Harnessing Endogenous Neuroprotection Following ICH

 描述（由申请人提供）：目前，脑出血（ICH）是一种常见且往往致命的卒中亚型，尚无持续有效的治疗方法。已知ICH后继发性脑损伤涉及血脑屏障（BBB）破坏，随后形成脑水肿，这表明临床预后不良。有趣的是，病理过程，如ICH，也引发内源性防御机制，拮抗破坏性事件和介导修复。我们建议研究脑如何保护自己免受ICH诱导的神经血管损伤，并随后将这些保护机制作为一种创新和特异性的治疗策略。基于我们的初步观察，我们认为多巴胺诱导的多巴胺受体D2（DRD 2）的刺激可能会赋予这种内源性保护ICH后。我们发现实验性脑出血小鼠脑内多巴胺水平升高。此外，DRD 2的药理学刺激减弱了脑出血后的BBB破坏、脑水肿和神经功能缺损。DRD 2的Gβγ亚基已被证明激活细胞外信号调节激酶1/2（ERK 1/2），ERK 1/2又激活α B-晶体蛋白（α B-crystallin，α B-AB），一种广泛表达的小热休克蛋白。ESPAAB作为分子伴侣发挥作用，防止重要的细胞蛋白质受到应激诱导的降解。我们认为，ESTABAB可以保护内皮屏障形成紧密连接和粘附连接蛋白，从而保持脑出血后血脑屏障的完整性。我们假设DRD 2刺激将减弱BBB破坏，并通过Gβγ/ERK诱导的ECONAB激活减轻随后的脑水肿形成，从而改善ICH后的短期和长期神经功能结局。我们将利用纹状体内注射胶原酶（引起自发性血管破裂） 或自体全血来诱导啮齿动物的ICH。我们将测量脑出血动物脑中多巴胺及其受体的浓度。在此之后，我们将确定DRD 2及其下游靶点在ICH后提供神经血管保护中的作用。我们的具体目标1将研究内源性和药理学DRD 2刺激在减少脑出血后BBB破坏、脑水肿形成和神经功能缺损中的作用。具体目标2将研究ICH后DRD 2诱导的Gβγ/ERK/GABAB信号传导的拟定机制。该提案的长期目标是将DRD 2激动剂确立为ICH的新型治疗策略，证明其潜在的保护机制，并为DRD 2激动剂在ICH患者中的临床转化和实施提供基础。

 DESCRIPTION (provided by applicant): At present, there are no consistently effective treatments available for intracerebral hemorrhage (ICH), a common and often fatal stroke subtype. Secondary brain injury after ICH is known to involve disruption of the blood-brain barrier (BBB), followed by formation of brain edema, which is indicative of a poor clinical prognosis. Interestingly, pathological processes, such as ICH, also elicit endogenous defense mechanisms that antagonize the damaging events and mediate repair. We propose to investigate how the brain protects itself from ICH-induced neurovascular injury, and subsequently, augment these protective mechanisms as an innovative and specific treatment strategy. Based on our preliminary observations, we suggest that dopamine-induced stimulation of the dopamine receptor D2 (DRD2) may confer such endogenous protection following ICH. We found increased dopamine levels in the brain of mice subjected to experimental ICH. Furthermore, pharmacological stimulation of the DRD2 attenuated BBB disruption, brain edema, and neurological deficits following ICH. The Gβγ subunit of the DRD2 has been shown to activate extracellular-signal-regulated kinase1/2 (ERK1/2), which in turn activate αB-crystallin (CRYAB), a widely expressed small heat shock protein. CRYAB functions as a molecular chaperone, preventing vital cellular proteins from stress-induced degradation. We believe that CRYAB can protect endothelial barrier-forming tight junction and adherens junction proteins, thus preserving BBB integrity following ICH. We hypothesize that DRD2 stimulation will attenuate BBB disruption, and consequent brain edema formation through Gβγ/ERK-induced activation of CRYAB, thereby improving short- and long-term neurological outcomes after ICH. We will utilize intrastriatal injections of either collagenase (causing spontaneous vessel rupture) or autologous whole blood to induce ICH in rodents. We will measure the concentrations of dopamine and its receptors in the brain of ICH animals. Following that, we will establish the role of DRD2 and its downstream targets in providing neurovascular protection following ICH. Our specific Aim 1 will investigate the role of endogenous and pharmacological DRD2 stimulation in reducing BBB disruption, brain edema formation, and neurological deficits following ICH. Specific Aim 2 will investigate the proposed mechanism of DRD2-induced Gβγ/ERK/CRYAB signaling following ICH. The long-term goals of this proposal are to establish DRD2 agonism as a novel treatment strategy for ICH, demonstrate its underlying protective mechanism, and provide a basis for clinical translation and implementation of DRD2 agonists in patients suffering from ICH.