Changes in membrane fluidity and lipid peroxidation of skeletal muscle mitochondria after exhausting exercise in rats

Green tea catechin prevents oxidative stress-regulated autophagy and apoptosis signaling, and inhibits tenderness in postmortem bovine longissimus thoracis et lumborum muscle

Although green tea catechin has been reported to be an antioxidant and preservative in meat, the extent to which it affects the tenderization of bovine muscle remains largely unknown. This study seeks to evaluate the effect of catechin on the interplay between apoptosis and autophagy, and subsequently, the development of bovine muscle tenderness. The results indicate that catechin significantly alleviated oxidative stress. A concomitant reduction of autophagic markers LC3-II/LC3-I ratio, Beclin-1, and Atg7 levels were caused by catechin. Besides, aforementioned autophagy inhibition was further augmented by PI3K/Akt/mTOR activation. Additionally, catechin protected against mitochondrial dysfunction and inhibited mitochondria-dependent caspase apoptosis pathway. Furthermore, there was a reciprocal inhibition between autophagy and apoptosis. Ultimately, tenderness at 24 and 120 h, an increase in the gap between muscle fiber bundles, and disintegration of myofibrillar architectures were all inhibited by catechin. Therefore, despite alleviating oxidative stress, catechin may hamper tenderization pattern of postmortem bovine muscle.

Dynamic changes in postmortem quality of mirror carp (Cyprinus carpio L.): Based on oxidation reaction and mitochondrial function properties

The dynamic changes in the postmortem quality of mirror carp (Cyprinus carpio L.) were investigated. With extended postmortem time, conductivity, redness, lipid oxidation, and protein oxidation all increased, while lightness, whiteness, and freshness decreased. At 4 h postmortem, the pH value reached a minimum (6.58), while the centrifugal loss and hardness reached a maximum (17.13% and 2539 g). Additionally, variations in mitochondria-related parameters during apoptosis were studied. Within 72 h postmortem, the content of reactive oxygen species initially decreased and subsequently increased; furthermore, there was a significant increase in the mitochondrial membrane permeability transition pore, membrane fluidity, and swelling (P < 0.05). Meanwhile, the cytosolic cytochrome c level decreased from 0.71 to 0.23, which indicated potential mitochondrial damage. Thus, mitochondrial dysfunction during postmortem aging can give rise to oxidation and the production of ammonia and amine compounds, which leads to flesh quality deterioration.

High oxygen-modified packaging (HiOx-MAP) mediates HIF-1α regulation of tenderness changes during postmortem aging of yak meat

In the present study, we studied the effect of high oxygen-modified packaging (HiOx-MAP) on yak meat tenderness and the underlying mechanism. HiOx-MAP significantly increased the myofibril fragmentation index (MFI) of yak meat. In addition, western blotting showed that the expression of hypoxia-inducible factor (HIF-1α) and ryanodine receptors (RyR) in the HiOx-MAP group was reduced. HiOx-MAP increased the activity of sarcoplasmic reticulum calcium-ATPase (SERCA). The energy disperse spectroscopy (EDS) mapping showed gradually reduced calcium distribution in the treated endoplasmic reticulum. Furthermore, HiOx-MAP treatment increased the caspase-3 activity and the apoptosis rate. The activity of calmodulin protein (CaMKKβ) and AMP-activated protein kinase (AMPK) was down-regulated leading to apoptosis. These results indicated that HiOx-MAP promoted apoptosis during postmortem aging to improve the tenderization of meat.

Effects of nitric oxide synthase inhibitor on mitochondria apoptosis and meat quality in postmortem Gannan yak (Bos grunniens) meat

