Regulation of CCL2/MCP-1 production in astrocytes by desipramine and atomoxetine: involvement of α2 adrenergic receptors.

Having previously observed that noradrenaline activation of β adrenergic receptors induces the synthesis of the chemokine monocyte chemoattractant protein (CCL2/MCP-1) in astrocytes, it is our interest to analyze the mechanisms involved in this process, particularly the possible effect of noradrenaline-modulating drugs. The treatment of primary rat astrocyte cultures with the noradrenaline transporter inhibitors desipramine or atomoxetine induced the expression and synthesis of CCL2/MCP-1 in these cells. This effect of both drugs in vitro suggests that CCL2/MCP-1 expression could also be modulated by some mechanism independent of the elevation of brain noradrenaline levels. This was confirmed by measuring a reduction in CCL2/MCP-1 production by the treatment with the α2 adrenergic receptor agonist clonidine. Accordingly, the blockade of α2 adrenergic receptors with yohimbine potentiated the production of MCP-1 stimulated by the activation of β receptors. While the activation of β adrenergic receptors and the subsequent elevation of cAMP levels seem to be the main pathway for noradrenaline to induce CCL2/MCP-1 in astrocytes, our data indicate that the α2 adrenergic receptors also regulate CCL2/MCP-1 expression working as inhibitory mediators.