A high-whey-protein diet does not enhance mechanical and structural remodeling of cardiac muscle in response to aerobic exercise in rats

[Purpose]Aerobic exercise training results in distinct structural and mechanical myocardial adaptations. In skeletal muscle, whey protein supplementation is effective in enhancing muscle adaptation following resistance exercise. However, it is unclear whether cardiac adaptation to aerobic exercise can be enhanced by systematic protein supplementation.[Methods]Twelve-week-old rats were assigned to 12 weeks of either sedentary or aerobic exercise with either a standard (Sed+Standard, Ex+Standard) or high-protein (Sed+Pro, Ex+Pro) diet. Echocardiography was used to measure cardiac structural remodeling and performance. Skinned cardiac fiber bundles were used to determine the active and passive stress properties, maximum shortening velocity, and calcium sensitivity.[Results]Aerobic training was characterized structurally by increases in ventricle volume (Ex+Standard, 19%; Ex+Pro, 29%) and myocardial thickness (Ex+Standard, 26%; Ex+-Pro, 12%) compared to that of baseline. Skinned trabecula r fiber bundles also had a greater unloaded shortening velocity (Sed+Standard, 1.04±0.05; Sed+Pro, 1.07±0.03; Ex-+Standard, 1.16±0.04; Ex+Pro, 1.18±0.05 FL/s) and calcium sensitivity (pCa₅₀: Sed+Standard, 6.04±0.17; Sed+Pro, 6.08±0.19; Ex+Standard, 6.30±0.09; Ex+Pro, 6.36±0.12) in trained hearts compared to that of hearts from sedentary animals. However, the addition of a high-protein diet did not provide additional benefits to either the structural or mechanical adaptations of the myocardium.[Conclusion]Therefore, it seems that a high-whey-protein diet does not significantly enhance adaptations of the heart to aerobic exercise in comparison to that of a standard diet.     

Impact of chronic exercise training on the blood pressure response to orthostatic stimulation

Exercise training elicits morphological adaptations in the left ventricle (LV) and large-conduit arteries that are specific to the type of training performed (i.e., endurance vs. resistance exercise). We investigated whether the mode of chronic exercise training, and the associated cardiovascular adaptations, influence the blood pressure responses to orthostatic stimulation in 30 young healthy men (10 sedentary, 10 endurance trained, and 10 resistance trained). The endurance-trained group had a significantly larger LV end-diastolic volume normalized by body surface area (vs. sedentary and resistance-trained groups), whereas the resistance-trained group had a significantly higher LV wall thickness and aortic pulse wave velocity (PWV) compared with the endurance-trained group. In response to 60° head-up tilt (HUT), mean arterial pressure (MAP) rose in the resistance-trained group (+6.5 ± 1.6 mmHg, P < 0.05) but did not change significantly in sedentary and the endurance-trained groups. Systolic blood pressure (SBP) decreased in endurance-trained group (-8.3 ± 2.4 mmHg, P < 0.05) but did not significantly change in sedentary and resistance-trained groups. A forward stepwise multiple regression analysis revealed that LV wall thickness and aortic PWV were significantly and independently associated with the MAP response to HUT, explaining ～41% of its variability (R(2) =0.414, P < 0.001). Likewise, aortic PWV and the corresponding HUT-mediated change in stroke volume were significantly and independently associated with the SBP response to HUT, explaining ～52% of its variability (R(2) = 0.519, P < 0.0001). Furthermore, the change in stroke volume significantly correlated with LV wall thickness (r = 0.39, P < 0.01). These results indicate that chronic resistance and endurance exercise training differentially affect the BP response to HUT, and that this appears to be associated with training-induced morphological adaptations of the LV and large-conduit arteries.     

