担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nutrients  

Sarcopenia is the decline in skeletal muscle mass, strength, and functions, which decreases the quality of life in elderly people. This study investigated the suppressive effect of turmeric (Curcuma longa) extract (TE) on muscle atrophy in dexamethasone (DEX)-treated mice and C2C12 myotubes. DEX treatment significantly decreased the muscle weight and significantly increased Fbxo32 and Murf1 expression in mice, and these changes were suppressed by the supplementation of an AIN-93 based diet with 2% TE. A similar pattern was observed in FBXO32 and MuRF1 protein expression. In C2C12 myotubes, DEX treatment significantly increased FBXO32 and MuRF1 gene and protein expression, and these increases were significantly suppressed by TE supplementation at a concentration of 200 µg/mL. Furthermore, one of the five TE fractions, which were separated by high-performance liquid chromatography had a similar effect with TE supplementation. The present study proposes the suppressive effect of turmeric on sarcopenia.

DOI： 10.3390/nu14193979

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PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Cachexia, Sarcopenia and Muscle  

Background: Cachexia is a life-threatening condition observed in several pathologies, such as cancer or chronic diseases. Interleukin 10 (Il10) gene transfer is known to improve cachexia by downregulating Il6. Here, we used an IL10-knockout mouse model to simulate cachexia and investigate the effects of eggshell membrane (ESM), a resistant protein, on general pre-cachexia symptoms, which is particularly important for the development of cachexia therapeutics. Methods: Five-week-old male C57BL6/J mice were fed an AIN-93G powdered diet (WT), and 5-week-old male B6.129P2-Il10 < tm1Cgn>/J (IL10−/−) mice were fed either the AIN-93G diet (KO) or an 8% ESM-containing diet (KOE) for 28 weeks. The tissue weight and levels of anaemia-, blood glucose-, lipid metabolism-, and muscular and colonic inflammation-related biochemical markers were measured. Transcriptomic analysis on liver and colon mucus and proteomic analysis on skeletal muscle were performed. Ingenuity Pathway Analysis was used to identify molecular pathways and networks. Caecal short-chain fatty acids (SCFAs) were identified using HPLC, and caecal bacteria DNA were subjected to metagenomic analysis. Flow cytometry analysis was performed to measure the CD4+ IL17+ T cells in mesenteric lymph nodes. Results: The body weight, weight of gastrocnemius muscle and fat tissues, colon weight/length ratio, plasma HDL and NEFA, muscular PECAM-1 levels (P < 0.01), plasma glucose and colonic mucosal myeloperoxidase activity (P < 0.05) and T helper (Th) 17 cell abundance (P = 0.071) were improved in KOE mice over KO mice. Proteomic analysis indicated the protective role of ESM in muscle weakness and maintenance of muscle formation (>1.5-fold). Transcriptomic analysis revealed that ESM supplementation suppressed the LPS/IL1-mediated inhibition of RXR function pathway in the liver and downregulated the colonic mucosal expression of chemokines and Th cell differentiation-related markers (P < 0.01) by suppressing the upstream BATF pathway. Analysis of the intestinal microenvironment revealed that ESM supplementation ameliorated the microbial alpha diversity and the abundance of microbiota associated with the degree of inflammation (P < 0.05) and increased the level of total organic acids, particularly of SCFAs such as butyrate (2.3-fold), which could inhibit Th1 and Th17 production. Conclusions: ESM supplementation ameliorated the chief symptoms of cachexia, including anorexia, lean fat tissue mass, skeletal muscle wasting and reduced physical function. ESM also improved colon and skeletal muscle inflammation, lipid metabolism and microbial dysbiosis. These results along with the suppressed differentiation of Th cells could be associated with the beneficial intestinal microenvironment and, subsequently, attenuation of pre-cachexia. Our findings provide insights into the potential of ESM in complementary interventions for pre-cachexia prevention.

