NEUROTROPHIN-3 INDUCES NEURAL CREST-DERIVED CELLS FROM FETAL-RAT GUT TO DEVELOP IN-VITRO AS NEURONS OR GLIA

The precursor cells that form the enteric nervous system (ENS) are mul tipotent when they arrive in the gut from the neural crest. Their diff erentiation thus depends on signals from the enteric microenvironment. Crest-derived cells were isolated from the fetal rat bowel by immunos election at E14 with NC-1/HNK-1 antibodies and secondary antibodies co upled to magnetic beads. NC-1/HNK-1-immunoreactive cells were enriched similar to 36-fold. The NC-1/HNK-1-selected population and the residu al population were plated at equal cell density and maintained in a de fined medium for 6-7 d. The total number of cells found in the culture s of the residual cells was three- to fourfold that in cultures of imm unoselected cells. Neurotrophin-3 (NT-3), but not nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), or neurotrophin-4/5 ( NT-4/5), was found to increase the proportion of neurons (neurofilamen t-immunoreactive or neuron-specific enolase-immunoreactive) or glia (S -100-immunoreactive) (from 6.6 +/- 0.9% to 15.2 +/- 1.4%; p < 0.001). This effect was concentration dependent (from 1 to 40 ng/ ml) and obse rved only in the cultures of immunoselected cells. NT-3 also enhanced neurite outgrowth. NT-3 increased neither cell number nor bromodeoxyur idine incorporation and thus was not mitogenic. Exposure of immunosele cted cells to NT-3 rapidly and transiently induced the appearance of n uclear Fos immunoreactivity. Transcripts coding for TrkC, the transduc ing receptor for NT-3, were identified in the fetal rat gut (E14-E16) and in the immunoselected population of cells using reverse transcript ase and the polymerase chain reaction. It is concluded that NT-3 speci fically promotes the differentiation of enteric crest-derived cells as neurons or glia and may thus play a role in the development and/or ma intenance of the ENS.