Effects of Platelet Activating Factor go Rat Mesenteric Microcirculation

The actions of platelet activating factor(PAF) on rat mesenteric microcirculation were studied by laser Doppler microscopy in vivo. Injection of PAF 0.2～0.6μg/kg intravenously produced a dose-related decrease in the blood flow velocity and an increase in the diameters of the mesenteric arterioles     

The progress of the research on cardio-vascular effects and acting mechanism of polydatin

Rhizoma Polygoni Cuspidati,a Chinese herbal drug,has actions of dispelling dampness, alleviating jaundice,clearing heat,subsiding toxin,activating blood,and removing stasis.Polydatin(PD),one of its chief active ingredients,has been proved by modern pharmacological studies to possess extensive cardiovascular pharmacological activity,showing marked effects on protecting cardio-myocyte,dilating blood vessel, antagonizing platelet aggregation,thrombosis,and atherosclerosis.The progress of the research on cardiovascular pharmacological actions and the acting mechanism of PD was reviewed in this paper.     

Effects of antipsoriatic drugs on biosynthesis of platelet activating factor by human keratinocytes.

Human keratinocytes in primary culture stimulated by Ca~(2 ) innophore A23187(Io) could synthesize and release a material which might aggregate aspirin-treated washed rabbit platelets and was identified as platelet activating factor (PAF) by four methods. Io stimulated the production of PAF by keratinocytes in a time- and dose-dependent manner. The PAF precursors, i.e., AAGPC and Lyso-PAF, were detected in keratinocytes. Nitrogen mustard and dexamethasone could time- and dose-dependently inhibit PAF biosynthesis from Io to induce human keratinocytes in culture. The IC50 of nitrogen mustard and dexamethasone were 6.34×10~(-9) M and 1.005×10~(-8) M respectively. The results showed that the synthesis and release of PAF by normal human keratinocytes may be accounted for the development of cutaneous inflammation and the pathogenesis of some skin disorders and application of drugs that inhibit PAF synthesis may be a new and effective approach to the management of some inflammatory skin diseases such as psori     

Effects of MTX and BN52021 on PAF-induced chemotaxis of PMNs and intraepidermal accumulation of inflammatory cells in guinea pigs.

OBJECTIVE To investigate the effects of methotrexate (MTX) and platelet activating factor (PAF) antagonist ginkgolide B (BN52021) on PAF induced chemotaxis of neutrophils.

METHODS All guinea pigs were randomly divided into 12 groups. They were given different dosages of MTX and BN52021 by intra-abdominal injections. The random and chemotactic migration of polymorphonuclear leukocytes (PMNs) were measured by the agarose method. The backs of all guinea pigs were given intradermal injections of PAF and the numbers of the infiltration of inflammatory cells into the skin were determined.

RESULTS MTX inhibited random migration and chemotactic migration of PMNs to PAF, LTB4 and PAF-induced intraepidermal accumulation of inflammatory cells in dose- and time-dependent fashion. BN52021 specially inhibited PAF-induced chemotaxis of PMNs and intraepidermal accumulation of inflammatory cells, but did not inhibit PMNs random migration and LTB4-induced chemotaxis of PMNs.

CONCLUSIONS The inhibition of PMNs activities may be part of the mechanism of MTX therapy for psoriasis; BN52021 is a selective inhibitor of PAF-induced chemotaxis of PMNs, and therefore can be useful in the treatment of some inflammatory dermatoses such as psoriasis.

     

Elevated Platelet Activating Factor Level in Ischemia-Related Arrhythmia and Its Electrophysiological Effect on Myocardium

