红景天提取物提高高强度跑台运动小鼠的抗氧化能力

为了考察红景天提取物对高强度跑台运动小鼠的抗氧化能力的影响,本研究将30只昆明小鼠随机分成对照组、模型组和红景天提取物组,每组10只。红景天提取物组小鼠按照500 mg/kg bw的剂量灌胃红景天提取液(2 m L)。对照组和模型组小鼠灌胃等体积的蒸馏水,共灌胃4周。采用硫酸蒽酮比色法检测小鼠肝脏和肌肉组织糖原的含量;采用硫代巴比妥酸比色法检测小鼠骨骼肌组织中的丙二醛(MDA)水平;采用RT-PCR和Western blotting检测骨骼肌组织中的超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)和过氧化氢酶(CAT)的表达水平;采用苏木精和伊红(HE)染色评价骨骼肌病理改变。研究显示,模型组小鼠的跑台运动时间显著低于红景天提取物组(61.32 min vs 83.22 min,p<0.05);与模型组相比,红景天提取物组小鼠骨骼肌的炎性细胞浸润明显减轻,肌纤维排列明显改善;红景天提取物组的肝糖原和肌糖原含量均显著高于模型组;红景天提取物组小鼠骨骼肌组织中的MDA水平显著低于模型组;红景天提取物组的SOD、GSH-Px和CAT m RNA和蛋白表达水平均显著高于模型组;红景天提取物可通过上调抗氧化酶表达来增加抗氧化能力,减弱骨骼肌损伤,并增加机体的抗疲劳能力。     

小球藻摄入干预对抗阻运动诱发的肌肉损伤的影响

为探究小球藻摄入干预对抗阻运动诱发的肌肉损伤的影响,本研究招募32名排球运动员为受试者,进行随机对照双盲实验设计,分别随机分为安慰剂组(n=16)与小球藻组(n=16),每位受试者以4.5 g/d的剂量连续服食小球藻或安慰剂35 d,进行单次抗阻运动以诱发肌肉损伤,损伤模式以85%最大肌力为负荷进行大腿蹬卧推、大腿曲屈、卧推3个动作各进行4组,每组动作重复8次。在摄入小球藻或安慰剂前,运动后24 h,运动后48 h分别测量血清肌酸激酶和乳酸脱氢酶活性,以量表评估肌肉疼痛程度,并在运动后第3天、第4天、第5天测量最大肌力表现。研究发现,抗阻运动造成血液肌酸激酶活性与肌肉酸痛感增加,肌肉力量降低;小球藻组运动后第24 h和第48 h血液肌酸激酶活性与肌肉酸痛感显著低于安慰剂组;小球藻组运动后3～4 d大腿推蹬力量显著高于安慰剂组,运动后4～5 d大腿曲屈与卧推力量显著高于安慰剂组。研究表明,小球藻摄入干预可以改善抗阻运动诱发的肌肉损伤,避免运动后的肌肉疲劳,同时降低恢复期的肌肉损伤。     

