研究课题：咖啡因和腺苷对疲劳影响的中枢神经机制
供稿：运动科学系，公共卫生学院，南卡洛莱纳大学

    主要内容：运动时摄入咖啡因可以延缓疲劳，但机制不明。此研究的目的是验证下述假设：咖啡因对解除疲劳的正面作用是通过阻断中枢神经系统（CNS）的腺苷受体实现的。实验首先要证实CNS的咖啡因/腺苷A1/A2受体颉颃剂NECA对于自发运动功能的作用。在测量自发运动（即穿越旋转平台）前30分钟内，分别给予雄性大鼠咖啡因、NECA、咖啡因+NECA或单纯旋转平台，共四次间隔一周。中枢神经系统内咖啡因与NECA（脑脊腔内给药）水平分别与自发运动的增加和减少有关，而两者同时使用会减少NECA的副性作用。与对照组比较，CNS咖啡因的水平使疲劳时间延长60%，而NECA缩短68%；但不同于自发运动的是，预选给予咖啡因可以有效阻断NECA的副性作用，但外周（腹腔）给药无效。

    结论：咖啡因可以通过CNS抑制延迟疲劳出现，至少部分是通过阻断腺苷受体发挥作用。

Central nervous system effects of caffeine and adenosine on fatigue.
Davis JM, Zhao Z, Stock HS, Mehl KA, Buggy J, Hand GA. Am J Physiol Regul Integr Comp Physiol. 2003 Feb;284(2):R399-404.
Department of Exercise Science, Schools of Public Health and Medicine, University of South Carolina, Columbia, SC.

     Caffeine ingestion can delay fatigue during exercise, but the mechanisms remain elusive. This study was designed to test the hypothesis that blockade of central nervous system (CNS) adenosine receptors may explain the beneficial effect of caffeine on fatigue. Initial experiments were done to confirm an effect of CNS caffeine and/or the adenosine A(1)/A(2) receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA) on spontaneous locomotor activity. Thirty minutes before measurement of spontaneous activity or treadmill running, male rats received caffeine, NECA, caffeine plus NECA, or vehicle during four sessions separated by approximately 1 wk. CNS caffeine and NECA (intracerebroventricular) were associated with increased and decreased spontaneous activity, respectively, but caffeine plus NECA did not block the reduction induced by NECA. CNS caffeine also increased run time to fatigue by 60% and NECA reduced it by 68% vs. vehicle. However, unlike the effects on spontaneous activity, pretreatment with caffeine was effective in blocking the decrease in run time by NECA. No differences were found after peripheral (intraperitoneal) drug administration. Results suggest that caffeine can delay fatigue through CNS mechanisms, at least in part by blocking adenosine receptors.

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