Date of Defense



Biological Sciences

First Advisor

Monica J. McCullough, Biological Sciences

Second Advisor

John M. Spitsbergen, Biological Sciences


The mammalian heart is innervated by both the parasympathetic and sympathetic nervous systems. In order for these nerves to remain healthy and functional neurotrophic factors glial cell line-derived neurotrophic factor (GDNF) and nerve growth factor (NGF) need to be present. Neurotrophic factors in mature nervous systems assist with the innervation of tissues and with the regeneration of damaged neurons. In aging rats GDNF and NGF protein levels in the heart have been found to decrease, which leads to negative changes observed in the innervation of cardiac muscle. Physical activity may help to defer this deterioration and help to restore GDNF and NGF protein levels in rat hearts. The focus of this study was to observe changes of GDNF and NGF protein content found in cardiac muscles of rats undergoing voluntary exercise. For this study the author used Sprague-Dawley rats that ranged from 4 weeks to 2 years of age and Fischer 344 rats which were 3 months old. The author found significant alterations in GDNF protein content from age control animals. A significant decrease in GDNF protein concentration was detected in exercised 3 month old Sprague-Dawley rats, however a significant increase was found in exercised 1 year old rats, both cases indicating that physical activity alters GDNF protein content. The only significant alteration of NGF protein levels occurred in control left ventricles from Fischer 344 rats.

Access Setting

Honors Thesis-Campus Only