Effects of 12-week Endurance Exercise on Dopamine Receptor Protein Expression in Hippocampus of Obese Rat

Abstract

PURPOSE: The purpose of this study was to investigate changes of body composition, D1 dopamine receptors (D1DR), and D2 dopamine receptors (D2DR) protein expression after 12 weeks of moderate-intensity treadmill exercise in hippocampus of high fat dietinduced obese rats.METHODS: Subjects were consisted of 40 male 10 weeks aged Sprague-Dawley rats, and were randomly divided into four experimental groups: chow, HFD, chow+exercise, and HFD+exercise. The exercise groups underwent aerobic training using treadmill running exercise with 3 days/week for a total of 12 weeks. Body composition, D1DR, D2DR, ERK1/2, and Akt protein expression in hippocampus were measured for the comparison among groups.RESULTS: High fat diet-induced obesity decreased the expression of D1DR and D2DR in hippocampus. 12 week of moderate-intensity treadmill exercise increased D1DR expression in hippocampus. 12 weeks of moderate-intensity treadmill exercise does not affect the improvement of the D1DR and D2DR receptors in obese rats. 12 weeks of moderate-intensity treadmill exercise had a positive effect on improvement of endurance capacity and insulin sensitivity.CONCLUSIONS: These results suggest that moderate-intensity treadmill exercise has a positive effect on the expression of dopamine receptors in hippocampal tissues, whereas high-fat diet intake is negative factor in the expression of dopamine receptors. However, based on the results of this study, it is somewhat lacking to clearly define the expression of dopamine receptors by high-fat diet and endurance exercise. Dopamine receptors are known to be expressed not only in hippocampus but also in all parts of the brain. Therefore, additional studies should be conducted to understand the correlation between various dopamine receptors expressed in other tissues as well as exercise methods and various factors.