The exciting origin of guinea-pig inferior mesenteric ganglion neurons in vivo

Intracellular recording in vivo showed that spontaneous activities of guinea-pig inferior mesenteric ganglion (IMG) neurons were inhibited when any one of the four groups of the nerves connected to the IMG was cutted or blocked, indicating that all the four groups of nerves sent in excitatory input. Colonic and hypogastric nerves convey the peripheral excitation respectively from colon and bladder. Intermesenteric nerve sends in peripheral excitatory input from colon and central from spinal cord. This finding suggests that the excitation of the prevertebral ganglia originates from not only spinal cord as claimed tranditionally, but also the peripheral organs. The latter exits stronger effect than the former. It seems that IMG is an integration neurocenter rather than a simple signal relay station from the central nervous system to peripheral effectors.