Myenteric plexus neurons in culture: developmental changes in neurofilament and related proteins

Myenteric plexus neurons appear to have unique features in their expression of cytoskeletal proteins. In particular, neurofilaments have been shown to be present in a subset of neurons, and the medium molecular weight subunit of neurofilament is modified during the first week of development. We utilized cultured myenteric plexus neurons to examine if these changes could be reproduced outside of the intestinal wall. Myenteric neurons from neonate rat small intestine were cultured using a dissection and enzymatic dispersion technique previously described, and cells were fixed after one day or seven days in culture. Antibodies to the neurofilament proteins, peripherin, alpha-internexin, nestin, and microtubule-associated proteins tau and tubulin were studied. Similar to what was seen in tissues, cultured cells initially stained and then lost staining for antibodies to one area of the carboxy terminal region of neurofilament during the first week in culture. Peripherin and alpha-internexin showed good staining both initially and after 7 days in culture (differing from intact tissues). Developmental modifications in immunoreactivity to neurofilament proteins in myenteric neurons occur both in culture and in intact tissues. However, the intermediate filament proteins peripherin and alpha-internexin immunolocalized in cultured neuron cells differently than in intact tissues. Thus, factors other than the intact intestinal wall appear to be responsible for these unique cytoskeletal characteristics in myenteric plexus neurons.