Research On Protective Effect Of Oyster Glycosaminoglycan On Vasular Endothelial Cell

Objectives: To investigate the influences of oyster glycosaminoglycan(O-GAG) on the synthesize and excretion functions of injured human vassel endothelial cell (VECs)., and to study its mechanism of anti-atherosclerosis (AS).Methods:1. The endothelial cell strain ofhuman umbilical vein (HUVECs, ECV304) had been cultured in vitro, and we estabilshed a model of endothelial cell oxidative damage induced by hydrogen peroxide (H₂O₂). We tested the influence of O-GAG on the proliferation activity of injured endothelial cell and normal vascular endothelial cell by means of MTT assay.2. We used chemical methods to analysis the content of Lactate Dehydrogenase (LDH), and so as to study the effect of O-GAG on endothelial cell oxidative damage induced by H₂O₂.3. To observe the effect of O-GAG on antioxidative function of endothelial cell oxidative damage induced by H₂O₂, xanthne oxidase method was used to analysis the activity of superoxide dismutase (SOD) , chemical methods was used to analysis the level of malanyldiadeyhde (MDA), the activity of Glutathione Peroxidase (GSH-PX) and the Total Antioxidative Capacity (T-AOC).4. The secretion of nitric oxide (NO) were measured with nitrate reductase method. Biochemistry methods were used to study the effect of O-GAG on the antioxidant fuction of VECs by testing the activities of the intracellular activities of total nitric oxide synthase (T-NOS) and Inducible nitric oxide synthase (iNOS).5. The radio-immunity methods was used to observe the 6-keto Prostacyclin F_1α(6-keto-PGF_1α) and Thromboxane-B₂ (TXB₂) contents of the vascular endothelial cells, and we analyse the effect of O-GAG on injured endothelial cells.6. We used radio-immunity methods to analysis the content of Endothelin (ET), to study the traction effect of O-GAG on endothelial cell oxidative damage induced by H₂O₂.Results:1. Compared with normal control groups, the proliferation activity of model groups injured by H₂O₂ remarkably decreased (P＜0.01) ; While pretreated by O-GAG (except 10μg/ml), the proliferative activity of VECs obviously increased (P＜0.05, P＜0.01). O-GAG can proliferate the normal VECs in a certain dosage. 2. LDH testing result showed that the content of LDH in model group was much higher than that in normal control group (P＜0.01 ); While the groups pretreated by O-GAG (terminal concentration were 50μg/ml, 100μg/ml, 200μg/ml), compared with model group, the content of LDH obsiously decreased (P＜0.01)3. The activities of SOD in model group remarkably decreased (P＜0.01)and the content of MDA obviously increased, compared with normal control groups (P＜0.01). While pretreated by O-GAG; the activities of SOD obviously increased.and the levels of MDA decresed. (P＜0.01). Compared with normal control groups, the activities of GSH-PX and T-AOC in model groups decreased remarkably (P＜0.01) ,but it increased obviously when pretreated by O-GAG (terminal concentration were 50μg/ml, 100μg/ml, 200μg/ml) (P＜0.01)4. Compared with normal control group, H₂O₂ remarkably decreased the levels of NO,the activity of T-NOS and increased the activities of iNOS (P＜0.01) ; Compared with the injured model group, the activities of T-NOS and the secretion of NO were higher (P＜0.01), and the activities of iNOS was decreased. (P＜0.01)5. The secretion of 6-keto-PGF_1α in model groups was much lower than normal control group (P＜0.01) ; But the levels in O-GAG protective groups (terminal concentration were 50μg/ml, 100μg/ml, 200μg/ml), was obviously increased, compared with injured model groups. (P＜0.05, P＜0.01) . The content of TXB₂in model groups was much higher than normal control group (P＜0.01) ; While compared with model groups, the levels of TXB₂ in O-GAG protective group (terminal concentration were 50μg/ml, 100μg/ml, 200μg/ml) was obviously decreased (P＜0.05, P＜0.01)6. The secretion of ET in injured model group was much higher than normal control group (P＜0.01); While the groups pretreated by O-GAG (terminal concentration were 50μg/ml, 100μg/ml, 200μg/ml), compared with the model group, the content of ET obviously decreased. (P＜0.01).Conclusion: O-GAG can lessen proliferatory inhibition of endothelial cell induced by H₂O₂, decrease the secretion of MDA and LDH, promote the activities of SOD,GSH-PX and T-NOS, increase the excretion of NO, weaken the activity of iNOS, enhance the level of. 6-keto-PGF_1α, and decrease the contents of ET and TXB₂. According to these studies, they can indicate that O-GAG has the protective action on injuered endothelial cell induced by H₂O₂. This study had important actions on the prevention and treatment of heart and vascular disease such as hypertention, AS and so on.