<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">The present study was designed to evaluate the behavioral and neurochemical profiles of clozapine and risperidone in rats in a dose-dependent manner. Animals injected intraperitoneally (<italic>i.p.</italic>) with clozapine (2.5, 5.0 and 10.0 mg kg-1) or risperidone (1.0, 2.5 and 5.0 mg kg-1) were sacrificed 1 h later to collect brain samples. Hypolocomotive effects (home cage activity and catalepsy) were successively monitored in each animal after the drug or saline administration. Both drugs significantly (<italic>p</italic> &lt; 0.01) decreased locomotor activity at high doses and in a dose-dependent manner. Maximum (100%) cataleptic potential was achieved at a high dose (5.0 mg kg-1) of risperidone. Neurochemical estimations were carried out by HPLC with electrochemical detection. Both drugs, at all doses, significantly (<italic>p</italic> &lt; 0.01) increased the concentration of homovanillic acid (HVA), a metabolite of dopamine (DA), in the striatum. Dihydroxyphenylacetic acid (DOPAC) levels increased in the striatum and decreased in the rest of the brain, particularly in clozapine-injected rats. 5-Hydroxyindoleacetic acid (5-HIAA), the predominant metabolite of serotonin, significantly (<italic>p</italic> &lt; 0.01) decreased in the striatum. 5-Hydroxytryptamine (5-HT) was significantly (<italic>p</italic> &lt; 0.01) increased by risperidone and decreased by clozapine in the rest of the brain. Striatal tryptophan (TRP) was significantly (<italic>p</italic> &lt; 0.01) decreased by risperidone and increased in the rest of the brain. The striatal HVA/DA ratio increased and the 5-HT turnover rate remained unchanged in the rest of the brain. Results suggest that the affinity of the two drugs towards D2/5-HT1A receptors interaction is involved in lower incidence of extrapyramidal side effects. Role of 5-HT1A receptors in the treatment of schizophrenia is discussed.</abstract>

The present study was designed to evaluate the behavioral and neurochemical profiles of clozapine and risperidone in rats in a dose-dependent manner. Animals injected intraperitoneally (i.p.) with clozapine (2.5, 5.0 and 10.0 mg kg-1) or risperidone (1.0, 2.5 and 5.0 mg kg-1) were sacrificed 1 h later to collect brain samples. Hypolocomotive effects (home cage activity and catalepsy) were successively monitored in each animal after the drug or saline administration. Both drugs significantly (p < 0.01) decreased locomotor activity at high doses and in a dose-dependent manner. Maximum (100%) cataleptic potential was achieved at a high dose (5.0 mg kg-1) of risperidone. Neurochemical estimations were carried out by HPLC with electrochemical detection. Both drugs, at all doses, significantly (p < 0.01) increased the concentration of homovanillic acid (HVA), a metabolite of dopamine (DA), in the striatum. Dihydroxyphenylacetic acid (DOPAC) levels increased in the striatum and decreased in the rest of the brain, particularly in clozapine-injected rats. 5-Hydroxyindoleacetic acid (5-HIAA), the predominant metabolite of serotonin, significantly (p < 0.01) decreased in the striatum. 5-Hydroxytryptamine (5-HT) was significantly (p < 0.01) increased by risperidone and decreased by clozapine in the rest of the brain. Striatal tryptophan (TRP) was significantly (p < 0.01) decreased by risperidone and increased in the rest of the brain. The striatal HVA/DA ratio increased and the 5-HT turnover rate remained unchanged in the rest of the brain. Results suggest that the affinity of the two drugs towards D2/5-HT1A receptors interaction is involved in lower incidence of extrapyramidal side effects. Role of 5-HT1A receptors in the treatment of schizophrenia is discussed.

Dose-related effects of clozapine and risperidone on the pattern of brain regional serotonin and dopamine metabolism and on tests related to extrapyramidal functions in rats

Neurochemistry and Biochemical Neuropharmacology Research Laboratory, Department of Biochemistry, University of Karachi, Karachi-75270 Pakistan

Department of Biomedical Engineering, Sir Syed University of Engineering and Technology, Karachi, Pakistan

Acta Pharmaceutica

The present study was designed to evaluate the behavioral and neurochemical profiles of clozapine and risperidone in rats in a dose-dependent manner. Animals...

Dose-related effects of clozapine and risperidone on the pattern of brain regional serotonin and dopamine metabolism and on tests related to extrapyramidal functions in rats

Published Online: Dec 06, 2010

Page range: 129 - 140

DOI: https://doi.org/10.2478/v1007-010-0014-y

Keywords
atipični antipsihotici, dopaminski D receptori, ekstrapiramidalne nuspojave, serotoninski receptori, šizofrenija

This content is open access.

Dose-related effects of clozapine and risperidone on the pattern of brain regional serotonin and dopamine metabolism and on tests related to extrapyramidal functions in rats

Published Online: Dec 06, 2010

Page range: 129 - 140

DOI: https://doi.org/10.2478/v1007-010-0014-y

Keywordsatipični antipsihotici, dopaminski D receptori, ekstrapiramidalne nuspojave, serotoninski receptori, šizofrenija

This content is open access.

Keywords
atipični antipsihotici, dopaminski D receptori, ekstrapiramidalne nuspojave, serotoninski receptori, šizofrenija