An immunohistochemical study of methionine-enkephalin-Arg6-Gly7-Leu8-like immunoreactivity-containing neurons in the parasympathetic preganglionic regions of the rat spinal cord.

The localization of the methionine-enkephalin-Arg6-Gly7-Leu8 (Met-Enk-Arg-Gly-Leu)-like immunoreactivity-containing neurons in the rat lumbosacral spinal cord was immunohistochemically examined by an antiserum very specific to Met-Enk-Arg-Gly-Leu. The immunoreactive neurons occupied the positions corresponding to the parasympathetic preganglionic nuclei determined by the previous horseradish peroxidase (HRP)-tracing experiments. The present study suggests that the parasympathetic preganglionic neurons in the rat lumbosacral spinal cord produce preproenkephalin A and its related peptides.