Liu Hongyu, Xue Jinjuan
aDepartment of Exercise Science, Institute of Sport and Exercise Medicine, North University of China, Taiyuan bDepartment of Radiology, Tangdu Hospital of the Fourth Military Medical University, Xi'an, China.
Neuroreport. 2017 May 3;28(7):408-413. doi: 10.1097/WNR.0000000000000763.
The aim of this study was to explore the effect of nitric oxide (NO) in some regions of the hypothalamus on exercise capacity.
To assess the role of central NO in exercise capacity, L-arginine (L-Arg, a precursor of NO synthesis), NG-nitro-L-arginine methyl ester (L-NAME, a NO synthase inhibitor), or placebo saline was injected into the lateral cerebral ventricle of rats once a day for 4 consecutive days. Thereafter, an one-time exhaustive treadmill exercise was performed, and the levels of nitrate/nitrite, as a marker of NO production, in blood plasma and hypothalamus were assayed. Neuronal nitric oxide synthase (nNOS)-expressing cells were immunohistochemically stained and analyzed in the paraventricular nucleus (PVN), the dorsomedial hypothalamus (DMH), and the ventromedial hypothalamus. Exercise time to exhaustion and total workload were determined.
Compared with the rats in the saline group, the exercise time to exhaustion and total workload increased 50% in the L-Arg group and decreased 50% in the L-NAME group. The nitrate/nitrite level of hypothalamus in the L-Arg group increased 50% and decreased 29.4% in the L-NAME group. The number of nNOS-positive cells was significantly increased, 56.5%, in PVN and, 119%, in DMH, but not in ventromedial hypothalamus. No significant changes in nNOS-positive cells were found in L-NAME-treated rats.
These results show that the modulation of hypothalamic NO signaling can affect the rat's running performance during a treadmill exercise and that enhanced NO signaling by induction of nNOS in PVN and DMH plays a role in improving exercise capacity after central administration of L-Arg. NO signaling in PVN and DMH may be a useful target for the pharmacological intervention of exercise performance or capacity.
本研究旨在探讨下丘脑某些区域的一氧化氮（NO）对运动能力的影响。
为评估中枢NO在运动能力中的作用，将L-精氨酸（L-Arg，NO合成的前体）、NG-硝基-L-精氨酸甲酯（L-NAME，一种NO合酶抑制剂）或安慰剂生理盐水每天一次注入大鼠侧脑室，连续4天。此后，进行一次力竭性跑步机运动，并测定血浆和下丘脑中作为NO产生标志物的硝酸盐/亚硝酸盐水平。对室旁核（PVN）、下丘脑背内侧核（DMH）和下丘脑腹内侧核中表达神经元型一氧化氮合酶（nNOS）的细胞进行免疫组织化学染色和分析。测定力竭运动时间和总工作量。
与生理盐水组大鼠相比，L-Arg组的力竭运动时间和总工作量增加了50%，L-NAME组减少了50%。L-Arg组下丘脑的硝酸盐/亚硝酸盐水平增加了50%，L-NAME组降低了29.4%。PVN中nNOS阳性细胞数量显著增加56.5%，DMH中增加119%，但下丘脑腹内侧核中未增加。L-NAME处理的大鼠中nNOS阳性细胞无显著变化。
这些结果表明，下丘脑NO信号的调节可影响大鼠在跑步机运动中的跑步表现，并且通过在PVN和DMH中诱导nNOS增强NO信号在中枢给予L-Arg后改善运动能力中起作用。PVN和DMH中的NO信号可能是运动表现或能力药物干预的有用靶点。