Serum lipids and cholesterol distribution in lipoproteins of exercise-trained female rats fed sucrose

This study was undertaken to evaluate the combined effects of sucrose feeding and exercise training on serum insulin, triglycerides, as well as cholesterol and its distribution into lipoproteins of female Wistar rats. The animals were fed ad libitum either laboratory chow alone, or chow and a 32% aqueous sucrose solution. Half of each dietary group was submitted to an exercise-training program. Both sucrose feeding and exercise training elicited greater energy intake. Sucrose feeding produced a marked elevation in triglyceridemia that was prevented by exercise training. Insulin levels paralleled those of triglycerides. The sucrose-fed animals had higher total cholesterol levels than the animals given chow. Although exercise training did not affect total cholesterol in the chow-fed animals, it partly prevented the sucrose-induced elevation in total cholesterol. Cholesterol in the lipoproteins of lower densities was increased significantly with sucrose feeding, and exercise training totally prevented this augmentation. The amount of cholesterol carried by high-density lipoprotein (HDL) was not affected by exercise training in the chow-fed animals. In contrast, sucrose feeding increased HDL-cholesterol in sedentary animals, whereas exercise training partly prevented this increase. The HDL/total cholesterol ratio was similar in all groups. Changes in insulin concentration underline the importance of this hormone in the regulation of blood lipid levels.     

Altered single cell force-velocity and power properties in exercise-trained rat myocardium.

Myocardial function is enhanced by endurance exercise training, but the cellular mechanisms underlying this improved function remain unclear. The ability of the myocardium to perform external work is a critical aspect of ventricular function, but previous studies of myocardial adaptation to exercise training have been limited to measurements of isometric tension or unloaded shortening velocity, conditions in which work output is zero. We measured force-velocity properties in single permeabilized myocyte preparations to determine the effect of exercise training on loaded shortening and power output. Female Sprague-Dawley rats were divided into sedentary control (C) and exercise trained (T) groups. T rats underwent 11 wk of progressive treadmill exercise. Myocytes were isolated from T and C hearts, chemically skinned, and attached to a force transducer. Shortening velocity was determined during loaded contractions at 15 degrees C by using a force-clamp technique. Power output was calculated by multiplying force times velocity values. We found that unloaded shortening velocity was not significantly different in T vs. C myocytes (T = 1.43 muscle lengths/s, n = 46 myocytes; C = 1.12 muscle lengths/s, n = 43 myocytes). Training increased the velocity of loaded shortening and increased peak power output (peak power = 0.16 P/P(o) x muscle length/s for T myocytes; peak power = 0.10 P/P(o) x muscle length/s for C myocytes, where P/P(o) is relative tension). We found no effect of training on myosin heavy chain isoform content. These results suggest that training alters power output properties of single cardiac myocytes and that this adaptation may improve the work capacity of the myocardium.     

Porcine cardiac myocyte power output is increased after chronic exercise training.

Chronic exercise training increases the functional capacity of the heart, perhaps by increased myocyte contractile function, as has been observed in rodent exercise models. We examined whether cardiac myocyte function is enhanced after chronic exercise training in Yucatan miniature swine, whose heart characteristics are similar to humans. Animals were designated as either sedentary (Sed), i.e., cage confined, or exercise trained (Ex), i.e., underwent 16-20 wk of progressive treadmill training. Exercise training efficacy was shown with significantly increased heart weight-to-body weight ratios, skeletal muscle citrate synthase activity, and exercise tolerance. Force-velocity properties were measured by attaching skinned cardiac myocytes between a force transducer and position motor, and shortening velocities were measured over a range of loads during maximal Ca2+ activation. Myocytes (n = 9) from nine Ex pigs had comparable force production but a approximately 30% increase in peak power output compared with myocytes (n = 8) from eight Sed. Interestingly, Ex myofibrillar samples also had higher baseline PKA-induced phosphorylation levels of cardiac troponin I, which may contribute to the increase in power. Overall, these results suggest that enhanced power-generating capacity of porcine cardiac myofibrils contributes to improved cardiac function after chronic exercise training.     

