Central resetting of body weight control and decrease of body fat induced by exercise in rats.

动态运动可以改变能量代谢和自主神经功能。众所周知，运动导致的体重减轻不仅是因为能量消耗的增加，也是因为能量代谢的中枢调节发生了变化。然而，改变能量代谢控制的机制尚不清楚。本实验旨在探讨运动所致能量平衡设定值的中枢重置机制。随后进行了三个系列的实验，分别在运动前、运动中和运动后30min测量大鼠的氧耗量、呼吸商和肾交感神经活动。运动停止后2小时以上，呼吸商和肾交感神经活动持续下降。这表明交感神经系统参与了能量生产中营养物质利用率的调节，2-脱氧-D-葡萄糖(2-DG)引起的葡萄糖代谢导致能量生产中脂肪的相对利用率增加。肾神经测定的交感神经活动因给予2-DG而持续受到抑制。这些数据表明，自主神经系统可能参与调节清醒大鼠葡萄糖代谢过程中脂肪和碳水化合物的相对利用，以产生能量。将β-内啡肽(0.5和1.0nmol)注入清醒大鼠的侧脑室。注射β-内啡肽使肾交感神经活动在70min时增加75%，0.5nmol组增加70%。肾交感神经活动和体动脉压的增加与耗氧量增加的方式相似。这些结果提示，交感神经系统的中枢激活可能参与了大鼠能量代谢的调节。

Dynamic exercise modifies energy metabolism and autonomic functions. It is well established decrease in body weight due to the exercise is due to not only the increase in energy expenditure but also the changes central regulation of energy metabolism. However, mechanisms underling the modification of control of energy metabolism is not known. The purpose of the present experiments is to study the mechanisms of central resetting of the set point of energy balance induced by exercise. Following three series of experiments were performed to achieve this aim.Oxygen consumption, respiratory quotient and renal sympathetic nerve activity were measured before, during and after 30min treadmill exercise in rats. Respiratory quotient and renal sympathetic nerve activity decrease in sustained fashion over 2hrs after cessation of the exercise. This data indicate that the sympathetic nervous system involves in regulation of ratio of nutrient utilization for energy production.The glucoprivation incluced by 2-deoxy-D-glucose (2-DG) results in an increase in relative utilization of lipid for energy production. The sympathetic nerve activity measured by renal nerve suppressed in a sustained manner due to the 2-DG administration. These data suggest that the autonomic nervous system may involve in regulating the relative utilization of lipid and carbohydrate for energy production during glucoprivation in conscious rats.Beta-endorphin (0.5 and 1.0nmol) in saline solution was injected into the lateral cerbroventricular space in conscious rats. The injection of beta-endorphin increased renal sympathetic nerve activity by 75% at 70min in 1 nmol group and 70% in 0.5nmol group. Renal sympathetic nerve activity and systemic arterial pressure increases in similar manner of the increase in oxygen consumption. These results suggest that central activation of sympathetic nervous system may involve in regulating energy metabolism in rats.