of the gastrointestinal motor disturbances induced by acoustic stress in dogs.

The influence of various drugs on the gastric motor inhibition induced by acoustic stress (AS) was investigated in fasted dogs fitted with strain-gauge transducers implanted on the antrum and proximal jejunum at 10 and 80 cm from the pylorus respectively. Started 40-50 min after the last gastric migrating motor complex (MMC), a 1 h acoustic stress delayed by 75% the occurrence of the next gastric but not jejunal MMC and was associated with a 4-fold increase in plasma cortisol. This AS-induced inhibition of the gastric MMC cycle was abolished after previous administration of diazepam (0.2 and 0.5 mg/kg i.m.) or muscimol (10 micrograms/kg i.v.) and partially reduced by a lower dose of diazepam (0.1 mg/kg i.m.); in contrast, it was still present after either naloxone (0.1 mg/kg i.m.), phentolamine (0.2 mg/kg i.v.) or propranolol (0.1 mg/kg i.v.) treatment. This selective benzodiazepine or GABA agonist blockade of noise-induced gastric motor alteration supports the hypothesis that release of CRF may be responsible for the gastrointestinal motor effects induced by acoustic stress.