RESUMEN
3-(2-Carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP), a competitive N-methyl-D-aspartate (NMDA) receptor antagonist, produces rapid antidepressant-like effects in animal models of depression. However, the molecular mechanisms underlying these behavioral actions remain unknown. Here, we demonstrate that CPP rapidly stimulates histone deacetylase (HDAC) 5 phosphorylation and nuclear export in rat hippocampal neurons. These effects are accompanied by calcium/calmodulin kinase II (CaMKII) and protein kinase D (PKD) phosphorylation. Behavioral experiments revealed that viral-mediated hippocampal knockdown of HDAC5 blocked the antidepressant effects of CPP in stressed animals. Taken together, our results imply that CPP acts via HDAC5 and suggest that HDAC5 is a common regulator contributing to the antidepressant actions of NMDA receptor antagonists such as CPP.
RESUMEN
Ketamine shows promise as a therapeutic agent for the treatment of depression. The increased expression of brain-derived neurotrophic factor (BDNF) has been associated with the antidepressant-like effects of ketamine, but the mechanism of BDNF induction is not well understood. In the current study, we demonstrate that the treatment of rats with ketamine results in the dose-dependent rapid upregulation of Bdnf promoter IV activity and expression of Bdnf exon IV mRNAs in rat hippocampal neurons. Transfection of histone deacetylase 5 (HDAC5) into rat hippocampal neurons similarly induces Bdnf mRNA expression in response to ketamine, whereas transfection of a HDAC5 phosphorylation-defective mutant (Ser259 and Ser498 replaced by Ala259 and Ala498), results in the suppression of ketamine-mediated BDNF promoter IV transcriptional activity. Viral-mediated hippocampal knockdown of HDAC5 induces Bdnf mRNA and protein expression, and blocks the enhancing effects of ketamine on BDNF expression in both unstressed and stressed rats, and thereby providing evidence for the role of HDAC5 in the regulation of Bdnf expression. Taken together, our findings implicate HDAC5 in the ketamine-induced transcriptional regulation of Bdnf, and suggest that the phosphorylation of HDAC5 regulates the therapeutic actions of ketamine.