Electrical activity of ganglion cells in the celiac plexus of the guinea pig

The celiac plexus (CP), which consists of the right and left celiac ganglia and the superior mesenteric ganglion (SMG) each joined to one another by commissures, is connected to the CNS and the gastrointestinal tract by an abundant and complex supply of nerve fibers. In vitro experiments were performed on the celiac plexus with portions of the stomach, intestine and nerve trunks attached to determine the source of input to neurons in the plexus. Electrical activity of ganglion cells was monitored with intracellular microelectrodes and nerve fibers were stimulated with external electrodes. In the SMG, ganglion cells received excitatory synaptic input from the intermesenteric and colonic nerves; when the distal colon was left attached there were spontaneous EPSPs and action potentials. A few ganglion cells in the SMG received excitatory input from the hypogastric nerves and from gastric-splenic-hepatic fibers. In the celiac ganglia, neurons received excitatory synaptic input from colonic and intermesenteric nerves as well as from nerve trunks located between the ganglia and the stomach and proximal small bowel. When these portions of the GI tract were left attached to the ganglia, there were spontaneous EPSPs in some cells. These observations suggest that the celiac plexus receives synaptic input from both proximal and distal gastrointestinal tract.