Essential role of interleukin-15 receptor in normal anxiety behavior

The interactions between the cytokine interleukin (IL)-15 and the classical neurotransmitter GABA have been shown in IL15R alpha receptor knockout mice by observations of memory deficits and reduction of GABA To test the hypothesis that IL15 affects anxiety-like behavior, knockout mice without 115, IL15R alpha, or the co-receptor IL2R gamma were subjected to open-field and elevated plus maze tests All three strains showed reduction of anxiety, with greater changes in the IL15R alpha knockout mice than in the IL15 or IL2R gamma knockout mice This unexpected observation is opposite to the reported increase of anxiety in mice lacking other proinflammatory cytokines or their receptors The reduced anxiety was not associated with changes in associated serum cytokines However, Western blotting, qPCR, and immunohistochemistry all showed that IL15R alpha knockout mice had mild microgliosis and astrogliosis in the hippocampus. To determine whether this ghosts plays a role in decreasing anxiety, IL15R alpha knockout mice were treated with minocycline, but this did not cause a change in open field performance To determine whether IL15 plays a direct role in anxiety, wildtype mice were treated with IL15R alpha by intraperitoneal injection This also failed to cause a change in open field behavior under the experimental conditions tested Thus, IL15R alpha is essential for normal anxiety-like behavior, but inhibition of gliosis in the fearless IL15R alpha knockout mice Or IL15 treatment of normal mice did not acutely modulate behavioral performance as tested (C) 2010 Elsevier Inc All rights reserved