DOI： 10.1002/jcsm.13019

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Animal Science  

This study determined the oxidation of amino acids, glucose and fatty acid in enterocytes of developing chickens. Jejunal enterocytes were isolated from 0-, 7-, 21-, and 42-d-old broiler chickens, and incubated at 40°C for 30 min in Krebs-Henseleit bicarbonate buffer (pH 7.4) containing 5 mM D-glucose and one of the following: 0.5-5 mM L-[U-14C]glutamate, 0.5-5 mM L-[U-14C]glutamine, 0.5-5 mM L-[U-14C]aspartate, 0.5-5 mM L-[U-14C]alanine, 0.5-2 mM [U-14C]palmitate, D-[U-14C]glucose, 0.5-5 mM [U-14C]propionate, and 0.5-5 mM [1-14C]butyrate. 14CO2 produced from each 14C-labeled substrate was collected for determination of radioactivity. Among all the substrates studied, glutamate had the greatest rate of oxidation in enterocytes from 0- to 42-d-old chickens. Glutamate transaminases, rather than glutamate dehydrogenase, may be primarily responsible for initiating glutamate degradation. Rates of amino acid and fatty acid oxidation by cells increased (P < 0.05) with increasing their extracellular concentrations from 0.5 to 5 mM. Rates of glutamate and glucose oxidation in enterocytes decreased (P < 0.05) with increasing age, and rates of glutamine, aspartate, propionate, and butyrate oxidation were lower (P < 0.05) in 42-d-old chickens than in 0-d-old chickens. By contrast, oxidation of palmitate at 2 mM increased (P < 0.05) by 118% in cells from 42-d-old chickens, compared with 0-d-old chickens. Compared with glutamate, oxidation of glutamine, aspartate, alanine, propionate, butyrate, and palmitate was limited in cells from all age groups of chickens. Collectively, these results indicate that glutamate is the major metabolic fuel in enterocytes of 0- to 42-d-old chickens.

DOI： 10.1093/jas/skac053

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PubMed

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Amino Acids  

Polyamines (putrescine, spermidine, and spermine) are synthesized primarily from ornithine via ornithine decarboxylase (ODC) in mammals. Although avian tissues contain ODC activity, little is known about intracellular sources of ornithine for their polyamine synthesis. This study tested the hypothesis that arginase and proline oxidase contribute to polyamine synthesis in chickens. Kidney, jejunum, leg muscle, and liver from 0-, 7-, 14- and 21-day-old broiler chickens were assayed for the activities of arginase, proline oxidase (POX), ornithine aminotransferase (OAT), and ornithine decarboxylase (ODC). Kidney slices were also used to determine 14C-polyamine synthesis from [U-14C]arginine and [U-14C]proline. Furthermore, these tissues and plasma were analyzed for polyamines. Results indicate that all tissues contained OAT (mitochondrial) and ODC (cytosolic) activities, but arginase and POX activities were only detected in the mitochondria of chicken kidneys. Renal POX and arginase activities were greater at 7 days of age compared to newly hatched birds, and declined by Day 14. Renal arginase activity was greater at 21 days compared to 14 days of age, but there was no change in renal POX activity during that same period. Concentrations of polyamines in the kidneys and plasma were greater on Day 7 compared to Day 0 and decreased thereafter on Days 14 and 21. Kidney slices readily converted arginine and proline into polyamines, with peak rates being on Day 7. Concentrations of putrescine, spermidine and spermine in the plasma of chickens were about 20- to 100-fold greater than those in mammals. Our results indicate that polyamines are synthesized from arginine and proline in avian kidneys. Unlike mammals, polyamines released from the kidneys are likely the major source of polyamines in the blood and other extra-renal tissues in chickens.

