Lifelong sedentary behaviour and femur structure

The aim of the present study was to analyze the lifelong differences of femur structure in sedentary and physically active animal models. Thirty male C57BL/6 mice, 2 months old, were either: i) housed in cages with running wheel (AA; n=10), ii) housed in cages without running wheel (AS; n=10), iii) or sacrificed without intervention (Y; n=10). AA and AS animals were sacrificed after 23 months of housing. Right femur structure was analyzed in all animals by histomorphometry. Significant differences in several microarchitectural parameters of cancellous and cortical bone were identified between Y mice and both groups of aged mice, as well as between AA and AS groups. Lifelong physically active mice had significantly higher cancellous bone surface (Cn.BS) and trabecular number (Tb.N) and decreased trabecular separation (Tb.Sp) at both epiphyses when compared to AS animals. No differences were observed between Y and AA groups regarding osteocyte number (N.Ot) despite its significant reduction in AS animals, suggesting that age alone was not a cause for decreases in N.Ot. Our results suggest that the reduced bone quality observed in the elderly is not only a consequence of age but also of lack of physical activity since sedentary behaviour significantly aggravated the degenerative age-related bone differences.     

Potentiation of cytostatic but not cytolytic activity of murine macrophages after running stress

The influence of physical exercise on the tumortoxicity of peritoneal murine macrophages (PMM) was investigated. The tumortoxic activity was discriminated into cytostatic and cytolytic effects. Cytostatic activity of PMM on tumor cells in vitro was studied using the proliferation assay of S-180 sarcoma cells. Cytolytic activity was monitored using the method of the slow form of antibody-dependent cellular cytotoxicity (ADCC) on SW 707 tumor cells. After a single exhaustive running session an increased cytostatic activity of PMM was observed as compared to PMM of sedentary animals. In PMM mediated ADCC no difference was detected between trained and untrained animals. It is concluded that physical exercise is a complex stimulus for macrophages that, at least in parts, triggers their cytotoxic activity against tumor cells.     

Effects of resistance training on matrix metalloproteinase-2 activity and biomechanical and physical properties of bone in ovariectomized and intact rats

The purpose of this study was to investigate the influence of resistance training on the activity of matrix metalloproteinase (MMP)-2 and bone biomechanical properties in ovariectomized and intact rats. Forty-eight female rats were divided into two distinct groups, ovariectomized (OVX) and intact (Int), which were subdivided into three similar subgroups: sedentary, acute exercise and chronic exercise. Rats performed a resistance training for 12 weeks in which animals climbed a vertical ladder of 1.1 m with weights attached to their tails. Sessions were performed with an interval of 3, 4-9 and 8-12 days scaled dynamic movements of climbing. Biomechanical and physical analyses were performed using a universal testing machine, and MMP-2 activity analysis by zymography. Bone density (BD), mineral density (MD), maximum load and fracture load was reduced in sedentary and acute exercise OVX groups compared with the sedentary intact group (P<0.05); in contrast, chronically trained groups (OVX and Int) showed a significant increase in BD, MD and fracture load compared with all the other groups. MMP-2 activity in chronically trained groups also showed a significant increase, while the sedentary OVX group showed a decrease in MMP-2 activity compared with the intact sedentary group (P<0.05). Our results suggest that the resistance training proposed in our work was efficient in reverting the deleterious effects of ovariectomy on bone tissue, and also produced modeling effects in intact rats. On the other hand, ovariectomy reduced the activity of MMP-2 and produced deleterious effects on bone tissue, mimicking menopause intrinsically.     

