Effects of centrally administered pituitary adenylate cyclase-activating polypeptide on c-fos gene expression and heteronuclear RNA for vasopressin in rat paraventricular and supraoptic nuclei
M. Nomura et al., Effects of centrally administered pituitary adenylate cyclase-activating polypeptide on c-fos gene expression and heteronuclear RNA for vasopressin in rat paraventricular and supraoptic nuclei, NEUROENDOCR, 69(3), 1999, pp. 167-180
The effects of intracerebroventricular (i.c.v.) administration of pituitary
adenylate cyclase-activating polypeptide (PACAP) on the expression of c-fo
s gene as well as heteronuclear (hn) RNA for arginine vasopressin (AVP) in
paraventricular (PVN) and supraoptic nuclei (SON) of rats were investigated
by immunohistochemistry for c-fos protein (Fos) and in situ hybridization
histochemistry for c-fos mRNA and AVP hnRNA. The i.c.v. administration of P
ACAP (200 pmol/rat) caused a marked induction of Fos-like immunoreactivity
(LI) in PVN and SON. The nuclear Fos-LI existed in AVP-LI containing cells
in the PVN and SON. The expression of the c-fos gene in the PVN and SON was
increased in a dose-related manner 30 min after i.c.v. administration of P
ACAP. PACAP-induced expression of the c-fos gene was significantly reduced
by pretreatment with a PACAP receptor antagonist, PACAP-(6-38)-NH2. In addi
tion, Fos-LI and the expression of the c-fos gene were also observed in the
periventricular region of the third ventricle after i.c.v. administration
of PACAP. The induction of c-fos gene expression in the PVN and SON reached
a maximum 30 min after PACAP administration. The expression of c-fos gene
in the PVN and SON induced by i.c.v. administration of vasoactive intestina
l peptide (200 pmol/rat) was weaker than that induced by PACAP. The hnRNA f
or AVP in the PVN and SON was significantly increased 30 min after i.c.v. a
dministration of PACAP (200 pmol/rat). Our results suggest that PACAP activ
ates PVN and SON neurons via PACAP receptors and, in parallel, transcriptio
n of the AVP gene in the PVN and SON.