CHANGES IN ENKEPHALIN IMMUNOREACTIVITY OF SYMPATHETIC-GANGLIA AND DIGESTIVE-TRACT OF THE CAT AFTER SPLANCHNIC NERVE LIGATION

The aim of the present study was to analyze changes in the enkephalin immunoreactivity of sympathetic prevertebral ganglia coeliac plexus an d inferior mesenteric ganglion) and intestinal tract (myenteric plexus and external muscle layers) in cats 2 days after left thoracic splanc hnic nerve ligation, using radioimmunoassay and immunohistochemical te chniques. Specific polyclonal antibodies directed against methionine- and leucine-enkephalin were used. The nerve ligation led to a consider able increase in the enkephalin immunoreactivity in the cranial part o f the ligated nerves. This finding confirms the presence, in the cat, of an enkephalin output originating from thoracic spinal structures wh ich are probably enkephalin-containing preganglionic neurons. In preve rtebral ganglia the nerve ligation induced a marked decrease in the en kephalin immunoreactivity, which was probably due to the interruption of thoracic enkephalin efferents projecting towards both the coeliac p lexus and the inferior mesenteric ganglion. In the digestive tract, th e nerve ligation depressed the methionine-enkephalin immunoreactivity only in the gastro-duodenal region, and had no effect on the ileo-colo nic region. The results of the present study add to the growing eviden ce that the sympathetic nervous system is involved in regulating the e nteric enkephalinergic innervation, which is probably involved in cont rolling the intestinal motility.