A 12-week aerobic exercise intervention results in improved metabolic function and lower adipose tissue and ectopic fat in high-fat diet fed rats

Investigations of long-term exercise interventions in humans to reverse obesity is expensive and is hampered by poor compliance and confounders. In the present study, we investigated intrahepatic and muscle fat, visceral and subcutaneous fat pads, plasma metabolic profile and skeletal muscle inflammatory markers in response to 12-week aerobic exercise in an obese rodent model. Six-week-old male Wistar rats (n=20) were randomized to chow-fed control (Control, n=5), sedentary high-fat diet (HFD, n=5), chow-fed exercise (Exercise, n=5) and HFD-fed exercise (HFD+Exercise, n=5) groups. The exercise groups were subjected to 12 weeks of motorized treadmill running at a speed of 18 m/min for 30 min/day. Differences in post-intervention measures were assessed by analysis of covariance (ANCOVA), adjusted for baseline bodyweight and pre-intervention measures, where available. Post-hoc analyses were performed with Bonferroni correction. Plasma metabolic profile was worsened and fat pads, ectopic fat in muscle and liver and inflammatory markers in skeletal muscle were elevated in sedentary HFD-fed animals relative to chow-fed controls. HFD+Exercise animals had significantly lower leptin (P=0.0004), triglycerides (P=0.007), homeostatic model assessment of insulin resistance (HOMA-IR; P=0.065), intramyocellular lipids (IMCLs; P=0.003), intrahepatic lipids (IHLs; P<0.0001), body fat% (P=0.001), subcutaneous adipose tissue (SAT; P<0.0001), visceral adipose (P<0.0001) and total fat mass (P<0.0001), relative to sedentary HFD-fed animals, despite only modestly lower bodyweight. Messenger RNA (mRNA) expression of inflammatory markers Interleukin 6 (IL6) and Tumor necrosis factor α (TNFα) were also reduced with aerobic exercise in skeletal muscle. Our results suggest that 12 weeks of aerobic exercise training is effective in improving metabolic health, fat depots, ectopic fat and inflammation even against a high-fat dietary background.     

Cardiac adaptations to endurance training in rats with a chronic myocardial infarction

The hemodynamic response to maximal exercise was determined in sedentary and trained rats with a chronic myocardial infarction (MI) produced by coronary artery ligation and in rats that underwent sham operations (SHAM). Infarct size in the MI groups of rats comprised 28-29% of the total left ventricle and resulted in both metabolic and hemodynamic changes that suggested that these animals had moderate compensated heart failure. The training regimen used in the present study produced significant increases in maximal O2 uptake (VO2max) when expressed in absolute terms (ml/min) or when normalized for body weight (ml.min-1.kg-1) and consisted of treadmill running at work loads that were equivalent to 70-80% of the animal's VO2max for a period of 60 min/day, 5 days/wk over an 8- to 10-wk interval. This training paradigm produced two major cardiocirculatory adaptations in the MI rat that had not been elicited previously when using a training paradigm of a lower intensity. First, the decrement in the maximal heart rate response to exercise (known as "chronotropic incompetence") found in the sedentary MI rat was completely reversed by endurance training. Second, the downregulation of cardiac myosin isozyme composition from the fast ATPase V1 isoform toward the slower ATPase (V2 and V3) isoforms in the MI rat was partially reversed by endurance training. These cardiac adaptations occurred without a significant increase in left ventricular pump function as an increase in maximal cardiac output (Qmax) and maximal stroke volume (SVmax) did not occur in the trained MI rat.(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise,but not quercetin,ameliorates inflammation,mitochondrial biogenesis,and lipid metabolism in skeletal muscle after strenuous exercise by high-fat diet mice

[Purpose]

The purpose of this study was to investigate whether moderate exercise and quercetin intake with a low fat diet contribute to inflammatory cytokine production, mitochondrial biogenesis, and lipid metabolism in skeletal muscle after strenuous exercise by high-fat diet mice.

