Central injection of IL-10 antagonizes the behavioural effects of lipopolysaccharide in rats

Peripheral (IP) and central (ICV) injections of lipopolysaccharide (LPS) ha ve been shown to induce brain expression of proinflammatory cytokines and t o depress social behaviour in rats, increase duration of immobility and ind uce body weight loss. To determine if the anti-inflammatory cytokine, inter leukin-10 (IL-10) is able to modulate these effects, recombinant rat IL-10 was injected in the lateral ventricle of the brain (30, 100, 300 ng/rat) pr ior to IP or ICV injection of LPS (250 mu g/kg or 60 ng/rat, respectively). Social exploration was depressed for 6 h after IP LPS injection. This effe ct was attenuated by IL-10 (30 and 100 ng) 2 h after injection, whereas the highest dose of IL-10 blocked the depression of social interaction for 6 h after LPS injection. IL-10 produced the same effects on the increase of im mobility although the results did not reach significance. Social exploratio n was depressed 3 h after ICV LPS injection, and this was accompanied by in creased immobility. These effects were totaly blocked by ICV IL-10 (300 ng/ rat). Rats lost body weight after ICV LPS, and this effect was attenuated b y ICV IL-10. These results indicate that IL-10 is able to modulate the prod uction and/or action of central proinflammatory cytokines. (C) 1999 Elsevie r Science Ltd. All rights reserved.