Long-term untreated streptozotocin-diabetes leads to increased expression and elevated activity of prostaglandin H2 synthase in blood platelets.
In diabetes-related states of chronic hyperglycaemia elevated concentrations of glucose may alter the functioning of platelet enzymes involved in arachidonic acid metabolism, including prostaglandin H2 synthase (cyclooxygenase) (PGHS, COX). Therefore, the principal aim of this study was to assess the effects of experimental chronic hyperglycaemia on platelet PGHS-1 (COX-1) expression and activity. Blood platelet activation and reactivity were assessed in Sprague-Dawley rats with the 5-month streptozotocin (STZ) diabetes. The PGHS-1 abundance in platelets was evaluated with flow cytometry and Western blotting, while its activity monitored using a high resolution respirometry and the peroxidase fluorescent assay. The production of prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) in platelets were assayed immunoenzymatically. Circulating platelets from diabetic were characterised by increased size, elevated 'priming' and altered reactivity, compared to non-diabetic animals. Both Western blot analysis and flow cytometry revealed significantly elevated expressions of platelet PGHS-1 in STZ-diabetic rats (p < 0.05). We also observed significantly elevated platelet PGHS-1-related arachidonic acid metabolism in diabetic vs. non-diabetic animals, with the use of polarographic (p < 0.05) and total activity assay (p < 0.001). Such increases were accompanied by the elevated production of PGE2 (p < 0.001) and TXB2 (p < 0.05) in diabetic animals. The increased PGHS-1-dependent oxygen consumption and the total activity of PGHS-1 in diabetic animals remained very significant (p < 0.001) also upon adjusting for blood platelet PGHS-1 abundance. Therefore, our results further contribute to the explanation of the increased metabolism of arachidonic acid observed in diabetes.
a Department of Haemostasis and Haemostatic Disorders , Chair of Biomedical Sciences, Medical University of Lodz , Lodz , Poland and.
Karolina
K
Siewiera
a Department of Haemostasis and Haemostatic Disorders , Chair of Biomedical Sciences, Medical University of Lodz , Lodz , Poland and.
Hassan
H
Kassassir
a Department of Haemostasis and Haemostatic Disorders , Chair of Biomedical Sciences, Medical University of Lodz , Lodz , Poland and.
Marcin
M
Talar
b Department of Medical Biochemistry , Medical University of Lodz , Lodz , Poland.
Lukasz
L
Wieteska
a Department of Haemostasis and Haemostatic Disorders , Chair of Biomedical Sciences, Medical University of Lodz , Lodz , Poland and.
Cezary
C
Watala
D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D015415:Biomarkers; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D051545:Cyclooxygenase 1 / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000235:genetics* / Q000378:metabolism*; D015232:Dinoprostone / Q000096:biosynthesis; D004195:Disease Models, Animal; D004789:Enzyme Activation; D015870:Gene Expression; D008297:Male; D015539:Platelet Activation; D010974:Platelet Aggregation; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D013929:Thromboxane B2 / Q000096:biosynthesis
D015415:Biomarkers; D012333:RNA, Messenger; D016718:Arachidonic Acid; D013929:Thromboxane B2; D051545:Cyclooxygenase 1; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone
Blood platelets; COX-1; PGHS-1; cyclooxygenase-1; diabetes mellitus; prostaglandin H2 synthase-1