Regular and moderate aerobic training before allergic asthma induction reduces lung inflammation and remodeling

Experimental studies have reported that aerobic exercise after asthma induction reduces lung inflammation and remodeling. Nevertheless, no experimental study has analyzed whether regular/moderate aerobic training before the induction of allergic asthma may prevent these inflammatory and remodeling processes. For this purpose, BALB/c mice (n = 96) were assigned into non‐trained and trained groups. Trained animals ran on a motorized treadmill at moderate intensity, 30 min/day, 3 times/week, for 8 weeks, and were further randomized into subgroups to undergo ovalbumin sensitization and challenge or receive saline using the same protocol. Aerobic training continued until the last challenge. Twenty‐four hours after challenge, compared to non‐trained animals, trained mice exhibited: (a) increased systolic output and left ventricular mass on echocardiography; (b) improved lung mechanics; (c) decreased smooth muscle actin expression and collagen fiber content in airways and lung parenchyma; (d) decreased transforming growth factor (TGF)‐β levels in bronchoalveolar lavage fluid (BALF) and blood; (e) increased interferon (IFN)‐γ in BALF and interleukin (IL)‐10 in blood; and (f) decreased IL‐4 and IL‐13 in BALF. In conclusion, regular/moderate aerobic training prior to allergic asthma induction reduced inflammation and remodeling, perhaps through increased IL‐10 and IFN‐γ in tandem with decreased Th2 cytokines.     

Physical inactivity is a major contributor to ovariectomy-induced sarcopenia

Since the mechanism(s) underlying menopause-related sarcopenia remain unknown we aimed to investigate the role of physical inactivity in its etiology. Ovariectomized and sham-operated rats were allocated into 2 experimental groups: (1) sedentary-standard housing; and (2) exercise-housed with running wheel. After a 9-month experimental period, soleus muscle structure and biochemical properties were analyzed. No differences existed in muscle fibre size or ultrastructure between sedentary sham and ovariectomized animals housed in standard conditions. In the exercise groups, average daily running distance was 10-fold less in ovariectomized compared to sham-animals. Further, in exercised animals, soleus fibre size was smaller in ovariectomized compared to sham-animals. Nonetheless, compared to both sedentary groups, muscle fibre size was larger in the exercised ovariectomized animals. Our results indicate that ovariectomy-induced sarcopenia is not due to the loss of ovarian hormones per se, but is largely due to physical inactivity.     

12周游泳运动对老龄小鼠免疫细胞功能的影响

对游泳１２周后的老龄Ｃ５７ＢＬ／６小鼠脾脏Ｔ细胞对ＣｏｎＡ的增殖反应能力、ＮＫ细胞活性及ＩＬ－１活性进行了研究。结果：（１）与年轻小鼠相比,老龄小鼠Ｔ淋巴细胞对ＣｏｎＡ的增殖能力、ＮＫ细胞活性、ＩＬ－１活性略有下降,但无显著差异（Ｐ＜０．０５）。（２）１２周训练后,隔天训练的老龄鼠Ｔ淋巴细胞对ＣｏｎＡ的增殖反应能力显著升高。（３）每天训练的老龄小鼠Ｔ淋巴细胞的增殖反应能力下降（Ｐ＜０．０５）。（４）１２周的训练没有使ＮＫ亚细胞和ＩＬ－１的活性发生显著性变化。     

Resting cellular and physiological effects of freewheel running

INTRODUCTION/PURPOSE: Exercise modulates many aspects of physiology. The purpose of the current experiment was to characterize the impact of regular, moderate physical activity on resting, baseline measures of cellular immunity blood lipids, and muscle enzyme. METHODS: Male Fischer 344 rats were housed with either mobile (run, N = 10) or immobile (sedentary, N = 10) running wheels. After 4 wk of running, rats were sacrificed. Blood and muscle (long and medial heads of the triceps) were collected. From blood, white blood cell (WBC) differentials, red blood cell (RBC) count, hemoglobin, hematocrit, and lipid profiles were measured. Muscle citrate synthase (CS) activity was measured by spectrophotometric analysis. RESULTS: Rats ran an average of 9.89 +/- 0.79 km.wk(-1). There were no differences in the total number of circulating WBC, RBC, or eosinophils. Freewheel running decreased the number of circulating neutrophils (P < 0.001), monocytes (P < 0.01), and basophils (P < 0.01), while increasing the number of lymphocytes (P < 0.001), when compared with sedentary animals. Mean corpuscular content of hemoglobin was elevated in the freewheel group (P < 0.01). Physically active animals had slightly lower triglycerides and LDL, and elevated HDL. These changes resulted in a significant improvement in LDL/HDL ratio (P < 0.05). Muscle CS activity was unchanged between groups. CONCLUSION: Both the alterations in the RBC hemoglobin and lipid proteins are positive health changes associated with exercise training. The impact of the alterations in WBC differentials remains unknown but could indicate a reduction in inflammatory load. In conclusion, freewheel running provides sufficient exercise stimulus to produce some, but not all, training associated physiological adaptations.     