高强度间歇运动通过调控Nrf2/ARE和NF-κB信号通路调节高脂饮食诱导肥胖大鼠的氧化应激和炎症反应

为了揭示高强度间歇运动对肥胖大鼠的氧化应激和炎症反应的调节作用及机制,本研究将60只大鼠随机分为对照组、肥胖组、中强度持续运动组(MICE)和高强度间歇运动组(HIIE)。对照组大鼠采用标准饲料喂养,其他组大鼠采用高脂饲料喂养以建立肥胖大鼠模型。MICE组大鼠进行中强度持续运动,HIIE组大鼠进行高强度间歇运动,共运动4周。采用苏木精-伊红(HE)染色检测大鼠骨骼肌形态。采用TUNEL法检测骨骼肌细胞凋亡。通过商用试剂盒检测活性氧(ROS)水平。通过RT-PCR或Western blotting检测大鼠骨骼肌组织中Nrf2、SOD、GSH-PX、CAT、p65、p-p65、IκB、p-IκB、TNF-α、IL-1β和IL-6的表达。研究显示,与肥胖组比较,MICE组和HIIE组大鼠骨骼肌组织中的ROS水平均显著降低,HIIE组大鼠骨骼肌组织中的ROS水平显著低于MICE组。MICE组和HIIE组大鼠的骨骼肌形态基本正常,仅少量肌纤维排列异常。与肥胖组比较,MICE组和HIIE组大鼠骨骼肌细胞凋亡率均显著降低,HIIE组大鼠骨骼肌细胞凋亡率显著低于MICE组。与肥胖组比较,MICE组和HIIE组大鼠骨骼肌组织中Nrf2、SOD、GSH-PX和CAT的蛋白水平均显著升高,HIIE组均显著高于MICE组。与肥胖组比较,MICE组和HIIE组大鼠骨骼肌组织中p-p65、p-IκB、TNF-α、IL-1β和IL-6的蛋白水平均显著降低,HIIE组均显著低于MICE组。总之,HIIE运动可通过抑制NF-κB信号通路来抑制肥胖引起的慢性炎症。HIIE运动可通过激活Nrf2/ARE信号通路来提高机体抗氧化能力并减弱氧化应激损伤。     

全氟辛烷磺酸钾对小鼠肾脏的氧化性损伤

目的:以小鼠肾脏细胞中的活性氧(ROS)、丙二醛(MDA)、谷胱甘肽(GSH)含量和超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)活力为指标,探讨全氟辛烷磺酸钾(PFOS-K)对小鼠肾脏的氧化性损伤作用。方法:以剂量为6mg/kg·bw、12 mg/kg·bw、24 mg/kg·bw 3个浓度的PFOS-K混悬液,每天分别给小鼠经口灌胃一次,连续染毒20天后检测肾脏脏器系数,以及肾脏中ROS、MDA、GSH含量的变化和SOD、GSH-Px、CAT活性的改变。结果:与阴性对照组相比,在6-24 mg/kg·bw剂量范围内,PFOS-K使小鼠体重下降、肾脏重量增加、肾脏脏器系数增大,且表现出一定的剂量-效应关系(r小鼠体重=-0.905,r肾脏湿重=0.938,r脏器系数=0.936)。PFOS-K使小鼠肾脏内活性氧(ROS)及丙二醛(MDA)含量增多(rROS=0.990,rMDA=0.997)、谷胱甘肽(GSH)含量减少(rGSH=-0.994),超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)活力降低(rSOD=-0.917,rGSH-Px=-0.986,rCAT=-0.991)。结论:本试验条件下,PFOS-K致使小鼠肾脏肿大,影响了肾脏的发育;造成了肾脏的氧化性损伤,肾组织内抗氧化酶系统遭到破坏,氧化应激反应增强,具有氧化损伤作用。     

芪蝎活血通络汤对局灶性脑缺血再灌注损伤模型大鼠神经功能、氧化应激及炎症因子的影响

目的:探讨芪蝎活血通络汤对局灶性脑缺血再灌注损伤模型大鼠神经功能、氧化应激及炎症因子的影响。方法:50只SD大鼠随机选取40只采用线栓法构建脑缺血再灌注模型,其中36只成功,4只死亡。随机数字表法将36只脑缺血再灌注模型大鼠分为模型组、低剂量组(芪蝎活血通络汤2.0 mg/kg灌胃处理)、中剂量组(芪蝎活血通络汤4.0 mg/kg灌胃处理)和高剂量组(芪蝎活血通络汤8.0 mg/kg灌胃处理),每组9只,剩余10只大鼠仅切开皮肤分离和夹闭血管(对照组)。建模后芪蝎活血通络汤各剂量组给予相应剂量灌胃,对照组和模型组给予同剂量生理盐水灌胃,持续4周。用药4周后测评各组大鼠神经功能缺损程度、双侧贴纸去除时间、平衡木过杆时间,并测定各组大鼠脑组织中含水量、脑梗死面积以及氧化应激[过氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)、丙二醛(MDA)]和炎症因子[白细胞介素-1β(IL-1β),白细胞介素-6(IL-6),肿瘤坏死因子-α(TNF-α)]指标。结果:与对照组比较,模型组大鼠m NSS评分、脑组织含水量、MDA含量、IL-6、IL-1β、TNF-α水平升高(P<0.05),双侧贴纸去除时间、平衡木过杆时间延长(P<0.05),脑梗死面积增大(P<0.05),SOD、GSH-Px、CAT活性降低(P<0.05);与模型组比较,芪蝎活血通络汤各剂量组大鼠m NSS评分、脑组织含水量、MDA含量、IL-6、IL-1β、TNF-α水平降低(P<0.05),双侧贴纸去除时间、平衡木过杆时间缩短(P<0.05),脑梗死面积缩小(P<0.05),SOD、GSH-Px、CAT活性升高(P<0.05);与低剂量组比较,中、高剂量组大鼠m NSS评分降低(P<0.05),双侧贴纸去除时间、平衡木过杆时间缩短(P<0.05);高剂量组大鼠脑梗死面积、脑组织MDA、IL-6、IL-1β、TNF-α低于低剂量组(P<0.05),SOD、GSH-Px、CAT高于低剂量组(P<0.05)。结论:芪蝎活血通络汤可降低大鼠脑缺血再灌注损伤,改善神经功能,其治疗作用可能与抗氧化,抗炎作用有关,8.0 mg/kg剂量效果最显著。     

