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

Abstract

Background/Aims : 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 α-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. Methods : 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, α-internexin, peripherin, and nestin was studied in comparison with the neuronal marker protein gene product (PGP) 9.5 in myenteric neurons. Results : Sixty-five percent of neurons contained neurofilament triplet proteins, α-lnternexin 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 α-internexin. Nestin was not found in either neonate or adult myenteric neurons but was seen in glial cells in culture. Conclusions : The results suggest that a subpopulation of myenteric neurons lacks neurofilament triplet proteins but contains either peripherin, α-internexin, or both. This selective distribution of intermediate filaments in subpopulations of enteric neurons may support differential roles in these structurally unique neurons.