Interleukin-1 receptor antagonist does not reverse lipopolysaccharide-induced inhibition of water intake in rat

The involvement of interleukin-1 in antidipsogenic effects induced by intraperitoneal (i.p.) administration of lipopolysaccharide (0.32, 0.64 and 0.96 mg/kg) in 24-h water-deprived rats, was evaluated by injection of human interleukin-1 receptor antagonist (10, 25 and 50 μg/rat) into the lateral cerebral ventricle (i.c.v.). The effects of either lipopolysacharide or human interleukin-1 receptor antagonist treatment on rectal temperature of 24-h water-deprived rats, were examined. Our date show that human interleukin-1 receptor antagonist administration is able to reverse, dose dependently, fever, but not lipopolysaccharide inhibition of thirst. The reduction of pyrogenic, but not of antidipsogenic, effects of lipopolysaccharide following human interleukin-1 receptor antagonist administration suggests that lipopolysaccharide inhibition of thirst is not dependent on interleukin-1-induced fever and that interleukin-1 is not a direct mediator implicated in inhibition of water intake provoked by peripheral injection of lipopolysaccharide.