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Exp Neurol. 2015 Jul;269:56-66. doi: 10.1016/j.expneurol.2015.03.015. Epub 2015 Mar 24.

Post-trauma administration of the pifithrin-α oxygen analog improves histological and functional outcomes after experimental traumatic brain injury.

Author information

1
Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
2
Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, USA.
3
Department of Anatomy and Anthropology, Sackler School of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
4
Department of Neurosurgery, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
5
Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. Electronic address: jywang2010@tmu.edu.tw.

Abstract

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Programmed death of neuronal cells plays a crucial role in acute and chronic neurodegeneration following TBI. The tumor suppressor protein p53, a transcription factor, has been recognized as an important regulator of apoptotic neuronal death. The p53 inactivator pifithrin-α (PFT-α) has been shown to be neuroprotective against stroke. A previous cellular study indicated that PFT-α oxygen analog (PFT-α (O)) is more stable and active than PFT-α. We aimed to investigate whether inhibition of p53 using PFT-α or PFT-α (O) would be a potential neuroprotective strategy for TBI. To evaluate whether these drugs protect against excitotoxicity in vitro, primary rat cortical cultures were challenged with glutamate (50mM) in the presence or absence of various concentrations of the p53 inhibitors PFT-α or PFT-α (O). Cell viability was estimated by LDH assay. In vivo, adult Sprague Dawley rats were subjected to controlled cortical impact (CCI, with 4m/s velocity, 2mm deformation). Five hours after injury, PFT-α or PFT-α (O) (2mg/kg, i.v.) was administered to animals. Sensory and motor functions were evaluated by behavioral tests at 24h after TBI. The p53-positive neurons were identified by double staining with cell-specific markers. Levels of mRNA encoding for p53-regulated genes (BAX, PUMA, Bcl-2 and p21) were measured by reverse transcription followed by real time-PCR from TBI animals without or with PFT-α/PFT-α (O) treatment. We found that PFT-α(O) (10 μM) enhanced neuronal survival against glutamate-induced cytotoxicity in vitro more effectively than PFT-α (10 μM). In vivo PFT-α (O) treatment enhanced functional recovery and decreased contusion volume at 24h post-injury. Neuroprotection by PFT-α (O) treatment also reduced p53-positive neurons in the cortical contusion region. In addition, p53-regulated PUMA mRNA levels at 8h were significantly reduced by PFT-α (O) administration after TBI. PFT-α (O) treatment also decreased phospho-p53 positive neurons in the cortical contusion region. Our data suggest that PFT-α (O) provided a significant reduction of cortical cell death and protected neurons from glutamate-induced excitotoxicity in vitro, as well as improved neurological functional outcome and reduced brain injury in vivo via anti-apoptotic mechanisms. The inhibition of p53-induced apoptosis by PFT-α (O) provides a useful tool to evaluate reversible apoptotic mechanisms and may develop into a novel therapeutic strategy for TBI.

KEYWORDS:

Apoptosis; Controlled cortical impact; PFT-α oxygen analog; Pifithrin-α (PFT-α); Traumatic brain injury (TBI); p53

PMID:
25819102
PMCID:
PMC5193498
DOI:
10.1016/j.expneurol.2015.03.015
[Indexed for MEDLINE]
Free PMC Article

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