RT Journal Article SR Electronic T1 Desipramine Reduces Stress-Activated Dynorphin Expression and CREB Phosphorylation in NAc Tissue JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 704 OP 712 DO 10.1124/mol.108.051417 VO 75 IS 3 A1 Elena H. Chartoff A1 Maria Papadopoulou A1 Matt L. MacDonald A1 Aram Parsegian A1 David Potter A1 Christine Konradi A1 William A. Carlezon, Jr. YR 2009 UL http://molpharm.aspetjournals.org/content/75/3/704.abstract AB The nucleus accumbens (NAc) is a critical brain area for reward and motivated behavior. Accumulating evidence suggests that altered function of the transcription factor cAMP response element binding protein (CREB) within the NAc is involved in depressive behavior. In rats, stress activates CREB within the NAc, and elevation of CREB expression in this region produces depressive-like behaviors that are accompanied by activation of CREB-regulated target genes. The depressive-like behaviors seem to be due, at least in part, to CREB-mediated increases in dynorphin function, because they are mimicked by κ-opioid receptor (KOR) agonists and attenuated by KOR antagonists. We hypothesized that if CREB-mediated dynorphin expression in the NAc contributes to depressive behavior, then antidepressants might reduce dynorphin function in this region. Here, we demonstrate that desipramine (DMI), a norepinephrine reuptake inhibitor that has been used for decades to treat clinical depression, blocks swim stress-induced activation of prodynorphin (encodes dynorphin) in the NAc. In primary cultures of NAc and striatum, DMI decreases basal and stimulated CREB phosphorylation by causing reductions in intracellular calcium (Ca2+) availability that are independent of norepinephrine or other monoaminergic inputs, identifying a potential mechanism for alterations in CREB-mediated gene expression. Fluoxetine (FLX), a selective serotonin reuptake inhibitor, has similar effects in culture, suggesting a common intracellular effect of these antidepressants. These findings raise the possibility that a therapeutically relevant mechanism of action of DMI occurs through attenuation of CREB-mediated gene transcription, which is mediated via previously uncharacterized mechanisms that occur directly within the NAc. The American Society for Pharmacology and Experimental Therapeutics