The extended amygdala is composed of the central and medial amygdaloid nucleus which through the sublenticular extended amygdala (SLEA) and the interstitial nucleus of the posterior limb of the anterior commissure (IPAC) merge into the bed nucleus of stria terminals (BST). Based on anatomical connections with limbic areas, the extended amygdala has been proposed to play an important role in cognitive and affective processes. This study examines the effect of the atypical antipsychotic clozapine and the classical antipsychotic haloperidol on Fos-like-immunoreactivity (FLI) induction in areas belonging to the extended amygdala. Acute administration of clozapine (10-20 mg/kg) induced FLI in the central amygdaloid nucleus, IPAC, SLEA, and BST lateral division and, as previously described, in areas connected to the extended amygdala, such as the prefrontal cortex and nucleus accumbens shell. In contrast, acute administration of haloperidol (0.1-1 mg/kg) failed to induce FLI in the BST lateral division and SLEA but increased FLI in the IPAC. A small increase in FLI was observed in the central amygdaloid nucleus after 0.1 but not after 1 mg/kg of haloperidol. The present results, showing a preferential influence of clozapine, as compared to haloperidol, in the extended amygdala propose a new brain structure involved in the pharmacological effects of atypical antipsychotics.
Differential induction of Fos-like-immunoreactivity in the extended amygdala after haloperidol and clozapine
MORELLI, MICAELA;
1999-01-01
Abstract
The extended amygdala is composed of the central and medial amygdaloid nucleus which through the sublenticular extended amygdala (SLEA) and the interstitial nucleus of the posterior limb of the anterior commissure (IPAC) merge into the bed nucleus of stria terminals (BST). Based on anatomical connections with limbic areas, the extended amygdala has been proposed to play an important role in cognitive and affective processes. This study examines the effect of the atypical antipsychotic clozapine and the classical antipsychotic haloperidol on Fos-like-immunoreactivity (FLI) induction in areas belonging to the extended amygdala. Acute administration of clozapine (10-20 mg/kg) induced FLI in the central amygdaloid nucleus, IPAC, SLEA, and BST lateral division and, as previously described, in areas connected to the extended amygdala, such as the prefrontal cortex and nucleus accumbens shell. In contrast, acute administration of haloperidol (0.1-1 mg/kg) failed to induce FLI in the BST lateral division and SLEA but increased FLI in the IPAC. A small increase in FLI was observed in the central amygdaloid nucleus after 0.1 but not after 1 mg/kg of haloperidol. The present results, showing a preferential influence of clozapine, as compared to haloperidol, in the extended amygdala propose a new brain structure involved in the pharmacological effects of atypical antipsychotics.
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