2-Bromoterguride–a potential atypical antipsychotic drug without metabolic effects in rats

RATIONALE: Recently, we showed that 2-bromoterguride acted as a dopamine D(2) receptor partial agonist, a serotonin 5-HT(2A) and α(2C)-adrenergic receptor antagonist, and exhibited antidopaminergic efficacy in amphetamine-induced locomotion (AIL) in rats without inducing catalepsy. OBJECTIVE: To extend our knowledge on the antipsychotic effects of 2-bromoterguride, we used convergent preclinical animal models and tests; i.e., conditioned avoidance response (CAR), predictive of antipsychotic-like effects; Fos protein expression, a molecular marker for (atypical) antipsychotic activity; wet dog shake behavior, a test for the in vivo effects of drugs acting on central 5-HT(2A) receptors; and investigated metabolic changes as a common side effect of atypical antipsychotic drugs (APDs). RESULTS: Acute treatment with 2-bromoterguride (0.1 and 0.3 mg/kg) decreased the CAR at 30, 90, and 270 min post-injection in rats without inducing escape failures at any time. Fos protein expression, as shown by Western blotting, was enhanced by 2-bromoterguride in the nucleus accumbens (NAc), the dorsolateral striatum (dStr), and the medial prefrontal cortex (mPFC). (±)-2,5-Dimethoxy-4-iodoamphetamine (DOI)-induced wet dog shakes in rats were reduced by 2-bromoterguride. Chronic treatment with 2-bromoterguride did not affect metabolic parameters such as body weight development and body fat composition as well as behavioral parameters such as food intake and locomotor activity. CONCLUSIONS: Our data suggest that 2-bromoterguride is a promising candidate in the treatment of schizophrenia due to its atypical antipsychotic-like activity and its inability to induce weight gain.