This research aimed to explore the effects of the nitric oxide synthase (NOS) inhibitor (L-NAME) on mitochondria apoptosis in postmortem Gannan yak (Bos grunniens) longissimus dorsi (LD) muscle and to explore its effect on meat quality further. The Gannan yak meat samples were treated with the control group (0.9% NaCl) and L-NAME (20, 60, and 100 mM) for 24 h and then stored for 0, 1, 3, 5, and 7 days at 4°C. NOS activity and NO content were investigated, and the parameters of mitochondrial apoptosis of the postmortem Gannan yak meat were determined. Meanwhile, the meat quality such as the centrifugation loss, meat color, and myofibril fragmentation index (MFI) was evaluated. The results indicated that after treatment with L-NAME, NOS activity and NO content decreased, causing mitochondrial membrane damage, Bax protein, and Cyt-c levels increased, and resulted in increased activities of caspase-9 and -3, promoting the occurrence of mitochondrial apoptosis. Furthermore, it increased the tenderness and water retention of Gannan yak meat. The results indicated that NOS inhibitor played a regulatory role in postmortem Gannan yak meat quality by regulating mitochondria apoptosis during postmortem aging. PRACTICAL APPLICATIONS: The meat's tenderness is often considered the most important factor affecting consumers' willingness to repurchase. The relationship of caspases and MFI suggested that L-NAME played a regulatory role in postmortem Gannan yak meat quality by regulating mitochondria apoptosis during postmortem aging. This study provides valuable information for the development of the Gannan yak economy in Tibetan areas.

Puerarin mitigates oxidative injuries, opening of mitochondrial permeability transition pores and pathological damage associated with liver and kidney in Xanthium strumarium-intoxicated rats

In this study, the therapeutic effects of puerarin on Xanthium strumarium toxicity, which can develop in many species and does not have a specific antidote, were investigated. A single dose of 100 g/kg X. strumarium seeds was administered by gavage to female Sprague-Dawley rats, 6 h following which 200 mg/kg puerarin was administered by the same route, with puerarin administration being repeated daily at the same time. After completing the application, the blood, liver and kidney tissues of the rats were examined. Further, the biochemical parameters, glucose, MDA, GSH, SOD, mitochondrial Ca²⁺ and mitochondrial permeability transition pore (mPTP) opening levels, apoptotic factors (TUNEL, Bax and Bcl-2), ATP synthase and histopathological changes of the experimental rats were examined. The results revealed that while the administration of X. strumarium resulted in increased blood AST, ALT, ALP, LDH, CK, BUN and creatinine levels, it decreased glucose levels. In addition, it increased the MDA levels in the tissues and significantly increased the oxidative stress levels by decreasing the GSH levels and SOD activity. X. strumarium caused an increase in the mitochondrial Ca²⁺ and mPTP opening levels. Moreover, it increased the immunohistochemically determined ATP synthase expression and histopathologically identified necrotic liver cell death rates. Owing to its antioxidant properties and inhibitory effects on mPTP opening, puerarin administered for therapeutic purposes decreased the oxidative damage caused by X. strumarium toxicity, blood biochemical parameter levels, mitochondrial Ca²⁺ levels, mPTP opening, ATP synthase expression and the percentage of necrotic cells. Hence, the reduction in the liver and kidney damage in X. strumarium toxicity by puerarin indicates its potential use as an antidote for X. strumarium poisoning.

Influence of Ca2+ on mitochondrial apoptosis activation and yak meat tenderization during postmortem aging

The objective of this study was to investigate the underlying molecular mechanisms of mitochondrial Ca2+ homeostasis disequilibrium in mitochondrial apoptosis and its impact on yak meat tenderness. Results indicated that CaCl2 treatment significantly promoted glycolysis by increasing lactic acid level and decreasing glycogen content, pH, and ATP production (P < 0.01 and P < 0.05). The activities of Na+-K+-ATPase pump and Ca2+-ATPase pump in the early aging stage were significantly influenced by CaCl2 treatment. The activities of synchronous digital hierarchy and citrate synthase were also significantly improved by CaCl2 treatment (P < 0.01 and P < 0.05). Mitochondrial reactive oxygen species (ROS) levels were significantly higher in the CaCl2 group than in the control group (P < 0.01); at 24 h, the value in the Ca2+ group was 64.27% higher than that in the control group. Furthermore, CaCl2 treatment significantly enhanced the mitochondrial apoptosis cascade reaction and meat tenderization by improving the myofibril fragmentation index and shear force (P < 0.01). These results demonstrated that the imbalance of mitochondrial Ca2+ homeostasis played a significant role in the mitochondrial apoptosis pathway by regulating energy metabolism factors, meat intracellular environment, mitochondrial functions, and ROS-mediated oxidative stress. These conditions further improved meat tenderization during postmortem aging.

