Huber J D, Campos C R, Mark K S, Davis T P
Department of Basic Pharmaceutical Sciences, West Virginia University, Morgantown, USA.
Am J Physiol Heart Circ Physiol. 2006 Feb;290(2):H732-40. doi: 10.1152/ajpheart.00747.2005. Epub 2005 Sep 30.
Previous studies showed that peripheral inflammatory pain increased blood-brain barrier (BBB) permeability and altered tight junction protein expression and the delivery of opioid analgesics to the brain. What remains unknown is which pathways and mediators during peripheral inflammation affect BBB function and structure. The current study investigated effects of lambda-carrageenan-induced inflammatory pain (CIP) on BBB expression of ICAM-1. We also examined the systemic contribution of a number of proinflammatory cytokines and microglial activation in the brain to elucidate pathways involved in BBB disruption during CIP. We investigated ICAM-1 RNA and protein expression levels in isolated rat brain microvessels after CIP using RT-PCR and Western blot analyses, screened inflammatory cytokines during the time course of inflammation, assessed white blood cell counts, and probed for BBB and central nervous system stimulation and leukocyte transmigration using immunohistochemistry and flow cytometry. Results showed an early increase in ICAM-1 RNA and protein expression after CIP with no change in circulating levels of several proinflammatory cytokines. Changes in ICAM-1 protein expression were noted at 48 h. Immunohistochemistry showed that the induction of ICAM-1 was region specific with increased expression noted in the thalamus and frontal and parietal cortices, which directly correlated with increased expression of activated microglia. The findings of the present study were that CIP induces increased ICAM-1 mRNA and protein expression at the BBB and that systemic proinflammatory mediators play no apparent role in the early response (1-6 h); however, brain region-specific increases in microglial activation suggest a potential for a central-mediated response.
先前的研究表明，外周炎性疼痛会增加血脑屏障（BBB）的通透性，改变紧密连接蛋白的表达以及阿片类镇痛药向脑内的递送。尚不清楚外周炎症期间哪些途径和介质会影响血脑屏障的功能和结构。本研究调查了λ-角叉菜胶诱导的炎性疼痛（CIP）对血脑屏障ICAM-1表达的影响。我们还研究了多种促炎细胞因子的全身作用以及脑内小胶质细胞的激活情况，以阐明CIP期间血脑屏障破坏所涉及的途径。我们使用逆转录-聚合酶链反应（RT-PCR）和蛋白质印迹分析，研究了CIP后分离的大鼠脑微血管中ICAM-1的RNA和蛋白质表达水平，筛选了炎症过程中的炎性细胞因子，评估了白细胞计数，并使用免疫组织化学和流式细胞术检测了血脑屏障、中枢神经系统刺激和白细胞迁移情况。结果显示，CIP后ICAM-1的RNA和蛋白质表达早期增加，而几种促炎细胞因子的循环水平没有变化。ICAM-1蛋白表达在48小时出现变化。免疫组织化学显示，ICAM-1的诱导具有区域特异性，丘脑、额叶和顶叶皮质的表达增加，这与活化小胶质细胞表达的增加直接相关。本研究的结果是，CIP诱导血脑屏障处ICAM-1的mRNA和蛋白质表达增加，全身促炎介质在早期反应（1-6小时）中没有明显作用；然而，脑区特异性小胶质细胞激活增加表明存在中枢介导反应的可能性。
