Effect of Splanchnic Nerve Stimulation on Glucagon and Insulin Secretion

Abstract

In order to study the role of the splanchnic nerves in the control of glucagon and insulin secretion, the distal stump of the splanchnic nerve was electrically stimulated at the diaphragmatic level first on the left side and then on the right with an interval of 100 min in an anesthetized dog. During the stimulation, systemic plasma glucose level rapidly rose and glucagon and insulin in the pancreatic vein blood showed a delayed rise in response to the stimulation, followed by a rebound rise in pancreatic vein blood insulin on cessation of the stimulation. An immediate augmentation of the pancreatic venous blood flow and a slower increase in hematocrit were also found. A significant increase of glucagon and insulin secretion was found upon taking into consideration of these hemodynamic changes. Pretreatment with phentolamine resulted in a rise of the basal level of insulin in the pancreatic vein blood and disappearance of the rebound after stimulation. In propranolol-pretreated animals, the basal secretion of glucagon was significantly suppressed and the rise during the first stimulation was smaller, along with a significant decrease of insulin secretion during the stimulation and exaggerated poststimulatory rebound phenomenon. These effects of the blocking agents suggest a possibility of adrenergic receptor mechanisms operating in glucagon secretion as well as insulin release.