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Antipsychotics and single-cell activity in the rat superior colliculus
Annelies Broerse1, Wia Timmerman, Ben H C Westerink
1Department of Psychiatry, University Hospital Groningen, The Netherlands. a.broerse@acggn.azg.nl
Progress in Neuro-Psychopharmacology & Biological Psychiatry
|February 2, 2002
Summary
Antipsychotic medications affect eye movements in schizophrenia. Clozapine, an atypical antipsychotic, significantly decreased superior colliculus (SC) cell activity in rats, unlike other tested drugs.
Area of Science:
- Neuroscience
- Psychopharmacology
- Ophthalmology
Background:
- Schizophrenia is associated with impaired saccadic eye movements, indicating a loss of control over the saccadic system.
- Antipsychotic medications' effects on saccades are variable, with potential to disrupt or improve performance.
- The superior colliculus (SC) is vital for saccade generation, and its regulation by the substantia nigra reticulata (SNr) differs between antipsychotic classes.
Purpose of the Study:
- To investigate the effects of atypical (clozapine, olanzapine, risperidone) and classical (haloperidol) antipsychotics on the firing rate of SC neurons in rats.
- To explore the neural mechanisms underlying antipsychotic action on saccadic eye movement control.
Main Methods:
- Extracellular recordings were performed on spontaneous active neurons in the intermediate and deep layers of the rat SC under anesthesia.
- Antipsychotic drugs or saline were administered subcutaneously, and changes in neuronal firing rates were compared.
Main Results:
- Clozapine (10.0 mg/kg) induced a significant, albeit short-lasting, decrease in SC cell firing rate.
- Olanzapine, risperidone, and haloperidol did not significantly alter SC cell activity at the tested doses.
- The observed effects of clozapine on the SC were distinct from its effects on the SNr, suggesting a unique mechanism.
Conclusions:
- Clozapine exhibits a unique effect on SC neuronal activity compared to other atypical and classical antipsychotics tested.
- These findings suggest that clozapine's distinct pharmacological profile may contribute to its differential impact on saccadic eye movements in schizophrenia.