Xue Jin-Juan, Liu Hong-Yu
Radiology Department, Tangdu Hospital of the Fourth Military Medical University, Xi'an 710038.
Zhongguo Ying Yong Sheng Li Xue Za Zhi. 2013 Mar;29(2):158-61.
To explore the relationship between nitric oxide (NO) in central nervous system and exercise-induced fatigue stress and to study the effect of L-arginine (L-Arg), as a substrate of nitric oxide, on the exercise capacity and NO content in the exhausted rat brain and blood.
Through an implanted cannula, the normal saline or L-Arg was microinjected into rat's intracerebroventrical for consecutive four days. Then an acute exhaustive model (on the speed of 18 m/min, an inclination of 5 degrees) was established with animal treadmill. The time of exercise till exhaustion was recorded, and the total workload was calculated that represented the exercise capacity. Nitrate and nitrite (NO3/NO2-, NOx-) levels in blood, hypothalamus and hippocampus were assayed.
Both the time of exercise till exhaustion and total workload in the LArg group increased respectively by 51.8% and 50.08% (P < 0.05), compared with those in the control. The NOx- content in hypothalamus in the L-Arg group (8.93 +/- 1.83) micromol/g pro was larger than that in the control (4.25 +/- 0.79) micromol/g pro, (P < 0.01). There was no significant difference in NOx- content in brain and hippocampus between the two groups. The total workload was positively correlated with NOx- concentration in hypothalamus (P < 0.01). However, there was no correlation between workload and changes in hippocampus NOx- content at fatigue.
Intracerebroventricular microinjection of L-Arg may enhance the exercise capacity and lead to up-regulation of NO by means of L-Arg-NO signal path in the hypothalamus. Hypothalamus may be a key site in brain in the modulation of physiological exercise.
探讨中枢神经系统中一氧化氮（NO）与运动性疲劳应激的关系，并研究作为一氧化氮底物的L-精氨酸（L-Arg）对力竭大鼠脑和血液中运动能力及NO含量的影响。
通过植入套管，连续4天向大鼠脑室内微量注射生理盐水或L-Arg。然后用动物跑步机建立急性力竭模型（速度为18米/分钟，坡度为5度）。记录运动至力竭的时间，并计算代表运动能力的总工作量。检测血液、下丘脑和海马中硝酸盐和亚硝酸盐（NO3/NO2-，NOx-）水平。
与对照组相比，L-Arg组运动至力竭的时间和总工作量分别增加了51.8%和50.08%（P<0.05）。L-Arg组下丘脑的NOx-含量（8.93±1.83）微摩尔/克蛋白高于对照组（4.25±0.79）微摩尔/克蛋白（P<0.01）。两组脑和海马中的NOx-含量无显著差异。总工作量与下丘脑NOx-浓度呈正相关（P<0.01）。然而，工作量与疲劳时海马中NOx-含量的变化之间无相关性。
脑室内微量注射L-Arg可能通过下丘脑的L-Arg-NO信号通路增强运动能力并导致NO上调。下丘脑可能是大脑中调节生理性运动的关键部位。
