Induction of Fos-like-immunoreactivity in the central extended amygdala byantidepressant drugs

The induction of the early gene c-fos was evaluated through Fos immunohisto chemistry in areas belonging to the extended amygdala after acute administr ation of two antidepressants, citalopram and imipramine. Both citalopram an d imipramine at the dose of 5 and 20 mg/kg, respectively, induced Fos-like immunoreactivity (FLI) in the central amygdaloid nucleus, lateral division of the bed nucleus of the stria terminalis (BSTL), and interstitial nucleus of the posterior Limb of the anterior commissure (IPAC). The shell of the nucleus accumbens, which forms a continuum with the central extended amygda la, showed a decrease of FLI after administration of either citalopram or i mipramine. The mechanism of action and the brain areas affected by antidepr essants are still a matter of debate. By showing that the central extended amygdala is a common site of action for two different antidepressant types, these results provide new insight into the mechanism of action of antidepr essants. Synapse 31:1-4, 1999. (C) 1999 Wiley-Liss, Inc.