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

动态运动改变能量代谢和自主神经功能。众所周知，运动导致的体重下降不仅是由于能量消耗的增加，而且还由于能量代谢的中枢调节的变化。然而，改变能量代谢控制的机制尚不清楚。本实验的目的是研究运动引起能量平衡设定点的中枢重置机制。本研究通过三个系列的实验来达到这一目的：测定大鼠在30 min跑台运动前、中、后的耗氧量、呼吸商和肾交感神经活动。呼吸商和肾交感神经活性在运动停止后2小时内持续下降。结果表明，交感神经系统参与调节能量生产对营养物质的利用率，2-脱氧-D-葡萄糖（2-DG）的葡萄糖缺乏作用导致能量生产对脂质的相对利用率增加。通过肾神经测量的交感神经活动由于2-DG给药而以持续的方式受到抑制。在清醒大鼠侧脑室注射β-内啡肽（0.5nmol和1.0nmol）。注射β-内啡肽70 min时，1 nmol组肾交感神经活动增加75%，0.5nmol组增加70%。肾交感神经活动和全身动脉压以与耗氧量增加相似的方式增加。提示交感神经系统的中枢激活可能参与了能量代谢的调节。

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.