食品级槲皮素粉对机体最大摄氧量和耐力的影响

为了考察食品级槲皮素粉对机体最大摄氧量和耐力的影响,本研究纳入20名健康的大学生志愿者作为本研究的研究对象。将受试者随机分为A组和B组,每组10名,A组饮用剂量为1 mg/mL的槲皮素饮料,B组饮用安慰剂饮料,每天饮用1 000 m L。饮用7 d后,通过自行车分级运动测试最大摄氧量(VO2max),通过骑行疲劳时间测试耐力,同时检测血清丙二醛(MDA)、超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)含量。然后进行交叉实验并测试VO2max、骑行疲劳时间及抗氧化指标。研究显示,与基线VO2max相比,饮用槲皮素饮料后VO2max显著升高13.21%,而饮用安慰剂饮料后的VO2max与基线无显著差异。与基线骑行疲劳时间相比,饮用槲皮素饮料后骑行疲劳时间显著升高25.15%,而饮用安慰剂饮料后的骑行疲劳时间与基线无显著差异。与基线血清MDA相比,饮用安慰剂饮料后受试者血清MDA显著升高27.15%,而饮用槲皮素饮料可抑制血清MDA的升高。与基线血清SOD和GSH-Px相比,饮用安慰剂饮料后受试者血清SOD和GSH-Px分别降低了20.49%和21.08%,而饮用槲皮素饮料可抑制血清SOD和GSH-Px的降低,表明槲皮素可显著提高骑行运动过程中受试者的VO2max和耐力。本研究初步表明,补充槲皮素可通过降低运动过程中MDA水平来减少脂质过氧化损伤。另外,槲皮素通过抑制运动过程中SOD和GSH-Px的降低来提高机体的抗氧化能力,从而延缓疲劳。     

毛蕊花苷对递增负荷运动小鼠骨骼肌损伤的保护作用

本研究采用小鼠跑台训练模型,应用免疫共沉淀等方法,研究毛蕊花苷对递增负荷运动小鼠骨骼肌损伤的保护作用及对谷胱甘肽的影响。90只小鼠随机分为:正常对照组(A)、正常+毛蕊花苷组(B)、单纯运动组(C)、运动+毛蕊花苷低剂量组(D)、运动+毛蕊花苷中剂量组(E)、运动+毛蕊花苷高剂量组(F).结果表明:与C组比较,D、E、F组小鼠骨骼肌损伤程度依次减轻,F组小鼠骨骼肌形态基本正常。F组小鼠血浆CK水平、骨骼肌组织GSSG含量分别低于C、D、E组;但CK水平高于A、B组,均P0.01;GSSG含量与A、B组比较,差异无显著性,P0.05。F组小鼠骨骼肌组织GSH含量、GSH/GSSG比值、GCL和GR酶活性、RyR1复合物中GSH表达水平分别高于C、D、E组,但低于A、B组,均P0.01。研究结果提示毛蕊花苷能降低递增负荷运动小鼠血浆CK的活性,保护运动鼠骨骼肌的形态;其机理与其提高运动鼠骨骼肌组织GSH含量和GCL、GR酶的活性,降低GSSG/GSH比值;提高RyR1复合物中GSH表达水平有关。     

