Abstract 421: N-acetylcysteine Attenuates Systemic Platelet Activation and Cerebral Vessel Thrombosis in Diabetes

Abstract

Diabetes leads to higher risk for stroke and cerebral small vessel disease. Methylglyoxal (MG) is a metabolite of glucose that glycates proteins. We previously demonstrated that diabetes exacerbates stroke-induced brain injury, and that this correlates with brain methylglyoxal (MG)-to-glutathione (GSH). This was reversed by N-acetylcysteine. Here we tested if NAC could also protect against diabetes induced platelet activation and thrombosis. The streptozotocin (STZ)-induced mouse model of type 1 diabetes was used. Circulating blood platelet-leukocyte aggregates (PLAs) were analyzed by flow cytometry at 5 or 19 wks diabetes. Thrombus formation in venules and arterioles (pial circulation) was determined by intravital videomicroscopy one week later. Tail bleeding time was also measured at this time. NAC (2mM) was given in drinking water starting 3 wks before thrombosis assessment. As compared to Veh controls, # of PLAs were significantly increased by diabetes. This was primarily due to elevated lymphocyte-platelet aggregates at the early timepoint, whereas platelet-monocyte aggregates were significantly higher at the later timepoint. NAC decreased the formation of PLAs at both timepoints. At 6 wk diabetes, the onset of thrombus formation in cerebral venules and arterioles was accelerated, and time to complete occlusion of arterioles was shortened. Both the onset and cessation time in cerebral venules and arterioles were reduced at 20 wk diabetes compared with times in Veh mice. NAC significantly prolonged the thrombosis at both timepoints. Interestingly, the cessation times in arterioles and venules were shorter in the more advanced diabetic state than at 6 wks diabetes. The tail bleeding time was not changed at 6 wk, but significantly shortened at 20 wk. This was reversed by NAC treatment. Collectively, these results show that the diabetic blood and brain are more susceptible to platelet activation and thrombosis. Although the pro-thrombotic phenotype evolves with diabetes duration, NAC attenuate the thrombotic effects of diabetes. Future studies will determine if NAC is acting through its anti-oxidant capacity or by decreased dicarbonyl stress.