Comparison of the effects of antipsychotics on a delayed radial maze task in the rat.
BACKGROUND
The cognitive impairments evident in many schizophrenics are related to the severity of their negative symptoms and ability to function in society. Drugs that alleviate cognitive impairments, in addition to other psychotic symptoms, may have an important influence on treatment outcome and the course of the illness.


OBJECTIVE
A delayed non-match to sample task conducted in an eight-arm radial maze was used to determine the influence of four atypical antipsychotics (olanzapine, ziprasidone, risperidone, and clozapine), as well as a typical neuroleptic (haloperidol) on consolidation processes in healthy rats.


METHODS
Well-trained rats were required to recall after a 7-h delay where they had received food pellets during an information phase (first four arm choices) in order to obtain the remaining food pellets during a retention phase (second four arm choices).


RESULTS
The total number of errors that occurred during the retention session increased with increasing delay periods from 0 to 7 h. When administered orally immediately after the information phase, olanzapine (3 and 5 mg/kg) and risperidone (0.1 mg/kg) significantly reduced the number of errors made during the retention phase. Under the same conditions, clozapine, ziprasidone and haloperidol failed to affect the total number of retention phase errors.


CONCLUSIONS
Some atypical antipsychotics, such as olanzapine and risperidone, improve consolidation processes and may alleviate the cognitive impairments associated with schizophrenia.
Wolff
Mary C
MC
Lilly Research Laboratories, Lilly Corporate Center, Eli Lilly and Company, Mail Code No. 0510, Indianapolis, IN 46285, USA. wolff_mary_c@lilly.com
Leander
J David
JD
D000284:Administration, Oral; D000818:Animals; D014150:Antipsychotic Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D001569:Benzodiazepines; D003024:Clozapine / Q000008:administration & dosage / Q000493:pharmacokinetics; D003071:Cognition / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005508:Food Deprivation; D006220:Haloperidol / Q000008:administration & dosage / Q000493:pharmacokinetics; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D008568:Memory / Q000187:drug effects*; D000077152:Olanzapine; D010879:Piperazines / Q000008:administration & dosage / Q000493:pharmacokinetics; D010890:Pirenzepine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D018967:Risperidone / Q000008:administration & dosage / Q000493:pharmacokinetics; D013844:Thiazoles / Q000008:administration & dosage / Q000493:pharmacokinetics
D014150:Antipsychotic Agents; D010879:Piperazines; D013844:Thiazoles; D001569:Benzodiazepines; D010890:Pirenzepine; C092292:ziprasidone; D003024:Clozapine; D006220:Haloperidol; D018967:Risperidone; D000077152:Olanzapine