Effect of Different Denervation Procedures on Catecholamines in the Gut

Abstract

Sympathectomy has been used to study the role of the sympathetic nervous system in the control of gastric acid secretion. Conflicting results may reflect differences in the sympathectomy procedures used. In a previous study we showed a reduction of catecholamines by more than 90% in the gut wall of the rat after surgical upper abdominal sympathectomy. The aim of the present investigation was to ascertain whether chemical sympathectomy was equally effective and whether total denervation, including combined chemical and surgical sympathectomy together with bilateral truncal vagotomy, would lower the catecholamine levels further. The results showed that chemical sympathectomy reduced noradrenaline levels in fundus (oxyntic) and antrum mucosa to levels similar to those after surgical sympathectomy (< 5%), but the reduction was less pronounced in the muscle layer of the fundus and antrum and in the pancreas and spleen. Combined surgical and chemical sympathectomy did not reduce noradrenaline more effectively than surgical sympathectomy alone. Vagotomy reduced catecholamines in the stomach by about 50%; in extragastric tissues vagotomy was without effect. Total denervation, including combined surgical and chemical sympathectomy plus vagotomy, did not reduce noradrenaline levels more than surgical sympathectomy alone, suggesting that the proportion of adrenergic fibers that derive from the vagus is quantitatively insignificant but that the vagus exerts a local control of the sympathetic stores of gastric catecholamines. Thus, surgical upper abdominal sympathectomy is the method of choice in studies of the role of the sympathetic nervous system in regulating gastric functions. Adrenaline and dopamine levels were much lower than the noradrenaline levels but showed roughly the same trends of changes after the denervations (except that chemical sympathectomy did not affect dopamine). There was no evidence that a significant proportion of the catecholamines in the gut and pancreas were present in intramural neurones.

Key Words:

• Adrenaline
• catecholamines
• dopamine
• gastric function
• noradrenaline
• sympathectomy