Date of Award
Master of Science
Molecular Cellular and Systemic Physiology
AN ABSTRACT OF THE THESIS OF Elizabeth Dawn Grisley, for the Master’s degree in Cellular and Molecular Systemic Physiology, presented on November 6th, 2015, at Southern Illinois University Carbondale. TITLE: INFLUENCE OF DIET AND STROKE ON EXPRESSION OF GENES THAT MODULATE INFLAMMATION AND NEURONAL REMODELING IN THE ADULT AND AGED MALE RAT CEREBRAL CORTEX MAJOR PROFESSOR: Dr. Joseph L. Cheatwood Nearly 800,000 Americans are stricken by ischemic stroke each year. Other than care with post stroke rehabilitation there are no specific treatments for improving functional recovery. To improve the recovery of stroke patients we are investigating anti-inflammatory, anti-apoptotic, and neuronal remodeling pathways. Estrogen receptor activators are known to be neuroprotective by initiating pathways through ERβ and ERα. The bioactive soy isoflavones, daidzein and genistein, do bind to these estrogen receptors. However, this binding alone is not sufficient to explain the ability of soy-based diets and purified isoflavones to reduce inflammation and improve neuroprotection and recovery after stroke. Herein, we focused on the Pparg, Arg-1, 14-3-3ε, Sirt1, Gap43, Synaptophysin, Sod-1, Bcl-xl, Bcl-2, and the Rtn4(Nogo-A) pathways to test the hypothesis that diets containing soy isoflavones and/or soy protein isolate will reduce inflammation and promote the expression of neuronal plasticity markers following stroke in adult and aged rats via these mechanisms. Adult and aged male Hooded Long Evans rats were fed a semi-purified diet of either 1) sodium caseinate (CAS), 2) sodium caseinate plus the isoflavones daidzein and genistein (CAS+ISO), or 3) soy protein isolate (SPI) for two weeks prior to middle cerebral artery occlusion (MCAO). Permanent unilateral MCAO was performed and tissue was collected from both hemispheres at Day 0 (no stroke) and Day +3. Rats were maintained on their assigned diet throughout the experiment. RNA was extracted and cDNA synthesized for qPCR reaction. All data were normalized to Gapdh via the ΔΔCt method. qPCR analyses of the contralateral and ipsilateral brain tissue at 3 days after stroke resulted in upregulation of Sod-1, Sirt1, 14-3-3ε, Bcl-xl, Bcl-2, Gap43, Syp and Rtn4(Nogo-A) mRNA expression in the contralateral hemisphere. Only Pparg and Arg1 mRNA were found to be upregulated in the ipsilateral hemisphere. Through the upregulation of Pparg mRNA expression in the ipsilateral cortex we have established that the anti-inflammatory pathway is being initiated in our model. However it has been activated by a greater degree with the SPI treatment not the isoflavones daidzein and genistein alone as previously thought. It is unclear if the daidzein and genistein are working concurrently with one or more of the compounds found in the SPI treatment or if one or more additional compounds in the SPI has been the true activator. Since the tissue analyzed in this project was from animals that exhibited significant post stroke behavioral outcomes in a previous experiment we believed the influence of compensatory sprouting from the contralesional hemisphere was modulating the improvement of growth and anti-inflammatory factors to the injured ipsilateral hemisphere. Extensive research is still needed to confirm the source of activation in the PPARG pathway with the SPI treatment, the time and age points that transcriptional expression of our selected genes will activate or influence translational and/or post-translational effects and how the ischemic hemisphere is benefitting from compensatory sprouting from the contralateral hemisphere in this ischemic stroke model. By continuing in the directions mentioned above the mechanism by which isoflavones significantly improve post-stroke behavioral outcomes may be revealed.
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