Effects of acute and chronic exercise on the osmotic stability of erythrocyte membrane of competitive swimmers

This study aimed to evaluate the influence of acute and chronic exercise on erythrocyte membrane stability and various blood indices in a population consisting of five national-level male swimmers, over 18 weeks of training. The evaluations were made at the beginning and end of the 1st, 7th, 13th and 18th weeks, when volume and training intensity have changed. The effects manifested at the beginning of those weeks were considered due to chronic adaptations, while the effects observed at the end of the weeks were considered due to acute manifestations of the exercise load of that week. Acute changes resulting from the exercise comprised increases in creatine kinase activity (CK) and leukocyte count (Leu), and decrease in hematocrit (Ht) and mean corpuscular volume (MCV), at the end of the first week; increase in the activities of CK and lactate dehydrogenase (LDH), in the uric acid (UA) concentration and Leu count, at the end of the seventh week; increases in CK and LDH activities and in the mean corpuscular hemoglobin concentration (MCHC), at the end of the 13th week; and decrease in the value of the osmotic stability index 1/H₅₀ and increases in the CK activity and platelets (Plt) count, at the end of the 18th week. Chronic changes due to training comprised increase in the values of 1/H₅₀, CK, LDH, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), serum iron (Fe), MCV and Plt. Although acute training has resulted in decrease in the osmotic stability of erythrocytes, possibly associated with exacerbation of the oxidative processes during intense exercise, chronic training over 18 weeks resulted in increased osmotic stability of erythrocytes, possibly by modulation in the membrane cholesterol content by low and high density lipoproteins.

Silybum marianum oil attenuates oxidative stress and ameliorates mitochondrial dysfunction in mice treated with D-galactose

Background:

Silybum marianum has been used as herbal medicine for the treatment of liver disease, liver cirrhosis, and to prevent liver cancer in Europe and Asia since ancient times. Silybum marianum oil (SMO), a by-product of silymarin production, is rich in essential fatty acids, phospholipids, sterols, and vitamin E. However, it has not been very good development and use.

Objective:

In the present study, we used olive oil as a control to investigate the antioxidant and anti-aging effect of SMO in D-galactose (D-gal)-induced aging mice.

Materials and Methods:

D-gal was injected intraperitoneally (500 mg/kg body weight daily) for 7 weeks while SMO was simultaneously administered orally. The triglycerides (TRIG) and cholesterol (CHOL) levels were estimated in the serum. Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), monoamine oxidase (MAO), malondialdehyde (MDA), caspase-3, and Bcl-2 were determined in the liver and brain. The activities of Na⁺-K⁺-adenosine triphosphatase (ATPase), Ca²⁺-Mg²⁺-ATPase, membrane potential (ΔΨm), and membrane fluidity of the liver mitochondrial were estimated.

Results:

SMO decreased levels of TRIG and CHOL in aging mice. SMO administration elevated the activities of SOD, GSH-Px, and T-AOC, which are suppressed by aging. The levels of MAO and MDA in the liver and brain were reduced by SMO administration in aging mice. Enzyme linked immunosorbent assay showed that SMO significantly decreased the concentration of caspase-3 and improved the activity of Bcl-2 in the liver and brain of aging mice. Furthermore, SMO significantly attenuated the D-gal induced liver mitochondrial dysfunction by improving the activities of Na⁺-K⁺-ATPase, Ca²⁺-Mg²⁺-ATPase, membrane potential (ΔΨm), and membrane fluidity.

Conclusion:

These results indicate that SMO effectively attenuated oxidative damage and improved apoptosis related factors as well as liver mitochondrial dysfunction in aging mice.

Effect of short-term low-intensity exercise training on association of oxygen free radicals and nitric oxide production in patients with acute myocardial infarction

Moderate-to-high intensity of exercise training within 2 to 3 months decreases oxygen free radicals (reactive oxygen species, ROS) and increases nitric oxide (NO) in outpatients with myocardial infarction. There is no data about the association of ROS and NO after short-term low-intensity exercise training within 5 days in patients hospitalized with acute myocardial infarction (AMI). A total of 32 male patients with AMI were randomized into two groups: 15 patients with short-term low-intensity exercise training within 5 days formed the training group and 17 patients without such exercise training formed the control group. All patients performed exercise treadmill test with modified Bruce protocol before and after the study. F2-isoprostane and NO concentration of the training group increased slightly after modified Bruce exercise treadmill test. Compared with the control group, NO of the training group was also slightly higher. Baseline NO and uric acid were negative predictor variables for F2-isoprostane in all patients hospitalized with AMI, and triglyceride was a positive predictor variable. After the study, physical capacity of the training group was higher; but heart rate and systolic blood pressure were lower significantly. This study showed that short-term low-intensity exercise training for patients hospitalized with AMI did not change ROS and NO productions, but it improved physical capacity and lowered heart rate and systolic blood pressure. NO was negative predictor variable for F2-isoprostane in controlling ROS changes in dynamic compensation mechanism.

