Does cholecystokinin potentiate dopamine action in the nucleus accumbens?

Extracellular single unit recording and microiontophoretic techniques were used to determine whether sulfated cholecystokinin octapeptide (CCK-8S) potentiates the inhibitory action of dopamine (DA) on neurons in the nucleus accumbens of rats. The results show that CCK-8S attenuated, rather than enhanced the action of DA. The interaction between CCK-8S and DA does not appear to be specific because similar antagonizing actions between CCK-8S and serotonin were observed. In addition to opposing the inhibitory effects of DA and serotonin, CCK-8S potentiated the activation of glutamate. It is concluded that CCK-8S and DA exerted their actions independently via depolarizing and hyperpolarizing the neuronal membrane of the NAc neurons, respectively.