Regulation of the expression of key signalling molecules in mTOR pathway of skeletal muscle satellite cells in neonatal chicks: Effects of leucine and glycine–leucine peptide

This study was conducted to analyse the effects of leucine (Leu) and glycine (Gly)‐Leu peptide on expressions of key signalling molecules in mTOR pathway of skeletal muscle satellite cells in neonatal chicks. The 4‐day‐old male AA broilers with similar weight were selected to obtain the broiler skeletal muscle satellite cells with the two‐step method of collagenase‐I and trypsin digestion. The satellite cells were subjected to primary culture in vitro, and they were cultured in DMEM medium with the Leu concentration of 0.2 mM and 2 mM as well as with the Gly‐Leu peptide concentration of 0.2 mM and 2 mM. The experiment lasted for 5 days. The results showed that TOR, S6K1 and 4E‐BP1 mRNA expressions in the medium with Leu concentration of 2 mM were significantly higher than that in 0.2 mM group (p < 0.05). There was no difference between the medium with Gly‐Leu concentration of 2 mM and 0.2 mM on the TOR, S6K1 and 4E‐BP1 mRNA expressions (p > 0.05). In conclusion, Leu significantly increases TOR, S6K1 and 4E‐BP1 mRNA expressions of skeletal muscle satellite cells, but Gly‐Leu peptide has no effect on them.     

Effects of astaxanthin‐rich dried cell powder from Paracoccus carotinifaciens on carotenoid composition and lipid peroxidation in skeletal muscle of broiler chickens under thermo‐neutral or realistic high temperature conditions

Thirty‐two 15‐day old broiler chicks (Chunky strain ROSS 308) were randomly divided into four treatments in a 2 × 2 factorial design. The main factors were diet (basal diet or basal diet supplemented with 0.15% astaxanthin‐rich dried cell powder (Panaferd‐P [astaxanthin 30 ppm]) and ambient temperature (thermo‐neutral [25 ± 1°C] or high [35 ± 1°C for 6 hr]). Dietary supplementation with Panaferd‐P did not affect growth performance, though high ambient temperature decreased feed intake and the weight of breast tender muscle, liver, and heart. High ambient temperature also decreased redness in both breast and leg muscles of chickens, while Panaferd‐P increased redness and yellowness of breast and leg muscles of chickens. Panaferd‐P increased Paracoccus carotinifaciens‐derived pigments (i.e., adonixanthin, astaxanthin, adonirubin, and cantaxanthin) as well as corn‐derived pigments such as zeaxanthin and lutein in breast and leg muscles. High ambient temperature increased the malondialdehyde (MDA) concentration in breast muscle, while Panaferd‐P decreased the MDA concentration in breast muscle under both temperature conditions. Our results suggest that dietary supplementation with Panaferd‐P increases muscle carotenoid content, the redness and yellowness of meat and decreases the muscle MDA concentration in broiler chickens kept under thermo‐neutral or high ambient temperature conditions.     

Effect of in ovo glyphosate injection on embryonic development,serum biochemistry,antioxidant status and histopathological changes in newly hatched chicks

