Adjunctive alpha2-adrenoceptor blockade enhances the antipsychotic-like effect of risperidone and facilitates cortical dopaminergic and glutamatergic, NMDA receptor-mediated transmission.

Compared to both first- and second-generation antipsychotic drugs (APDs), clozapine shows superior efficacy in treatment-resistant schizophrenia. In contrast to most APDs clozapine possesses high affinity for alpha2-adrenoceptors, and clinical and preclinical studies provide evidence that the alpha2-adrenoceptor antagonist idazoxan enhances the antipsychotic efficacy of typical D2 receptor antagonists as well as olanzapine. Risperidone has lower affinity for alpha2-adrenoceptors than clozapine but higher than most other APDs.

Adjunctive treatment with mianserin enhances effects of raclopride on cortical dopamine output and, in parallel, its antipsychotic-like effect.

Clinical studies indicate that adjunctive treatment with the antidepressant drug mianserin, a 5-hydroxytryptamine (5-HT)(2A/C) receptor antagonist and an alpha(2)- and alpha(1)-adrenoceptor antagonist, may enhance the effect of conventional antipsychotic drugs in schizophrenia, in particular on negative symptoms such as withdrawal retardation, akathisia, and some aspects of cognitive impairment. Here, we have examined the effect of mianserin in combination with the selective dopamine (DA) D(2/3) receptor antagonist raclopride on conditioned avoidance response (CAR), a preclinical test of antipsychotic efficacy with high predictive validity; catalepsy, a preclinical test of extrapyramidal side effect liability; and DA output in the medial prefrontal cortex (mPFC) and the nucleus accumbens (NAC), respectively. Mianserin (5 mg/kg intraperitoneal) significantly enhanced the suppressant effect of a low dose of raclopride (0.

Adjunctive treatment with mianserin enhances effects of raclopride on cortical dopamine output and, in parallel, its antipsychotic-like effect.

Clinical studies indicate that adjunctive treatment with the antidepressant drug mianserin, a 5-hydroxytryptamine (5-HT)(2A/C) receptor antagonist and an alpha(2)- and alpha(1)-adrenoceptor antagonist, may enhance the effect of conventional antipsychotic drugs in schizophrenia, in particular on negative symptoms such as withdrawal retardation, akathisia, and some aspects of cognitive impairment. Here, we have examined the effect of mianserin in combination with the selective dopamine (DA) D(2/3) receptor antagonist raclopride on conditioned avoidance response (CAR), a preclinical test of antipsychotic efficacy with high predictive validity; catalepsy, a preclinical test of extrapyramidal side effect liability; and DA output in the medial prefrontal cortex (mPFC) and the nucleus accumbens (NAC), respectively. Mianserin (5 mg/kg intraperitoneal) significantly enhanced the suppressant effect of a low dose of raclopride (0.

Adjunctive galantamine, but not donepezil, enhances the antipsychotic-like effect of raclopride in rats.

Acetylcholine (ACh) esterase inhibitors like galantamine and donepezil have been tested as adjunct treatment in schizophrenia. Although ACh esterase inhibition might confer some antipsychotic activity, the role of allosteric potentiation of nicotinic ACh receptors (nAChRs), which is an additional mechanism of galantamine, remains elusive. Therefore, the potential antipsychotic-like effects of galantamine and donepezil, respectively, alone, and in combination with the dopamine D2/3 receptor antagonist, raclopride, were tested in the conditioned avoidance response (CAR) test and extrapyramidal side-effect liability was assessed with the catalepsy test.

Asenapine, a novel psychopharmacologic agent: preclinical evidence for clinical effects in schizophrenia.

Rationale: Asenapine is a novel psychopharmacologic agent being developed for the treatment of schizophrenia and bipolar disorder.

Materials And Methods: The present study was undertaken to investigate the effects of asenapine using animal models predictive of antipsychotic efficacy (conditioned avoidance response [CAR]) and extrapyramidal side effects (EPS; catalepsy). In parallel, the effects of asenapine on regional dopamine output using in vivo microdialysis in freely moving rats, dopamine output in the core and shell subregions of nucleus accumbens (NAc) using in vivo voltammetry in anesthetized rats, and N-methyl-D: -aspartate (NMDA)-induced currents in pyramidal neurons of the medial prefrontal cortex (mPFC) using the electrophysiological technique intracellular recording in vitro were assessed.

Enhanced efficacy of both typical and atypical antipsychotic drugs by adjunctive alpha2 adrenoceptor blockade: experimental evidence.

Adjunctive treatment with the selective alpha2 adrenoceptor antagonist idazoxan augments the effect of conventional antipsychotics in treatment-resistant schizophrenics comparing favourably with clozapine. Clozapine has high affinity for alpha2 adrenoceptors. Previously, we found that adjunctive idazoxan treatment to the dopamine (DA) D2/3 antagonist raclopride enhanced raclopride-induced effects in an animal model of antipsychotic activity (conditioned avoidance response, CAR) and, similarly to clozapine, reversed the disruption of working memory induced by N-methyl-D-aspartate receptor blockade in rats with a concomitant increase in prefrontal DA efflux.

Galantamine enhances dopaminergic neurotransmission in vivo via allosteric potentiation of nicotinic acetylcholine receptors.

Clinical studies suggest that adjunct galantamine may improve negative and cognitive symptoms in schizophrenia. These symptoms may be related to impaired dopaminergic function in the prefrontal cortex. Indeed, galantamine has been shown to increase dopamine release in vitro.

Noradrenaline reuptake inhibition enhances the antipsychotic-like effect of raclopride and potentiates D2-blockage-induced dopamine release in the medial prefrontal cortex of the rat.

We have previously observed that addition of an alpha(2)-adrenoceptor antagonist to a selective dopamine (DA) D(2) receptor antagonist enhances the antipsychotic-like effect of the D(2) blocker and also selectively increases DA output in the medial prefrontal cortex (mPFC) in rats. These data also correlate well with previous clinical trials showing augmentation by an equivalent drug combination in schizophrenia. Since the selective noradrenaline reuptake inhibitor reboxetine was found to cause similar effects on the mesolimbocortical DA system as alpha(2)-adrenoceptor antagonists, the present study was undertaken to explore whether also reboxetine might augment the effect of the DA D(2) receptor antagonist raclopride in the same preclinical model of antipsychotic activity, the conditioned avoidance response (CAR) test.