[Methods]

Male C57BL/6 mice were randomly divided into four groups: (1) High-fat for 12 weeks and low-fat diet control (C; n = 6); (2) high-fat diet for 12 weeks and low-fat diet with quercetin (Q; n = 4); (3) high-fat diet for 12 weeks and low-fat diet with exercise (E; n = 4); or (4) high-fat diet for 12 weeks and low-fat diet with exercise and quercetin (EQ; n = 5). Quercetin (10 mg/kg) was administered once per day, 5 day/week for 8 weeks. Exercise training was performed at moderate intensity for 8 weeks, 5 days/week for 30–60 min/day. Mice were subjected to a strenuous exercise bout of 60 min at a speed of 25 m/min (VO₂ max 85%) conducted as an exercise-induced fatigue just before sacrifice.

[Results]

As results, body weights were significantly different among the groups. Exercise training significantly reduced inflammatory cytokines after strenuous exercise in skeletal muscle of high-fat diet mice. Exercise training increased Tfam mRNA in the soleus muscle after strenuous exercise. Exercise training significantly decreased lipogenesis markers in skeletal muscle of obese mice after strenuous exercise. Moderate exercise significantly increased lipolysis markers in the tibialis anterior muscle.

[Conclusion]

These findings suggest that exercise training reduced inflammatory cytokine levels and improved mitochondrial biogenesis and lipid metabolism. However quercetin supplementation did not affect these parameters. Thus, long-term moderate exercise training has positive effects on obesity.     

Marine phytoplankton improves recovery and sustains immune function in humans and lowers proinflammatory immunoregulatory cytokines in a rat model

[Purpose] This study investigated the effects of marine phytoplankton supplementation (Oceanix^®, Tetraselmis chuii) on 1) maximal isometric strength and immune function in healthy humans following a oneweek high-intensity resistance-training program and 2) the proinflammatory cytokine response to exercise in a rat model.[Methods] In the human trial, 22 healthy male and female participants were randomly divided into marine phytoplankton and placebo groups. Following baseline testing, participants underwent a 14-day supplement loading phase before completing five consecutive days of intense resistance training. In the rat model, rats were randomly divided into four groups (n=7 per condition): (i) control, (ii) exercise, (iii) exercise + marine phytoplankton (2.55 mg/kg/day), or (iv) exercise + marine phytoplankton (5.1 mg/kg/day). Rats in the exercising groups performed treadmill exercise 5 days per week for 6 weeks.[Results] In the human model, marine phytoplankton prevented significant declines in the isometric peak rate of force development compared to placebo. Additionally, salivary immunoglobulin A concentration was significantly lower following the resistance training protocol in the placebo group but not in the marine phytoplankton group. Marine phytoplankton in exercising rats decreased intramuscular levels and serum concentrations of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) and intramuscular concentrations of malondialdehyde.[Conclusion] Marine phytoplankton prevented decrements in indices of functional exercise recovery and immune function. Mechanistically, these outcomes could be prompted by modulating the oxidative stress and proinflammatory cytokine response to exercise.     

Dietary flaxseed reduces Myocardial Ischemic Lesions,improves cardiac function and lowers cholesterol levels despite the presence of severe obesity in JCR:LA-cp Rats