This study aimed to investigate the potential toxic effects of pure glyphosate or Roundup^® on hatchability, serum biochemistry and histopathological observation of the liver and kidney of newly hatched chicks. On day six, a total of 225 fertile eggs were obtained from Huafeng breeder hens. The eggs were randomly divided into three treatments: (a) the control group injected with deionized water, (b) the glyphosate group injected 10 mg pure glyphosate/Kg egg mass and (c) the Roundup group injected 10 mg the active ingredient glyphosate in Roundup^®/Kg egg. The results showed a decrease of hatchability rate in chicks treated with Roundup^® (66%). In addition, no significant change was observed in body weights, yolk sac weight and relative weight organs except the liver and kidney were significantly increased with groups treated with glyphosate and Roundup^® compared to the control group. The results showed that serum protein profiles were linearly significantly increased of serum phosphor, uric acid, aspirate aminotransferase, alanine transaminase and alkaline phosphatase in groups treated with Roundup^®, as well as the serum concentrations of triglyceride altered after treatment with glyphosate. Furthermore, oxidative stress was observed in the treated chicks, the glyphosate and Roundup^® induced changes of the content of malondialdehyde in both the liver and kidney, moreover decrease of glutathione peroxidase, total superoxide dismutase and catalase activity in the kidney tissue and serum. Additionally, changes also happened in the histomorphology of the liver and kidney tissue of the treated chicks. It can be concluded that Roundup^® as a probable decrease of hatchability. Exposure to glyphosate alone or Roundup^® caused liver and kidney histopathological alterations, serum parameters imbalances and oxidative stress, also induced a variety of liver and kidney biochemical alterations that might impair normal organ functioning in newly hatched chicks.     

间歇光照对肉鸡体内脂质过氧化作用和抗氧化酶活性的影响

低温诱发肉鸡肺动脉高压综合征（PHS）,动态观察限制光照对肉鸡PHS发病率及体内脂质过氧化作用的影响。将320羽1日龄肉鸡随机分为4组。常温组按常规饲养,24 h连续光照。3个低温组从14日龄起逐步降温诱发PHS,并于9～30日龄分别在夜间停止光照0、35、h。结果,低温组PHS发病率、右心全心比（RV/TV）、肺厚壁末梢血管百分率（%TWPV）和丙二醛（MDA）水平显著升高,而血浆超氧化物歧化酶（SOD）活性降低。限制光照组SOD活性升高而PHS发病率、RV/TV、TWPV和MDA显著降低。间歇光照组早期生长速度减慢,后期体质量得到补偿性增长,并在44日龄与连续光照组差异不显著。这一结果表明,减轻体内脂质过氧化作用,提高机体抗氧化酶活性并减轻以非肌型肺动脉肌型化为特征的肺血管重构,可能是限制光照使肉鸡PHS发病率降低的机理之一。     

Effects of lycopene supplementation in both maternal and offspring diets on growth performance,antioxidant capacity and biochemical parameters in chicks

This study investigated the effects of different supplementation ways of lycopene during pre‐hatch (from the diet of hens) and post‐hatch (from the diet of progeny) on production performance, antioxidant capacity and biochemical parameters in chicks. In total, 360 hens were fed diets supplemented with 0 (control group) or 40 mg lycopene/kg diet. From 28 to 34 days after the start of supplementation (30 weeks old), 650 qualified eggs were collected to artificial incubation. In this trial, 2 × 2 factorial designs were used. Male chicks hatched from hens fed with 0 or 40 mg lycopene/kg diet were fed a diet containing either 0 or 40 mg lycopene/kg diet. The results showed that, relative to control, in ovo‐deposited lycopene significantly increased chick birth body weight, improved liver total antioxidant capacity (T‐AOC), glutathione peroxidase (GSH‐Px) and glutathione to oxidized glutathione ratio (GSH: GSSG), and significantly declined liver malondialdehyde (MDA) level and increased liver lycopene content during 0–14 days after hatching. On days 14 after hatching, dietary lycopene in diet began to take over gradually. Both supplementation ways of lycopene increased immune organ index, serum high‐density lipoprotein (HDL) cholesterol, villus length and villus/crypt in duodenum, jejunum and ileum. Data in this study suggested lycopene supplementation could improve antioxidant capacity and immune function, and regulate lipid metabolism in chicks.     

