K_ATP-dependent neurotransmitter release in the neuronal network of the rat caudate nucleus

K_ATP channels can couple the bioenergetic metabolism of the cell to membrane excitability. Here, we show γ-aminobutyric acid (GABA) mediated inhibition of dopamine outflow from slices of the rat caudate nucleus that is regulated by extracellular glucose via high- and low-affinity K_ATP channels. During glucose reduction, a biphasic dopamine effect could be observed with first a dopamine increase followed by a decline at low glucose concentrations. Both phases were inhibited by glibenclamide. Pinacidil decreased DA outflow without an effect of glucose reduction implying an overall activation of K_ATP channels. The first phase with dopamine increase was related to reduced GABAergic activity and could be blocked by bicuculline. Our results may be explained by different types of K_ATP channels with low affinity of ATP and glibenclamide on inhibitory GABAergic and high-affinity on excitatory DAergic neurons. This led us to suggest a biological principle through which neuronal networks are functioning.