裸花紫珠提取物促血小板活化作用及其机制

目的:研究裸花紫珠Callicarpa nudiflora提取物对血小板活化的影响,并探讨其作用机制。方法:雄性SD大鼠50只,随机分为空白组,云南白药组(0.930 g·kg-1),裸花紫珠提取物低、中、高剂量(0.131,0.263,0.525 g·kg~(-1))组,连续给药10 d。给药结束后分别提取各组动物血小板,采用微量版法测定二磷酸腺苷(adenosine diphosphate,ADP)诱导的血小板聚集率;采用酶联免疫吸附法(ELISA)测定血小板中血栓素(thromboxane B2,TXB2),5-羟色胺(5-serotonin,5-HT)含量。采用ELISA法检测血小板中环磷酸腺苷(cyclic adenosine 5'-monophosphate,c AMP)的释放量。采用蛋白免疫印迹法(Western blot)检测裸花紫珠提取物对血小板中磷酸化-磷脂酰肌醇3激酶(phosphatidylinositol-3-kinases,p-PI3K)蛋白表达的影响。结果:给药后,裸花紫珠提取物可明显增强ADP诱导的血小板聚集反应(P0.05),可明显促进血小板释放TXB2和5-HT(P0.05)。另外,裸花紫珠提取物低、高剂量组血小板c AMP含量分别为(3.074±0.538),(3.340±0.265)nmol·L~(-1),较空白组(3.795±0.586)nmol·L~(-1)明显降低(P0.05),裸花紫珠提取物中剂量组血小板中c AMP为(3.003±0.242)nmol·L-1,较空白组有显著提高(P0.01)。裸花紫珠提取物可显著提高p-PI3K激酶蛋白表达量(P0.01)。结论:裸花紫珠提取物可显著上调ADP诱导的血小板活化,其机制可能与其显著增强血小板ADP受体(P2Y12)所介导的信号转导有关。

Extracts from Callicarpa nudiflora Leaves Enhances Platelet Activation

Objective: To study the effects of extracts from Callicarpa nudiflora(ECN) leaves on platelet activation and to elucidate its mechanisms. Method: The 50 male SD rats were randomly divided into blank group, Yunnan Baiyao group (0.930 g·kg^-1), ECN low, medium and high dose groups (0.131, 0.263, 0.525 g·kg^-1). All the rats were treated for 10 days. After treatment, the platelets of the rats in all groups were extracted, and microscale plate method was used to determine adenosine diphosphate (ADP)-induced platelet aggregation rate; enzyme linked immunosorbent assay (ELISA) was used to determine thromboxane B₂(TXB₂) and 5-serotonin (5-HT) levels in platelet as well as cyclic adenosine 5''-monophosphate (cAMP) release level in platelet. Furthermore, the effect of ECN on phosphatidylinositol-3-kinases (p-PI3K) protein expression levels was determined by using Western blot assay. Result: ECN enhanced ADP-induced platelet aggregation significantly (P<0.05), and it could significantly promote TXB₂ and 5-HT release (P<0.05). Furthermore, cAMP level in platelet was (3.074±0.538), (3.340±0.265) nmol·L^-1respectively in ECN low dose group and high dose group, lower than (3.795±0.586) nmol·L^-1 in blank group (P<0.05), and cAMP level in ECN medium dose group was (3.003±0.242) nmol·L^-1, significantly lower than that in blank group (P<0.01). In Western blot assay, it was found that ECN could significantly increase p-PI3K kinase protein expression (P<0.01). Conclusion: Collectively, the data presented here demonstrated that ECN enhanced the development of platelet aggregation and amplification of platelet activation. These effects may be associated with its up-regulation on P2Y₁₂ receptors.