Influence of acoustic stress by noise on gastrointestinal motility in dogs.

The effects of acoustic stress (AS) on gastrointestinal motility and their prevention by previous treatment with naloxone, phentolamine, propranolol, muscimol, and diazepam were investigated in intact and vagotomized fasted dogs fitted with chronically implanted strain gauges on the antrum at 10 cm from pylorus and on the jejunum at 70 and 140 cm from the pylorus. These effects were compared to those produced by intracerebroventricular administration of ovine corticotropin releasing factor (oCRF). Beginning 40-50 min after the occurrence of a gastric migrating motor complex (MMC), a 1-hr hearing of prerecorded intense music through earpieces (less than 100 dB) delayed the occurrence of the next gastric MMC observed after 2.8 +/- 1.2 hr, while jejunal MMC were still present at a normal frequency. During AS, heart rate and plasma cortisol were significantly increased by 32.7 and 215%, respectively, 10-15 min after the beginning of hearing. The AS-induced lengthening of the gastric MMC cycle as well as cortisol increase were abolished after previous administration of diazepam (0.5 mg/kg intramuscular) or muscimol (10 micrograms/kg intravenous), while they were still present after naloxone (0.1 mg/kg intravenous), phentolamine (0.2 mg/kg intravenous), or propranolol (0.1 mg/kg intravenous). CRF administered intracerebroventricularly (100 ng/kg) also delayed the occurrence of gastric MMC without affecting jejunal motility, and this effect was not antagonized by previous treatment with diazepam or muscimol. Both the effects of AS and CRF were abolished after bilateral thoracic vagotomy.(ABSTRACT TRUNCATED AT 250 WORDS)