秀珍菇粉对H22荷瘤小鼠体内抗肿瘤作用研究

目的本试验旨在研究秀珍菇抗肿瘤作用及其抑瘤机制。方法选用ICR雄性小鼠60只,取10只作为空白组,剩余50只小鼠通过腋部皮下接种H22小鼠腹水构建荷瘤小鼠模型,造模后随机分为模型组、阳性药(CTX)组、秀珍菇低、中、高剂量组,每组10只。模型组小鼠灌服生理盐水,阳性药组小鼠按20 mg/kg体重隔天腹腔注射注射环磷酰胺(CTX)生理盐水溶液,秀珍菇低、中、高剂量组小鼠分别按750、1500、3000 mg/kg体重每天剂量灌服秀珍菇生理盐水混悬液。给药10 d后,测定各组小鼠平均瘤重,肿瘤抑制率;测定免疫器官脏器指数、血清免疫球蛋白和细胞因子含量;测定肝、肾抗氧化指标;观察肿瘤和脾组织HE染色病理切片。结果 (1) CTX及秀珍菇低、中、高剂量组小鼠的平均瘤重均极显著低于模型组(P0. 01),四组小鼠肿瘤抑制率分别为55. 18%,29. 06%、47. 47%和48. 80%。(2)与空白组比较,模型组小鼠脾指数、血清Ig A和TNF-α含量及肝MDA含量显著升高(P0. 05,P0. 01),血清IL-6含量有上升趋势(P 0. 05),而血清IL-2含量、肝CAT和GSH-Px活性及肾SOD、GSH-Px和CAT活性显著降低(P0. 05,P0. 01);同时,CTX组小鼠胸腺指数显著低于空白组(P0. 05)。(3)秀珍菇对荷瘤小鼠免疫和抗氧化功能异常改变具有逆转作用:与模型组比较,秀珍菇各剂量组小鼠血清Ig A和TNF-α含量及高剂量组小鼠IL-6水平显著降低(P 0. 05,P 0. 01),低剂量组小鼠血清IL-2水平显著升高(P 0. 01);秀珍菇处理还显著提高了各剂量组荷瘤小鼠肝CAT活性及肾SOD和CAT活性(P 0. 05,P 0. 01),显著升高中、高剂量组肝GSH-Px活性和低、中剂量组肾GSH-Px活性(P 0. 05,P 0. 01),并显著降低中剂量组的肝MDA含量(P 0. 05)。(4)与CTX组比较,秀珍菇高剂量组小鼠脾指数显著提高(P 0. 05),而血清IL-6水平显著降低(P 0. 05)。(5)肿瘤组织病理切片显示CTX组和秀珍菇各剂量组的肿瘤坏死面积明显增加。结论秀珍菇可抑制H22实体移植瘤生长,其机制与其具有较强的免疫调节和抗氧化作用有关。     

DBP致雌性仔鼠卵巢的氧化应激及VC的干预作用

为探明邻苯二甲酸二丁酯(DBP)宫内暴露对雌性仔鼠卵巢脂质过氧化水平的影响及维生素C(Vit C)的抗氧化应激作用。本研究将20只Wistar孕鼠随机分为5组,分别为高(500 mg/kg)、低(100 mg/kg)剂量DBP染毒组以及高(500 mg/kg)、低(100 mg/kg)剂量DBP+Vit C(125 g/L)干预组和对照(玉米油)组,每组4只。自妊娠第1~19天,每天1次灌胃染毒DBP(10 m L/kg);采用自由饮水方式进食Vit C(约40 m L/d)。待雌性仔鼠出生21 d时,取其卵巢组织,称重,并测定MDA、GSH含量和GSH-Px、SOD、CAT活性。研究发现,与对照组相比,高、低剂量DBP染毒组MDA含量均明显升高,SOD、CAT、GSH-Px活性均明显降低(p0.05)。高、低剂量DBP+Vit C干预组的仔鼠卵巢组织中MDA含量与相同剂量DBP染毒组相比显著下降,GSH-Px、SOD、CAT活性显著升高(p0.05)。综上所述,DBP宫内暴露可致雌性仔鼠卵巢组织产生脂质过氧化反应,诱导氧化应激,造成潜在生殖毒性,抗氧化剂Vit C对于DBP所致生殖系统的氧化损伤具有一定的保护作用。这为进一步开展DBP生殖发育毒性的机制研究和预防干预提供理论依据。     

