ACTIVATION OF RAT PANCREAS MECHANOSENSITIVE SPINAL AFFERENTS IN A NOVEL IN VITRO PREPARATION

Abstract

Few studies have recorded afferent nerve discharge from the pancreas and the role of afferent nerves in pancreatic physiology and pathophysiology is very poorly understood. Aims: To map and characterise mechanosensitive afferents in the normal rat pancreas. Methods: A preparation consisting of the pancreas, attached spleen and duodenum, and including the pancreatic duct (PD), common bile duct (CBD) and the sympathetic chain was obtained from anaesthetised Sprague Dawley rats (n = 9). The CBD was cannulated. The preparation was placed in a 2 chamber organ bath. Extracellular nerve recordings were obtained from fibers teased from the sympathetic chain adjacent to the coeliac ganglia. Nerve discharge evoked by blunt probing, CBD/PD distension (44 mmHg), or electrical field stimulation (EFS; n = 3; 20 V, 0.5 ms duration) of pancreas was recorded. Results: Discharge from 137 fibers was recorded, of which 50% displayed spontaneous activity. Blunt probing evoked a discharge in 20% of fibers whereas EFS evoked discharge in 11/42 fibers, of which 3 receptive fields responded to blunt probing. Based on conduction velocity measurements (0.36 ± 0.06 m/s; n = 16 fibers), recordings were from C fibers. Mechanosensitive receptive fields were associated with arteries/blood vessels in the pancreas (16/32), pancreas near lymph nodes (2/32), pancreatic tissue (12/32), CBD (1/32) and duodenal mesentery (1/32). Non-mechanosensitive receptive fields were located in pancreatic tissue (5/11), arteries/blood vessels (5/11) or CBD/PD (1/11). CBD/PD distension did not evoke any discharge. Conclusion: Mechanosensitive and non-mechanosensitive afferent nerves are associated with several structures in the pancreas. Their role in physiological and pathophysiological signaling remains to be established. Supported by the FMC Foundation.