Altered cellular membrane fluidity levels and lipid peroxidation during experimental pancreas transplantation

Although the pathogenesis of ischemia reperfusion (IR) injury is based on complex mechanisms, free radicals play a central role. We evaluated membrane fluidity and lipid peroxidation during pancreas transplantation (PT) performed in 12 pigs (six donors and six recipients). Fluidity was measured by fluorescence spectroscopy, and malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA) concentrations were used as an index of lipid oxidation. Pancreatic tissues were collected as follows: (A) donor, immediately before vascular clamping; (B) graft, following perfusion lavage with University of Wisconsin preservation fluid; (C) graft, after 16 h of cold ischemia; and (D) recipient, 30 min vascular postreperfusion. Fluidity and MDA and 4-HDA concentrations were similar in cases A, B, and C. However, there was significant membrane rigidity and increased lipid peroxidation after reperfusion (D). These findings suggest that reperfusion exaggerates oxidative damage and may account for the rigidity in the membranes of allografts during PT.

Exercise and Duchenne muscular dystrophy: toward evidence-based exercise prescription

To develop a rational framework for answering questions about the role of exercise in Duchenne muscular dystrophy (DMD), we focused on five pathophysiological mechanisms and offer brief hypotheses regarding how exercise may beneficially modulate pertinent cellular and molecular pathways. We aimed to provide an integrative overview of mechanisms of DMD pathology that may improve or worsen as a result of exercise. We also sought to stimulate discussion of what outcomes/dependent variables most appropriately measure these mechanisms, with the purpose of defining criteria for well-designed, controlled studies of exercise in DMD. The five mechanisms include pathways that are both intrinsic and extrinsic to the diseased muscle cells.

Effect of exercise on oxidative stress biomarkers

Acute bouts of aerobic and anaerobic exercise can induce a state of oxidative stress, as indicated by an increase in oxidized molecules in a variety of tissues and body fluids. The extent of oxidation is dependent on the exercise mode, intensity, and duration, and is specifically related to the degree of oxidant production. Findings of increased oxidative stress have been reported for both healthy and diseased subjects following single bouts of exercise. While acute exercise has the ability to induce an oxidative stress, this same exercise stimulus appears necessary to allow for an upregulation in endogenous antioxidant defenses. This chapter presents a summary of exercise-induced oxidative stress.

The apoptotic response to strenuous exercise of the gastrocnemius and solues muscle fibers in rats

The purposes of this study were to investigate the effects of strenuous exercise on apoptosis of the gastrocnemius and soleus muscle fibers and clarify the role of oxidative metabolism in the strenuous exercise-induced apoptosis. The experiment was designed with 49 (n = 49) male, 24-week-old, L. Wistar albino rats. Strenuous exercise model was applied to 42 (n = 42) rats and seven (n = 7) rats served as rested controls. All rats were randomly assigned to one of the following groups (n = 7): rested control (C), immediately after exercise (0 h) and 3, 6, 12, 24, and 48 h after exercise. Apoptotic nuclei were shown by single stranded DNA (ssDNA) determination. Oxidative damage in mitochondrial fractions of the muscle tissues was evaluated by malondialdehyde (MDA) levels and reduced/oxidized glutathione (GSH/GSSG) ratios. Caspase-9, -8 and -3 activities and the level of cytochrome c (Cyt c) were measured in the cytosolic fractions of muscle tissues to follow mitochondrial-dependent (intrinsic) or ligand-mediated death receptor (extrinsic) pathways of apoptosis. Plasma interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) levels were also determined. Based on our results, apoptosis is significantly triggered in muscle fibers by strenuous exercise (P < 0.05). Apoptosis in the soleus muscle tissues mostly depends on the intrinsic pathway and may be triggered by increased oxidative stress. In contrast, extrinsic pathway of apoptosis was predominant in the gastrocnemius muscle and increases of TNF-alpha and IL-6 may play a significant role.

