Neural mechanisms involved in the delay of gastric emptying and gastrointestinal transit of liquid after thoracic spinal cord transection in awake rats

Spinal cord transection (SCT) delays gastric emptying (GE), and intestinal and gastrointestinal (GI) transit of liquid in awake rats. This study evalu ates the neural mechanisms involved in this phenomenon. Male Wistar rats (N = 147) were fasted for 16 h and had the left jugular vein cannulated follo wed by laminectomy or laminectomy + complete SCT between T-4 and T-5 verteb rae. The next day, a test meal (1.5 ml of a phenol red solution, 0.5 mg/ml in 5% glucose) was administered by gavage feeding and 10 min later cervical dislocation was performed. Dye recovery in the stomach, and proximal, mid and distal small intestine was determined by spectrophotometry. SCT inhibit ed GE and GI transit since it increased gastric recovery by 71.3% and decre ased mid small intestine recovery by 100% (P < 0.05). Subdiaphragmatic vago tomy, celiac ganglionectomy + section of the splanchnic nerves, i.v. hexame thonium (20 mg/kg) or yohimbine (3 mg/kg) prevented the development of the SCT effect on GE and GI transit. Pretreatment with i.v. naloxone (3, mg/kg) , L-NAME (3 mg/kg) or propranolol (2 mg/kg) was ineffective. Bilateral adre nalectomy or guanethidine (10 mg/kg) increased the magnitude of the GE inhi bition, while i.v. prazosin (1 mg/kg) or atropine (0.5 mg/kg) decreased the magnitude but did not abolish the GE inhibition. In summary, the inhibitio n of GI motility observed 1 day after thoracic SCT in awake rats seems to i nvolve vagal and possibly splanchnic pathways. (C) 2001 Elsevier Science B. V. All rights reserved.