Establishment of molecular mechanism of exercise motivation using a novel rat-strain featured by high levels of wheel-running activity

我们建立了一种新的大鼠品系，其特点是高水平的自愿轮跑，这被称为SPORTS（自发性跑步德岛四国）大鼠。本研究的目的是研究高强度或低强度的自主运动对久坐和轮跑运动时心脏交感神经和迷走神经控制的影响。在15周龄时，每只大鼠被转移到一个有或没有运动轮的新笼子里，并分为四组；1)有运动轮的运动大鼠（跑步），2)没有运动轮的运动大鼠（久坐），3)有运动轮的对照组大鼠（跑步），4)没有运动轮的对照组大鼠（久坐）。与对照组大鼠相比，久坐运动大鼠的心率显著增加。运动大鼠在高强度跑步后静息心率显著降低。运动大鼠自发跑步后，反映心脏交感神经活动的低频/高频（LF/HF）比明显降低。然而，在大约1/10轮跑活动的对照大鼠中，没有观察到交感神经活动的减少。轮跑使对照组大鼠低频功率增强，运动组大鼠低频功率明显降低。高强度的自主跑步会降低静息期（久坐）的平均心率，同时抑制交感神经活动。这些结果表明，高强度的自愿运动不仅在运动期间，而且在休息期间也会减弱交感神经活动，这是一种持久的影响。

We established a novel rat strain featured by high levels of voluntary wheel-running, which is called SPORTS(Spontaneously-Running Tokushima-Shikoku) rat. The aim of this study was to investigate the effect of high-or low-intensities in voluntary exercise on sympathetic and vagal controls of heart at sedentary and during wheel-running exercise by use of SPORTS rats. At 15 weeks of age, each rat was moved to a new cage with or without an exercise wheel, and sorted into four groups ; 1) SPORTS rat with an exercise wheel(running), 2) SPORTS rat without an exercise wheel(sedentary), 3) control rat with an exercise wheel(running), and 4) control rat without an exercise wheel(sedentary). Heart rate was significantly increased in sedentary SPORTS rats compared to those in control rats. SPORTS rats show a significant reduction in resting heart rate by high-intensity running. The low frequency/high frequency(LF/HF) ratio, which reflects cardiac sympathetic nerve activity, was significantly decreased in SPORTS rats by voluntary running. However, a decrease of sympathetic nerve activity was not observed in control rats with approximately 1/10 wheel-running activity. By wheel running, the low frequency(LF) power was augmented in control rats, and was markedly depressed in SPORTS rats. High-intensity voluntary running decreases mean heart rate during resting period(sedentary) with a depression of sympathetic nerve activity. These results suggest that high-intensity voluntary exercise attenuates sympathetic nerve activity not only during exercise but also during resting period as a lasting effects.