DOI： 10.1007/s00726-021-03084-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Advances in Experimental Medicine and Biology  

L-glutamine (Gln) is the most abundant amino acid (AA) in the plasma and skeletal muscle of poultry, and L-glutamate (Glu) is among the most abundant AAs in the whole bodies of all avian tissues. During the first-pass through the small intestine into the portal circulation, dietary Glu is extensively oxidized to CO2, but dietary Gln undergoes limited catabolism in birds. Their extra-intestinal tissues (e.g., skeletal muscle, kidneys, and lymphoid organs) have a high capacity to degrade Gln. To maintain Glu and Gln homeostasis in the body, they are actively synthesized from branched-chain AAs (abundant AAs in both plant and animal proteins) and glucose via interorgan metabolism involving primarily the skeletal muscle, heart, adipose tissue, and brain. In addition, ammonia (produced from the general catabolism of AAs) and α-ketoglutarate (α-KG, derived primarily from glucose) serve as substrates for the synthesis of Glu and Gln in avian tissues, particularly the liver. Over the past 20 years, there has been growing interest in Glu and Gln metabolism in the chicken, which is an agriculturally important species and also a useful model for studying some aspects of human physiology and diseases. Increasing evidence shows that the adequate supply of dietary Glu and Gln is crucial for the optimum growth, anti-oxidative responses, productivity, and health of chickens, ducklings, turkeys, and laying fowl, particularly under stress conditions. Like mammals, poultry have dietary requirements for both Glu and Gln. Based on feed intake, tissue integrity, growth performance, and health status, birds can tolerate up to 12% Glu and 3.5% Gln in diets (on the dry matter basis). Glu and Gln are quantitatively major nutrients for chickens and other avian species to support their maximum growth, production, and feed efficiency, as well as their optimum health and well-being.

DOI： 10.1007/978-3-030-74180-8_7

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nutrients  

Skin aging is one of the hallmarks of the aging process that causes physiological and morphological changes. Recently, several nutritional studies were conducted to delay or suppress the aging process. This study investigated whether nutritional supplementation of the eggshell membrane (ESM) has a beneficial effect on maintaining skin health and improving the skin aging process in vitro using neonatal normal human epidermal keratinocytes (NHEK‐Neo) and in vivo using in-terleukin‐10 knockout (IL‐10 KO) mice. In NHEK‐Neo cells, 1 mg/mL of enzymatically hydrolyzed ESM (eESM) upregulated the expression of keratinocyte differentiation markers, including keratin 1, filaggrin and involucrin, and changed the keratinocyte morphology. In IL‐10 KO mice, oral sup-plementation of 8% powdered‐ESM (pESM) upregulated the expression of growth factors, including transforming growth factor β1, platelet‐derived growth factor‐β and connective tissue growth factor, and suppressed skin thinning. Furthermore, voltage‐gated calcium channel, transient receptor potential cation channel subfamily V members were upregulated by eESM treatment in NHEK‐ Neo cells and pESM supplementation in IL‐10 KO mice. Collectively, these data suggest that ESM has an important role in improving skin health and aging, possibly via upregulating calcium sig-naling.

DOI： 10.3390/nu13072144

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Amino Acids  

While it has been hypothesized that brown adipocytes responsible for mammalian thermogenesis are absent in birds, the existence of beige fat has yet to be studied directly. The present study tests the hypothesis that beige fat emerges in birds as a mechanism of physiological adaptation to cold environments. Subcutaneous neck adipose tissue from cold-acclimated or triiodothyronine (T3)-treated chickens exhibited increases in the expression of avian uncoupling protein (avUCP, an ortholog of mammalian UCP2 and UCP3) gene and some known mammalian beige adipocyte-specific markers. Morphological characteristics of white adipose tissues of treated chickens showed increased numbers of both small and larger clusters of multilocular fat cells within the tissues. Increases in protein levels of avUCP and mitochondrial marker protein, voltage-dependent anion channel, and immunohistochemical analysis for subcutaneous neck fat revealed the presence of potentially thermogenic mitochondria-rich cells. This is the first evidence that the capacity for thermogenesis may be acquired by differentiating adipose tissue into beige-like fat for maintaining temperature homeostasis in the subcutaneous fat ‘neck warmer’ in chickens exposed to a cold environment.

