Depression Treatment: Acute Antidepressant Treatment Differently Modulates ERK/MAPK Activation in Neurons and Astrocytes of the Adult Mouse Prefrontal Cortex.

Acute antidepressant treatment differently modulates ERK/MAPK activation in neurons and astrocytes of the adult mouse prefrontal cortex.

Filed under: Depression Treatment

Neuroscience. 2012 Dec 10;
Barbara DB, Julika R, Schmidt Mathias V, Rainer R

The onset of action of antidepressants (ADs) usually takes several weeks, but first molecular responses to these drugs may appear already after acute administration. The ERK/MAPK signalling pathway is a target of antidepressants and an important pathway involved in cellular plasticity. In major depressive disorder (MDD), especially the prefrontal cortex and hippocampus are most likely affected in depressive patients and recent work revealed a hyperactivated ERK signalling in the rat prefrontal cortex after chronic stress, a precipitating factor for MDD. Strong evidences support that not only neurons but also astrocytes participate in neuronal activity and may therefore additionally be substrate of antidepressant action. In this study, we show by Western blot that neither fluoxetine nor desipramine preferentially affects the activation of one of the two ERK isoforms, ERK1 and ERK2, in respect to the other. Further immunohistochemical analysis in the prefrontal cortex revealed that basal levels of phospho-activated ERK (pERK) are mostly found in neurons in contrast to very few astrocytes. Both ADs can inhibit neuronal pERK as early as 15 minutes after drug administration with peculiar regional and layer specificities. Contrarily, at this time point none of the two ADs shows a clear modulation of astrocytic pERK. We propose that this mechanism of action of ADs may be protective against an exacerbated cortical ERK activity that may exert detrimental effects on susceptible neuronal populations. Our findings on acute effects of AD treatment in the adult mouse prefrontal cortex encourage to examine further how this treatment might influence pERK in animal models of depression to identify early targets of AD action.
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