Depressed fatigue-induced oxidative stress in chronic hypoxemic humans and rats

It was already documented that acute hypoxemia reduces the oxidative stress following static as well as dynamic handgrip bouts in humans. Then, we examined if chronic hypoxemia could produce the same effect in patients suffering from chronic respiratory insufficiency. In rats, we studied the respective consequence of a one-month exposure to normobaric hypoxia on two muscles (soleus, SOL, and extensor digitorum longus, EDL) which have high and low aerobic metabolism, respectively. Compared to healthy humans, the resting level of erythrocyte reduced glutathione (GSH) was significantly lower in chronic hypoxemic patients, and after a handgrip contraction sustained at 50% of maximal until exhaustion the GSH level and plasma thiobarbituric acid reactive substances (TBARS) did not vary. A 20-min period of oxygen supplementation partly restored the post-handgrip oxidative stress. Compared to control rats, SOL muscle of hypoxemic animals had lower intra-muscular resting level of GSH; after a 3-min muscle stimulation (MS) leading to fatigue, TBARS did not vary in SOL and EDL and the GSH decrease was absent in SOL whereas it persisted in EDL. We concluded that chronic hypoxemia depressed the fatigue-induced oxidative stress, the effects prevailing in muscles having a high oxygen demand.

Mitochondrial, sarcoplasmic membrane integrity and protein degradation in heart and skeletal muscle in exercised rats

Several different exercise regimens varied in the severity of tissue damage induced. Therefore, this study investigated the effects of a single bout of exercise versus endurance training in heart and skeletal muscles with different predominant fiber types on indices of mitochondrial, endoplasmic reticulum (ER) integrity and protein degradation. Male Wistar rats performed different treadmill exercise protocols: exhaustive, maximal exhaustive, eccentric, training and exhaustive exercise after training. The maximal and eccentric exercises resulted in a significant loss of integrity of the sarcoplasmic and ER muscle, while no changes were observed in cardiac muscle. Mitochondrial membrane fluidity measured by the fluorescence polarization method was significantly increased post-acute exercises in heart and oxidative muscles. Regular exercise can stabilize and preserve the viscoelastic nature of mitochondrial membranes in both tissues. The highest increase in carbonyl content was obtained in heart after exhaustive exercise protocol, from 1+/-0.1 to 3.6+/-0.14 nmol mg protein(-1), such increase were not found after regular exercise with values significantly decreased. Nitrate heart levels showed attenuated generation of nitric oxide after training. Muscle protein oxidation was produced in all exhaustive exercises including eccentric exercise.

Carbohydrate-energy restriction may protect the rat brain against oxidative damage and improve physical performance

Chronic energy restriction, alpha-tocopherol supplementation and their interaction with exhaustive exercise were investigated. Eleven-week-old male Wistar rats (n 6x 10) were fed either a control (C), a 30 % carbohydrate-energy-restricted control (R) or an alpha-tocopherol-supplemented (S) diet for 5 months. The animals in each diet were divided into exercised (E) and non-exercised (NE) groups. Before killing, the exercised rats were required to run to exhaustion (39 (se 6), 69 (se 11) and 18 (se 2) min for the C, R and S groups, respectively). Lipid peroxidation (thiobarbituric acid-reactive substances; TBARS), protein damage (reactive carbonyls) and alpha-tocopherol were determined in gastrocnemius, liver, brain and/or plasma. There was no difference in lipid peroxidation between the R and C groups, but in liver and muscle peroxidation appeared significantly lower in the S than the other two diets. TBARS in the brain were similar in all groups. On the other hand, reactive carbonyls showed that both the R and S diets reduced protein damage in the brain, while exhaustive exercise increased it. For liver and muscle, however, reactive carbonyl levels were similar in all groups. alpha-Tocopherol supplementation increased the vitamin concentrations in liver, muscle and plasma, but exercise decreased them in plasma and brain. Carbohydrate-energy restriction increased (P=0.0025) resistance to exhaustive exercise considerably without depleting stores of alpha-tocopherol or exacerbating oxidative damage in monitored tissues. It is concluded that while exhaustive exercise promotes a tissue-specific oxidative damage detectable only in brain proteins, both experimental diets tended to ameliorate this condition.