The distribution of novel intermediate filament proteins defines subpopulations of myenteric neurons in rat intestine.

Abstract

Recent studies with neurofilament antibodies as neuronal markers have shown subpopulations of myenteric neurons that do not contain neurofilament proteins. Novel neuronal intermediate filament proteins alpha-internexin, peripherin, and nestin have been identified. The aim of this study was to examine the distribution of these novel intermediate filaments in comparison with neurofilaments in myenteric plexus neurons. Using indirect immunofluorescence techniques in whole-mount cryostat sections from neonate and adult rat small intestine and in primary cultures of myenteric neurons, the distribution of neurofilaments, alpha-internexin, peripherin, and nestin was studied in comparison with the neuronal marker protein gene product (PGP) 9.5 in myenteric neurons. Sixty-five percent of neurons contained neurofilament triplet proteins. alpha-Internexin and/or peripherin were found in the neurofilament-negative neurons. PGP 9.5 was present in 80% of the myenteric neurons. Of the neurons that were PGP negative, > 95% contained peripherin or alpha-internexin. Nestin was not found in either neonate or adult myenteric neurons but was seen in glial cells in culture. The results suggest that a subpopulation of myenteric neurons lacks neurofilament triplet proteins but contains either peripherin, alpha-internexin, or both. This selective distribution of intermediate filaments in subpopulations of enteric neurons may support differential roles in these structurally unique neurons.