Objective The mechanism through which platelet activating factor (PAF) induces cardiac electrical activity and arrhythmia is not well understood and previous studies have suggested a potential involvement of ion channels in its action. The present study was aimed to clarify the role of PAF in fatal arrhythmias following acute myocardia infarction (AMI) and the underlying mechanism. Methods (1) Blood PAF levels were measured among 72 AMI patients at the time of diagnosis with AMI and 48 h later, and their electrocardiogram (ECG) was recorded continuously. (2) Ischemia simulation and surface electrocardiogram were conducted in 20 pigs and their PAF levels were measured. (3) PAF perfusion and standard microelectrode recording were performed on guinea pig papillarymuscles. Results In both humans and pigs, elevated PAF levels were detected in AMI and simulated ischemia, respectively, and even higher PAF levels were found when fatal arrhythmias occurred. In guinea pig myocardium, PAF induced a shortening of action potential duration at 90% level of repolarization (APD 90 )under non-ischemic conditions and a more pronounced shortening under early simulated ischemic conditions. Conclusion AMI and ischemia are associated with increased PAF levels in humans and pigs, which are further raised when fatal arrhythmia follows. The effects of PAF on the myocardium may be mediated by multiple ion channels.     

Metformin ameliorates insulin resistance in L6 rat skeletal muscle cells through upregulation of SIRT3

Background SIRT3 is an important regulator in cell metabolism, and recent studies have shown that it may be involved in the pharmacological effects of metformin. However, the molecular mechanisms underlying this process are unclear. Methods The effects of SIRT3 on the regulation of oxidative stress and insulin resistance in skeletal muscle were evaluated in vitro. Differentiated L6 skeletal muscle cells were treated with 750 pmol/L palmitic acid to induce insulin resistance. SIRT3 was knocked down and overexpressed in L6 cells. SIRT3, nuclear factor kappa-light-chain-enhancer of activated B cells （NF-KB） p65, c-Jun N-terminal kinase 1 （JNK1）, and superoxide dismutase 2 （SOD2） were evaluated by Western blotting. Results Over expression of SIRT3 increased glucose uptake and decreased ROS production in L6-1R cells as well as in L6 cells. Knock-down of SIRT3 induced increased production of ROS while decreased glucose uptake in both L6 and L6- IR cells, and these effects were reversed by N-acetyI-L-cysteine （NAC）. Metformin increased the expression of SIRT3 （1.5- fold） and SOD2 （2-fold） while down regulating NF-KB p65 （1.5-fold） and JNK1 （1.5-fold）. Knockdown of SIRT3 （P〈0.05） reversed the metformin-induced decreases in NF-KB p65 and JNK1 and the metformin-induced increase in SOD2 （P〈0.05）. Conclusions Upregulated SIRT3 is involved in the pharmacological mechanism by which metformin promotes glucose uptake. Additionally, SIRT3 may function as an important regulator of oxidative stress and a new alternative approach for targeting insulin resistance-related diseases.     

Synergistic Effects of Chuanxiong-Chishao Herb-Pair on Promoting Angiogenesis at Network Pharmacological and Pharmacodynamic Levels

Objective: To investigate the synergistic effects of Chuanxiong-Chishao herb-pair(CCHP) on promoting angiogenesis in silico and in vivo. Methods: The mechanisms of action of an herb-pair, ChuanxiongChishao, were investigated using the network pharmacological and pharmacodynamic strategies involving computational drug target prediction and network analysis, and experimental validation. A set of network pharmacology methods were created to study the herbs in the context of targets and diseases networks, including prediction of target profiles and pharmacological actions of main active compounds in Chuanxiong and Chishao. Furthermore, the therapeutic effects and putative molecular mechanisms of Chuanxiong-Chishao actions were experimentally validated in a chemical-induced vascular insufficiency model of transgenic zebrafish in vivo. The m RNA expression of the predicted targets were further analyzed by real-time polymerase chain reaction(RT-PCR). Results: The computational prediction results found that the compounds in Chuanxiong have antithrombotic, antihypertensive, antiarrhythmic, and antiatherosclerotic activities, which were closely related to protecting against hypoxic-ischemic encephalopathy, ischemic stroke, myocardial infarction and heart failure. In addition, compounds in Chishao were found to participate in anti-inflammatory effect and analgesics. Particularly, estrogen receptor α(ESRα) and hypoxia-inducible factor 1-α(HIF-1α) were the most important potential protein targets in the predicted results. In vivo experimental validation showed that post-treatment of tetramethylpyrazine hydrochloride(TMP·HCl) and paeoniflorin(PF) promoted the regeneration of new blood vessels in zebrafish involving up-regulating ESRα m RNA expression. Co-treatment of TMP·HCl and PF could enhance the vessel sprouting in chemical-induced vascular insufficiency zebrafish at the optimal compatibility proportion of PF 10 μmol/L with TMP·HCl 1 μmol/L. Conclusions: The network pharmacological strategies combining drug target prediction and network analysis identified some putative targets of CCHP. Moreover, the transgenic zebrafish experiments demonstrated that the Chuanxiong-Chishao combination synergistically promoted angiogenic activity, probably involving ESRα signaling pathway.     

