IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy.
Shock. 2009 Dec;32(6):578-85. doi: 10.1097/SHK.0b013e3181a20792.
Permanent functional deficit after spinal cord injury (SCI) arises from both mechanical injury and from secondary tissue reactions involving inflammation. Adenosine is an important regulator of inflammatory mechanisms. Although functional studies indicate a protective effect of adenosine A2A receptor agonists in SCI, the basic molecular mechanisms accounting for the their protective effects from SCI have to be fully elucidated. In this study, we investigated if the selective A2A receptor agonist 2-[p-(2-carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamidoadenosine (CGS 21680) administered after SCI has protective effects against tissue damage, motor deficit, and different inflammatory readouts. Spinal cord injury was induced in mice by extradural compression of a section of the SC exposed via a four-level T5-T8 laminectomy. CGS 21680, administered by subcutaneously implanted osmotic minipumps after SCI, clearly reduced motor deficit for up to 19 days after operation. The drug repeatedly administered intraperitoneally after SCI reduced tissue damage, influx of myeloperoxidase-positive leukocytes, nuclear factor-kappaB activation and iNOS expression in injured spinal cord tissue 24 h after SCI. Enhanced immunoreactivity of microglia, astrocytes, and oligodendrocytes (stained by anti-CD11/B, anti-glial fibrillary acidic protein, and anti-Olig2 antibodies, respectively) was also observed 24 h after SCI. Neurons lose immunoreactivity in the nucleus. c-Jun amino-terminal kinase (JNK) mitogen-activated protein kinase, quantified by Western blot, was definitely activated in injured tissue. CGS 21680 treatment significantly reduced JNK phosporylation. Phospho-JNK mitogen-activated protein kinase was de novo expressed selectively in oligodendrocytes. CGS 21680 reduced phospho-JNK immunostaining in oligodendrocytes. Data indicate that protection by the A2A agonist is secondary to reduced leukocyte recruitment in the damaged area. A reducing effect of JNK activation in oligodendrocytes might account for protective effect of the A2A agonist against SCI-induced demyelination.
脊髓损伤（SCI）后的永久性功能缺陷既来自机械损伤，也来自涉及炎症的继发性组织反应。腺苷是炎症机制的重要调节剂。尽管功能研究表明腺苷 A2A 受体激动剂在 SCI 中有保护作用，但必须充分阐明其对 SCI 保护作用的基本分子机制。在这项研究中，我们研究了 SCI 后给予选择性 A2A 受体激动剂 2-[p-(2-羧乙基)-苯乙胺]-5'-N-乙基羧酰胺腺苷（CGS 21680）是否对组织损伤、运动缺陷和不同的炎症指标有保护作用。通过 T5-T8 椎管切开术暴露的脊髓节段的硬膜外压迫，在小鼠中诱导脊髓损伤。SCI 后通过皮下植入的渗透微型泵给予 CGS 21680，可明显减轻术后 19 天的运动缺陷。SCI 后重复腹腔内给予该药物可减少 24 小时后损伤脊髓组织中的髓过氧化物酶阳性白细胞浸润、核因子-κB 激活和诱导型一氧化氮合酶表达。24 小时后 SCI 还观察到小胶质细胞、星形胶质细胞和少突胶质细胞（分别用抗 CD11/B、抗胶质纤维酸性蛋白和抗 Olig2 抗体染色）的增强免疫反应。神经元在核内失去免疫反应。通过 Western blot 定量的 c-Jun 氨基末端激酶（JNK）丝裂原激活蛋白激酶在损伤组织中明显被激活。CGS 21680 处理显著降低了 JNK 磷酸化。磷酸化 JNK 丝裂原激活蛋白激酶在少突胶质细胞中选择性地从头表达。CGS 21680 减少了少突胶质细胞中的磷酸化 JNK 免疫染色。数据表明，A2A 激动剂的保护作用是继发于损伤区域白细胞募集减少。JNK 激活在少突胶质细胞中的减少可能是 A2A 激动剂对 SCI 诱导脱髓鞘的保护作用的原因。
