Effect of Voluntary Exercise on Neurotrophic Factor Protein Content in Cardiac Muscle of Young Rats
Authors: Alves Gabriel Almeida , Spitsbergen John M. 
Published: June 2021

The sensory nervous system and the two branches of the autonomic nervous system, the sympathetic and parasympathetic nervous systems, work complementarily to regulate function of the heart. The literature shows that neurotrophic factors such as nerve growth factor (NGF) and glial cell line‐derived neurotrophic factor (GDNF) are responsible for controlling development, plasticity, and survival of sensory, sympathetic and parasympathetic innervation in cardiovascular tissues. Preliminary studies in our laboratory have shown that as we age, the innervation pattern in mesenteric vessels may shift from a balanced sensory/sympathetic to primarily sympathetic, with a concomitant increase in blood pressure. Little is known about how neurotrophic factor expression is regulated in cardiac muscle of adult rats and how changes in expression will impact the pattern of innervation in the heart. Therefore, the purpose of this study is to measure neurotrophic factor content and patterns of innervation in the hearts of sedentary and exercised rats. Sedentary animals (n=6) were kept in individual cages, while the exercised animals (n=6) were kept in individual cages with access to running wheels. Animal weight was measured throughout the study. Following 10 weeks of exercise animals were euthanized and cardiac tissues were removed. Each heart was divided into three parts: right atria, left atria, and ventricles. Tissues were processed and neurotrophic factor protein content was measured using enzyme‐linked immunosorbent assay. Our results show that body weight was lower in the exercised group compared to the sedentary group (P<0.05). GDNF protein content in right atria (2.97 ± 0.27 pg of GDNF/mg of tissue), left atria (2.06 ± 0.23 pg of GDNF/mg of tissue), and ventricles (2.58 ± 0.31 pg of GDNF/mg of tissue) of exercised animals were significantly higher than in right atria (1.20 ± 0.16 pg of GDNF/mg of tissue), left atria (1.30 ± 0.13 pg of GDNF/mg of tissue), and ventricles (1.27 ± 0.10 pg of GDNF/mg of tissue) of sedentary animals (P<0.001). NGF protein content in right atria (0.029 ± 0.019 pg of NGF/mg of tissue), left atria (0.112 ± 0.100 pg of NGF/mg of tissue), and ventricles (0.043 ± 0.030 pg of NGF/mg of tissue) of exercised animals were significantly lower than in right atria (0.037 ± 0.016 pg of NGF/mg of tissue), left atria (0.66 ± 0.45 pg of NGF/mg of tissue), and ventricles (0.67 ± 0.45 pg of NGF/mg of tissue) of sedentary animals (P<0.05). Previous studies have shown that exercise may restore the balance in autonomic neural drive to the heart. Our results suggest that exercise increases GDNF and reduces NGF protein content in the heart. This could provide a potential mechanism by which the innervation balance is restored in the heart, preventing cardiovascular diseases and improving quality of life.Support or Funding InformationNIH grant 1 R15 AG022908‐01A2, Western Michigan University, Conselho Nacional de Desenvolvimento Científico e TecnológicoThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.