Molecular Pharmacological Studies on Effect of Docosahexaenoic Acid on Vascular Cell Functions

本项目的目的是研究二十二碳六烯酸（DHA）和二十碳五烯酸（EPA），n-3多不饱和脂肪酸，诱导型一氧化氮合酶（iNOS）和环氧合酶-2（考克斯-2）在6-7周龄易卒中型自发性高血压大鼠（SHRSP）血管平滑肌细胞中的蛋白和mRNA表达。匹配的血压正常的Wistar京都大鼠（WKY）。SHRSP细胞在IL-1β诱导下的NO生成和iNOS表达均显著低于WKY细胞，且SHRSP细胞的前列腺素（PG）I2生成和考克斯-2表达均显著低于WKY细胞，而考克斯-1表达无显著差异。两株SHRSP细胞iNOS和考克斯-2 mRNA表达无明显差异，提示这些蛋白的表达可能在转录后过程中受到损伤。DHA和EPA可显著增强IL-1β诱导的WKY细胞NO生成，并呈浓度依赖性。DHA和EPA对IL-10诱导的SHRSP细胞iNOS蛋白和mRNA的表达也有明显的促进作用，DHA和EPA可显著增加IL-1β诱导的WKY细胞考克斯-2蛋白表达，但对考克斯-1蛋白表达无影响，对考克斯-2 mRNA表达无影响。上述结果提示，血管平滑肌细胞iNOS和考克斯-2表达的降低可能与SHRSP的病理生理有关，DHA促进NO和PGI 2的生成可能是其治疗心血管疾病的机制之一。

The aim of the present project was to investigate the effects of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), n-3 polyunsaturated fatty acids, on protein and mRNA expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in cultured vascular smooth muscle cells isolated from 6-7 week-old stroke-prone spontaneously hypertensive rats (SHRSP) and age-matched normotensive Wistar Kyoto rats (WKY). The IL-1β-induced nitric oxide (NO) production and iNOS expression in cells of SHRSP were significantly lower than those in cells of WKY.Similarly, prostaglandins (PG)I2 production and COX-2 expression were significantly lower in cells of SHRSP than WKY, whereas there was no difference in the COX-1 expression. There were no significant differences in iNOS and COX-2 mRNA expressions between the two strains, suggesting that these protein expression may be impaired at post-transcriptional process in cells of SHRSP.DHA and EPA significantly enhanced the IL-1β-induced NO production in a concentration-dependent manner in cells of WKY, whereas had no effect in cells of SHRSP.DHA and EPA also significantly enhanced iNOS protein and mRNA expressions induced by IL-1β in cells of WKY but not in cells of SHRSP.DHA and EPA significantly increased COX-2, but not COX-1, protein expression induced by IL-1β in cells of WKY, but had no effect on COX-2 mRNA expression. These results suggest that the impairment of iNOS and COX-2 expressions in vascular smooth muscle cells may have relevance to the pathophysiology in SHRSP.These results further suggest that enhancement of NO and PGI2 productions by DHA may account for its beneficial effect on cardiovascular disorders.