Transgenic mice lacking CREB and CREM in noradrenergic and serotonergic neurons respond differently to common antidepressants on tail suspension test.

Evidence exists that chronic antidepressant therapy enhances CREB levels and activity. Nevertheless, the data are not conclusive, as previous analysis of transgenic mouse models has suggested that CREB inactivation in fact contributes to antidepressant-like behavior. The aim of this study was to evaluate the role of CREB in this context by exploiting novel transgenic mouse models, characterized by selective ablation of CREB restricted to noradrenergic (Creb1DBHCre /Crem-/-) or serotonergic (Creb1TPH2CreERT2 /Crem-/-) neurons in a CREM-deficient background to avoid possible compensatory effects of CREM. Selective and functional ablation of CREB affected antidepressant-like behavior in a tail suspension test (TST) after antidepressant treatment. Contrary to single Creb1DBHCre mutants, Creb1DBHCre /Crem-/- mice did not respond to acute desipramine administration (20 mg/kg) on the TST. On the other hand, single Creb1TPH2CreERT2 mutants displayed reduced responses to fluoxetine (10 mg/kg) on the TST, while the effects in Creb1TPH2CreERT2 /Crem-/- mice differed by gender. Our results provide further evidence for the important role of CREM as a compensatory factor. Additionally, the results indicate that new models based on the functional ablation of CREB in select neuronal populations may represent a valuable tool for investigating the role of CREB in the mechanism of antidepressant therapy.