干旱胁迫和复水对锡金微孔草抗氧化酶系统的影响(简报)

用盆栽法研究了干旱胁迫和复水对锡金微孔草抗氧化酶系统的影响。结果显示,锡金微孔草暂时萎焉期和永久萎焉期土壤含水量分别为7.06%和6.20%;处于暂时萎焉期的锡金微孔草复水后吸水迅速,萎焉状态逐渐消除,复水6 h后处理组外貌与对照基本一致;SOD活性在胁迫处理期间与对照相比无显著变化,复水后有一定幅度的上升;CAT和POD活性在胁迫期间先上升后下降,均显著高于对照水平,且复水后仍然保持较高的活性;MDA含量随着干旱胁迫处理时间的延长而迅速增加,到胁迫第8天时达到最大值,复水后叶片中MDA含量迅速下降,到复水后第5天,胁迫组叶片中MDA含量已接近对照水平。综合各生理生化指标的变化情况来看,锡金微孔草具有较强的抗旱能力。     

Effects of exercise on skeletal muscle and serum enzyme activities in pigs

In order to determine skeletal muscle and serum enzyme activities following exercise, six adult Landrace pigs were submitted to 10 min running on a treadmill (0.5 m/s, on a 12% gradient) and compared to six controls. Blood samples were obtained just before the exercise, immediately after, and 24 h, 48 h and 144 h after exercise. Muscle biopsies were taken from the longissimus dorsi and biceps femoris 24 h after exercise. Total lactic dehydrogenase (LDH) and LDH isoenzymes in muscle and serum were unchanged. In muscle homogenates, there was no difference in total creatine phosphokinase (CK) activity between the two groups. Total CK activity in the biceps femoris muscle represented only 59% of that observed in the longissimus dorsi muscle. A mean CK-MB value of 2.5% was found in the control group for both muscles but after exercise it was 9.5% (p<0.05) for the biceps femoris and 12.2% (p<0.01) of the longissimus dorsi muscle. In serum, the total CK (p<0.05), CK-MM (p<0.05) and CK-BB (p<0.05) increased immediately after the exercise, followed by a progressive decrease.     

In ovo leptin administration accelerates post‐hatch muscle growth and changes myofibre characteristics,gene expression and enzymes activity in broiler chickens

To evaluate the effect of maternal leptin on muscle growth, we injected 0 μg (control, CON), 0.5 μg (low leptin dose, LL) or 5.0 μg (high leptin dose, HL) of recombinant murine leptin dissolved in 100 μl of PBS into the albumen of broiler eggs prior to incubation. The newly hatched chicks were all raised under the same conditions until 21 days of age (D21), when body weight was measured and samples of gastrocnemius muscle were collected and weighed. Myosin ATPase staining was applied to identify myofibre types and measure the cross‐sectional area (CSA) of myofibres. Real‐time PCR was performed to quantify leptin receptor (LEPR), insulin‐like growth factor 1 (IGF‐1), IGF‐1 receptor (IGF‐1R), growth hormone receptor (GHR) and myostatin (MSTN) mRNA expression in the gastrocnemius muscle. The activity of calpains (CAPNs) in the gastrocnemius muscle was measured using a quantitative fluorescence detection kit. Male chickens treated with both high and low doses of leptin had significantly higher (p < 0.05) body weight on D21. The high leptin significantly increased the CSA (p < 0.05) of gastrocnemius muscle in male chickens, which coincided with a 93% increase (p < 0.05) in IGF‐1 mRNA expression. Likewise, the LL dose increased the weight of gastrocnemius muscle in male chickens (p < 0.05), which was accompanied by a 41% down‐regulation (p < 0.05) of MSTN mRNA expression and a decreased activity of CAPNs. However, all these changes were not observed in female chickens. The proportion of myofibre types did not altered. No significant change was detected for LEPR and GHR mRNA expression. These results indicate that in ovo leptin treatment affects skeletal muscle growth in chickens in a dose‐dependent and sex‐specific manner. The altered expression of IGF‐1, MSTN mRNA and activity of CAPNs in skeletal muscle may be responsible for such effects.     

