The influence of neurite-inducing agents on cholinergic activity in human neuroblastoma cells

Various factors capable of inducing morphological differentiation of neuroblastoma cells were studied to determine whether they may also specifically regulate cholinergic function in human cholinergic neuroblastoma cells MC-IXC. Choline acetyltransferase (CAT) activity was monitored to reflect cholinergic function while Mg(2+) ATPase activity was monitored to reflect effects which are not related specifically to neuronal function. Among the agents, dimethylsulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMA), D-α-tocopherol, ascorbic acid and dibutyryl-cAMP, only low doses of DMSO were found to selectively inhibit CAT activity while Mg(2+) ATPase activity along with population growth remained unaffected. Of the three chemically related organic compounds tested (DMSO, DMF, DMA), DMSO was the least potent with regard to inhibition of population growth and Mg(2+) ATPase activity while DMA was the most potent inhibitor. Sodium butyrate caused a decline in CAT activity while retinoic acid induced an enhancement. The combination of sodium butyrate with retinoic acid caused an enhancement of CAT activity similar in magnitude to that observed with retinoic acid alone. Lastly, CAT activity was found to be independent of population density unlike that in different neuroblastoma cell lines.(8,12,19.)