Effects of green tea catechin on phospholipase A(2) activity and antithrombus in streptozotocin diabetic rats

The purpose of this study was to investigate the effects of dietary green t ea catechin on phospholipase A(2) (PLA(2)) activity and the antithrombotic reaction of platelets in streptozotocin (STZ)-diabetic rats. Sprague-Dawley male rats weighing 100 +/- 10 g were randomly divided into one normal and three STZ-diabetic groups, which were subdivided into catechin-free group ( DM-0C), 0.5% catechin group (DM-0.5C) and 1% catechin group (DM-1C). The ac tivity level of platelet phospholipase A(2) was higher in the diabetic grou ps than in the normal group, while it was lower in DM-0.5C and DM-1C than i n DM-0C. The activity of platelet cyclooxygenase in DM-0C was 1.1-fold as h igh as in the normal group, but was significantly reduced by catechin suppl ementation. The platelet thromboxane A(2) (TXA(2)) formation became higher in DM-0C as compared to the normal group, but not in DM-0.5C and DM-1C. The synthesis of aortic prostacyclin (PGI,) was lower in DM-0C and DM-0.5C tha n in the normal group. The PGI(2)/TXA(2) ratio was decreased to 55% in DM-0 C, but was restored by catechin supplementation. These results indicate tha t STZ-diabetic rats are sensitive to platelet aggregation and thrombosis, a nd that the abnormality can be improved by dietary catechin.