氮素对不同氮效率小黑麦基因型叶片保护酶活性和膜脂过氧化的影响

采用盆栽试验,以氮高效小黑麦基因型(PI429186)和氮低效小黑麦基因型(CIxt74)为材料,设置4个氮素水平0,0.25,0.50,和1.00 g N/盆,探讨氮素供应对不同氮效率小黑麦各生育期 (苗期、分蘖期、拔节期和最佳刈割时期-抽穗期) 植株地上部生物量、叶片保护性酶活性和膜脂过氧化程度的影响。结果表明,1) 在同一生育期同一供氮条件下,氮高效小黑麦基因型地上部生物量显著高于氮低效基因型。在同一生育期,小黑麦地上部生物量随供氮量的增加而增大,氮高效小黑麦基因型增加幅度大于氮低效基因型。2)氮高效小黑麦基因型的超氧化物歧化酶(superxoide dismutase,SOD)、过氧化物酶(peroxidase,POD)、过氧化氢酶(catalase,CAT)活性随生育期表现出在同一供氮条件下强于氮低效基因型的趋势,而膜脂过氧化产物丙二醛(malondialdehyde,MDA)含量显著低于氮低效基因型小黑麦。3)相关分析表明,小黑麦地上部生物量与SOD、POD、CAT活性的相关性因生育期不同其相关程度不一;地上部生物量与MDA含量呈负相关关系。这表明氮高效小黑麦基因型叶片保护酶在各生育期通过协同作用,共同起到阻止高浓度氧积累和膜脂过氧化,提高其光合性能,达到增产目的。     

Effects of dietary supplementation with carnosine on meat quality and antioxidant capacity in broiler chickens

1. This study aimed to investigate the effects of carnosine supplementation on meat quality, antioxidant capacity and lipid peroxidation status in broiler chickens.

2. A total of 256 1-d-old male Arbor Acres broilers were randomly assigned to 4 treatments consisting of 8 replicates of 8 chickens each. The birds were supplied with 4 different diets: a basal diet or a basal diet supplemented with 100, 200 or 400 mg/kg carnosine, respectively. The whole experiment lasted 42 d.

3. The results showed that dietary supplementation with carnosine linearly increased the values of pH_45 min and redness and reduced drip loss of breast meat. Dietary carnosine increased the activity of antioxidant enzymes in liver, serum and breast meat and decreased the contents of lipid peroxides at 21 and 42 d of age.

4. These findings indicated that dietary supplementation with carnosine was beneficial to enhance meat quality, antioxidant capacity and decrease lipid peroxidation status of breast meat.     

Increased expression of NOR‐1 mRNA in the skeletal muscles of cold‐exposed neonatal chicks

Nuclear receptor subfamily 4, group A (NR4A) subgroup orphan receptors are rapidly induced by various physiological stimuli and have been suggested to regulate oxidative metabolism and muscle mass in mammalian skeletal muscle. The results showed that the NR4A subgroup orphan receptor, NOR‐1 (NR4A3), was acutely increased in skeletal muscles of neonatal chicks in response to short‐term cold exposure. The increased NOR‐1 gene expression was concomitant with cold‐induced changes in gene expression of both myostatin and proliferator‐activated receptor‐gamma coactivator‐1 (PGC‐1α), and the increase in skeletal muscle mass. These observations suggest that NOR‐1 might play a role in controlling skeletal muscle growth in cold‐exposed neonatal chicks.     

Effects of dietary leucine on antioxidant activity and expression of antioxidant and mitochondrial‐related genes in longissimus dorsi muscle and liver of piglets

