The effects of carbamylcholine (CCh) on the gene expression of the neu
ropeptide vasoactive intestinal polypeptide (VIP) were studied using t
wo human neuroblastoma cell lines, NB-1 and BE(2)M17. CCh caused a fas
t increase in VIP mRNA level in both cell Lines which was followed by
an increase in VIP immunoreactivity. The time-course of the induction
of both mRNA and peptide differed, however, between the two cell lines
. No morphological changes of the cells were observed during 6 days of
stimulation. The effect was mediated by the muscarinic class of acety
lcholine receptors, since it could be totally abolished by atropine. S
ince CCh caused an accumulation of inositol-1,4,5-triphosphate, it is
likely that muscarinic receptor subtype M1, M3 or M5 is involved. Expe
riments with the translational inhibitor, cycloheximide, showed that C
Ch mediated a direct effect on the VIP gene expression. By combining g
el permeation chromatography with radioimmunoassays using antisera spe
cific for the various VIP-precursor products, immunoreactive peaks elu
ting as the synthetic peptides were found in both cell lines. In addit
ion, earlier eluting peaks which could represent partially processed o
r extended VIP forms were found. After CCh induction the concentration
of all prepro VIP-derived products increased, and there was a tendenc
y towards a shift to more fully processed VIP. The findings give new e
vidence for a direct regulation of VIP gene expression in human neuron
al cells by cholinergic agents. (C) 1997 Elsevier Science B.V.