Journal of Neuroscience, Vol 15, 1854-1868, Copyright © 1995 by Society for Neuroscience
Neuronal regulation of c-fos, c-jun, and junB immediate-early genes in rat adrenal medulla
M Pelto-Huikko, A Dagerlind, J Kononen, JM Lundberg, M Villar, J Koistinaho, R Bravo and T Hokfelt
Department of Biomedical Sciences, University of Tampere, Finland.
We have applied in situ hybridization histochemistry, Northern analysis,
and immunocytochemistry to study the regulation of the immediate-early gene
(IEG) c-fos, c-jun, and junB mRNAs and the respective proteins in the rat
adrenal medulla. Electrophoresis mobility shift assay was used to examine
changes in AP-1 DNA binding activity. In nontreated rats the mRNA and
protein levels for these three IEGs were low. Reflex stimulation of adrenal
medulla elicited by a single capsaicin injection induced a rapid and marked
elevation in the mRNA levels for these IEGs. Stimulation with nicotine also
caused a drastic increase in the mRNA levels, whereas muscarine only
induced moderate elevations. c-fos and c-jun were induced strongly in
adrenaline cells and only weakly in noradrenaline cells. junB was
upregulated mainly in adrenaline cells. The AP-1 DNA binding activity was
low in control adrenals, whereas a marked increase was observed after
nicotine treatment. Treatment of the animals with a nicotinic
(chlorisondamine) or a muscarinic (atropine) receptor antagonist did not
change the expression of IEGs studied. The combination of the two drugs,
however elevated the mRNA levels for all three IEGs, especially for junB.
Pretreatment of the rats with chlorisondamine alone or in combination with
atropine diminished the capsaicin-induced increase in c-fos, whereas
atropine alone was less efficient. Increase in c-jun mRNA was not affected
by these drugs. The capsaicin-induced elevation of junB mRNA levels was not
influenced by chlorisondamine or atropine alone, whereas both combined
potentiated the effect of capsaicin. The present results demonstrate that
neurotransmitters released from splanchnic nerve terminals induce
expression of c-fos, c-jun, and junB in adrenal chromaffin cells which
results in increased AP-1 DNA binding activity. Although stimulation of
both nicotinic and muscarinic cholinergic receptors may mediate the
induction of these IEGs, it is possible that also another
neurotransmitter(s), in addition to ACh, released from splanchnic nerve
terminals is involved in the regulation of their expression, especially of
c-jun and junB.