Control of Microvascular Tone in Traumatic Brain Injury

创伤性脑损伤中微血管张力的控制

• 批准号: 7055387
• 负责人: JOSE A RAFOLS
• 金额: $ 33.86万
• 依托单位: WAYNE STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-10 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7055387
• 关键词: antisense nucleic acid; brain injury; cardiovascular pharmacology; densitometry; endothelin; gene expression; genetic regulation; genetic translation; heart contraction; histopathology; hormone biosynthesis; hormone inhibitor; hormone receptor; immunocytochemistry; in situ hybridization; laboratory rat; messenger RNA; nucleic acid biosynthesis; perfusion; receptor expression; smooth muscle; vascular endothelium

DESCRIPTION (provided by applicant): A major event following brain trauma is the loss of autoregulatory capacity of brain microvessels which results in sustained hypoperfusion and improper delivery of vital metabolites to brain tissue. Previously we established that the sustained hypoperfusion and the lack of autoregulatory capacity post trauma are largely due to the capability of injured cells in the vascular wall and in other brain compartments to synthesize and maintain excessive amounts of endothelin-1 (ET-1). ET-1, as well as its two isoforms ET-2 and ET-3, exert signal-transducing, vasoconstrictor effects through their only known receptors ET-RA and ET-RB. Although activation of both receptors is known to cause vasoconstriction in both in vitro preparations and non-neural tissues, little is known of their role in the injured brain and the development of secondary cell injury. In fact the role of ET-RA and ET-RB in vasoconstriction and their pharmacological manipulation to prevent cell injury after traumatic brain injury (TBI) have never been studied. We propose that upregulation of the genes encoding for the synthesis of ET-RA and ET-RB in smooth muscle and endothelium (where they are expressed most abundantly), as well as in other perivascular cells, underlie the enhanced contractility previously observed in the microvascular wall after TBt. In this proposal our specific aims are to: 1) characterize quantitatively in time the expressions of ET- RA and ET- RB (mRNA) in distinct cellular compartments of the vascular wall and surrounding neuropil prior to and after TBI, 2) translationaly inhibit the expression of ET- RA and ET- RB before TBI to improve the impaired microcirculation, and 3) pharmacologically attenuate hypoperfusion post TBI by application of selective antagonists to ET- RA and ET- RB. We will use in situ hybridization to measure mRNA synthesis and in vivo intracerebroventricular application of antisense oligodeoxynucleotides to attenuate ET- RA and ET- RB gene expressions." In tandem use of selective receptor antagonist with the 14C iodoantipyrine technique we will assess antagonist effects on cerebral cortical blood flow. By similar in tandem use of antisense application and the 14C iodoantipyrine technique we will determine the reciprocal effects of the receptors and their antgonist on each other and respective affect on the microcirculation after TBI. Histological and motor behavior studies will be used to assess neurological outcome following the therapeutic interventions. The results will provide valuable information on the expression of endothelin receptors (mRNA and proteins), their cellular distribution and the causal relationships of this expression to the alterations in the brain microcirculation after TBI. Precise times of ET- RA and ET- RB expressions will be established that should allow us to establish effective therapeutic interventions. The study will also provide direct evidence on the therapeutic value of suppressing gene regulation or receptor activation on cortical perfusion, histologic or neurologic injury, and its effect on impaired motor skills after TBI.

描述（由申请人提供）：脑创伤后的一个重大事件是脑微血管的自动调节能力丧失，导致持续下降灌注和不当将重要代谢物传递到脑组织。以前，我们确定创伤后的持续下降灌注和缺乏自动调节能力的原因很大程度上是由于血管壁中受伤的细胞的能力以及其他大脑隔室在合成和维持过多量的内皮素-1（ET-1）的能力。 ET-1及其两个同工型ET-2和ET-3，通过其唯一已知的受体ET-RA和ET-RB发挥信号传递，血管收缩效应。尽管已知两种受体的激活都会在体外制剂和非神经组织中引起血管收缩，但对它们在受伤的大脑中的作用和继发性细胞损伤的发展知之甚少。实际上，从未研究过ET-RA和ET-RB在血管收缩及其药理操作中的作用，以防止创伤性脑损伤后细胞损伤（TBI）。 我们提出，在平滑肌和内皮中（最多表达它们）以及其他血管周围细胞中编码的基因编码为ET-RA和ET-RB合成的基因，这是TBT后在微血管壁中观察到的增强的收缩力。在该提议中，我们的具体目的是：1）在及时定量表征ET-ra和et-rb（mRNA）在血管壁的不同细胞室中的表达以及TBI之前和之后的神经纤维的不同细胞室的表达，2）翻译抑制Et-ra和Et-rb的TBI的表达，并在脑中的表达抑制了责任的脑中的表达，并在3）中受到了3）的表达。选择性拮抗剂的应用到ET-RA和ETBB。 我们将利用原位杂交来测量mRNA合成和体内脑室内施用反义寡脱氧核苷酸来减轻ET-ETRA和ET-RB基因表达。”在统一使用14ciodoantipyrine技术的统一使用中，我们将对植物的使用conterical cortoral cort and tandem使用选择性受体拮抗剂，从而对统一的植物进行抗衡。应用和14C碘氨基吡啶技术我们将确定受体及其对彼此的互惠效应，并在组织学和运动行为研究后对微循环的各个影响。 结果将提供有关内皮素受体（mRNA和蛋白质）表达，其细胞分布以及该表达与TBI后脑微循环改变的因果关系的有价值信息。将确定ET-RB表达式的精确时间，以使我们能够建立有效的治疗干预措施。该研究还将直接证明抑制基因调节或受体激活对皮质灌注，组织学或神经系统损伤的治疗价值及其对TBI后运动技能受损的影响。