Melatonin does not affect disseminated intravascular coagulation but diminishes decreases in platelet count during subacute endotoxaemia in rats

• We examine the influence of exogenous melatonin on haemostasis during endotoxaemia.
• Melatonin does not affect disseminated intravascular coagulation during endotoxaemia.
• Melatonin causes a reduction of thrombocytopenia and haemolysis during endotoxaemia.

IntroductionInhibitory effects of exogenous melatonin (MLT) on plasma coagulation and platelet aggregation have already been observed in vivo and in vitro under normal conditions. Here, we studied whether MLT also diminishes the lipopolysaccharide (LPS)-induced disseminated intravascular coagulation (DIC) during subacute endotoxaemia.Materials and methodsSubacute endotoxaemia was induced in male Wistar rats by an intravenous infusion of LPS over a period of 300 min (0.5 mg LPS/kg × h). MLT was administered intravenously 15 min before and 120 min and 240 min after starting of the LPS infusion (3 × 3 mg MLT/kg × 15 min). The kinetic of clot formation was analysed by thromboelastometry.ResultsInfusion of LPS led initially to a significant reduction of clotting time (120 min, LPS: 150 ± 21 s vs. SHAM: 292 ± 36 s), and finally a significant increase of clotting time (300 min, LPS: 2768 ± 853 s vs. SHAM: 299 ± 67 s) and a slight increase of clot formation time (300 min, LPS: 1038 ± 657 s vs. SHAM: 98 ± 14 s) as well as a significant decrease of alpha-angle (300 min, LPS: 35 ± 15° vs. SHAM: 72 ± 3°), maximum clot firmness (300 min, LPS: 22 ± 6 mm vs. SHAM: 68 ± 3 mm), and area under the curve (300 min, LPS: 1657 ± 552 mm × 100 vs. SHAM: 6849 ± 307 mm × 100). Simultaneously, a decrease of platelet count (300 min, LPS: 55 ± 8 vs. SHAM: 180 ± 55) and a release of cell-free haemoglobin (240 min, LPS: 46 ± 5 μmol/L vs. SHAM: 16 ± 2 μmol/L) could be observed in the course of subacute endotoxaemia. The additional administration of MLT did not reduce the LPS-induced alterations in parameters of thromboelastometry, but significantly reduced the LPS-induced decrease of platelet count (300 min, LPS + MLT: 130 ± 10) and release of cell-free haemoglobin (240 min, LPS + MLT: 29 ± 3 μmol/L).ConclusionMelatonin does not affect DIC but diminishes thrombocytopenia and haemolysis during endotoxaemia.