a Jagiellonian Centre for Experimental Therapeutics (JCET), Jagiellonian University , Krakow , Poland.
b Department of Haemostasis and Haemostatic Disorders , Chair of Biomedical Sciences, Medical University of Lodz , Lodz , Poland.
Platelets. 2017 Nov;28(7):657-667. doi: 10.1080/09537104.2016.1254764. Epub 2017 Jan 9.
Strenuous physical exercise leads to platelet activation that is normally counterbalanced by the production of endothelium-derived anti-platelet mediators, including prostacyclin (PGI) and nitric oxide (NO). However, in the case of endothelial dysfunction, e.g. in atherosclerosis, there exists an increased risk for intravascular thrombosis during exercise that might be due to an impairment in endothelial anti-platelet mechanisms. In the present work, we evaluated platelet activation at rest and following a single bout of strenuous treadmill exercise in female ApoE/LDLR mice with early (3-month-old) and advanced (7-month-old) atherosclerosis compared to female age-matched WT mice. In sedentary and post-exercise groups of animals, we analyzed TXB generation and the expression of platelet activation markers in the whole blood ex vivo assay. We also measured pre- and post-exercise plasma concentration of 6-keto-PGF, nitrite/nitrate, lipid profile, and blood cell count. Sedentary 3- and 7-month-old ApoE/LDLR mice displayed significantly higher activation of platelets compared to age-matched wild-type (WT) mice, as evidenced by increased TXB production, expression of P-selectin, and activation of GPIIb/IIIa receptors, as well as increased fibrinogen and von Willebrand factor (vWf) binding. Interestingly, in ApoE/LDLR but not in WT mice, strenuous exercise partially inhibited TXB production, the expression of activated GPIIb/IIIa receptors, and fibrinogen binding, with no effect on the P-selectin expression and vWf binding. Post-exercise down-regulation of the activated GPIIb/IIIa receptor expression and fibrinogen binding was not significantly different between 3- and 7-month-old ApoE/LDLR mice; however, only 7-month-old ApoE/LDLR mice showed lower TXB production after exercise. In female 4-6-month-old ApoE/LDLR but not in WT mice, an elevated pre- and post-exercise plasma concentration of 6-keto-PGF was observed. In turn, the pre- and post-exercise plasma concentrations of nitrite (NO) and nitrate (NO) were decreased in ApoE/LDLR as compared to that in age-matched WT mice. In conclusion, we demonstrated overactivation of platelets in ApoE/LDLR as compared to WT mice. However, platelet activation in ApoE/LDLR mice was not further increased by strenuous exercise, but was instead attenuated, a phenomenon not observed in WT mice. This phenomenon could be linked to compensatory up-regulation of PGI-dependent anti-platelet mechanisms in ApoE/LDLR mice.
剧烈的体力活动会导致血小板活化，而正常情况下，内皮细胞会产生抗血小板介质来平衡这种活化，包括前列环素（PGI）和一氧化氮（NO）。然而，在血管内皮功能障碍的情况下，例如在动脉粥样硬化中，运动期间可能会发生血管内血栓形成的风险增加，这可能是由于内皮抗血小板机制受损所致。在本研究中，我们比较了同龄 WT 小鼠，评估了具有早期（3 个月大）和晚期（7 个月大）动脉粥样硬化的雌性 ApoE/LDLR 小鼠在静息状态和剧烈跑步机运动后血小板的激活情况。在静息和运动后组的动物中，我们分析了 TXB 的生成以及全血体外试验中血小板活化标志物的表达。我们还测量了运动前后的血浆 6-酮-PGF1α、亚硝酸盐/硝酸盐、血脂谱和血细胞计数。与同龄的 WT 小鼠相比，3 个月大和 7 个月大的 ApoE/LDLR 小鼠的血小板激活明显升高，表现为 TXB 生成增加、P-选择素表达增加、GPIIb/IIIa 受体激活以及纤维蛋白原和血管性血友病因子（vWf）结合增加。有趣的是，在 ApoE/LDLR 小鼠中，但在 WT 小鼠中，剧烈运动部分抑制了 TXB 的生成、激活的 GPIIb/IIIa 受体的表达和纤维蛋白原的结合，而对 P-选择素的表达和 vWf 的结合没有影响。与 3 个月大的 ApoE/LDLR 小鼠相比，7 个月大的 ApoE/LDLR 小鼠在运动后激活的 GPIIb/IIIa 受体表达和纤维蛋白原结合的下调没有明显差异；然而，只有 7 个月大的 ApoE/LDLR 小鼠在运动后 TXB 的生成降低。与同龄 WT 小鼠相比，在 4-6 个月大的 ApoE/LDLR 小鼠中，运动前后的血浆 6-酮-PGF1α浓度升高。相反，与同龄 WT 小鼠相比，ApoE/LDLR 小鼠的运动前后的血浆亚硝酸盐（NO）和硝酸盐（NO）浓度降低。总之，与 WT 小鼠相比，我们发现 ApoE/LDLR 小鼠的血小板过度激活。然而，在 ApoE/LDLR 小鼠中，剧烈运动并没有进一步增加血小板的激活，反而减弱了这种激活，这一现象在 WT 小鼠中没有观察到。这种现象可能与 ApoE/LDLR 小鼠中 PGI 依赖性抗血小板机制的代偿性上调有关。