DOI： 10.1007/s00726-021-02953-5

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PubMed

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Domestic Animal Endocrinology  

Excess glucocorticoid secretion induces oxidative damage and muscle proteolysis and modulates glucose and lipid metabolism. It is known that the high-temperature (HT) treatment enhances corticosterone (CORT) secretion, muscle proteolysis, and mitochondrial reactive oxygen species (mtROS) generation in chickens. The present study investigated the co-effects of CORT on proteolysis and mtROS production, together with glucose, fatty acid, and amino acid metabolism in HT-treated cells. Myoblast cells were isolated from the major pectoralis muscle of five 0- or 1-day-old neonatal chicks and were precultured at 37°C/CO2 conditions for 48 h to reach subconfluent (80%–90%) conditions. Cells were then reseeded onto a 6- or 24-well microplate for the subsequent measurement, followed by the culture under a control temperature (37°C, control) or HT (41°C) conditions for 1 or 6 h. The HT-treated cells were cocultured with physiologically relevant concentrations of CORT (20 ng/mL in dimethyl sulfoxide). The HT treatment decreased cellular protein content (P < 0.05) and increased atrogin-1 mRNA levels and mtROS generation levels compared to the control group (P < 0.05), whereas HT/CORT co-treatment did not induce changes in either parameter. The mRNA level of glucose transporter-1 was decreased in HT-treated cells compared to that in normal cells (P < 0.05), and the decrease was increased in the CORT co-treatment (P < 0.05). While HT treatment did not alter pyruvate dehydrogenase kinase-4 mRNA level, the level was increased in the CORT co-treatment compared to the control and HT-treated cells (P < 0.05). Neither HT nor HT/CORT treatments altered the mRNA levels of fatty acid oxidation-related factors, carnitine palmitoyl transferase-1, and cluster of differentiation 36. The study conducted a metabolic analysis using gas chromatography-mass spectrometry. The results showed that HT/CORT-treated cells had decreased intracellular citrate and α-ketoglutarate levels (P < 0.05) and increased extracellular alanine and amino acid that have gluconeogenic properties, as well as increased aspartate, isoleucine, serine, methionine, and threonine levels (P < 0.05) compared to HT-treated cells. These results suggest that CORT may not affect proteolysis and mtROS production but can suppress pyruvate oxidation and promote alanine production in HT-treated chickens.

DOI： 10.1016/j.domaniend.2021.106608

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PubMed

担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nutrients  

Several genome-wide association studies (GWASs) have reported the association between genetic variants and the habitual consumption of foods and drinks; however, no association data are available regarding the consumption of black tea. The present study aimed to identify genetic variants associated with black tea consumption in 12,258 Japanese participants. Data on black tea consumption were collected by a self-administered questionnaire, and genotype data were obtained from a single nucleotide polymorphism array. In the discovery GWAS, two loci met suggestive significance (p < 1.0 × 10−6). Three genetic variants (rs2074356, rs144504271, and rs12231737) at 12q24 locus were also significantly associated with black tea consumption in the replication stage (p < 0.05) and during the meta-analysis (p < 5.0 × 10−8). The association of rs2074356 with black tea consumption was slightly attenuated by the additional adjustment for alcohol drinking frequency. In conclusion, genetic variants at the 12q24 locus were associated with black tea consumption in Japanese populations, and the association is at least partly mediated by alcohol drinking frequency.

