Pharmacological reduction of small conductance calcium-activated potassium current (SK) potentiates the excitatory effect of ethanol on ventral tegmental area dopamine neurons

Dopaminergic neurons in the ventral tegmental area (VTA) are important for the rewarding properties of drugs of abuse, in-cluding ethanol. We previously demonstrated that ethanol ex-cites VTA neurons and that ethanol reduces the amplitude of the after hyperpolarization (AHP) that follows spontaneous ac-tion potentials. Because the small conductance calcium-acti-vated potassium current (SK) is a component of the AHP of VTA neurons, we assessed the effect of the SK blockers apamin and d-tubocurarine (d-TC) on the action of ethanol on dopaminergic VTA neurons with intracellular and extracellular recording in rat brain slices. Apamin (1–200 nM) and d-TC (100 and 400 mM) caused concentration-dependent reductions in the AHP ampli-tude. Ethanol (80 mM) caused a small reduction in the AHP. In the presence of apamin (40 nM), ethanol (80 mM) caused