Gastric emptying and gastrointestinal transit of liquid throughout the first month after thoracic spinal cord transection in awake rats.

Spinal cord transection (SCT) inhibits gastrointestinal motility in awake rats. We studied the gastric emptying (GE) and gastrointestinal transit of liquid throughout the first month after thoracic SCT. Male Wistar rats (N = 66) were submitted to laminectomy followed or not by complete SCT between T4 and T5 vertebrae. Phenol red recovery in the stomach, proximal, mid-and distal small intestine was determined 1, 7, 10, 15, and 30 days thereafter. Gastric recovery increased by 51.2 and 38.9% and mid-intestinal recovery decreased by 45.5 and 66.6% at one and seven days after SCT (P < 0.05). Proximal small intestine recovery increased by 45.9% 10 days after SCT but no inhibition of gastrointestinal motility was observed thereafter. Stool output significantly decreased in the first seven days after SCT (P < 0.05). In summary, gastrointestinal motility in awake rats is inhibited throughout the first 10 days after thoracic SCT but not thereafter.

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 evaluates the neural mechanisms involved in this phenomenon. Male Wistar rats (N = 147) were fasted for 16 h and had the left jugular vein cannulated followed by laminectomy or laminectomy + complete SCT between T4 and T5 vertebrae. 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 inhibited GE and GI transit since it increased gastric recovery by 71.3% and decreased mid small intestine recovery by 100% (P < 0.05). Subdiaphragmatic vagotomy, celiac ganglionectomy + section of the splanchnic nerves, i.v. hexamethonium (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 (2 mg/kg), L-NAME (3 mg/kg) or propranolol (2 mg/kg) was ineffective. Bilateral adrenalectomy or guanethidine (10 mg/kg) increased the magnitude of the GE inhibition, 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 inhibition of GI motility observed 1 day after thoracic SCT in awake rats seems to involve vagal and possibly splanchnic pathways.