Striatal microinjections of interleukin-2 and rat behaviour in the elevated plus-maze.

We showed that the relationship between cytokine mRNA in the rat brain and elevated plus-maze behaviour is site- (striatum, prefrontal cortex), and cytokine-specific (interleukin-2). Here, we investigated whether a striatal microinjection of interleukin-2 (1, 10, 25 ng) affects elevated plus-maze behaviour. Analyses showed no acute effects of IL-2 on open arm time, whereas dose-dependent differences in rearing activity, and open arm entries became apparent between IL-2 doses. Twenty-four hours later, a previous dose of 25 ng IL-2 showed a trend for more open arm time compared to vehicle. These behavioural changes are discussed in relation to anxiety-relevant and exploratory behaviour, and possible neurochemical mechanisms.