The study was conducted to investigate the effects of dietary leucine on antioxidant activity and expression of antioxidant‐ and mitochondrial‐related genes in longissimus dorsi muscle and liver of piglets. Three diets were formulated with different levels of supplemented leucine (0%, 0.25%, 0.5%). Results showed that supplementation of 0.25% leucine significantly increased antisuperoxide anion (ASA) and antihydroxyl radical (AHR) levels and activities of total superoxide dismutade (T‐SOD), glutathione peroxidase (GPx), glutathione S‐transferase (GST), and total antioxidant capacity (T‐AOC) in serum, longissimus dorsi muscle and liver of piglets as compared with the control group. The SOD2, catalase (CAT), GPx, GST, glutathione reductase (GR), and nuclear factor erythroid 2‐related factor 2 (Nrf2) mRNA levels in longissimus dorsi muscle and liver were significantly increased by 0.25% leucine supplementation. However, the malondialdehyde (MDA) content and the mRNA level of Kelch‐like ECH‐associated protein 1 (Keap1) exhibited an opposite tendency. Additionally, supplementation of 0.25% leucine significantly increased the mRNA levels of mitochondrial‐related genes in longissimus dorsi muscle and liver of piglets. Results suggested that supplementation of 0.25% leucine improved antioxidant activity and mitochondrial biogenesis and function of piglets, which was related to the increase in antioxidant enzymes activities and upregulation of expression of antioxidant‐ and mitochondrial‐related genes.     

Leucine‐induced promotion of post‐absorptive EAA utilization and hepatic gluconeogenesis contributes to protein synthesis in skeletal muscle of dairy calves

The high rate of protein synthesis in skeletal muscle of dairy calves can benefit their first lactation even lifetime milk yield. Since the rate of protein synthesis is relatively low in the post‐absorptive state, the aim of this research was to determine whether leucine supplementation could increase the post‐absorptive essential amino acid (EAA) utilization and protein synthesis in the skeletal muscle. Ten male neonatal dairy calves (38 ± 3 kg) were randomly assigned to either the control (CON, no leucine supplementation, n = 5) or supplementation with 1.435 g leucine/L milk (LEU, n = 5). Results showed that leucine significantly increased the length and protein concentration in longissimus dorsi (LD) muscle, whereas it decreased creatinine concentration and glutamic‐oxalacetic transaminase (GOT) activity. Compared to the control group, leucine supplementation also reduced the glutamic‐pyruvic transaminase (GPT) activity. Supplementation of leucine improved the phosphorylation of mammalian target of rapamycin (mTOR), eukaryotic initiation factor 4E‐binding protein 1 (4EBP1) and substrates ribosomal protein S6 kinase 1 (p70S6K). Supplementation of leucine resulted in increased concentrations of glucose, methionine, threonine, histidine and EAAs and decreased concentration of arginine in serum. Liver glucose concentration was higher and pyranic acid was lower in LEU compared to CON. In conclusion, leucine supplementation can promote post‐absorptive EAA utilization and hepatic gluconeogenesis, which contributes to protein synthesis in skeletal muscle of dairy calves.     

Effect of dosage and application mode of l‐carnitine on plasma lipid and egg‐yolk cholesterol of turkeys,hatchability of eggs and post‐hatch growth of their offsprings

The effect of dosage and application mode of l ‐carnitine on plasma lipid and egg‐yolk cholesterol of breeder turkeys, hatchability of eggs and post‐hatch growth response was investigated using 180 breeder hens. The hens were assigned to six dietary treatments in a 2 × 3 factorial arrangements of two application modes of l ‐carnitine (diet and drinking water) supplemented at 0, 50 and 100 ppm (mg/kg or mg/l) levels, respectively. Each treatment was replicated five times with six hens per replicate. Dietary inclusion of 50 ppm l ‐carnitine showed the lowest (p < 0.01) plasma total cholesterol (TC) and low‐density lipoprotein concentration (LDL). Breeder hens offered 50 ppm l ‐carnitine with no regard to application mode recorded the highest (p < 0.01) plasma high‐density lipoprotein (HDL). Hens offered 50 and 100 ppm l ‐carnitine irrespective of application mode also showed reduced (p < 0.01) egg‐yolk TC concentration at 32 weeks of age. Dietary supplementation of 50 ppm l ‐carnitine for breeder turkeys recorded the lowest (p < 0.01) egg‐yolk triglyceride (TG) at 40 weeks of age. Hens offered 50 ppm l ‐carnitine irrespective of application mode recorded the highest (p < 0.05) hen‐day egg production. Incidence of dead‐in‐shell also reduced (p < 0.05) with increasing dosage of l ‐carnitine. Dietary supplementation of 50 ppm and oral application in drinking water of 100 ppm l ‐carnitine for breeder turkeys resulted in highest (p < 0.05) egg fertility. Offsprings from breeder hens fed diets supplemented with l ‐carnitine recorded no post‐hatch mortality. Highest (p < 0.05) post‐hatch final live weight and weight gain was obtained with poults obtained from hens fed diet supplemented with 50 ppm l ‐carnitine. In conclusion, dietary supplementation of 50 ppm l ‐carnitine for turkey hens showed improved serum lipid profile, egg fertility, reduced dead‐in‐shell, egg‐yolk cholesterol and resulted in improved post‐hatch growth performance.     