DOI： 10.3390/nu12103182

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers in Veterinary Science  

Broiler chickens are highly sensitive to high ambient temperatures due to their feathers, lack of skin sweat glands, and high productivity. Heat stress (HS) is a major concern for the poultry industry because it negatively affects growth as well as immune functions, which increase the potential risk of infectious disease outbreaks. Therefore, it is vital to elucidate HS's effect on the avian immune system, especially considering the global rise in average surface temperature. Our study identified a series of immunological disorders in heat-stressed broiler chickens. We exposed 22-day-old broiler chickens to a continuous HS condition (34.5 ± 0.5°C) for 14 days and immunized them with a prototype bovine serum albumin (BSA) antigen. The plasma and lymphoid tissues (thymus, bursa of Fabricius, and spleen) were harvested at the end of the experiments to investigate the induction of BSA-specific immune responses. Our results revealed that plasma titers of immunoglobulin (Ig)Y, IgM, and IgA antibodies specific for BSA were lower than those of thermoneutral chickens immunized with BSA. Furthermore, the spleens of the heat-stressed broiler chickens displayed severe depression of Bu1+ B cells and CD3+ T cells, including CD4+ T cells and CD8+ T cells, and lacked a fully developed germinal center (GC), which is crucial for B cell proliferation. These immunological abnormalities might be associated with severe depression of CD4−CD8− or CD4+CD8+ cells, which are precursors of either helper or killer T cells in the thymus and Bu1+ B cells in the bursa of Fabricius. Importantly, HS severely damaged the morphology of the thymic cortex and bursal follicles, where functional maturation of T and B cells occur. These results indicate that HS causes multiple immune abnormalities in broiler chickens by impairing the developmental process and functional maturation of T and B cells in both primary and secondary lymphoid tissues.

DOI： 10.3389/fvets.2020.00046

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PubMed

掲載種別：研究論文（学術雑誌）   出版者・発行元：Food Science and Nutrition  

Obesity is a major global lifestyle disorder associated with gut microbiota. The health benefits of eggshell membrane (ESM) have been shown in previous reports, particularly as regards gut microbiota composition. Here, we investigated whether ESM improves lipid metabolism and alters gut microbiota in high-fat diet-fed mice. A total of 20 C57BL/6J mice aged 6 weeks were given either a control diet (CON), high-fat diet (HFD), or high-fat diet + 8% ESM powder (HESM) for 20 weeks. ESM supplementation in HFD-fed mice reduced plasma triglycerides (TG) and liver total cholesterol (TC) and upregulated the expression of lipid metabolism genes carnitine palmitoyltransferase 1A and suppressor of cytokine signaling 2. Microbiota analysis showed increased relative abundance of the anti-obesity bacterium, Lactobacillus reuteri, at 4, 12, and 16 weeks and reduced the abundance of inflammation-related Blautia hydrogenotrophica, Roseburia faecis, and Ruminococcus callidus at 12 and 20 weeks. ESM-supplemented mice had increased cecal isobutyrate, negatively correlated with B. hydrogenotrophica and Parabacteroides goldsteinii abundance. The results indicate that ESM supplementation in HFD-fed mice reduced plasma TG and liver TC, possibly through alteration of lipid metabolism gene expression and gut microbiota composition, suggesting that ESM may be effective in obesity management.

DOI： 10.1002/fsn3.1545

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掲載種別：研究論文（学術雑誌）   出版者・発行元：British Poultry Science  

1. Oleuropein (Ole) is a major phenolic compound in Olea europaea, with anti-oxidative, anti-obesity, and anti-inflammatory properties. To explore the effect of Ole on the physiology and metabolism of poultry, this study, evaluated the effects of feeding low-dose Ole on the growth performance, metabolic hormonal status, muscle oxidative status in growing broiler chickens. 2. Thirty-two 8-day-old chickens were assigned to four different treatments, and fed either 0 (control), 0.1, 0.5, or 2.5 ppm Ole-supplemented diets for 2 weeks. 3. There were no differences in the body weight gain, feed consumption, and feed efficiency during the feeding periods between the groups tested. Birds fed Ole 0.5- and 2.5 ppm-supplemented diets exhibited a significant decrease in muscle carbonyl content compared to the control group. In the group fed Ole 0.5 ppm, the mRNA expression levels of mitochondrial ROS-reducing factors: avian uncoupling protein and manganese superoxide dismutase, as well as peroxisome proliferator-activated receptor γ coactivator 1-α, sirtuin-1 and −3 (each of which co-ordinately induce the transcription of the previous two factors) were upregulated compared to the control group, and the changes were independent of plasma noradrenaline and thyroid hormone levels. The group fed Ole-2.5 ppm did not show such transcriptional changes, but exhibited a higher corticosterone concentration. 4. This study demonstrates that ingesting a low dose of Ole can reduce muscle oxidative damage, and that the suppression machinery may differ depending on the amount of Ole ingested by growing broiler chickens.

