Harnessing Endogenous Neuroprotection Following ICH

 描述(由申请人提供)：目前，对于脑出血(ICH)，一种常见的、往往是致命的中风亚型，还没有持续有效的治疗方法。众所周知，脑出血后继发性脑损伤包括血脑屏障(BBB)的破坏，随后是脑水肿的形成，这表明临床预后很差。有趣的是，病理过程，如脑出血，也诱导内源性防御机制，对抗损害事件和中介修复。我们建议研究大脑如何保护自己免受脑出血引起的神经血管损伤，并随后加强这些保护机制，作为一种创新和特定的治疗策略。根据我们的初步观察，我们认为多巴胺诱导的刺激多巴胺受体D2(DRD2)可能在脑出血后提供这种内源性保护。我们发现实验性脑出血小鼠大脑中的多巴胺水平升高。此外，药物刺激DRD2可减轻脑出血后血脑屏障紊乱、脑水肿和神经功能障碍。研究表明，βγ的G亚基可以激活细胞外信号调节蛋白1/2，进而激活广泛表达的小分子热休克蛋白αB-晶体蛋白。CryAB作为分子伴侣发挥作用，防止重要的细胞蛋白在应激诱导下降解。我们认为，CryAB可以保护内皮屏障形成的紧密连接并黏附连接蛋白，从而保护脑出血后血脑屏障的完整性。我们假设，刺激DRD2将通过Gβγ/ERK诱导的CryAB的激活来减轻血脑屏障的破坏和随之而来的脑水肿形成，从而改善脑出血后的短期和长期神经预后。我们将使用纹状体内注射胶原酶(导致自发性血管破裂)。 或自体全血诱导啮齿类动物脑出血。我们将测量脑出血动物大脑中多巴胺及其受体的浓度。之后，我们将确定DRD2及其下游靶点在脑出血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的DRD2刺激在减少脑出血后血脑屏障破坏、脑水肿形成和神经功能障碍方面的作用。具体目的2研究DRD2诱导脑出血后Gβγ/ERK/CryAB信号转导的可能机制。这项建议的长期目标是建立DRD2激动剂作为治疗脑出血的新策略，展示其潜在的保护机制，并为DRD2激动剂在脑出血患者中的临床翻译和实施提供基础。

 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.