Previous work has shown that dietary flaxseed can significantly reduce cardiac damage from a coronary artery ligation-induced myocardial infarction. However, this model uses healthy animals and the ligation creates the infarct in an artificial manner. The purpose of this study was to determine if dietary flaxseed can protect the hearts of JCR:LA-cp rats, a model of genetic obesity and metabolic syndrome, from naturally occurring myocardial ischemic lesions. Male and female obese rats were randomized into four groups (n = 8 each) to receive, for 12 weeks, either a) control diet (Con), b) control diet supplemented with 10% ground flaxseed (CFlax), c) a high-fat, high sucrose (HFHS) diet, or d) HFHS supplemented with 10% ground flaxseed (HFlax). Male and female JCR:LA-cp lean rats served as genetic controls and received similar dietary interventions. In male obese rats, serum total cholesterol and LDL-C were significantly lower in CFlax compared to Con.  Obese rats on HFHS exhibited increased myocardial ischemic lesions and diastolic dysfunction regardless of sex. HFlax significantly lowered the frequency of cardiac lesions and improved diastolic function in male and female obese rats compared to HFHS. Blood pressures were similar in obese and lean rats. No aortic atherosclerotic lesions were detectable in any group. Collectively, this study shows that a HFHS diet increased myocardial ischemic lesion frequency and abolished the protective effect of female sex on cardiac function. More importantly, the data demonstrates dietary flaxseed protected against the development of small spontaneous cardiac infarcts despite the ingestion of a HFHS diet and the presence of morbid obesity.     

Antioxidant and antiapoptotic effects of pine needle powder ingestion and endurance training in high cholesterol-fed rats

[Purpose]

Pine needle is a kind of medicinal plant ingested traditionally for a variety of purposes. Therefore, we examined the antioxidant and antiapoptotic capacities of pine needle ingestion in high cholesterol-fed and endurance exercise-trained rats.

[Methods]

Animals were divided into six groups as; CON: normal diet control group; EX: normal diet and exercise training group; HC: high cholesterol diet group; HCE: high cholesterol diet and exercise training group; HCP: high cholesterol and pine needle group; HCPE: high-cholesterol and pine needle diet with exercise training group, respectively. Each group consisted of seven Sprague-Dawley male rats. The swim-training groups, EX, HCE, and HCPE swam in the swim pool 60 min/d and 5 d/week for 5 weeks. During the rearing periods, freeze-dried pine needle powder mix with 5% of the high cholesterol diet was supplied to the HCP and HCPE groups. Gastrocnemius muscle was used as the skeletal muscle. Malondialdehyde (MDA), Mn-containing superoxide dismutase (Mn-SOD), Cu, Zn containing superoxide dismutase (Cu,Zn-SOD), and glutathione peroxidase (GPx) were analyzed for their antioxidant capacities. Finally, p53, Bcl-2 (B-cell lymphoma 2), caspase-3 protein expression was analyzed to determine antiapoptotic ability.

[Results]

MDA showed low content in HCPE compared to the HC. Mn-SOD, Cu,Zn-SOD, and GPx protein expression was significantly increased by pine needle ingestion and/or exercise training. In addition, suppression of p53 protein expression resulted in Bcl-2 increase followed by caspase-3 decrease with/without pine needle ingestion and exercise training.

[Conclusion]

When exercise training in addition to pine needle powder ingestion may be a helpful nutritional regimen to athletes and exercisers.     

Moderate exercise training is more effective than resveratrol supplementation for ameliorating lipid metabolic complication in skeletal muscle of high fat diet-induced obese mice

[Purpose]

The aim of this study was to compare the effectiveness of moderate exercise training or resveratrol supplementation with a low fat diet on lipid metabolism in the skeletal muscle of high fat diet-induced obese mice.

[Methods]

C57BL/6J mice (5 weeks old, n = 30) were fed a high fat diet (45% fat) for 8 weeks first to make them obese. Afterward, all the mice were fed a low fat diet during 8 weeks of intervention with moderate exercise training and resveratrol supplementation. Before the intervention, the mice were separated into 3 groups: low-fat diet control (HLC; n = 10), low fat diet with resveratrol (HLR; n = 10) or low fat diet with exercise (HLE n = 10). The exercise group (HLE) performed treadmill running for 30-60 min/day at 10-22 m/min, 0% grade, 5 times/week for 8 weeks, while the resveratrol group (HLR) received a daily dose of resveratrol (10 mg/kg of body weight), 5 days/week for 8 weeks.