Inhibitory Effects of Qushuanling Capsule (祛栓灵胶囊) on Thrombus Formation and Platelet Aggregation in Rats

Objective:To investigate the effects of Qushuanling Capsule（祛栓灵胶囊,QSLC） on thrombus formation and platelet aggregation in rats.Methods:Arteriovenous bypass,venous thrombosis,and middle cerebral artery thrombosis models were used in rats to investigate the anti-thrombotic effects of QSLC,a compound of nine Chinese herbs.The platelet aggregation induced by adenosine diphosphate（ADP）,thrombin or arachidonic acid（AA）,as well as the contents of thromboxane B₂（TXB₂） and 6-keto-prostaglandin F1α（6-keto-PGF1α） in rat plasma and aortic walls,were determined to investigate the possible mechanisms of the anti-thrombotic effects of QSLC.Results:After oral administration with QSLC for 7 days,arteriovenous bypass thrombosis was obviously suppressed compared with the model group,venous thrombosis was also obviously suppressed,rat behaviors were obviously improved,and brain infarct size as well as water content were also reduced.The platelet aggregation induced by ADP or thrombin was inhibited by QSLC,but the drug had no effect on AA-induced platelet aggregation and content of TXB₂ and 6-keto-PGF1αin plasma and the aortic wall.Conclusion:These results suggest that QSLC can be used in the prevention and treatment of thrombotic diseases,and that its mechanism of action may be related to inhibition of platelet aggregation.     

Changes of distribution of platelet activating factor in the lung of rats with hypoxic pulmonary hypertension.

OBJECTIVE To investigate the role of platelet activating factor (PAF) in the hypoxic pulmonary hypertension.

METHODS Fifteen of 30 male Wistar rats were exposed to hypoxia for 3 weeks, and another 15 rats served as controls. The pulmonary arterial pressure was examined by catheterization. The sections of rat lung were treated by the avidin-biotin-peroxidase complex method to expose the location of PAF.

RESULTS The rats developed pulmonary hypertension and right ventricular hypertrophy after hypoxic exposure. Under the light microscope, PAF is distributed on the vascular and alveolar walls of normal lung, and the content of PAF in the lung of rats with hypoxic pulmonary hypertension are remarkably higher than those of normoxic controls.

CONCLUSIONS PAF plays not only a physiological role in the rat lung, but also a pathophysiologic role in hypoxic pulmonary hypertension.

     

Effect of volatile oil of amomum on expressions of platelet activating factor and mastocarcinoma-related peptide in the gastric membrane of chronic gastritis patients with helicobacter-pylori infection

Objective： To observe the effect of volatile oil of amomum （VOA） on the expressions of mastocarcinoma-related peptide （PS2） and platelet activating factor （PAF） in helicobacter pylori- associated gastritis （HPG） and to analyze its potential mechanism. Methods： Eighty patients with HPG were randomly assigned to two groups, 42 patients in the treated group treated with 0.5 mL VOA, thrice per day; and the 38 patients in the control group receiving Western tertiary medicinal treatment. Gastroscopic picture and helicobacter pylori （HP） infection （by quick urease and Warthin- Starry stain） of the gastro-membrane, expressions of PS2 and PAF （by immunohistochemical assay and Western blotting） as well as the contents of aminohexose and phospholipid （by Neuhaus method） in the gastric membrane of all patients were detected before treatment and 4 weeks after treatment. The clinical efficacy in the two groups was compared. Results： The total effective rate in the treated group was 88.1%, which was significantly higher than that in the control group （78.9%, P〈0.05）. After treatment, in the treated group, gastric membranous contents of aminohexose and phospholipid was increased, expression of PS2 elevated but that of PAF lowered, all showing significant difference as compared with those in the control group （P〈0.01）. In the control group, the expressions of PS2 and PAF changed insignificantly. The radical eliminating rate of HP in the treated group and the control group was insignificantly different between them （76.1% vs. 65.8%, P 〉 0.05）. Conclusion： The mechanism of VOA for anti-gastritis might be related with its action in increasing the expression of PS2 and decreasing the expression of PAF, and thus regulating the hydrophobicity of the gastric membrane.     

