Neuroprotective effects of gamma-glutamylcysteine ethyl ester on an in vivo moderate traumatic brain injury-mediated model and in vitro in cortical astrocytes and neurons

<p>Neurodegeneration is the loss of neuronal structures or functions, while neuroprotection is the delay or prevention of neurodegeneration. In traumatic brain injury (TBI), neurodegeneration can occur as the result of oxidative stress, the imbalance of oxidants and antioxidants levels; therefore, antioxidant approaches can be effective therapeutic methods for neuroprotection by attenuating oxidative stress. Glutathione (GSH), a naturally occurring antioxidant, plays an important role in the maintenance of intracellular redox homeostasis by scavenging reactive oxygen species (ROS) and reactive nitrogen species (RNS). In this thesis, we attempted to evaluate the abilities of a GSH precursor, gamma-glutamylcysteine ethyl ester (GCEE), to prevent neurodegeneration by combating intracellular oxidative stress in neurons and astrocytes. For in vivo experiments, controlled cortical impact (CCI) was performed on Wistar rats to simulate moderate TBI, and GCEE (150 mg/kg) or saline was administrated 30 min or 60 min after the brain injury. Fluoro Jade-B (FJB), an ionic fluorescein derivate, was adapted to selectively stain the degenerating neurons on the brain tissues, and FJB-positive neurons were quantified. Administration of GCEE (150 mg/kg) post- injury decreased the number of FJB positive neurons that were significantly increased in saline treated groups. Next, the protective roles of GCEE in vitro in rat primary cortical astrocytes were investigated using various concentrations of tert-butyl hydroperoxide (tBHP) in order to induce oxidative stress and further toxicity. Cell viability was measured by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. The status of oxidative stress was determined by measuring intracellular ROS levels through dichlorofluorescein (DCF) assay. GCEE restored cell viability that was significantly decreased in untreated cells by decreasing oxidative stress. Lastly, the antioxidant properties of GCEE in neurons and astrocytes were investigated in a time-dependent manner. GCEE was able to immediately attenuate intracellular oxidative stress both in neurons and astrocytes. Such decreased oxidative stress was progressively increased in neurons, whereas decreased oxidative stress remained in astrocytes. Overall, our current findings suggest the protective roles of GCEE in both neurons and astrocytes may contribute to the potential therapeutic effects on oxidative stress-associated neurodegeneration following traumatic brain injury. </p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Master's

Discipline thesis:degree_discipline

Chemistry

Grantor dc:publisher

Eastern Kentucky University

Year

2014

Author dc:creator

• Cho, Jooyoung

• Astrocyte
• Glutathione
• Neurodegeneration
• Neuron
• Oxidative stress
• Traumatic brain injury
• Medical Biochemistry

Statement dc:rights

• Copyright 2014 Jooyoung Cho

Repository record dc:identifier

https://encompass.eku.edu/etd/247

OAI identifier oai:identifier

oai:encompass.eku.edu:etd-1245