Department of Clinical Experimental Research, Glostrup Research Institute, Ndr. Ringvej 69, 2600, Glostrup, Denmark.
Exp Brain Res. 2012 Jun;219(4):507-20. doi: 10.1007/s00221-012-3108-6. Epub 2012 May 15.
Cerebral arteries subjected to different types of experimental stroke upregulate their expression of certain G-protein-coupled vasoconstrictor receptors, a phenomenon that worsens the ischemic brain damage. Upregulation of contractile endothelin B (ET(B)) and 5-hydroxytryptamine 1B (5-HT(1B)) receptors has been demonstrated after subarachnoid hemorrhage and global ischemic stroke, but the situation is less clear after focal ischemic stroke. Changes in smooth muscle calcium handling have been implicated in different vascular diseases but have not hitherto been investigated in cerebral arteries after stroke. Here, we evaluate changes of ET(B) and 5-HT(1B) receptors, intracellular calcium levels, and calcium channel expression in rat middle cerebral artery (MCA) after focal cerebral ischemia and in vitro organ culture, a proposed model of vasoconstrictor receptor changes after stroke. Rats were subjected to 2 h MCA occlusion followed by reperfusion for 1 or 24 h. Alternatively, MCAs from naïve rats were cultured for 1 or 24 h. ET(B) and 5-HT(1B) receptor-mediated contractions were evaluated by wire myography. Receptor and channel expressions were measured by real-time PCR and immunohistochemistry. Intracellular calcium was measured by FURA-2. Expression and contractile functions of ET(B) and 5-HT(1B) receptors were strongly upregulated and slightly downregulated, respectively, 24 h after experimental stroke or organ culture. ET(B) receptor-mediated contraction was mediated by calcium from intracellular and extracellular sources, whereas 5-HT(1B) receptor-mediated contraction was solely dependent on extracellular calcium. Organ culture and stroke increased basal intracellular calcium levels in MCA smooth muscle cells and decreased the expression of inositol triphosphate receptor and transient receptor potential canonical calcium channels, but not voltage-operated calcium channels.
大脑动脉受到不同类型的实验性中风的影响，会上调某些 G 蛋白偶联血管收缩受体的表达，这种现象会使缺血性脑损伤恶化。蛛网膜下腔出血和全脑缺血性中风后，已经证明收缩型内皮素 B（ET（B））和 5-羟色胺 1B（5-HT（1B））受体上调，但在局灶性缺血性中风后情况不太清楚。平滑肌钙处理的变化与不同的血管疾病有关，但迄今为止尚未在中风后的大脑动脉中进行研究。在这里，我们评估了局灶性脑缺血后大鼠大脑中动脉（MCA）和体外器官培养中 ET（B）和 5-HT（1B）受体、细胞内钙水平和钙通道表达的变化，这是中风后血管收缩受体变化的一种拟议模型。大鼠接受 2 小时 MCA 闭塞，然后再灌注 1 或 24 小时。或者，将来自未处理大鼠的 MCA 培养 1 或 24 小时。通过电测法评估 ET（B）和 5-HT（1B）受体介导的收缩。通过实时 PCR 和免疫组织化学测量受体和通道表达。通过 FURA-2 测量细胞内钙。实验性中风或器官培养后 24 小时，ET（B）和 5-HT（1B）受体的表达和收缩功能均明显上调，而 5-HT（1B）受体的表达和收缩功能则略有下调。ET（B）受体介导的收缩是由细胞内和细胞外来源的钙介导的，而 5-HT（1B）受体介导的收缩仅依赖于细胞外钙。器官培养和中风增加了 MCA 平滑肌细胞的基础细胞内钙水平，并降低了三磷酸肌醇受体和瞬时受体电位经典钙通道的表达，但不降低电压门控钙通道的表达。
