Blunted oral body temperature response to MK-212 in cocaine addicts.

Previous studies have suggested that chronic cocaine administration may affect serotonergic function and that serotonin (5-HT) may be of importance in cocaine craving. Ten male cocaine addicts and 28 male normal controls were challenged with MK-212 (6-chlor-2-[1-piperazinyl]-pyrazine) (20 mg), a direct acting 5-HT receptor agonist which has affinity for a variety of 5-HT receptor subtypes, and placebo, on separate days. The plasma cortisol and prolactin (PRL) concentrations and oral body temperature responses to MK-212 and placebo were compared between groups. The temperature response to MK-212 was significantly blunted in cocaine addicts compared to normal controls. However, the plasma cortisol and PRL responses to MK-212 did not differ between the two groups. These results suggest selective alteration of presynaptic 5-HT1A or postsynaptic 5-HT2A/2C function in cocaine addicts.