DOI： 10.1080/00071668.2019.1662886

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PubMed

掲載種別：研究論文（学術雑誌）   出版者・発行元：EAAP Scientific Series  

Harmful effects of heat stress on organisms are a matter of concern for environmental health and global warming. High ambient temperature, whether it is ‘acute' or ‘chronic' in nature, constitutes a significant hindrance to the growth of animals. Heat-induced reactive oxygen species (ROS) formation may be a factor that causes molecular changes in DNA, proteins, lipids and other biological molecules. To create a method for nutritional regulation of ROS production and protein degradation of skeletal muscle in heat-stressed chickens, we focused on elucidating underlying effects of heat stress on ROS production of skeletal muscle with two models to identify conditions for making broiler chickens more tolerant to heat stress. ‘Acute' heat stress in broiler chickens under 34 °C conditions induces increased mitochondrial ROS production via increased β-oxidation and downregulation of the avian form of mitochondrial uncoupling protein (avUCP), resulting in higher oxidative damage to mitochondrial proteins and lipids. Similarly, ‘chronic' heat stress induces increased ROS production in skeletal muscle mitochondria, probably via elevation of the membrane potential DY in state 4, resulting from enhanced oxygen consumption in the initial stage of heat exposure. However, animals can become acclimatized to environmental heat stress. Muscle protein degradation can occur after a short time (3 d) after heat exposure and this may be due to the activation of ubiquitination by atrogin-1 involved with mitochondrial ROS production. Nutritional regulation of ROS production and protein degradation, such as via enhanced avUCP gene expression, are important for making broiler chickens more tolerant to heat stress.

DOI： 10.3920/978-90-8686-891-9_5

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Animal Science Journal  

It has been shown that oleuropein, a phenolic compound in the fruit and leaves of the olive tree (Olea europaea) induces mammalian uncoupling protein 1 (UCP1) expression via an increased secretion of noradrenaline and adrenaline. This study investigated the effects of oleuropein on avian UCP (avUCP) expression as well as genes related to mitochondrial oxidative phosphorylation and biogenesis in cultured avian muscle cells, together with reactive oxygen species generation. Oleuropein induced avUCP as well as peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), nuclear respiratory factor-1 (NRF1), mitochondrial transcription factor A (TFAM) and ATP5a1 (a component of mitochondrial adenosine triphosphate synthase) gene expression and cytochrome c oxidase activity, indicating the induction of mitochondrial biogenesis. Sirtuin-1 (SIRT1) gene expression was also up-regulated by this compound, which could contribute to an increase in PGC-1α activity. Oleuropein suppressed the level of superoxide generation per mitochondrion, possibly via the up-regulation of avUCP and manganese superoxide dismutase (MnSOD) expression. Based on these findings, this study is the first to show that oleuropein may induce avUCP expression in avian muscle cells independent of the catecholamines, in which PGC-1α may be involved.

