Early role of the κ opioid receptor in ethanol-induced reinforcement

► Prolonged activation of the KOR system promoted ethanol-induced conditioning. ► Blockade of KOR function promoted ethanol-induced tactile conditioning. ► Blockade of KOR function promoted the expression of taste conditioning by ethanol. ► Ethanol-induced motor activation was blocked by spiradoline (U62,066E). ► U62,066E affected spontaneous open field exploration in vehicle-treated controls.