Antro-pancreatic reflexes: long- and short-route reflexes in exocrine and endocrine pancreatic secretion in dogs

Pancreatic exocrine secretion is known to be facilitated by gastric antral distension via long- and short-route reflexes. In this study, we studied the effects of gastric distension on intra-pancreatic nerve discharges and blood insulin level as well as pancreatic exocrine secretion. Mongrel dogs were anesthetized with ketamine and thiopental, and immediately decerebrated. This study consisted of two series of experiments. In the first series, efferent discharges in an intra-pancreatic nerve branch were recorded, and its responses to antral distension were analyzed. In the second series, effects of antral distension on pancreatic exocrine secretion and blood insulin level were observed before and after vagotomy in splanchnicectomized dogs. Efferent discharges in a pancreatic nerve branch were increased by antral distension. Neither vagotomy nor splanchnicectomy produced obvious changes in the neural response. In splanchnicectomized dogs, antral distension elevated blood insulin level and increased pancreatic exocrine secretion. After subsequent vagotomy, these effects were reduced, but the increases were still greater than 50%. These results indicate that the antro-pancreatic short-route reflex plays a significant role in exocrine secretion, and also suggest that insulin release is increased by antral distension independent of blood glucose level.