拟黑多刺蚁提取液可缓解小鼠体力疲劳

研究拟黑多刺蚁Polyrhachis vicina Roger提取液的缓解体力疲劳作用。采用清洁级雄性昆明种小鼠,拟黑多刺蚁水和乙醇双重提取液按8.3mL/kg.bw,16.7mL/kg.bw,25.0mL/kg.bw连续灌胃30d,测定小鼠负重游泳时间、血乳酸、血清尿素氮和肝糖原含量。结果:3个实验组及乙醇对照组小鼠负重游泳时间均显著长于蒸馏水对照组(P<0.05,P<0.01);8.3mL/kg.bw剂量组小鼠负重游泳时间显著长于乙醇对照组(P<0.01)。8.3mL/kg.bw剂量组小鼠3个时点血乳酸曲线下面积显著低于蒸馏水对照组和乙醇对照组(P<0.05、P<0.01),16.7mL/kg.bw剂量组小鼠3个时点血乳酸曲线下面积明显低于蒸馏水对照组(P<0.01)。乙醇对照组及拟黑多刺蚁提取液3个剂量组小鼠血清尿素氮含量均显著低于蒸馏水对照组(P<0.05、P<0.01),16.7mL/kg.bw剂量组小鼠血清尿素氮含量低于乙醇对照组(P<0.05)。拟黑多刺蚁提取液具有缓解体力疲劳的作用。     

Resistance and aerobic exercise: the influence of mode on the relationship between IL-6 and glucose tolerance in young men who are obese

Regular exercise lowers indicators of disease risk including some inflammatory cytokines; however, the relationship between different modes of acute exercise, cytokine levels, and subsequent glucose tolerance is unclear. The purpose was to determine the effects of resistance (RES) and aerobic (AER) exercises on interleukin-6 (IL-6) and its association with glucose tolerance 24 hours after exercise. After testing for 1 repetition maximum (1RM) and VO2peak, 10 obese (body mass index > 30 kg · m(-2)), untrained men aged 18-26 years completed 3 protocols: 60 minutes of RES, AER, and a resting (CON) condition. The RES was 2 sets of 8 repetitions and a third set to fatigue at 80% 1RM of 8 lifts using all major muscle groups. The AER was 60 minutes of cycling at 70% of VO2peak. On day 1, subjects completed the 60-minute exercise or resting protocol, and on day 2, they completed an oral glucose tolerance test (OGTT). Blood was collected before and after exercise, at 2 and 7 hour postexercise, and before and every 30 minutes during the OGTT and was analyzed for IL-6, glucose and insulin. Postexercise IL-6 was greater in RES (8.01 ± 2.08 pg · mL(-1)) vs. in AER (4.26 ± 0.27 pg · mL(-1)), and both were greater than in CON (1.61 ± 0.18 pg · mL(-1)). During the OGTT, there were no differences in glucose or insulin between conditions for single time points or as area under the curve. The RES caused greater IL-6 levels immediately after exercise that may be related to the greater active muscle mass compared to AER. Neither exercise produced enhanced glucose removal compared to control; thus, despite the greater elevation in IL-6 in RES, for these exercise conditions and this population, this cytokine did not influence glucose tolerance.     

Glutamine supplementation further enhances exercise-induced plasma IL-6.