CD94 expression and natural killer cell activity after acute exercise

This study examined the effects of acute exercise on natural killer (NK) cell numbers, their expression of CD94 and cytotoxic capacity in triathletes over a 10-week training period. Nine highly trained male triathletes (age 25.9+/-4.1 yrs, VO2max 5.14+/-0.33 L.min(-1)) attended the laboratory on weeks 0, 2, 5 and 10 for incremental submaximal and maximal cycle ergometry. Peripheral blood was analysed for white blood cell counts, lymphocyte phenotype and cytolytic activity (51Cr release from K562 cells). Maximum oxygen consumption increased from week 2 (5.14+/-0.33 L.min(-1)) to week 10 (5.28+/-0.32 L.min(-1)). Resting NK cell numbers and their expression of CD94 were not altered over the 10-week study period. Natural killer cells expressing CD94+ were not differentially recruited into the circulation and cytolytic activity of exercise-recruited NKs did not differ from those present at rest. There was longitudinal stability (over the 10 weeks of the study) in CD94 expression on NK cells, exercise recruitment of CD94+ NK cells and cytolytic capacity of NK cells. The distribution and functional activity of NK cells are not markedly influenced by 10 weeks of training in competitive triathletes. Natural killer cytotoxic activity after exercise reflects numbers of NK cells and not a changed activation state of these cells per se.     

运动预适应下调帕金森小鼠中脑bax/bcl-2 mRNA表达比值

目的:探讨运动预适应是否下调帕金森小鼠中脑细胞bax/bcl-2mRNA表达比值。方法:32只雄性小鼠(8～9周龄)首先随机分为安静组、运动组。运动组连续5周,每天1次中等强度(12米/分,20分钟)跑台训练。然后以上两组再各自随机分成两组,于训练结束后第2天分别注射生理盐水或中等剂量MPTP(30mg/kg×2次)。只有表现典型行为变化的MPTP小鼠被认为是成功帕金森模型小鼠,进入最终分组,分为安静+生理盐水组(Se+Sa)、运动+生理盐水组(E+Sa)、安静+MPTP组(Se+M)、运动+MPTP组(E+M)4组,每组8只。训练结束后第11天处死动物,检测小鼠中脑bax、bcl-2mRNA表达,计算bax/bcl-2mRNA表达比值。结果:E+M组小鼠中脑baxmRNA表达较Se+M组显著降低(P<0.05),E+M组bcl-2mRNA表达较Se+M组显著增加(P<0.05),E+M组bax/bcl-2比值显著小于Se+M组(P<0.05)。结论:运动预适应改变帕金森小鼠中脑黑质细胞凋亡信号分子bcl-2、baxmRNA表达,降低bax/bcl-2mRNA表达比值。     

Rat myocellular and perimysial intramuscular triacylglycerol: a histological approach

PURPOSE: There is controversy as to the use of intramuscular triacylglycerol (IMTAG) during exercise and to whether endurance training increases its utilization, despite the various methodologies used to address these questions. We used a histological-morphometrical approach to study the relative contribution of the two compartments of IMTAG storage, intramyocellular, and perimysial adipocytes, during exercise in sedentary and endurance-trained rats. METHODS: After osmium impregnation, the soleus (SOL) and gastrocnemius (GAS) were studied under light and electron microscopy. IMTAG content (after Triton WR1339 treatment or not) and 14C-oleate incorporation into the muscles were studied. RESULTS: In GAS, training, but not exercise alone, decreased extramyocellular lipid (P < 0.001 vs sedentary), an effect not found for SOL. Both muscles presented reduced lipid inclusion number (P < 0.001) and area (P < 0.05), immediately after exercise in sedentary and trained rats. For SOL, a greater number (P < 0.001 vs sedentary) of inclusions was found 24 h after exercise in trained rats. Triton WR1339 treatment decreased IMTAG content 12 h after exercise in SOL (but not in GAS), in sedentary (33%), and trained rats (52%). CONCLUSIONS: The multi-analytical approach adopted allowed the discernment between the IMTAG compartments and provided evidence for an effect of training upon storage of lipid in perimysial adipocytes in rat gastrocnemius, as well as clearly showed that the IMTAG mobilized during submaximal exercise in sedentary and trained rats derives from intramyocellular lipid, both in SOL and GAS. Moreover, the reposition of these stores 12 h after exercise was shown to be different in GAS and SOL, as plasma triacylglycerol clearly contributed to the process only in the latter, possibly reflecting the differences in lipoprotein lipase activity in the muscles reported by others.     