[Results]

Body weight was significantly reduced in HLE. Further, the lipogenesis marker SREBP and the inflammatory cytokine TNF-α were significant reduced in HLE. However, there was no significant effect from resveratrol supplementation with a low fat diet. Taken together, exercise training with a low fat diet has the positive effect of ameliorating lipid disturbance in the skeletal muscle of high fat diet-induced obese mice.

[Conclusion]

These findings suggest that exercise training with a low fat diet is most effective to improve lipid metabolism by reducing lipogenesis and inflammation in the skeletal muscle of high fat diet-induced obese mice.     

American Society of Biomechanics Journal of Biomechanics Award 2017: High-acceleration training during growth increases optimal muscle fascicle lengths in an avian bipedal model

Sprinters have been found to possess longer muscle fascicles than non-sprinters, which is thought to be beneficial for high-acceleration movements based on muscle force-length-velocity properties. However, it is unknown if their morphology is a result of genetics or training during growth. To explore the influence of training during growth, thirty guinea fowl (Numida meleagris) were split into exercise and sedentary groups. Exercise birds were housed in a large pen and underwent high-acceleration training during their growth period (age 4–14 weeks), while sedentary birds were housed in small pens to restrict movement. Morphological analyses (muscle mass, PCSA, optimal fascicle length, pennation angle) of a hip extensor muscle (ILPO) and plantarflexor muscle (LG), which differ in architecture and function during running, were performed post-mortem. Muscle mass for both ILPO and LG was not different between the two groups. Exercise birds were found to have ∼12% and ∼14% longer optimal fascicle lengths in ILPO and LG, respectively, than the sedentary group despite having ∼3% shorter limbs. From this study we can conclude that optimal fascicle lengths can increase as a result of high-acceleration training during growth. This increase in optimal fascicle length appears to occur irrespective of muscle architecture and in the absence of a change in muscle mass. Our findings suggest high-acceleration training during growth results in muscles that prioritize adaptations for lower strain and shortening velocity over isometric strength. Thus, the adaptations observed suggest these muscles produce higher force during dynamic contractions, which is beneficial for movements requiring large power outputs.     

Effect of dietary polyunsaturated fatty acids on contractile function of hearts isolated from sedentary and trained rats

Moderate physical training induced a decrease in arterial blood pressure in fish oil-fed rats as compared to sunflower seed oil-fed rats. The purpose of this study was to determine if these changes were due to modifications of the left ventricular function of the heart. Forty rats were fed a semi-purified diet containing either 10% sunflower seed oil or 10% fish oil (EPAX 3000TG, Pronova). Each dietary group was assigned to two sub-groups, one being constituted by sedentary animals and the other by trained animals. Training was achieved by daily running for 60 minutes at moderate intensity for three weeks. At the end of the training period, the animals were sacrificed and their hearts were immediately perfused according to the working mode. The phospholipid fatty acid composition and parameters of the left ventricular function were determined. Feeding fish oil markedly reduced the proportion of n-6 polyunsaturated fatty acids (PUFA, 18:2 n-6, 20:4 n-6, 22:4 n-6 and 22:5 n-6) in cardiac phospholipids. The n-6 PUFA were replaced by n-3 PUFA (mainly docosahexaenoic acid). In sedentary animals, the fluid dynamic (aortic and coronary flow, cardiac output) was not modified by the diet. The heart rate was reduced (-10%) in n-3 PUFA-rich hearts. Physical training did not markedly alter the polyunsaturated fatty acid profile of cardiac phospholipids. Conversely, it reduced the heart rate, aortic flow and cardiac output (-11, -21 and -14%, respectively) at a similar extent in the two dietary groups. In a second set of experiments, the training period was repeated in animals fed a commercially available diet (A103, UAR) which simultaneously provided n-6 and n-3 fatty acids. In these dietary conditions, neither the aortic flow nor the heart rate was decreased by physical exercise. These results suggest that both n-6 and n-3 PUFA in the diet are necessary to ensure a good cardiac adaptation to moderate physical training. Furthermore, the fish oil-induced decrease in arterial blood pressure in trained animals was not related to changes in cardiac contractility, but to a decrease in vascular resistances. Moderate physical training + dietary n-3 PUFA might be used to prevent hypertension and cardiovascular diseases.     