Effects of a skullcap root supplement on haematology,serum parameters and antioxidant enzymes in rabbits on a high‐cholesterol diet

We studied the effects of Scutellaria baicalensis root on blood parameters and antioxidant enzyme activities in rabbits fed a high‐cholesterol diet. Thirty‐two New Zealand White rabbits were divided into four groups of eight animals each. They were fed a standard diet (C group), a diet with a 1% pure cholesterol supplement (CH group), a diet with a 1% pure cholesterol supplement and a 9% skullcap root supplement (CH + SR group), or a diet with a 9% skullcap root supplement (SR group). After 6 weeks, the rabbits fed the high‐cholesterol diet had significantly decreased RBC and Hb levels and significantly increased MCV, MCH and Fe levels (p ≤ 0.05). The skullcap root supplement had no adverse effects on the haematological parameters. The values for RBC, Hb, HCT, MCV, MCH and MCHC were similar in the skullcap root‐treated and control rabbits. We also observed a remarkable elevation in the serum TC, LDL and TG levels at the end of the 6‐week period. The rabbits fed the cholesterol diet showed decreased activity of the erythrocyte GSH‐Px compared with the rabbits fed the basal diet. The GSH‐Px activity was significantly higher in the rabbits fed the CH + SR diet than in those on the CH diet. The erythrocyte SOD activity was also significantly decreased in the rabbits on the CH diet. However, the CH + SR group rabbits showed significantly enhanced erythrocyte SOD activity. The SOD level in the CH + SR rabbits was 34.91 U/ml, which was a 23% increase (p ≤ 0.05) in relation to the results for the CH group and only 15% diminished in relation to the control group. These results suggest that the dietary supplementation of skullcap root may improve rabbit antioxidant systems and protect against the risks from a high‐cholesterol diet.     

Changes in the regulation and activity of glutathione redox system,and lipid peroxidation processes in short‐term aflatoxin B1 exposure in liver of laying hens

The purpose of this study was to investigate the short‐term (48 hr) effects of feeding aflatoxin contaminated diet (170.3 μg/kg AFB1) in 49‐week‐old laying hens. Liver samples were taken at 12‐hr intervals. Feed intake, body weight, absolute and relative liver weight were the same in groups. However, there was no feed intake during both dark periods (between 12nd to 24th and 36th to 48th hours of the experiment); therefore, aflatoxin intake was also negligible. Markers of initial phase of lipid peroxidation, conjugated dienes and trienes did not change as effect of aflatoxin, but terminal marker, malondialdehyde content was significantly higher at 12 hr as effect of aflatoxin. No significant difference was found in reduced glutathione concentration and glutathione peroxidase activity between the groups. Expression of glutathione peroxidase 4 gene (GPX4) was significantly reduced due to aflatoxin treatment at 12 and 24 hr, but induced later, while glutathione reductase gene (GSR) expression was significantly lower at 24 hr and glutathione synthetase gene (GSS) in aflatoxin‐treated group at 12 hr. The results suggest that aflatoxin induced oxygen‐free radical formation, but it did not reach critical level during this short period of time to cause activation of the expression of glutathione system.     

