Rationale Paired associates learning (PAL) has been suggested to be predictive of functional outcomes in first episode psychosis and of conversion from mild cognitive impairment to Alzheimer’s disease. An automated touch screen-based rodent PAL (rPAL) task has been developed and is sensitive to manipulations of the dopaminergic and glutamatergic system. Accordingly, rPAL when used with pharmacological models of schizophrenia, like NMDA receptor blockade with MK-801 or dopaminergic stimulation with amphetamine, may have utility as a translational model of cognitive impairment in schizophrenia. Objective The purpose of this study was to determine if amphetamine- and MK-801-induced impairment represent distinct models of cognitive impairment by testing their sensitivity to common antipsychotics and determine the relative contributions of D1 versus D2 receptors on performance of PAL. Method Rats were trained in rPAL and were then treated with MK-801, amphetamine, risperidone, haloperidol, quinpirole, SK-82958, or SCH-23390 alone and in combination. Results While both amphetamine and MK-801 caused clear impairments in accuracy, MK-801 induced a profound “perseverative” type behavior that was more pronounced when compared to amphetamine. Moreover, amphetamine-induced impairments, but not the effects of MK-801, could be reversed by antipsychotics as well as the D1 receptor antagonist SCH-23390, suggesting a role for both the D1 and D2 receptor in the amphetamine impairment model. Conclusions These data suggest that amphetamine and MK-801 represent dissociable models of impairment in PAL, dependent on different underlying neurobiology. The ability to distinguish dopaminergic versus glutamatergic effects on performance in rPAL makes it a unique and useful tool in the modeling of cognitive impairments in schizophrenia.

Establishing preclinical models is essential for novel drug discovery in schizophrenia. Most existing models are characterized by abnormalities in behavioral readouts, which are informative, but do not necessarily translate to the symptoms of the human disease. Therefore, there is a necessity of characterizing the preclinical models from a molecular point of view. Selective reaction monitoring (SRM) has already shown promise in preclinical and clinical studies for multiplex measurement of diagnostic, prognostic and treatment-related biomarkers.

Novel 4-phenyl-4-[1H-imidazol-2-yl]-piperidine derivatives have been prepared and their synthesis described herein. In vitro affinities for delta-, micro-, and kappa-opioid receptors are reported. Evaluation of some representative compounds from this series in the mouse neonatal ultrasonic vocalization test and the mouse tail suspension test revealed anxiolytic- and antidepressant-like effects, respectively, upon subcutaneous administration.

The differential reinforcement of low-rate 72 seconds schedule (DRL-72) is a standard behavioral test procedure for screening potential antidepressant compounds. The protocol for the DRL-72 experiment, proposed by Evenden et al. (1993), consists of using a crossover design for the experiment and one-way ANOVA for the statistical analysis. In this paper we discuss the choice of several crossover designs for the DRL-72 experiment and propose to estimate the treatment effects using either generalized linear mixed models (GLMM) or generalized estimating equation (GEE) models for clustered binary data.

RATIONALE:Group I metabotropic glutamate receptor antagonists, which block both the mGlu1 and mGlu5 receptors, have been shown to have anxiolytic effects in the lick suppression test in rats.OBJECTIVE:The anxiolytic potential of the selective mGlu1 antagonist 3,4-dihydro-2H-pyrano[2,3]beta-quinolin-7-yl)(cis-4-methoxycyclohexyl)methanone (JNJ16259685) was investigated and compared with the mGlu5 antagonist MPEP.METHODS:Anxiety-related behaviour was assessed in lick suppression and in the elevated zero maze in rats. Non-specific effects on pain threshold, water intake and locomotor activity were also measured.RESULTS:Acute administration of JNJ16259685 or MPEP increased the number of licks (lowest active dose 2.5 mg/kg IP for each compound). JNJ16259685 did not increase water intake or reduce acute pain threshold, suggesting that the anxiolytic-like properties are specific. However, acute administration decreased locomotor activity. The effects of chronic administration of JNJ16259685 over 14 days (5 mg/kg bid) on lick suppression were comparable to those seen after acute administration, arguing against development of behavioural tolerance or sensitisation. Yet, there was a tendency for an increase in locomotor activity after cessation of chronic treatment. Acute co-administration of both JNJ16259685 and MPEP had additive effects on the number of licks. No anxiolytic-like properties of JNJ16259685 were observed in the elevated zero maze.CONCLUSION:Our data suggest that the anxiolytic-like effects induced by group I metabotropic glutamate receptor antagonists are mediated through both mGlu1 and mGlu5 receptors. Rather than producing a general anxiolytic-like effect, the effects seen following mGlu1 antagonism seem task-dependent, as prominent effects were seen in a conflict procedure, but not in a task based on spontaneous exploration.