Time-dependent in-vivo effects of interleukin-2 on neurotransmitters in various cortices: Relationships with depressive-related and anxiety-like behaviour

We investigated the impact of systemically injected IL-2 (2.5 μg/kg, i.p.) on serotonergic and dopaminergic neurotransmission in various cortical areas by in-vivo microdialysis. IL-2 lastingly reduced extracellular 5-HT levels in the medial prefrontal (− 75%), occipital (− 70%), and temporal cortices (− 45%), whereas dopamine was only moderately reduced in the medial prefrontal cortex.Based on the serotonergic time profile, we conducted further experiments to test for acute and delayed (2 h post injection) depressive-related effects of systemic IL-2 (0–5.0 μg/kg) in a forced swim test and delayed effects on anxiety-like behaviour in the elevated plus-maze. IL-2 had dose-dependent effects on depressive-related behaviour after delayed but not acute testing, but no effects on anxiety-like behaviour.