Effects of Green Tea Catechin on Hepatic Microsomal Phospholipase A₂ Activities and Changes of Hepatic Phospholipid Species in Streptozotocin-Induced Diabetic Rats

Abstract

In this study, male Sprague-Dawley rats weighing 70±5g were divided into a control (normal) group and three different diabetes mellitus (DM) groups that were supplemented with catechin-free (DM-OC), 0.5% catechin dietary (DM-0.5C), and 100 catechin (DM-1.OC). The animals were maintained on an experimental diet for four weeks. At this point, they were injected with streptozotocin (STZ) to induce diabetes, and they were sacrificed on the 6th day to determine the activities of phospholipase A₂ (PLA₂) and the changes of phospholipid species by catechin supplementation. In liver tissues, no significant differences were found between the PC hydrolysis of a normal group and a diabetic group; however, PE hydrolysis of the DM-0C, DM-0.5C, and DM-1.OC groups increased by 68.9%, 34.01%, and 26.9%, respectively, compared with the normal group. Although the PLAz activity of the DM-OC group in the liver tissues increased 91 % compared with the normal group, the PLA2 activity of DM-0.5C and DM-I.OC, which were fed catechin, increased 50% and 56%, respectively, compared with the normal group. In the liver tissues, peroxide values of the DM-OC, the DM-0.5C, and the DM-1.0C groups were increased 109%, 32.8%, and 46.7%. respectively, compared with the normal group. Based on these results for STZ-induced diabetic rats, lipid peroxidation seems to be accelerated specifically with the increased PLA₂ activities.Thus if antioxidants like catechin were supplementation, the activity of PLA2 and PE hydrolysis can be altered and the accumulation of lipid peroxide would be decreased. Therefore we concluded that the antioxidant catechin for diabetic animals can significantly reduce PLA₂ activities and lipid peroxide formation.