Promotion of the Development of Enteric Neurons and Glia by Neuropoietic Cytokines: Interactions with Neurotrophin-3

Neurotrophin-3 (NT-3) is known to promote enteric neuronal and glial development. Ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF) were investigated to test the hypothesis that the development of subsets of enteric neurons and/or glia is also affected by a neuropoietic cytokine, by itself, or together with NT-3. Crest-derived cells, immunoselected from the fetal rat gut (E14) with antibodies to p75 NTR, were found by RT–PCR and immunocytochemistry (after culture) to express both α (CNTFRα) and β components (gp130 and LIFRβ) of the tripartite CNTF receptor. In situ,myenteric ganglia below the esophagus were CNTFRα-immunoreactive by E16–E18. In vitro,CNTF and LIF induced in crest-derived cells nuclear translocation of STAT3 (signal transducer and activator of transcription 3), a concentration-dependent increase in expression of neuronal or glial markers, and a decrease in expression of the precursor marker, nestin. LIFRβ was expressed by more cells than CNTFRα; therefore, although the factors were equipotent, the maximal effect of LIF > CNTF. The cytokines and NT-3 were additive in promoting neuronal but not glial development. Specifically, the development of neurons expressing NADPH-diaphorase activity (an early marker found in inhibitory motor neurons) was promoted by CNTF and NT-3. These observations support the idea that a ligand for the tripartite CNTF receptor complex plays a role in ENS development.