CHARACTERIZATION OF DOPAMINE-INDUCED DEPOLARIZATION OF PREFRONTAL CORTICAL-NEURONS

Dopamine (DA) has been reported to depolarize neurons in the prefronta l cortex (PFC). To further characterize this effect of DA, we made who le cell, recordings from PFC pyramidal cells in rat brain slices. As r eported previously, DA depolarized most PFC cells tested. This effect of DA was concentration-dependent and persisted in the presence of syn aptic blockade, indicating a direct effect of DA on the recorded cell. During DA-induced depolarization, PFC neurons consistently showed an increase in excitability, suggesting that the depolarization is not di rectly related to DA-induced inhibition of PFC neurons previously obse rved in vivo. Surprisingly, the effect of DA was not mimicked or block ed by several commonly used DA agonists and DA antagonists. The alpha and beta antagonists phentolamine and alprenolol and the atypical anti psychotic drug clozapine also showed no significant effect on DA-induc ed depolarization. These results suggest that DA-induced depolarizatio n may be mediated by a nonspecific mechanism. However, it remains poss ible that there exists a new type of DA receptors in the PFC not sensi tive to classical DA agonists and antagonists, particularly given the fact that DA applied in the same manner depolarized only PFC neurons b ut not those in the striatum or the substantia nigra. (C) 1997 Wiley-L iss, Inc.