Comparison of exercise effects on the hemodynamics of the Bio 14.6 cardiomyopathic hamster.

1. Comparisons of the effects of 4 and 16 weeks of exercise were made on; cardiac output, stroke volume, heart rate, left intraventricular systolic and diastolic pressures, dP/dt, and heart calcium in the Bio 14.6 cardiomyopathic and F1 B hamsters. 2. In the cardiomyopathic hamster the cardiac output, stroke volume, left intraventricular systolic pressure and dP/dt, which were all depressed in the age related sedentary animals, were increased by both periods of exercise. The left intraventricular diastolic pressure which was elevated was likewise decreased by both exercise periods. Only the 16 week exercise period decreased the resting heart rate. 3. In the normal F1 B hamster, both periods of exercise increased the cardiac output and stroke volume while the left intraventricular systolic pressure was decreased. Only the 16 week exercise decreased the resting heart rate and left intraventricular diastolic pressure and increased the left ventricular dP/dt. 4. Both periods of exercise increased the total heart calcium in the Bio 14.6 hamster while the heart calcium in the F1 B was increased only by the 16 week exercise period.     

Exercise Training Prevents TNF-α Induced Loss of Force in the Diaphragm of Mice

Rationale

Inflammatory cytokines like tumor necrosis factor alpha (TNF-α) are elevated in congestive heart failure and are known to induce the production of reactive oxygen species as well as to deteriorate respiratory muscle function.

Objectives

Given the antioxidative effects of exercise training, the aim of the present study was to investigate if exercise training is capable of preventing a TNF-α induced loss of diaphragmatic force in mice and, if so, to elucidate the potential underlying mechanisms.

Methods

Prior to intraperitoneal injection of TNF-α or saline, C57Bl6 mice were assigned to four weeks of exercise training or sedentary behavior. Diaphragmatic force and power generation were determined in vitro. Expression/activity of radical scavenger enzymes, enzymes producing reactive oxygen species and marker of oxidative stress were measured in the diaphragm.

Main Results

In sedentary animals, TNF-α reduced specific force development by 42% concomitant with a 2.6-fold increase in the amount of carbonylated α-actin and creatine kinase. Furthermore, TNF-α led to an increased NAD(P)H oxidase activity in both sedentary and exercised mice whereas xanthine oxidase activity and intramitochondrial ROS production was only enhanced in sedentary animals by TNF-α. Exercise training prevented the TNF-α induced force reduction and led to an enhanced mRNA expression and activity of glutathione peroxidase. Carbonylation of proteins, in particular of α-actin and creatine kinase, was diminished by exercise training.

Conclusion

TNF-α reduces the force development in the diaphragm of mice. This effect is almost abolished by exercise training. This may be a result of reduced carbonylation of proteins due to the antioxidative properties of exercise training.     

