Melatonin modulates mesenteric blood flow and TNFα concentrations after lipopolysaccharide challenge

Abstract

Objective: To investigate the effect of various doses of melatonin on reduction in mesenteric blood flow (MBF) and increase in tumour necrosis factor alpha (TNFα) concentration caused by injection of lipopolysaccharide (LPS). Design: University Hospital, Turkey. Setting: Open experimental study. Animals: 59 Swiss albino mice. Interventions: Animals were injected with melatonin solvent or 1, 10, 100, or 500: mg/kg melatonin. Ten minutes later control animals were injected with saline, and the experimental group with LPS. Main outcome measures: Mesenteric blood flow and serum TNFα concentration. Results: In control animals, 100 and 500 mg/kg melatonin reduced MBF. LPS reduced MBF in solvent, 1, and 10 mg/kg melatonin groups. The concentration of TNFα was considerably increased in the mice given LPS. Melatonin reduced this response significantly. Conclusion: In high doses melatonin directly reduces MBF. It has no protective effect on the LPS-induced decrease in MBF. In lower doses it blocks, but at higher doses reduces, LPS-induced TNFα production.