银杏内酯B对局灶性脑缺血时星形胶质细胞GFAP表达的影响

目的 观察血小板活化因子(PAF)受体拮抗剂银杏内酯B(GB)对局灶性脑缺血时星形胶质细胞胶质纤维酸性蛋白(GFAP)表达的影响,并探讨其作用机制.方法 建立光化学诱导树局灶性脑缺血模型,用HE染色和电镜技术观察缺血后不同时间脑组织星形胶质细胞的形态学改变;用免疫组织化学法观察脑缺血后4 h、24 h、72 h及给予GB后24 h半暗区及对侧皮层星形胶质细胞GFAP的表达,并测定其平均灰度值.结果 光镜下可见,HE染色显示树局灶性脑缺血后,随缺血时间延长,星形胶质细胞形态有不同程度改变;电镜观察显示缺血24 h时星形胶质细胞明显肿胀.免疫组织化学染色可见,半暗区星形胶质细胞GFAP表达在4 h时没有明显改变, 24 h时增加 (P＜0.01),72 h时仍维持在较高水平(P＜0.01);对侧皮层星形胶质细胞GFAP表达于72 h时开始增加(P＜0.05).缺血后6 h舌下静脉注射GB至缺血24 h时,星形胶质细胞GFAP表达少于缺血组(P＜0.05),但仍较假手术组高.结论 脑缺血后星形胶质细胞GFAP表达增强,GB可通过减少星形胶质细胞GFAP的表达而起脑保护作用.     

不同银杏内酯化合物抗血小板活聚集(PAF)活性的研究

目的:探讨不同银杏内酯化合物对家兔血小板聚集作用的影响。方法:进行体外实验观察不同银杏内酯化合物对由血小板活化因子(PAF)诱导的家兔血小板聚集作用的影响。结果:不同银杏内酯化合物体对PAF诱导的血小板聚集均有抑制作用,IC50在0.24～27.44μg/mL之间。结论:不同银杏内酯化合物体外对血小板聚集均有抑制作用差异明显。     

银杏苦内酯B对大鼠任意皮瓣血供的影响

目的：通过对皮瓣局部放射性核素显像,观察血小板活化因子拮抗剂BN52021（银杏苦内酯B）对大鼠任意皮瓣各区段血容量的影响。方法：使用BN52021对皮瓣局部进行处理,分别于术后3、6、9h,采用^99mTc体内标记红细胞的方法对皮瓣局部进行显像、绘制感兴趣区（ROI）并计算各段皮瓣的摄取比（UR),分别与对照组进行比较。结果：使用BN52021处理皮瓣局部,可使皮瓣中、末段的UR明显增加（P＜0．01）。结论：BN52021可以减轻皮瓣局部的炎症反应,减轻血流阻力,改善皮瓣血供。     

血小板激活因子在心肌缺血过程中的变化和意义

目的：探讨心肌缺血损伤过程中血小板激活因子（ＰＡＦ）变化和意义，研究牛磺酸心肌保护作用与ＰＡＦ的关系。方法：应用ＰＡＦ活性测定方法在家兔心肌梗塞模型和大鼠心肌缺血再灌注损伤模型上研究ＰＡＦ的变化及意义。结果：心肌缺血过程中血浆ＰＡＦ显著升高，ＰＡＦ拮抗剂可显著减轻心肌缺血损伤。牛磺酸可抑制心肌缺血过程中ＰＡＦ的增加并显著减轻心肌损伤。结论：ＰＡＦ是促进心肌缺血损伤的重要因素，牛磺酸保护缺血心肌的作用与抑制ＰＡＦ合成释放有关。     

