Galasso J M, Harrison J K, Silverstein F S
Neuroscience Program, University of Michigan, Ann Arbor 48109-0646, USA.
Am J Pathol. 1998 Nov;153(5):1631-40. doi: 10.1016/S0002-9440(10)65752-5.
Chemokines interact with specific G-protein-coupled receptors to activate and direct recruitment of immune cells. Some chemokines are up-regulated in pathological conditions of the central nervous system, and recently several chemokine receptors, including CCR5, were identified in the brain. However, little is known about the regulation of expression of chemokine receptors in the brain. Direct intracerebral injection of N-methyl-D-aspartate (NMDA), an excitatory amino acid agonist, elicits reproducible focal excitotoxic brain injury; in neonatal rats, intrahippocampal NMDA injection stimulates expression of pro-inflammatory cytokines and elicits a robust microglia/monocyte response. We hypothesized that NMDA-induced neurotoxicity would also stimulate expression of CCR5 in the neonatal rat brain. We evaluated the impact of intrahippocampal injections of NMDA on CCR5 expression in postnatal day 7 rats. Reverse transcription polymerase chain reaction revealed an increase in hippocampal CCR5 mRNA expression 24 hours after lesioning, and in situ hybridization analysis demonstrated that CCR5 mRNA was expressed in the lesioned hippocampus and adjacent regions. Western blot analysis demonstrated increased CCR5 protein in hippocampal tissue extracts 32 hours after lesioning. Complementary immunocytochemistry studies identified both infiltrating microglia/monocytes and injured neurons as the principal CCR5-immunoreactive cells. These results provide the first evidence that acute excitotoxic injury regulates CCR5 expression in the developing rat brain.
趋化因子与特定的G蛋白偶联受体相互作用，以激活并指导免疫细胞的募集。一些趋化因子在中枢神经系统的病理状态下会上调，最近在大脑中鉴定出了几种趋化因子受体，包括CCR5。然而，关于大脑中趋化因子受体表达的调控知之甚少。直接脑内注射N-甲基-D-天冬氨酸（NMDA），一种兴奋性氨基酸激动剂，会引发可重复的局灶性兴奋性毒性脑损伤；在新生大鼠中，海马内注射NMDA会刺激促炎细胞因子的表达，并引发强烈的小胶质细胞/单核细胞反应。我们假设NMDA诱导的神经毒性也会刺激新生大鼠大脑中CCR5的表达。我们评估了海马内注射NMDA对出生后第7天大鼠CCR5表达的影响。逆转录聚合酶链反应显示，损伤后24小时海马CCR5 mRNA表达增加，原位杂交分析表明CCR5 mRNA在损伤的海马和邻近区域表达。蛋白质印迹分析表明，损伤后32小时海马组织提取物中CCR5蛋白增加。补充免疫细胞化学研究确定浸润的小胶质细胞/单核细胞和受损神经元是主要的CCR5免疫反应性细胞。这些结果提供了首个证据，即急性兴奋性毒性损伤可调节发育中大鼠大脑中CCR5的表达。
