运动对胰岛素抵抗大鼠骨骼肌IRS-1与Tyr磷酸化及氧化应激的影响

目的研究运动对胰岛素抵抗大鼠骨骼肌IRS-1表达与酪氨酸磷酸化及MDA水平的影响,探讨运动改善骨骼肌胰岛素抵抗的机制。方法 22只SD雄性大鼠随机分为3组,空白对照组(CG)6只,胰岛素抵抗组(IRG)与胰岛素抵抗运动(EIRG)各8只,采用高脂膳食对IRG和EIRG大鼠诱导胰岛素抵抗模型。EIRG大鼠进行10周游泳训练,运动后测定各组大鼠骨骼肌IRS-1表达和其酪氨酸磷酸化水平及MDA含量。结果采用高脂膳食诱导胰岛素抵抗模型成功;运动干预后与CG比较I,RG大鼠骨骼肌IRS-1表达及其Tyr磷酸化水平显著降低(P<0.01),MDA含量与HOMA-IR显著升高(P<0.01);与IRG比较,EIRG大鼠骨骼肌IRS-1表达升高(P<0.05)I,RS-1Tyr磷酸化水平也显著增加(P<0.01);同时,胰岛素抵抗指数与MDA含量显著降低(P<0.05);MDA含量与IRS-1表达(r:-0.583;P:0.004)及其Tyr磷酸化水平(r:-0.634;P:0.002)均呈负相关。结论运动可提高胰岛素抵抗大鼠骨骼肌IRS-1蛋白表达,增加IRS-1 Tyr磷酸化水平,显著改善胰岛素抵抗;这可能主要与骨骼肌氧化应激降低诱导其IRS-1Tyr磷酸化水平增高有关。     

Antioxidant-rich beetroot juice does not adversely affect acute neuromuscular adaptation following eccentric exercise

This study examined the effects of beetroot juice on the repeated bout effect (RBE) to eccentric exercise. Twenty-nine recreationally active males performed two bouts of 100-drop jumps, separated by 14–21 days. Using a double-blind, independent groups design, participants consumed either a higher dose beetroot juice (H-BT; 250 ml, n = 10), a lower dose beetroot juice (L-BT; 125 ml, n = 9) or an isocaloric placebo (PLA; 250 ml, n = 10) for 3 days after bout 1; no drinks were consumed after bout 2. Maximal isometric voluntary contraction (MIVC), countermovement jump (CMJ), pressure-pain threshold (PPT) and creatine kinase (CK) were measured pre, post, 24, 48 and 72 h following both bouts. In bout 2, CMJ and MIVC recovered quicker and CK activity was attenuated (versus bout 1) (P < 0.05) in all groups, demonstrating an RBE. At 24 h post bout 1, MIVC was 84.1 ± 16.1, 83.6 ± 11.6, 79.7 ± 15.1% relative to baseline values in the H-BT, L-BT and PLA groups, respectively; at 24 h post bout 2, MIVC recovered to 90.7 ± 13.7, 92.9 ± 6.9, 87.8 ± 6.9, in the H-BT, L-BT and PLA groups, respectively. These findings suggest that supplementation with antioxidant-rich beetroot juice does not adversely affect acute adaptations to a bout of eccentric exercise.     

Increasing heat storage by wearing extra clothing during upper body exercise up-regulates heat shock protein 70 but does not modify the cytokine response

Plasma heat shock protein 70 (HSP70) concentrations rise during heat stress, which can independently induce cytokine production. Upper body exercise normally results in modest body temperature elevations. The aim of this study was to investigate the impacts of additional clothing on the body temperature, cytokine and HSP70 responses during this exercise modality. Thirteen males performed 45-min constant-load arm cranking at 63% maximum aerobic power (62 ± 7%V?O_2peak) in either a non-permeable whole-body suit (intervention, INT) or shorts and T-shirt (control, CON). Exercise resulted in a significant increase of IL-6 and IL-1ra plasma concentrations (P < 0.001), with no difference between conditions (P > 0.19). The increase in HSP70 from pre to post was only significant for INT (0.12 ± 0.11ng?mL^?1, P < 0.01 vs. 0.04 ± 0.18 ng?mL^?1, P = 0.77). Immediately following exercise, T_core was elevated by 0.46 ± 0.29 (INT) and 0.37 ± 0.23ºC (CON), respectively (P < 0.01), with no difference between conditions (P = 0.16). The rise in mean T_skin (2.88 ± 0.50 and 0.30 ± 0.89ºC, respectively) and maximum heat storage (3.24 ± 1.08 and 1.20 ± 1.04 J?g^?1, respectively) was higher during INT (P < 0.01). Despite large differences in heat storage between conditions, the HSP70 elevations during INT, even though significant, were very modest. Possibly, the T_core elevations were too low to induce a more pronounced HSP70 response to ultimately affect cytokine production.     

