Chlorpromazine and loxapine reduce interleukin-1β and interleukin-2 release by rat mixed glial and microglial cell cultures

The cytokines IL-1β and IL-2 are released from activated glial cells in the central nervous system and they are able to enhance catecholaminergic neurotransmission. There is no data concerning influence of antipsychotics on glial cell activity. Antipsychotics reaching the brain act not only on neurons but probably also on glial cells. The aim of this study was to evaluate the effect of chlorpromazine and loxapine on release of IL-1β and IL-2 by mixed glial and microglial cell cultures. Chlorpromazine in concentrations 2 and 20 μM, and loxapine 0.2, 2 and 20 μM reduced IL-1β secretion by LPS-activated mixed glia cultures after 1 and 3 days of exposure. Chlorpromazine in concentrations of 0.2, 2 and 20 μM reduced the IL-2 secretion in mixed glial cultures after 3 days of exposure. Loxapine in concentrations of 0.2, 2 and 20 μM reduced IL-2 secretion in mixed glia cultures after 1 and 3 days of exposure, and additionally loxapine decreased IL-1β and IL-2 secretion in LPS-induced microglia cultures in concentrations of 2, 10 and 20 μM. Quinpirole-a D2 dopaminergic agonist increased LPS-induced IL-1β and IL-2 secretion in mixed glia cultures only in the highest dose of 20 μM. These findings suggest the absence of functional dopamine receptors on cortical microglial cells. Mixed glia cultures deprived of microglia (by shaking and incubating with l-leucine methyl ester) did not release IL-1β and IL-2. This observation suggests that microglia can be a source of assessed cytokines. Results of the present study support the view that antipsychotics act not only on neurons but also on glial cells. However, the clinical significance of these observations still remains unclear.