Effects of rice feeding and carnitine addition on growth performance and mRNA expression of protein metabolism‐related genes in broiler grower chicks

This study was carried out to evaluate the nutritional effects of rice feeding and carnitine addition to a diet for broiler chicks. Thirty‐six male 10‐day‐old broiler chicks were assigned to one of the following four treatment groups: corn‐based diet (corn group), rice‐based diet (rice group), and each diet with added carnitine (100 ppm). The experimental period was 2 weeks. Rice feeding resulted in significantly higher growth performance (body weight gain and feed efficiency) compared to corn feeding. Carnitine addition also resulted in higher growth performance. Breast muscle and thigh muscle weight (g) were significantly higher in broiler chicks fed rice and those fed diets with added carnitine. Liver mRNA expression of IGF‐I was significantly higher in broiler chicks fed rice compared to those fed corn. There was no significant difference in mRNA expression of muscle atrogin‐1 or liver CPT‐I between broiler chicks fed rice and those fed corn, not between broilers chicks fed diets containing carnitine or not. Overall, these results show that rice feeding and carnitine addition improve the growth performance of broiler chicks by increasing mRNA expression of liver IGF‐I. In addition, carnitine action is not affected by different cereals (corn and rice).     

Effect of dexamethasone on the expression of atrogin‐1/MAFbx in chick skeletal muscle

Expression of atrogin‐1/MAFbx, a muscle‐specific E3 ubiquitin ligase, is high under catabolic conditions, that result in muscle atrophy. Messenger RNA (mRNA) expression of atrogin‐1/MAFbx is increased by the glucocorticoid dexamethasone in mammalian skeletal muscle. This study investigated the effects of dexamethasone on expression of atrogin‐1/MAFbx in skeletal muscle of neonatal chicks and in chick myotubes. Chicks were given a single intraperitoneal injection of dexamethasone at a concentration of 10 mg/kg body weight. Twenty‐four hours after dexamethasone administration, the Pectoralis muscle weight of chicks was decreased. mRNA expression of atrogin‐1/MAFbx in skeletal muscle of chicks was significantly increased by dexamethasone administration. Expression of other proteolytic‐related genes (20S proteasome C2 subunit, m‐calpain large subunit, and cathepsin B) in skeletal muscle of chicks was not increased by dexamethasone administration. Chick myotubes were incubated with dexamethasone (1, 10 or 100 µmol/L) for 6 h. Expression of atrogin‐1/MAFbx mRNA in chick myotubes was increased in the presence of all concentrations of dexamethasone. However, expression of other proteolytic‐related genes (20S proteasome C2 subunit, m‐calpain large subunit and cathepsin B) in chick myotubes was not affected by dexamethasone treatment. These results indicate that dexamethasone enhances atrogin‐1/MAFbx expression in chick skeletal muscle, resulting in increased muscle atrophy.     

Effect of biologically active substances present in water extracts of white mustard and coriander on antioxidant status and lipid peroxidation of mouse C2C12 skeletal muscle cells

Coriander and white mustard, an annual plants originated in the Mediterranean region, have been cultivated and used as spices for a long time. Recent studies have shown that they may constitute a potential source of phenolic compounds. The aim of this study was to evaluate the content of polyphenols in coriander and white mustard water extracts and to investigate their antioxidant activity in C2C12 mouse skeletal muscle cells, which serve as a good model of cells with intensive metabolism. HPLC analysis showed that polyphenols were able to permeate from the water extracts of studied plants into the undifferentiated myoblasts as well as myocytes undergoing differentiation, increasing the concentration of reduced glutathione and upregulating glutathione reductase and peroxidase activity. White mustard and coriander extracts also decreased the levels of oxysterols and sum of tiobarbituric acid reactive substances (TBARS) in both: myoblasts and differentiating myocytes, demonstrating protective effect on cell membranes. The obtained results indicate that polyphenols synthesized by both herbs may have beneficial effects on muscle tissue.