Dopamine D3 receptor antagonism inhibits cocaine-seeking and cocaine-enhanced brain reward in rats.

dopamine D3 receptor is preferentially localized to the mesocorticolimbic dopaminergic system and has been hypothesized to play a role in cocaine addiction. To study the involvement of the D3 receptor in brain mechanisms and behaviors commonly assumed to be involved in the addicting properties of cocaine, the potent and selective D3 receptor antagonist trans-N-[4-[2-(6-cyano-1,2,3,4-tetrahydroisoquinolin-2-yl)ethyl] cyclohexyl]-4-quinolininecarboxamide (SB-277011-A) was administered to laboratory rats, and the following measures were assessed: (1) cocaine-enhanced electrical brain-stimulation reward, (2) cocaine-induced conditioned place preference, and (3) cocaine-triggered reinstatement of cocaine seeking behavior. Systemic injections of SB-277011-A were found to (1) block enhancement of electrical brain stimulation reward by cocaine, (2) dose-dependently attenuate cocaine-induced conditioned place preference, and (3) dose-dependently attenuate cocaine-triggered reinstatement of cocaine seeking behavior. Thus, D3 receptor blockade attenuates both the rewarding effects of cocaine and cocaine-induced drug-seeking behavior. These data suggest an important role for D3 receptors in mediating the addictive properties of cocaine and suggest that blockade of dopamine D3 receptors may constitute a new and useful target for prospective pharmacotherapies for cocaine addiction.

Electrical and chemical stimulation of the basolateral complex of the amygdala reinstates cocaine-seeking behavior in the rat.

RATIONALE: The basolateral complex of the amygdala (BLC) is part of a neural circuit that is activated in humans during cocaine craving elicited by exposure to drug-related environmental cues. In animals, the BLC is necessary for cocaine-seeking behavior elicited by cocaine-associated cues. It has not been determined whether BLC activation is sufficient to reinstate cocaine seeking. OBJECTIVES: To determine whether electrical or excitatory amino-acid stimulation of the BLC is sufficient to induce reinstatement of cocaine seeking in rats. METHODS: Rats were catheterized and trained to lever-press for intravenous cocaine infusions on a fixed ratio (FR)-1 schedule of reinforcement. Once baseline cocaine-taking criteria were met, lever-pressing behavior was extinguished by substitution of saline for cocaine. After meeting criteria for extinction, animals were subjected to brief electrical (20 Hz, 400 microA or 2 Hz, 400 microA; 200 pulses per stimulation) or N-methyl- d-aspartate (NMDA; 250 ng/0.5 microl) BLC stimulation and lever pressing behavior was monitored. RESULTS. Electrical BLC stimulation with 20-Hz produced reinstatement of lever pressing previously associated with cocaine self-administration, while 2-Hz stimulation did not. Electrical stimulation of cerebellar and medial forebrain bundle loci did not reinstate cocaine seeking. Hence, the reinstatement was frequency dependent and anatomically selective. NMDA microinjections into the BLC also reinstated cocaine-seeking behavior. CONCLUSIONS: BLC stimulation is sufficient to reinstate cocaine-seeking behavior in the rat. These results are congruent with the hypothesis that the basolateral complex of the amygdala is part of a neural system mediating drug-seeking behavior.

Aripiprazole versus haloperidol treatment in early-stage schizophrenia.

We conducted a secondary analysis of a completed study of the differential efficacy and side effects of aripiprazole versus haloperidol in early-stage schizophrenia (ESS), a subpopulation of patients which does not include first episode or chronic patients. A subpopulation of 360 individuals with ESS were identified from a randomized, multi-center, double-blind study of 1294 individuals with schizophrenia at different stages of illness who were randomized to treatment with aripiprazole (ESS = 237) or haloperidol (ESS = 123) for one year. The primary outcome measure was response rate based on a 50% reduction of Positive and Negative Syndrome Scale (PANSS) total scores. Secondary outcomes included several efficacy and safety measures, as well as treatment discontinuation. More individuals in the aripiprazole group (48%) than in the haloperidol group (28%; p < 0.01) completed the study. Response rates were greater in the aripiprazole group (38% [N = 91]) than in the haloperidol group (22% [N = 27]; p < 0.01). Aripiprazole was associated with fewer extrapyramidal side effects. ESS subjects in the haloperidol group were more likely than those in the aripiprazole group to discontinue the study drug due to an adverse event other than worsening illness (29% and 11%, respectively; p < 0.01), and efficacy differences were reduced by interventions to mitigate side effects (decreasing antipsychotic dose with or without adding antiparkinsonian medication). Aripiprazole has a favorable efficacy/safety profile in ESS and appeared to be superior to haloperidol on a number of efficacy and safety outcomes. However, excessive dosing of the antipsychotic medications, in particular haloperidol, may have played an important role in accounting for the differences between aripiprazole and haloperidol in this study.

Teaching trainees to negotiate research collaborations with industry: a mentorship model.

Research collaborations with the pharmaceutical industry can offer valuable opportunities for academic psychiatrists to gain access to important resources. Such relationships, however, often produce significant conflicts of interest, and recent attention has focused on the ways in which these conflicts can compromise research integrity. Psychiatric residents generally receive little education about industry-academia interactions. The authors report their experience collaborating on a research project with representatives of a pharmaceutical company, and they propose a model for teaching psychiatric trainees responsible and productive engagement with industry investigators.