Date of Award

12-2012

Degree Name

Doctor of Philosophy

Department

Psychology

First Advisor

Dr. Lisa E. Baker

Second Advisor

Dr. Cynthia Pietras

Third Advisor

Dr. Wayne Fuqua

Fourth Advisor

Dr. John Spitsbergen

Abstract

Cognitive decline is a process frequently associated with aging. Physical exercise appears to counteract cognitive decline, specifically spatial abilities, and decreases the effects of reactive oxygen species (ROS) associated with aging. In addition, brain derived neurotrophic factor (BDNF) and glial derived neurotrophic factor (GDNF) are well recognized as chemical mediators of the neurophysiological benefits of exercise.

In order to study the impact of exercise on spatial memory and neurotrophic factors, this study utilized an animal model of accelerated aging involving chronic d-galactose administration. Specifically, previous research indicates daily injections of d-galactose for 6-10 weeks may increase ROS in mice and produce significant deficits in learning and memory. The current study investigated d-galactose's ability to simulate aging in rats. This study also further investigated the interaction between exercise, spatial abilities, and levels of BDNF and GDNF protein content within the hippocampus and pre-frontal cortex.

Forty-eight male Sprague-Dawley rats were randomly assigned to receive once daily injections of 100 mg/kg d-galactose (n=24) or saline (n=24) for a period of eight weeks. Half the animals in each group were also subjected to a moderate forced exercise regimen utilizing running wheels during the same eight week period (13 m/min, 30 min, 3 days per week), while the remaining rats were exposed to the apparatus for the same amount of time, but with the wheels turned off. Immediately following completion of the eight week injection and exercise regimen, rats underwent a 19 day radial arm maze (RAM) procedure. This procedure consisted of two trials per day with a one hour inter-trial interval. Subsequently, rats were euthanized, brains were removed, and prefrontal cortex and hippocampal tissues were dissected and processed for analysis of BDNF and GDNF protein content using the ELISA assay. The results indicate spatial navigation performance was not significantly altered by d-galactose or by exercise. Furthermore, BDNF and GDNF protein content in the hippocampus or pre-frontal cortex did not differ among treatment groups. Several possible reasons for negative findings are addressed.

Access Setting

Dissertation-Open Access

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