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

本项目旨在研究n-3多不饱和脂肪酸二十二碳六烯酸（DHA）和二十碳五烯酸（EPA）对6-7周龄卒中易发自发性高血压大鼠（SHRSP）和年龄匹配的正常血压Wistar Kyoto大鼠（WKY）血管平滑肌细胞中诱导型一氧化氮合酶（iNOS）和环氧化酶-2 （COX-2）蛋白和mRNA表达的影响。SHRSP细胞il -1β诱导的一氧化氮（NO）生成和iNOS表达量显著低于WKY细胞。同样，SHRSP细胞中前列腺素（PG）I2的产生和COX-2的表达明显低于WKY细胞，而COX-1的表达无差异。两株间iNOS和COX-2 mRNA的表达无显著差异，提示这些蛋白的表达可能在SHRSP细胞的转录后过程中受到损害。DHA和EPA对il -1β诱导的WKY细胞NO生成有浓度依赖性的促进作用，而对SHRSP细胞无影响。DHA和EPA也显著增强了WKY细胞中IL-1β诱导的iNOS蛋白和mRNA的表达，而对SHRSP细胞无显著影响。DHA和EPA可显著提高IL-1β诱导的WKY细胞COX-2蛋白表达，但对COX-1 mRNA表达无显著影响。这些结果提示血管平滑肌细胞iNOS和COX-2表达的损伤可能与SHRSP的病理生理有关。这些结果进一步表明，DHA对NO和PGI2产生的增强可能是其对心血管疾病有益的原因。

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.