Comparative influences of acoustic and cold stress on gastrointestinal transit in mice

The effects of acoustic and cold stress on gastric emptying and intestinal transit were evaluated in mice treated with saline, diazepam, muscimol, propranolol, and naloxone using a radiolabeled chromium test meal. Acoustic stress (AS) was produced by playing music from a magnetic tape through loudspeakers (less than 86 dB) in a confined box at room temperature; and cold stress (CS) was produced by cold (10 degrees C) exposure. AS and CS sessions lasted 20 min. Both AS and CS were accompanied by a significant (P less than 0.05) increase in gastric emptying during at least 1 h. When measured 30 min after the meal, AS and CS increased gastric emptying from 43% of the test meal to 63 and 73%, respectively. Only CS affected intestinal transit, causing a 12.1% increase of the geometric center when measured 30 min after the test meal. Diazepam (0.5 mg/kg) muscimol (0.5 mg/kg), or propranolol (1 mg/kg) administered intraperitoneally reduced or abolished the effects of AS and CS on both gastric emptying and intestinal transit. In contrast naloxone (0.2 mg/kg im), which increased gastric emptying when injected alone, was unable to affect the AS-induced alterations of gastric emptying but partially reduced those of CS. Intracerebroventricular administration of corticotropin-releasing factor (250 ng/kg) also increased by 52.1% the gastric emptying, whereas the geometric center was not affected. It is concluded that both AS and CS accelerate gastric emptying in mice.(ABSTRACT TRUNCATED AT 250 WORDS)