Serotonin-2C receptor agonists decrease potassium-stimulated GABA release in the nucleus accumbens

The serotonin 5-HT_2C receptor has shown promise in vivo as a pharmacotherapeutic target for alcoholism. For example, recently, a novel 4-phenyl-2-N,N-dimethylaminotetralin (PAT) drug candidate, that demonstrates 5-HT_2C receptor agonist activity together with 5-HT_2A/2B receptor inverse agonist activity, was shown to reduce operant responding for ethanol after peripheral administration to rats. Previous studies have shown that the 5-HT_2C receptor is found throughout the mesoaccumbens pathway and that 5-HT_2C receptor agonism causes activation of ventral tegmental area (VTA) GABA neurons. It is unknown what effect 5-HT_2C receptor modulation has on GABA release in the nucleus accumbens core (NAcc). To this end, microdialysis coupled to capillary electrophoresis with laser-induced fluorescence was used to quantify extracellular neurotransmitter concentrations in the NAcc under basal and after potassium stimulation conditions, in response to PAT analogs and other 5-HT_2C receptor modulators administered by reverse dialysis to rats. 5-HT_2C receptor agonists specifically attenuated stimulated GABA release in the NAcc while 5-HT_2C antagonists or inverse agonists had no effect. Agents with activity at 5-HT_2A receptors had no effect on GABA release. Thus, in contrast to results reported for the VTA, current results suggest 5-HT_2C receptor agonists decrease stimulated GABA release in the NAcc, and provide a possible mechanism of action for 5HT_2C-mediated negative modulation of ethanol self-administration.