Carmichael Martin D, Davis J Mark, Murphy E Angela, Brown Adrienne S, Carson James A, Mayer Eugene P, Ghaffar Abdul
Dept. of Exercise Science, Arnold School of Public Health, University of South Carolina, 1300 Wheat St., Columbia, SC 29208, USA.
Am J Physiol Regul Integr Comp Physiol. 2006 Nov;291(5):R1344-8. doi: 10.1152/ajpregu.00141.2006. Epub 2006 Jun 15.
Brain cytokines, induced by various inflammatory challenges, have been linked to sickness behaviors, including fatigue. However, the relationship between brain cytokines and fatigue after exercise is not well understood. Delayed recovery of running performance after muscle-damaging downhill running is associated with increased brain IL-1beta concentration compared with uphill running. However, there has been no systematic evaluation of the direct effect of brain IL-1beta on running performance after exercise-induced muscle damage. This study examined the specific role of brain IL-1beta on running performance (either treadmill or wheel running) after uphill and downhill running by manipulating brain IL-1beta activity via intracerebroventricular injection of either IL-1 receptor antagonist (ra; downhill runners) or IL-1beta (uphill runners). Male C57BL/6 mice were assigned to the following groups: uphill-saline, uphill-IL-1beta, downhill-saline, or downhill-IL-1ra. Mice initially ran on a motor-driven treadmill at 22 m/min and -14% or +14% grade for 150 min. After the run, at 8 h (wheel cage) or 22 h (treadmill), uphill mice received intracerebroventricular injections of IL-1beta (900 pg in 2 microl saline) or saline (2 microl), whereas downhill runners received IL-1ra (1.8 microg in 2 microl saline) or saline (2 microl). Later (2 h), running performance was measured (wheel running activity and treadmill run to fatigue). Injection of IL-1beta significantly decreased wheel running activity in uphill runners (P<0.01), whereas IL-1ra improved wheel running in downhill runners (P<0.05). Similarly, IL-1beta decreased and Il-1ra increased run time to fatigue in the uphill and downhill runners, respectively (P<0.01). These results support the hypothesis that increased brain IL-1beta plays an important role in fatigue after muscle-damaging exercise.
由各种炎症刺激诱导产生的脑源性细胞因子与包括疲劳在内的疾病行为有关。然而，脑源性细胞因子与运动后疲劳之间的关系尚未完全明确。与上坡跑相比，肌肉损伤性下坡跑后跑步能力的延迟恢复与脑内白细胞介素-1β（IL-1β）浓度升高有关。然而，对于运动诱导的肌肉损伤后脑内IL-1β对跑步能力的直接影响，尚未有系统的评估。本研究通过脑室内注射IL-1受体拮抗剂（IL-1ra；下坡跑组）或IL-1β（上坡跑组）来调控脑内IL-1β活性，从而研究脑内IL-1β在上坡跑和下坡跑后对跑步能力（跑步机跑步或跑轮跑步）的具体作用。将雄性C57BL/6小鼠分为以下几组：上坡跑-生理盐水组、上坡跑-IL-1β组、下坡跑-生理盐水组或下坡跑-IL-1ra组。小鼠最初在电动跑步机上以22米/分钟的速度、-14%或+14%的坡度跑150分钟。跑步结束后，在8小时（跑轮）或22小时（跑步机）时，上坡跑组小鼠脑室内注射IL-1β（900皮克溶于2微升生理盐水中）或生理盐水（2微升），而下坡跑组小鼠注射IL-1ra（1.8微克溶于2微升生理盐水中）或生理盐水（2微升）。随后（2小时），测量跑步能力（跑轮活动和跑步机跑步至疲劳）。注射IL-1β显著降低了上坡跑组小鼠的跑轮活动（P<0.01），而IL-1ra改善了下坡跑组小鼠的跑轮活动（P<0.05）。同样，IL-1β分别降低了上坡跑组和下坡跑组小鼠跑步至疲劳的时间，而IL-1ra则分别延长了这两组小鼠跑步至疲劳的时间（P<0.01）。这些结果支持了以下假设：脑内IL-1β水平升高在肌肉损伤性运动后的疲劳过程中起重要作用。
