The role of PKC in chronic effects of opioid or cannabinoid agonists has not been studied. One report184 has shown that chronic morphine treatment increases and decreases specific PKC isoforms in mouse brain, similar to psychostimulant treatment. In mice, repeated morphine injections increase PKCγ protein levels in the limbic forebrain but not in the lower midbrain. There is no effect of chronic morphine treatment on PKCα, PKCβI, PKCβII, or PKCε in either brain region.
