Biomedical subjects

J David Leander

Publications and source records attributed to J David Leander.

2 recordsLinked to original sources

PubMed2003

Comparison of the effects of antipsychotics on a delayed radial maze task in the rat.

RATIONALE: 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. OBJECTIVES: 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. METHOD: 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. CONCLUSION: Some atypical antipsychotics, such as olanzapine and risperidone, improve consolidation processes and may alleviate the cognitive impairments associated with schizophrenia.

Administration, Oral↗

PubMed2002

Selective serotonin reuptake inhibitors decrease impulsive behavior as measured by an adjusting delay procedure in the pigeon.

The inability to delay gratification (reinforcement or reward) is one index of impulsive behavior. In order to measure the willingness of pigeons to delay reinforcement, an adjustable delay schedule was developed that allowed daily approximations of an indifference point between immediate brief access to reinforcer and delayed, longer access to reinforcer. Acute administration of the anxiolytic alprazolam (5 mg/kg) decreased the length of delay tolerated before a larger reinforcement. Likewise, acute administration of the anxiolytic chlordiazepoxide (10 mg/kg) produced a similar, although not significant, effect. Neither acute nor five daily injections of 8-OH-DPAT, a 5-HT(1A) agonist, or WAY100635, a 5-HT(1A) antagonist, affected the length of the delay period. Chronic (17 day), but not acute injections of the selective serotonin reuptake inhibitors (SSRIs) fluoxetine (10 mg/kg), citalopram (10 mg/kg) and paroxetine (3 mg/kg) increased the delay period. When given in addition to 1 mg/kg of 8-OH-DPAT, but not 1 mg/kg WAY100635, the effect of fluoxetine was accelerated in that the increase in delay was observed earlier in the treatment. These data support the use of SSRIs to decrease impulsive behavior. Addition of a 5-HT(1A) agonist, but not a 5-HT(1A) antagonist, to the SSRI may hasten the therapeutic activity of the SSRI in treating impulsivity.

8-Hydroxy-2-(di-n-propylamino)tetralin↗