IL-6 increases choline acetyltransferase but not neuropeptide transcripts in sympathetic neurons

The effect of interleukin (IL)-6 on cell survival, and the expression of choline acetyltransferase (ChAT) and neuropeptide mRNAs was examined in cultured rat sympathetic neurons. Reverse transcription-polymerase chain reaction analysis indicated that IL-6 treatment led to six-fold increase in ChAT mRNA without a concomitant increase in ChAT immunoreactivity. In contrast, treatment with ciliary neurotrophic factor or leukemia inhibitory factor/cholinergic differentiation factor increased ChAT mRNA levels 25-fold and resulted in intense ChAT immunoreactivity. Moreover, the latter factors increased somatostatin and preprotachykinin mRNA levels 10-fold whereas IL-6 had no effect. Maximal doses of IL-6 had no effect on cell survival. These findings provide a basis for the overlapping and yet divergent actions of these three factors which share some components of their signal transduction machinery.