Immunohistochemical colocalization of Met5-enkephalin-Arg6-Gly7-Leu8 with tyrosine hydroxylase in neurons of the porcine inferior mesenteric and coeliac-superior mesenteric ganglia.

The localization and distribution of the proenkephalin A-derived octapeptide Met5-enkephalin-Arg6-Gly7-Leu8 (MEAGL) was studied in the porcine sympathetic prevertebral ganglia by using the indirect immunofluorescence technique. In the inferior mesenteric ganglion, a small population of principal neurons and SIF cells contained intense MEAGL immunoreactivity. A very dense plexus of MEAGL-immunoreactive nerve fibers was distributed in different parts of the ganglion. A low number of MEAGL- immunoreactive principal ganglion cells and SIF cells, as well as numerous nerve fibers were also present in the coeliac-superior mesenteric ganglion. Double staining experiments indicated that the MEAGL-immunoreactive principal neurons in the inferior mesenteric and coeliac-superior mesenteric ganglia also contained tyrosine hydroxylase immunoreactivity.