J Korean Neuropsychiatr Assoc.
2002 Jan;41(1):61-68.
Effects of Acute and Chronic Treatment of Olanzapine and Risperidone on the Extracellular Dopamine Concentrations of the Prefrontal Cortex in Rats
- Affiliations
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- 1Department of Psychiatry, Chonbuk National University Hospital, Jeonju, Korea.
- 2Department of Psychiatry, Institute for Medical Science and Research Institute of Clinical Medicine, Chonbuk National University, Medical School, Jeonju, Korea.
Abstract
- OBJECT: It is reported that the effect of antipsychotics on the extracellular dopamine levels in the prefrontal cortex is related to the their effect on the negative symptoms. Therefore, we investigated the acute and chronic effects of olanzapine and risperidone on the extracellular dopamine concentrations in the prefrontal cortex of rat. Samples were obtained using in vivo brain microdialysis.
METHOD: Dopamine levels in the samples were measured by high pressure liquid chromatography with electrochemical detection.
RESULTS
1) Both the acute treatment of olanzapine and risperidone increased the extracellular dopamine concentrations in the prefrontal cortex, dose-dependently. 2) There was a no significant difference in the maximal change of the extracellular dopamine concentrations in the prefrontal cortex induced by the acute treatment of olanzapine and risperidone. 3) Both the chronic treatment of olanzapine and risperidone also increased the extracellular dopamine concentrations in the prefrontal cortex, but they showed the tolerance effect that the degree of increase was smaller than that of the acute treatment. 4) As for the maximal changes of the extracellular dopamine concentrations in the prefrontal cortex induced by the chronic treatment of olanzapine and risperidone, the effect of the former was greater than that of the latter.
CONCLUSION
These results suggest that the effects of olanzapine and risperidone on the negative symptoms are related to the increased extracellular dopamine concentrations in the prefrontal cortex induced by these drugs.
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