日粮添加褐藻糖胶对断奶仔猪抗炎能力和肠道微生物多样性的影响

【目的】本试验旨在研究日粮添加海带提取物褐藻糖胶对断奶仔猪生长性能、营养物质消化率、机体免疫力和肠道微生物多样性的影响。【方法】试验选用36头初始体重为(7.43±0.12) kg的健康仔猪,按照随机区组设计分为3组,每组12头。日粮处理组分别为不含抗生素的基础日粮组、抗生素组和褐藻糖胶组;试验期为28d。评价褐藻糖胶对仔猪生长性能和营养物质消化率的影响;通过比色法和酶联免疫吸附法检测血清中与免疫相关的指标;通过16S rRNA扩增子高通量测序检测试验第0、14和28天肠道微生物多样性。【结果】日粮添加褐藻糖胶可降低试验0–14 d仔猪耗料增重比(P0.05),但对试验全期仔猪平均日增重和平均日采量无显著影响(P0.05)。与对照组相比,饲喂褐藻糖胶日粮后,仔猪的中性洗涤纤维和酸性洗涤纤维表观消化率显著提高(P0.05);仔猪饲喂抗生素和褐藻糖胶日粮后,血清IL-22含量显著降低。试验第14天,抗生素组和褐藻糖胶处理组中Bacteroidetes数量呈上升趋势(P=0.07);试验第28天,抗生素组和褐藻糖胶处理组Actinobacteria丰度显著高于对照组(P0.05),且褐藻糖胶处理组Bacteroides属的菌群丰度显著高于对照组和抗生素组。【结论】日粮添加褐藻糖胶提高了断奶仔猪纤维养分消化率和拟杆菌属的丰富度和多样性,并且降低了促炎性细胞因子IL-22含量,这有助于缓解仔猪的断奶应激反应,建立稳定健康肠道菌群。     

Influence of diet on the storage, mobilization and utilization of energy reserves in trained and untrained rats

The effect of the major dietary energy source (fat or carbohydrate) on some of the adaptations to physical training, particularly body composition and tissue glycogen concentrations, were studied in growing male Wistar rats. Resting liver glycogen concentrations were lower in both trained and sedentary rats fed a high fat diet compared to corresponding rats fed a high carbohydrate (low fat) diet. Trained rats on both diets had higher liver glycogen levels than corresponding sedentary controls. Resting gastrocnemius muscle glycogen concentrations were not influenced by diet or training. Rates of liver and muscle glycogen depletion during a 60-min swim were lower in trained rats but were not influenced by diet. Significant interactions were noted between the dietary energy source and exercise training with respect to body weight gain, body fat content, liver weight and liver glycogen concentrations.     

饲料类型对茶尺蠖幼虫肠道细菌多样性及幼虫存活率的影响

【目的】茶尺蠖是茶园中的重要害虫。研究茶尺蠖寄主食物-肠道菌群-茶尺蠖生长发育三者之间的关系对于茶尺蠖的防治具有重要的理论指导价值。【方法】分析不添加茶叶因子的纯人工饲料和茶树鲜叶对茶尺蠖幼虫的存活影响;用高通量测序技术分析不同饲料饲喂的茶尺蠖幼虫的肠道菌群异同。【结果】取食人工饲料的幼虫死亡率远远高于取食茶树鲜叶的幼虫;取食人工饲料的幼虫肠道细菌多样性和丰富度高于取食茶树鲜叶的幼虫;茶尺蠖幼虫肠道中存在很多促进宿主生长的细菌。【结论】饲料类型影响茶尺蠖幼虫的存活;饲料类型影响茶尺蠖幼虫肠道菌群结构。     

Effect of contractile activity on rat skeletal muscle beta-adrenoceptor properties

The effect of fiber type and endurance exercise training on skeletal muscle beta-adrenoceptor properties were assessed using a direct radioligand binding technique. Six separate muscles, composed of a variety of different fiber types, were examined in treadmill trained and sedentary rats. In trained animals, sarcolemmal preparations from heart and slow twitch soleus muscle exhibited a significantly greater receptor concentration than membranes from white fast twitch glycolytic fibers of the vastus lateralis. No significant changes were observed between trained and sedentary rat muscle beta-adrenoceptor density (beta max, fmole/mg protein) or affinity (Kd, nM) within each muscle type, despite significantly increased myocardial/body weight ratios and skeletal muscle enzyme adaptations associated with the exercise program. These results suggest that muscle beta-adrenoceptor properties may be influenced in part by the motor nerve innervation to that muscle, and are further discussed with respect to a possible relationship between exercise intensity and receptor regulation.