The effects of moderate exercise training on natural killer cells and acute upper respiratory tract infections

A randomly controlled 15-wk exercise training (ET) study (five 45-min sessions/wk, brisk walking at 60% heart rate reserve) with a group of 36 mildly obese, sedentary women was conducted to investigate the relationship between improvement in cardiorespiratory fitness, changes in natural killer (NK) cell number and activity, and acute upper respiratory tract infection (URI) symptomatology. The study was conducted using a 2 (exercise and nonexercise groups) x 3 (baseline, 6-, and 15-wk testing sessions) factorial design, with data analyzed using repeated measures ANOVA. No significant change in NK cell number occurred as a result of ET as measured by the CD16 and Leu-19 monoclonal antibodies. ET did have a significant effect on NK cell activity (E:T 50:1) especially during the initial 6-wk period [F(2.68) = 12.34, p less than 0.001]. Using data from daily logs kept by each subject, the exercise group was found to have significantly fewer URI symptom days/incident than the nonexercise group (3.6 +/- 0.7 vs 7.0 +/- 1.4 days, respectively, p = 0.049). Improvement in cardiorespiratory fitness was correlated significantly with a reduction in URI symptom days/incident (r = 0.37, p = 0.025) and a change in NK cell activity from baseline to six but not 15 wks (r = 0.35, p = 0.036). In summary, moderate ET is associated with elevated NK cell activity after six but not 15 weeks, and reduced URI symptomatology in comparison to a randomized, sedentary control group.     

Nandrolone inhibits MMP-2 in the left ventricle of rats

The indiscriminate use of anabolic-androgenic steroids has been shown to induce left ventricular dysfunctions. The main objective of the present study was to investigate the effects of nandrolone decanoate on matrix metalloprotease (MMP-2) activity and protein level in the left ventricle (LV) of rats after 7 weeks of mechanical load exercise. Wistar rats were grouped into: sedentary (S); nandrolone decanoate-treated sedentary (AAS); trained without AAS (T) and trained and treated with AAS (AAST). Exercised groups performed a 7-weeks water-jumping program. Training significantly increased the MMP-2 activity by zymography and the protein level by Western blotting analysis. However, the AAS treatment abolished both the increase in MMP activity and protein level induced by exercise. These results suggest that AAS may impair cardiac tissue remodeling which may lead to the heart malfunction.     

Cyclic AMP regulation of fuel metabolism during exercise: regulation of adipose tissue lipolysis during exercise

Adipocytes from trained rats release more free fatty acids in response to hormonal challenge compared to fat cells from sedentary rats. Lipolysis results from increased triglyceride hydrolysis that is catalyzed by a hormone-sensitive lipase, which, in turn, is activated by a phosphorylation mechanism involving cyclic AMP-dependent protein kinase. Cyclic AMP levels within the fat cell are regulated by beta-adrenergic receptor/adenylate cyclase interactions and cyclic AMP phosphodiesterase activity. This review focuses on cyclic AMP regulation of lipolysis in adipocytes from trained and sedentary animals. Although lipolysis is elevated in fat cells from trained rats, no differences are found in beta-adrenergic receptor number or affinity, adenylate cyclase activity, protein kinase activity, or partially purified hormone-sensitive lipase activity when compared to sedentary rats. The major lipolytic alteration induced by exercise training appears to occur at a site distal to hormonal regulation of the beta-adrenergic receptor.     