Exercise stimulates the production and release of interleukin-6 (IL-6) from skeletal muscle. Glutamine is also synthesized in skeletal muscle and is involved in protein synthesis within this tissue. During exercise, plasma levels of glutamine decline, and this may affect the concentration of plasma IL-6 via a decrease in IL-6 synthesis and release from muscle. We hypothesized that glutamine supplementation would attenuate the exercise-induced decrease in plasma glutamine concentration and, thus, further enhance levels of plasma IL-6. Eight healthy men participated in a randomized, double-blind, crossover study in which they performed 2 h of cycle ergometry at 75% of peak O2 uptake. They received glutamine, glutamine-rich protein, or placebo supplementation at intervals during and 2 h after exercise. Exercise induced an 11-fold increase in plasma IL-6, which was further enhanced by glutamine (18-fold) and glutamine-rich protein (14-fold) supplementation, administered at doses that attenuated the exercise-induced decrease in plasma glutamine concentration.     

CK-MM and ACE genotypes and physiological prediction of the creatine kinase response to exercise.

Exertional rhabdomyolysis (ERB) is a syndrome of severe skeletal muscle breakdown. Blood levels of creatine kinase (CK) are widely used as a marker to reflect muscle breakdown. Some individuals exhibit extreme increases in blood CK after exercise and have been characterized as high responders (HR), but no clinical definition of HR exists and reasons for the HR phenomenon are not understood. This study investigated possible associations between the magnitude of the CK response to exercise and polymorphisms of two genes: muscle-specific creatine kinase (CK-MM) NcoI and angiotensin-converting enzyme (ACE) I/D. An exercise test for defining HR was also investigated. Participants (n = 88) underwent an exercise test that included stepping up and down two stairs for 5 min followed by 15 squats while wearing a backpack weighted at 30% of their body weight. CK levels were measured before, immediately after, and 48 and 72 h after the test. Nine participants (10.2%) were defined as HR. Participants with the CK-MM NcoI AA genotype had a sixfold higher risk of being HR compared with GG and AG genotypes (P = 0.031). No significant differences were found for the ACE I/D polymorphism. Percent body fat was an independent predictor of being a HR. We conclude that the CK-MM AA genotype and percent body fat may be part of the constellation of mechanisms that explain susceptibility to ERB. A physiological test that may assist in predicting ERB is also presented.     

Effect of leucine supplementation on indices of muscle damage following drop jumps and resistance exercise

The purpose of this study was to determine the effect of leucine supplementation on indices of muscle damage following eccentric-based resistance exercise. In vitro, the amino acid leucine has been shown to reduce proteolysis and stimulate protein synthesis. Twenty-seven untrained males (height 178.6 ± 5.5 cm; body mass 77.7 ± 13.5 kg; age 21.3 ± 1.6 years) were randomly divided into three groups; leucine (L) (n = 10), placebo (P) (n = 9) and control (C) (n = 8). The two experimental groups (L and P) performed 100 depth jumps from 60 cm and six sets of ten repetitions of eccentric-only leg presses. Either leucine (250 mg/kg bm) or placebo was ingested 30 min before, during and immediately post-exercise and the morning of each recovery day following exercise. Muscle function was determined by peak force during an isometric squat and by jump height during a static jump at pre-exercise (PRE) and 24, 48, 72, and 96 h post-exercise (24, 48, 72, 96 h). Additionally, at these time points each group’s serum levels of creatine kinase (CK) and myoglobin (Mb) along with perceived feelings of muscle soreness were determined. None of the C group dependent variables was altered by the recurring testing procedures. Peak force was significantly decreased across all time points for both experimental groups. The L group experienced an attenuated drop in mean peak force across all post-exercise time points compared to the P group. Jump height significantly decreased from PRE for both the L and P group at 24 h and 48 h. CK and Mb was significantly elevated from PRE for both experimental groups at 24 h. Muscle soreness increased across all time points for the both the L and P group, and the L group experienced a significantly higher increase in mean muscle soreness post-exercise. Following exercise-induced muscle damage, high-dose leucine supplementation may help maintain force output during isometric contractions, however, not force output required for complex physical tasks thereby possibly limiting its ergogenic effectiveness.     

