Description
RN46A, an immortalised serotonergic neuronal cell line, was cloned by serial dilution following infection of dissociated embryonic day 13 rat medullary raphe cells with a retrovirus encoding the temperature-sensitive mutant of SV40 large T-antigen (T-ag), RN46A cells are capable of differentiating at 39°C the non-permissive temperature. Under differentiation conditions, RN46A cells cease dividing, take on a neuronal morphology, and express enhanced levels of NSE and all three NF proteins. Differentiated RN46A cells express low-affinity nerve growth factor (NGF) receptor (p75NGFR) and are immunoreactive using an antibody that recognizes the carboxy-terminal 13 amino acids of all three trk proteins (pan-trk). Both immunoreactivities could be potentiated by treatment with brain-derived neurotrophic factor (BDNF), NGF, and adrenocorticotropic hormone, fragment 4-10 (ACTH4-10). Differentiated RN46A cells express low levels of tryptophan hydroxylase (TPH) immunoreactivity, which could be enhanced by treatment with ACTH4-10, BDNF, or NGF. Low levels of serotonin immunoreactivity are detected in differentiated RN46A cells, and this was potentiated by differentiating RN46A cells with BDNF for 8 d and 40 mM KCl for days 4-8. RN46A cells should prove useful to elucidate intracellular mechanisms that control neurofilament assembly and 5-HT expression in differentiating raphe neurons