Tj. Sajdyk et Dr. Gehlert, Astressin, a corticotropin releasing factor antagonist, reverses the anxiogenic effects of urocortin when administered into the basolateral amygdala, BRAIN RES, 877(2), 2000, pp. 226-234
Previous work in our laboratory has shown that Urocortin (Ucn), a peptide r
elated to corticotropin releasing factor (CRF), injected into the basolater
al nucleus of the amygdala (BLA) in male Wistar rats would result in an anx
iogenic response as measured in the social interaction (SI) test. In additi
on, it was found that repeated injections of subthreshold doses of Ucn woul
d 'prime' the animal's response. This 'priming' effect induces a sensitivit
y to sodium lactate infusions that results in a panic-like reaction. Curren
tly, we examined the effects of the CRF1 and CRF2 antagonist Astressin (Asn
)on the anxiety-like responses produced during 'priming' as well as during
a sodium lactate infusion into 'primed' rats. The results showed that Asn (
60 pmoles) was able to reverse the anxiogenic effects seen during acute adm
inistration of Ucn, but was only able to partially antagonize the same resp
onse following 'priming' with Ucn. Furthermore, Asn administered either alo
ne or prior to a sodium lactate infusion had no effect on the printed wt's
behavior. Autoradiographic studies, in Ucn primed and sham-primed animals i
ndicated no significant changes in [I-125]-Sauvagine binding to CRF1 and CR
F2 receptors in several brain regions. Thus, a 60 pmole dose of Asn blocks
the effects of an acute injection of Ucn (100 pmoles), while only partially
blocking the behavioral effects after repeated injections of subthreshold
doses of Ucn (6 pmoles) are given. Furthermore, Asn has no effect on anxiog
enic responses due to sodium lactate infusions in 'primed' rats (C) 2000 El
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