The Acute Exercise-Induced Inflammatory Response: A Comparison of Young-Adult Smokers and Nonsmokers

Purpose: This study examined postexercise inflammatory and leukocyte responses in smokers and nonsmokers, as well as the effects of cigarette smoking on the acute postexercise inflammatory and leukocyte response in habitual smokers. Method: Eleven recreationally active male smokers and 11 nonsmokers matched for age and aerobic fitness were familiarized and underwent baseline fitness testing. Participants then completed 40 min of cycling at 50% peak aerobic workload. Smokers performed 2 randomized exercise sessions, including an acute postexercise smoking condition (2 cigarettes in 15 min of 12 mg tar and 1 mg nicotine) and a no-smoking condition, while nonsmokers performed 1 exercise session without smoking. Venous blood was obtained preexercise and postexercise for analysis of interleukin (IL)-6, IL-1 receptor antagonist (ra), tumor necrosis factor-alpha (TNF-α), and c-reactive protein (CRP). Results: No differences existed between groups for resting CRP (d = 0.25–0.46; p = .374–.617). Despite no baseline difference (d = 0.03–0.07; p = .141–.70), exercise-induced increases were observed for IL-1 ra in smokers (d = 0.50; p = .024–.033), which was not observed in the never-smoker group. No between-group difference was observed for IL-6 across all points (d = 0.09–0.5; p = .102–.728); however, all groups observed significant within-group change (d = 0.27–1.09; p = .001–.042). Further, TNF-α for smokers smoking was elevated above both smokers not smoking and nonsmokers at baseline and across the protocol (d = 1.20–1.80; d = 0.20–1.0; p = .001–.035). Additionally, a marked postexercise increase in leukocyte and neutrophil concentrations was evident in smokers smoking compared with nonsmokers and smokers not smoking as indicated by a moderate-to-large effect size (d = 0.72; d = 0.78). Conclusion: Consequently, male smokers exhibit an altered postexercise proinflammatory profile compared with age- and fitness-matched nonsmokers.     

急性炎症的病理变化及与延迟性肌肉酸痛的关系

采用文献综述的方法,对急性炎症的主要病理变化、急性炎症与延迟性肌肉酸痛的关系、以及延迟性酸痛发生的经过等问题进行讨论。     

Interleukin-6: Possible biological roles during exercise

Abstract

Interleukin-6 (IL-6) is a multifunctional cytokine that exerts its modulatory effects on cells that express membrane bound IL-6 receptors; however, IL-6 in a complex with soluble IL-6R can bind to any cell that express glycoprotein 130 (gp130). Thus, all cell types may respond to the pro- as well as anti-inflammatory properties of IL-6. Since the first report of acute exercise-induced increase in plasma IL-6 in the early 1990s, scientists have tried to elucidate the factors that influence the magnitude of change of plasma IL-6, as well as the possible biological roles of this cytokine. Evidence suggests that exercise intensity and duration as well as the form of contraction (e.g. eccentric or concentric) and muscle damage all influence IL-6 response to acute exercise. However, data on training status and performance on plasma IL-6 concentration changes during exercise are more inconclusive, as discussed in this review. In the last decade, most of the studies have focused on IL-6 as an ‘energy sensor’ possibly secreted by skeletal muscle that activates glycogenolysis in the liver and lipolysis in fat tissue in order to provide muscle with the growing energy demands during exercise.