Fig. 5. Regionally different contribution of GABA_A and GABA_B receptors in the soma and dendrites to firing inhibition of SNc DA neurons.

(A) Transmitted image of DA neuron with location of uncaging sites. (B) Spontaneous firing inhibited by caged-GABA uncaging in the soma, proximal dendrite, and distal dendrite (control). CGP55845 (2 µM), a GABA_B receptor specific antagonist, significantly blocked GABA effects in the proximal and distal dendrite. In the soma, GABA_A and GABA_B receptor antagonists elicited partial block of GABA-induced firing inhibition. Spontaneous firing inhibitions by activation of GABA_A and GABA_B receptors in three different regions are summarized. ^*p<0.05; ^**p<0.01; ^***p<0.001 by t-test, n.s., nonsignificant.