Antidepressants activate CaMKII in neuron cell body by Thr286 phosphorylation

CaM kinase II, a regulator of synaptic plasticity, is implicated in pathophysiology and pharmacology of psychiatric disorders. Chronic treatment with antidepressants desipramine and reboxetine up-regulated CaM kinase II in neuronal cell bodies of hippocampus. mRNA/protein expression for aCaM kinase II was unchanged, whereas Thr286 phosphorylation was increased in pyramidal/granular cell bodies, suggesting that increased phosphorylation is responsible for kinase activation. Short-term treatment of neuronal cultureswith reboxetine reduced kinase activation in a concentration-dependentmanner.The short-terminhibitory e¡ect of reboxetine suggests that kinase up-regulation during antidepressant drug treatment is an adaptive response compensating for initial functional down-regulation.