Creatine supplementation does not reduce muscle damage or enhance recovery from resistance exercise

Previous studies have shown that creatine supplementation reduces muscle damage and inflammation following running but not following high-force, eccentric exercise. Although the mechanical strain placed on muscle fibers during high-force, eccentric exercise may be too overwhelming for creatine to exert any protective effect, creatine supplementation may protect skeletal muscle stressed by a resistance training challenge that is more hypoxic in nature. The purpose of this study was to examine the effects of short-term creatine supplementation on markers of muscle damage (i.e., strength, range of motion, muscle soreness, muscle serum protein activity, C-reactive protein) to determine whether creatine supplementation offers protective effects on skeletal muscle following a hypoxic resistance exercise test. Twenty-two healthy, weight-trained men (19-27 years) ingested either creatine or a placebo for 10 days. Following 5 days of supplementation, subjects performed a squat exercise protocol (5 sets of 15-20 repetitions at 50% of 1 repetition maximum [1RM]). Assessments of creatine kinase (CK) and lactate dehydrogenase activity, high-sensitivity C-reactive protein, maximal strength, range of motion (ROM), and muscle soreness (SOR) with movement and palpation were conducted pre-exercise and during a 5-day follow up. Following the exercise test, maximal strength and ROM decreased, whereas SOR and CK increased. Creatine and placebo-supplemented subjects experienced significant decreases in maximal strength (creatine: 13.4 kg, placebo: 17.5 kg) and ROM (creatine: 2.4 degrees , placebo: 3.0 degrees ) immediately postexercise, with no difference between groups. Following the exercise test, there were significant increases in SOR with movement and palpation (p < 0.05 at 24, 48, and 72 hours postexercise), and CK activity (p < 0.05 at 24 and 48 hours postexercise), with no differences between groups at any time. These data suggest that oral creatine supplementation does not reduce skeletal muscle damage or enhance recovery following a hypoxic resistance exercise challenge.     

Vitamin E isoform-specific inhibition of the exercise-induced heat shock protein 72 expression in humans.

Increased levels of reactive oxygen and nitrogen species, as seen in response to exercise, challenge the cellular integrity. Important protective adaptive changes include induction of heat shock proteins (HSPs). We hypothesized that supplementation with antioxidant vitamins C (ascorbic acid) and E (tocopherol) would attenuate the exercise-induced increase of HSP72 in the skeletal muscle and in the circulation. Using randomization, we allocated 21 young men into three groups receiving one of the following oral supplementations: RRR-alpha-tocopherol 400 IU/day + ascorbic acid (AA) 500 mg/day (CEalpha), RRR-alpha-tocopherol 290 IU/day + RRR-gamma-tocopherol 130 IU/day + AA 500 mg/day (CEalphagamma), or placebo (Control). After 28 days of supplementation, the subjects performed 3 h of knee extensor exercise at 50% of the maximal power output. HSP72 mRNA and protein content was determined in muscle biopsies obtained from vastus lateralis at rest (0 h), postexercise (3 h), and after a 3-h recovery (6 h). In addition, blood was sampled for measurements of HSP72, alpha-tocopherol, gamma-tocopherol, AA, and 8-iso-prostaglandin-F2alpha (8-PGF2alpha). Postsupplementation, the groups differed with respect to plasma vitamin levels. The marker of lipid peroxidation, 8-iso-PGF2alpha, increased from 0 h to 3 h in all groups, however, markedly less (P < 0.05) in CEalpha. In Control, skeletal muscle HSP72 mRNA content increased 2.5-fold (P < 0.05) and serum HSP72 protein increased 4-fold (P < 0.05) in response to exercise, whereas a significant increase of skeletal muscle HSP72 protein content was not observed (P = 0.07). In CEalpha, skeletal muscle HSP72 mRNA, HSP72 protein, and serum HSP72 were not different from Control in response to exercise. In contrast, the effect of exercise on skeletal muscle HSP72 mRNA and protein, as well as circulating HSP72, was completely blunted in CEalphagamma. The results indicate that gamma-tocopherol comprises a potent inhibitor of the exercise-induced increase of HSP72 in skeletal muscle as well as in the circulation.     