血小板活化因子在烧伤大鼠早期肠源性内毒素血症发病中的作用

目的探讨血小板活化因子（ＰＡＦ）对烧伤后肠源性内毒素血症的影响。方法选用健康Ｗｉｓｔａｒ大鼠９０只制成３０％体表Ⅲ度烫伤模型,随机分为３组,正常对照组,单纯烫伤组,ＰＡＦ拮抗剂治疗组观察ＰＡＦ水平变化与肠源性内毒素血症的关系。结果大鼠烫伤后４８小时内肠粘膜通透性和血浆内毒素水平均显著升高,伤后１２小时为最高,分别为（０５８±０１８）ｍｌ·ｍｉｎ－１·１００ｇ－１、（１２９±２２）ｎｇ／Ｌ,与肠组织和血ＰＡＦ水平升高呈显著相关;ＰＡＦ拮抗剂治疗能显著降低肠粘膜通透性和血浆内毒素水平。健康大鼠静脉注射外源性ＰＡＦ后,肠粘膜通透性和血浆内毒素水平也显著升高,且与ＰＡＦ剂量呈显著依赖关系。结论大鼠烫伤后血浆及肠组织中ＰＡＦ水平升高是导致早期肠源性内毒素血症的一个重要因素。     

银杏内酯B对实验性糖尿病血管病变的保护作用

目的:探讨银杏内酯B对实验性糖尿病大鼠血管张力的作用及其可能机制。方法:雄性S-D大鼠24只,随机分成正常对照组(normal control group,NC group)、银杏内酯B组(Ginkgolide B group,GB group)、糖尿病模型组(diabetes melites group,DM group)、糖尿病模型+银杏内酯B(diabetes melites+Ginkgolide B group,DM+GBgroup)处理组。采用腹腔注射链脲佐菌素(Streptozocin,STZ)的方法建立糖尿病模型;银杏内酯B干预8周后,采用离体血管灌流的方法,测定各组大鼠胸主动脉环对乙酰胆碱(acetylcholine,ACh)诱导的内皮依赖性血管舒张反应,运用非特异性NOS抑制剂L-NAME与cGMP抑制剂亚甲蓝预孵育血管环20min后,观察其对去氧肾上腺素(Pheny-lephrine,PE)的收缩张力变化;同时检测各组大鼠血浆血小板活化因子(Platelet-Activating Factor,PAF)水平及胸主动脉环匀浆NO含量、NOS活性。结果:与NC组相比,DM组大鼠胸主动脉环对ACh诱导的血管舒张反应明显降低(P<0.01);与DM组相比,DM+GB组胸主动脉环对ACh诱导的舒张反应明显改善(P<0.05),与NC组相类似(P>0.05);而GB组与NC组相比其差异亦无统计学意义(P>0.05);NC组主动脉血管环分别经L-NAME和亚甲蓝预孵育后,与孵育前相比,其对PE诱导的收缩幅度明显增强(P<0.01);但在DM组中,抑制剂孵育前、后主动脉环对PE诱导的收缩幅度其差异无统计学意义(P>0.05);而在DM+GB组大鼠中,抑制剂孵育后主动脉环对PE诱导的收缩幅度高于孵育前(P<0.05),但GB组中抑制剂孵育前或孵育后主动脉环对PE诱导的收缩幅度分别与NC组相应的指标相比无统计学差异(P>0.05)。生化检查显示,与NC组相比,DM组血浆PAF水平增高,胸主动脉环NOS活性及NO含量降低(P<0.01);同DM组相比,DM+GB组大鼠血浆PAF水平降低(P<0.01),胸主动脉NOS活性及NO水平明显改善(P<0.01)。结论:GB具有降低PAF水平,从而改善实验性糖尿病大鼠血管张力的作用,其机制可能通过NOS-GC-NO途径而实现的,但其确切机制有待进一步的深入研究。     

