Interleukin 1β induces diabetes and fever in normal rats by nitric oxide via induction of different nitric oxide synthases

Abstract Substantial in vitro evidence suggests that nitric oxide may be a major mediator of interleukin 1 (IL-1) induced pancreatic beta-cell inhibition and destruction in the initial events leading to insulin-dependent diabetes mellitus. Using n G -nitro-L-arginine methyl ester, an inhibitor of both the constitutive and the cytokine inducible forms of nitric oxide synthase, and aminoguanidine, a preferential inhibitor of the inducible form of nitric oxide synthase, we investigated the impact of inhibiting nitric oxide production on food-intake, body weight and temperature, blood glucose, plasma insulin, glucagon, corticosterone and leukocyte- and differential-counts in normal rats injected once daily for 5 days with interleukin 1β (IL-1β) (0.8 μg/rat ≈ 4.0 μg/kg). Inhibition of both the constitutive and the inducible forms of nitric oxide synthase prevented IL-1β-induced fever, hyperglycaemia, hypoinsulinemia, and hyperglucagonemia, and partially prevented lymphopenia and neutrophilia, but had no effect on IL-1β-induced anorexia and changes in plasma corticosterone. Preferential inhibition of the inducible form of nitric oxide synthase using two daily injections of 5 mg/rat of aminoguanidine prevented IL-1β-induced hyperglycaemia and hypoinsulinaemia, and slightly reduced the pyrogenicity of IL-1 on 3 out of 5 days. Higher doses of aminoguanidine (100 mg/rat) prevented lymphopenia and neutrophilia. We conclude that nitric oxide produced by the inducible form of nitric oxide synthase, mediates the IL-1β-induced inhibition of insulin release and that the effect of IL-1β on temperature, pancreatic alpha-cells, and leukocyte differential counts seems to be mediated by nitric oxide produced by the constitutive form of nitric oxide synthase.