Anabolic steroid and gender-dependent modulation of cytosolic HSP70s in fast- and slow-twitch skeletal muscle

Besides their clinical uses, anabolic steroids (AASs) are self-administered by athletes to improve muscle mass and sports performance. The biological basis for their presumed effectiveness at suprapharmacological doses, however, remains uncertain. Since the expression of high levels of some stress proteins (HSPs) has been associated with an increased tolerance to stress and chronic exercise up-regulates HSP72 in skeletal muscle, this investigation was aimed at testing whether the administration of suprapharmacological doses of AASs, either alone or in conjunction with chronic exercise, induced changes in HSP72. Nandrolone decanoate (ND), an estrene derivative, but not stanozolol (ST), a derivative of the androstane series, up-regulated the levels of HSP72 and changed the proportions of various charge variants of the cytosolic HSP70s in sedentary and exercise-trained rats, exclusively in fast-twitch fibres. Since the expression of HSP73-levels in skeletal muscle was dependent on gender but not on muscle type, and that of HSP72-levels was muscle type specific but gender-independent, ND effects on cytosolic HSP70s could not be explained solely by a functional relationship with sex steroids. The reported results indicate that, by up-regulating the expression levels of HSP72 in fast-twitch fibres, nandrolone decanoate could contribute to improving the tolerance of skeletal muscle to high-intensity training.     

Visfatin mRNA expression in human subcutaneous adipose tissue is regulated by exercise

Visfatin [pre-beta-cell colony-enhancing factor (PBEF)] is a novel adipokine that is produced by adipose tissue, skeletal muscle, and liver and has insulin-mimetic actions. Regular exercise enhances insulin sensitivity. In the present study, we therefore examined visfatin mRNA expression in abdominal subcutaneous adipose tissue and skeletal muscle biopsies obtained from healthy young men at time points 0, 3, 4.5, 6, 9, and 24 h in relation to either 3 h of ergometer cycle exercise at 60% of Vo(2 max) or rest. Adipose tissue visfatin mRNA expression increased threefold at the time points 3, 4.5, and 6 h in response to exercise (n = 8) compared with preexercise samples and compared with the resting control group (n = 7, P = 0.001). Visfatin mRNA expression in skeletal muscle was not influenced by exercise. The exercise-induced increase in adipose tissue visfatin was, however, not accompanied by elevated levels of plasma visfatin. Recombinant human IL-6 infusion to mimic the exercise-induced IL-6 response (n = 6) had no effect on visfatin mRNA expression in adipose tissue compared with the effect of placebo infusion (n = 6). The finding that exercise enhances subcutaneous adipose tissue visfatin mRNA expression suggests that visfatin has a local metabolic role in the recovery period following exercise.     

Effect of exercise, training, and glycogen availability on IL-6 receptor expression in human skeletal muscle.

The cytokine interleukin-6 (IL-6) exerts it actions via the IL-6 receptor (IL-6R) in conjunction with the ubiquitously expressed gp130 receptor. IL-6 is tightly regulated in response to exercise, being affected by factors such as exercise intensity and duration, as well as energy availability. Although the IL-6 response to exercise has been extensively studied, little is known about the regulation of the IL-6R response. In the present study, we aimed to investigate the effect of exercise, training, and glycogen availability, factors known to affect IL-6, on the regulation of gene expression of the IL-6R in human skeletal muscle. Human subjects performed either 10 wk of training with an acute exercise bout before and after the training period, or a low-glycogen vs. normal-glycogen acute exercise trial. The IL-6R mRNA response was evaluated in both trials. In response to acute exercise, an increase in IL-6R mRNA levels was observed. Neither training nor intramuscular glycogen levels had an effect on the IL-6R mRNA response to exercise. However, after 10 wk of training, the skeletal muscle expressed a higher mRNA level of IL-6R compared with before training. The present study demonstrated that the IL-6R gene expression levels in skeletal muscle are increased in response to acute exercise, a response that is very well conserved, being affected by neither training status nor intramuscular glycogen levels, as opposed to IL-6. However, after the training period, IL-6R mRNA production was increased in skeletal muscle, suggesting a sensitization of skeletal muscle to IL-6 at rest.