血小板活化因子对颈髓损伤后血脊髓屏障的影响

探讨血小板活化因子对颈髓损伤后血脊髓屏障的影响。采用蛛钢膜下腔注射ＰＡＦ及静脉注射ＰＡＦ受体拮抗剂ＢＮ５２０２１，观察其对颈髓损伤后伤区信邻近脊髓组织ＰＡＦ含量，血脊髓屏障，颈髓水肿的影响。颈髓损伤后颈髓伤区及邻近脊髓组织ＰＡＦ含量，伊文思蓝含量，水含量均明显增加，蛛网膜下腔注射ＰＡＦ可使伤后ＰＡＦ含量，伊文思蓝含量，水含量增加更为显著。     

Effect of platelet activating factor on blood spinal cord barrier following cervical cord injury

Bloodspinalcordbarrierdamagefollowingcervicalcordinjuryplaysanimportantroleinthepathophysiologicalprocessofsecondarybleeding,edemaandnecrosisofcervicalcordtissue-Plateletactivatingfactor(PAF)isaverystrongbiologicalactivatinglipidmediator-Inrecentyears,interesthasbeenfocusedontheroleofPAFinbloodbrainbarrierdisruption'IthasbeenprovedthatPAFplaysanimportantroleininducingthepathologicalprocessofstrokeLlj.ThestudyoftherelationshipbetweenPAFandbloodspinalcordbarrierisrarelyreported.Inthepresen…     

Effect of Aqueous Extracts of Several Kinds of Herbs on Human Platelet Aggregation and Expression of P-Selectin in Vitro

Objective: To study the effect of aqueous extract of several kinds of herbs on human platelet aggregation and expression of P-selectin in vitro. Methods: Blood was collected from volunteers. Effects of the prepared water extracts of herbs on platelet aggregation were monitored on a Packs-4 aggregometer. The fluorescence intensity of water extracts of Caulis Spatholobi, Flos Carthami and Rhizoma Curcumae on the expression of P-selectin in human platelets of healthy persons was measured with flow cytometry. Results: Out of several herbs investigated, Flos Carthami and Rhizoma Curcumae potently inhibited platelet aggregation after incubation with platelet-rich plasma (PRP) for 15 min. Caulis Spatholobi, Flos Carthami and Rhizoma Curcumae inhibited adenosine-5''-diphosphate (ADP) or platelet activating factor (PAF)-induced platelet aggregation in PRP in a dose-dependent manner. In contrast to Flos Carthami and Rhizoma Curcumae, Caulis Spatholobi could not inhibit thrombin-induced platelet aggregation. Despite its inability to inhibit thrombin-induced platelet aggregation in PRP, Caulis Spatholobi had a greater anti-aggregating activity in PRP induced by ADP or PAF. Caulis Spatholobi and Flos Carthami showed significant inhibitory effects on the expression of P-selectin. Conclusions: Caulis Spatholobi, Flos Carthami and Rhizoma Curcumae have potent anti-platelet properties, and their inhibitory actions are mediated via different mechanisms. Caulis Spatholobi inhibited ADP-induced platelet aggregation but not by thrombin, indicating that its mechanism of action might be independent of the thromboxane pathway. The effect of Caulis Spatholobi and Flos Carthami were associated with suppressing the expression of P-selectin.     

银杏苦内酯B对哮喘豚鼠气道反应性和嗜酸性粒细胞的影响

作利用豚鼠哮喘模型观察豚鼠吸入卵蛋白（ＯＡ）或血小板激活因子（ＰＡＦ）后引起的气道反应，血浆和支气管肺泡灌洗液（ＢＡＬＦ）中溶血－ＰＡＦ（Ｌｙｓｏ－ＰＡＦ）含量和肺组织中嗜酸性粒细胞（Ｅ０）改变，及ＰＡＦ拮抗剂银杏苦内酯Ｂ（ＧＢ）的影响。结果提示致敏豚鼠ＯＡ激发和正常豚鼠ＰＡＦ激发后，与对照组相比，豚鼠血浆和ＢＡＬＦ中Ｌｙｓｏ－ＰＡＦ含量增高（Ｐ〈０．０１），肺组织中Ｅ０数增多（Ｐ〈０．０１），