Freewheel exercise training modifies pro- and anti-apoptotic protein expression in mouse splenic lymphocytes

The purpose of this study was to examine the effect of voluntary training in mice on the expression of apoptotic proteins in splenic lymphocytes following acute exercise. Thirty-three mice were randomized to four treatments: 1) control group (no training and no acute exercise), 2) training, no acute exercise, 3) no training, acute exercise and 4) training, acute exercise. Mice were sacrificed immediately after acute exercise. Western immunoblotting was used to detect apoptosis in splenic lymphocytes for concentrations of anti- (Bcl-2) and pro-apoptotic (caspase 3) proteins. Plasma corticosterone was used as an index of exercise stress. Trained mice not given acute exercise challenge had elevated Bcl-2 (p < 0.05) and lower caspase 3 (p < 0.05) levels relative to control mice. Following the acute exercise challenge, however, trained and untrained mice did not differ in the concentrations of these proteins in splenocytes. Thus, freewheel exercise training in mice reduces splenic lymphocyte apoptosis when tissue samples are obtained at rest but not after acute exercise.     

Subcutaneous and visceral fat distribution and daily physical activity: comparison between young and middle aged women.

OBJECTIVE: To examine the effects of aging and physical activity on distribution patterns in subcutaneous and visceral fat. METHODS: Distributions of subcutaneous rat mass at six segments (face and neck, forearm, upper arm, trunk, thigh, and lower leg) were determined by adipose tissue thickness measurements by B mode ultrasonogram and body surface areas. Visceral fat mass was calculated by subtracting subcutaneous fat mass from the total fat mass determined hydrodensitometrically. Measurements were made on young and middle aged, trained and sedentary women (four groups). RESULTS: Per cent body fat was lower in trained than in sedentary individuals, both in the young and the middle aged subjects. The distribution of subcutaneous fat mass differed between sedentary and trained women. Trained young women had a reduced subcutaneous fat mass compared to sedentary young subjects in all segments except face and neck; the disparity between middle aged sedentary and trained women was limited to upper arm and trunk (P < 0.01 each), with no significant difference in face and neck, forearm, and lower limb segments. Differences in visceral fat mass between sedentary and trained subjects were similar for young and middle aged women (young, 2.5 v 3.7 kg; middle aged, 4.0 v 6.5 kg). CONCLUSIONS: Women who exercise regularly appear to accumulate less adipose tissue, especially in upper arm and trunk segments as they get older, with visceral fat mass remaining lower than in sedentary individuals.     

Ibuprofen intake increases exercise time to exhaustion: A possible role for preventing exercise‐induced fatigue

Although the intake of nonsteroidal anti‐inflammatory drugs (NSAIDs) intake by athletes prevents soreness, little is known concerning their role in exercise performance. This study assessed the effects of ibuprofen intake on an exhaustive protocol test after 6 weeks of swimming training in rats. Animals were divided into sedentary and training groups. After training, animals were subdivided into two subsets: saline or ibuprofen. Afterwards, three repeated swimming bouts were performed by the groups. Ibuprofen (15 mg/kg) was administered once a day. Pain measurements were performed and inflammatory and oxidative stress parameters were assayed in cerebral cortex and gastrocnemius muscle. Training, ibuprofen administration, or both combined (P < 0.05; 211 ± 18s, 200 ± 31s, and 279 ± 23s) increased exercise time to exhaustion. Training decreased the acetylcholinesterase (AChE) activity (P < 0.05; 149 ± 11) in cerebral cortex. Ibuprofen intake decreased the AChE activity after exhaustive protocol test in trained and sedentary rats (P < 0.05; 270 ± 60; 171 ± 38; and 273 ± 29). It also prevented neuronal tumor necrosis factor‐α (TNF‐α) and interleukin (IL 1β) increase. Fatigue elicited by this exhaustive protocol may involve disturbances of the central nervous system. Additive anti‐inflammatory effects of exercise and ibuprofen intake support the hypothesis that this combination may constitute a more effective approach. In addition, ergogenic aids may be a useful means to prevent exercise‐induced fatigue.     

