Clozapine and olanzapine but not risperidone impair the pre-frontal striatal system in relation to egocentric spatial orientation in a Y-maze.
Many studies indicate a dissociation between two forms of orientation: allocentric orientation, in which an organism orients on the basis of cues external to the organism, and egocentric spatial orientation (ESO) by which an organism orients on the basis of proprioceptive information. While allocentric orientation is mediated primarily by the hippocampus and its afferent and efferent connections, ESO is mediated by the prefronto-striatal system. Striatal lesions as well as classical neuroleptics, which block dopamine receptors, act through the prefronto-striatal system and impair ESO. The purpose of the present study was to determine the effects of the atypical antipsychotics clozapine, olanzapine and risperidone which are believed to exert its antipsychotic effects mainly by dopaminergic, cholinergic and serotonergic mechanisms. A delayed-two-alternative-choice-task, under conditions that required ESO and at the same time excluded allocentric spatial orientation was used. Clozapine and olanzapine treated rats made more errors than risperidone treated rats in the delayed alternation in comparison with the controls. Motor abilities were not impaired by any of the drugs. Thus, with regard to the delayed alternation requiring ESO, clozapine and olanzapine but not risperidone affects the prefronto-striatal system in a similar way as classical neuroleptics does.
Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. chodron@terra.com.br
Cibele Canal
CC
Castro
Eleonora Araujo
EA
Dos Reis-Lunardelli
Werner J
WJ
Schmidt
Adriana Simon
AS
Coitinho
Iván
I
Izquierdo
D000704:Analysis of Variance; D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology*; D001569:Benzodiazepines / Q000494:pharmacology*; D002755:Choice Behavior / Q000187:drug effects; D003024:Clozapine / Q000494:pharmacology*; D003463:Cues; D018492:Dopamine Antagonists / Q000494:pharmacology*; D008297:Male; D017072:Neostriatum / Q000187:drug effects*; D000077152:Olanzapine; D009949:Orientation / Q000187:drug effects; D017397:Prefrontal Cortex / Q000187:drug effects*; D011597:Psychomotor Performance / Q000187:drug effects*; D051381:Rats; D020318:Rats, Long-Evans; D018967:Risperidone / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology*; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology*; D013028:Space Perception / Q000187:drug effects*
D014150:Antipsychotic Agents; D001569:Benzodiazepines; D003024:Clozapine; D018492:Dopamine Antagonists; D000077152:Olanzapine; D018967:Risperidone; D012702:Serotonin Antagonists; D017367:Selective Serotonin Reuptake Inhibitors