Figure 4
From: Presynaptic action of neurotensin on dopamine release through inhibition of D2 receptor function
Activation of D 2 autoreceptors during train pulse- but not single pulse-evoked DA overflow. A) The graphs represent the average amplitude and kinetics of train-evoked DA overflow in the presence of 5 μM sulpiride (left) or 1 μM quinpirole (right). B) Graph showing the effect of the D2 receptor agonist quinpirole (1 μM; n = 3), and the D2 receptor antagonist sulpiride (5 μM; n = 8) on DA overflow following pulse-train stimulation. Activation of D2 receptors by quinpirole inhibits peak DA overflow, whereas the blockade of these receptors by sulpiride considerably enhances it. C) Graph comparing the effect of quinpirole (1 μM; n = 5), and sulpiride (5 μM; n = 4) on DA overflow evoked by single-pulse stimulation. Under these conditions, D2 receptor activation also inhibits DA overflow, but D2 receptor blockade has no effect.