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 G?? subunit of the DRD2 has been shown to activate extracellular-signal-regulated kinase1/2 (ERK1/2), which in turn activate ?B-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 G??/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 G??/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.

Public Health Relevance

Intracerebral hemorrhage (ICH) is the deadliest and least treatable stroke subtype. ICH damages the blood-brain barrier (BBB), which leads to formation of brain edema, brain swelling, and possibly death. A prospective therapy that can protect the BBB and attenuate brain edema is expected to optimize the recovery in ICH patients. Based on our recent observations, we believe that stimulation of the dopamine receptor D2 results in such BBB protection following ICH. Therefore, we aim to evaluate the effects and molecular mechanisms of DRD2 stimulation in two different rodent models of ICH, thereby, providing the basis for clinical translation and implementation of DRD2 agonists in patients suffering from ICH

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS091042-02
Application #
9233211
Study Section
Acute Neural Injury and Epilepsy Study Section (ANIE)
Program Officer
Koenig, James I
Project Start
2016-03-01
Project End
2021-02-28
Budget Start
2017-03-01
Budget End
2018-02-28
Support Year
2
Fiscal Year
2017
Total Cost
$311,062
Indirect Cost
$114,187
Name
Loma Linda University
Department
Neurosurgery
Type
Schools of Medicine
DUNS #
009656273
City
Loma Linda
State
CA
Country
United States
Zip Code
92350
Yang, Peng; Manaenko, Anatol; Xu, Feng et al. (2016) Role of PDGF-D and PDGFR-β in neuroinflammation in experimental ICH mice model. Exp Neurol 283:157-64