运动训练对小鼠NK细胞杀伤功能和脾细胞IL－2产生能力的影响

本文对游泳训练三个月后的Ｃ＿（５７）ＢＬ／６小鼠ＮＫ细胞杀伤功能和脾细胞ＩＬ－２产生能力进行了研究。观察到ＮＫ细胞杀伤活性在每日训练３０分钟和６０分钟组分别较对照组上升２０．１％（ｐ＜０．００１）和１６．５％（ｐ＜０．０１），每日训练２小时组有降低趋势；脾细胞ＩＬ－２产生能力在６０分钟组明显增强，３０和１２０分钟组无显著性差异；ＮＫ细胞杀伤活性和脾细胞ＩＬ－２产生水平的改变有一定的相关性（ｒ＝０．２２）。     

Skeletal muscle metabolism in the offspring of trained rats.

To determine the effects of maternal exercise training during pregnancy on skeletal muscle metabolism of the progeny, eleven female Sprague-Dawley rats were divided into an exercise and a control group. The maternal training group (6) ran on a rodent treadmill for 4 weeks prior to pregnancy and daily throughout gestation (21 days) at 26.8 m/min, 1 hour/day, 5 days per week. The measurements were taken 28 days postpartum. No differences were noted between the sedentary and trained maternal animals for succinic dehydrogenase (SDH), phosphofructokinase (PFK), and myosin ATPase activities of the soleus, plantaris and gastrocnemius muscles. Maternal gastrocnemius SDH and soleus PFK levels were significantly (p less than 0.05) lower than levels found in the offspring. The liver glycogen of trained maternal animals was significantly higher than that found in all other groups. As well it was shown that maternal exercise had no effect on any of the aforementioned physiological parameters measured in the pups. The results indicate that exercise training during pregnancy does not modify the skeletal muscle metabolism of the offspring as observed 28 days after birth.     

Resistance training and glycogen content in ovariectomized rats

The aim of the present study was to investigate the effects of resistance training on glycogen content and muscle cross-sectional area (CSA) in ovariectomized rats. Wistar rats were divided into: sedentary; ovariectomized sedentary; resistance trained; and ovariectomized resistance trained. In the 12-week resistance training, the animals climbed a 1.1 m vertical ladder, 3 days per week, with 4-8 climbs. Cardiac, liver and muscle glycogen content was determined. After the 12-week resistance training period there was a higher hepatic and muscle glycogen content in the resistance training group compared with the other groups (p<0.01). CSA was higher in soleus for the resistance trained, ovariectomized resistance trained and sedentary compared with ovariectomized sedentary (p<0.05). Ovariectomy attenuated the increase in liver and muscle glycogen content, while soleus muscle cross-sectional area increased with resistance training, even in ovariectomized rats. Resistance training could be an important exercise to increase muscle function in situations of reduced estrogen and progesterone.     

Endurance exercise modifies cachexia of tumor growth in rats

Food intakes, body composition, skeletal muscle mass, muscle protein synthesis, and myofibrillar protein degradation were studied in normal, food-restricted (FR), and Walker 256 tumor-bearing (TB) male Sprague-Dawley rats which were exercised (E) or maintained in a sedentary state. Exercise was enforced 3 times per wk for 100 min X session-1 at 20 m X min-1 on a 13% incline for 7 wk. Tumors were transplanted 3 wk after beginning the exercise program and were allowed to grow for 29 d. Food restriction was initiated during the last 2 wk of tumor growth. Food intakes and body lipid stores were reduced in all E groups, whereas body nitrogen was reduced only in the TBS animals. All E animals had significantly higher gastrocnemius muscle/body weight ratios than their sedentary counterparts, with the greatest ratio noted for the TBE animals. Muscle protein synthesis, measured by incorporation of [3H]tyrosine into gastrocnemius muscle, was significantly depressed in both FR and TB animals. Muscle protein breakdown, estimated by urinary 3-methylhistidine excretion, was significantly elevated in TB animals and slightly increased in FR animals. The results suggest that tumor presence significantly alters protein turnover to a greater extent than elicited by food restriction alone. Additionally, although exercise may have initially protected the animal by retarding tumor growth and muscle mass depletion, in the end, the energy costs of exercise accelerated the catabolic state.