Chronic exposure to psychostimulants increases CaMKII activity when given continuously, intermittently, or by self-administration. In rats, chronic amphetamine treatment increases striatal CaMKII activity but not protein levels241 and chronic intermittent amphetamine treatment increases striatal CaMKIIβ mRNA.242 Chronic cocaine treatment in mice increases CaMKII protein in the VTA,243 and chronic cocaine self-administration in rats increases CaMKII mRNA in the VTA.244 In rats treated for 1 week with daily cocaine injections, the enhanced dopamine accumulation in the NAc resulting from acute amphetamine administration is blocked by intra-NAc injections of the CaMKII inhibitor KN93.245