DOI： 10.1111/asj.12559

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：General and Comparative Endocrinology  

Heat stress (HS) induces muscle protein degradation as well as production of mitochondrial reactive oxygen species (ROS). In the present study, to improve our understanding of how protein degradation is induced by HS treatment in birds, a time course analysis of changes in the circulating levels of glucocorticoid and Nτ-methylhistidine, muscle proteolysis-related gene expression, and mitochondrial ROS generation, was conducted. At 25 days of age, chickens were exposed to HS conditions (33 °C) for 0, 0.5, 1 or 3 days. While no alteration in plasma Nτ-methylhistidine concentration relative to that of the control group was observed in the 0.5 day HS group, the concentration was significantly higher in the 3-d HS treatment group. Plasma corticosterone concentrations increased in response to 0.5-d HS treatment, but subsequently returned to near-normal values. HS treatment for 0.5 days did not change the levels of μ-calpain, cathepsin B, or proteasome C2 subunit mRNA, but increased the levels of mRNA encoding atrogin-1 (P < 0.05) and its transcription factor, forkhead box O3 (P = 0.09). Under these hyperthermic conditions, mitochondrial superoxide production was significantly increased than that of thermoneutral control. Here, we show that HS-induced muscle protein degradation may be due to the activation of ubiquitination by atrogin-1, and that this process may involve mitochondrial ROS production as well as corticosterone secretion.

DOI： 10.1016/j.ygcen.2016.02.007

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Poultry Science  

Heat stress (HS) stimulates mitochondrial reactive oxygen species (ROS) production and protein degradation in skeletal muscle. The present study investigated the stimulatory effects of HS-induced mitochondrial ROS production on the ubiquitin-proteasome protein degradation system in primary cultured avian muscle cells. Cells were isolated from the breast muscle of neonatal chicks, and then grown for 48 h. Thereafter, the cells were subjected to 37�C or 41�C (HS). Exposure to 6 h of HS treatment significantly decreased the cellular protein content compared to that of normal cells, an effect was completely suppressed by the addition of a proteasome-specific inhibitor. Whereas the mRNA levels of the 20S proteasome C2 subunit, which is one of the subunits of the 26S proteasome, did not change at any time during HS treatment (1, 3, 6 h), the mRNA levels of atrogin-1 and muscle ring-finger protein 1, both of which are muscle-specific ubiquitin ligases, increased after 1 h of HS but then decreased to near-normal values with time. Intracellular ROS production (the sum of H2O2, hydroxyl radicals, peroxyl radicals, peroxynitrite) did not change in the 1 h HS-exposed cells, but was significantly increased after 3 h and 6 h of HS. Mitochondrial superoxide production was significantly increased after 1 h of HS, which might increase the mRNA expression of ubiquitin ligase in muscle cells. In cells pretreated with 4-hydroxy TEMPO, which is able to decrease mitochondrial superoxide production, the increases in mitochondrial superoxide production and ubiquitin ligase mRNA levels observed after 1 h of HS were suppressed. The protein content of these cells was not decreased, which was observed after the longest period of HS (6 h). These findings suggest that mitochondrial superoxide production may play an important role in activating the ubiquitin-proteasome system, probably via the induction of ubiquitin ligases, in HS-exposed muscle cells.

DOI： 10.2141/jpsa.0150028

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記述言語：日本語   出版者・発行元：家畜栄養生理研究会  

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記述言語：英語   出版者・発行元：(公社)日本畜産学会  

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記述言語：英語   出版者・発行元：家畜栄養生理研究会  

ニワトリ骨格筋におけるミトコンドリアの酸化的リン酸化および活性酸素産生の代謝調節能

CiNii Books

その他リンク： https://agriknowledge.affrc.go.jp/RN/2010902949

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記述言語：日本語   出版者・発行元：家畜栄養生理研究会  

暑熱環境下における肉用鶏の生産性低下は古くからの問題であり、近年激化の様相を示す夏季の暑熱によって肉用鶏産業が大きな損失を被ることは想像に難くない。それゆえに、暑熱時に発生する肉用鶏生産の量的・質的な低下を改善する生産技術体系の確立は重要な課題である。暑熱ストレスによる生産性の低下を真に改善するためには、肉用鶏が暑熱下でどのような生理反応・生体応答を示しているのか、その全貌を明らかにすることが肝要である。これまでの研究において、暑熱環境下では熱放散促進のための浅速呼吸にともなう呼吸性アルカローシスの発症、甲状腺ホルモンの低下・コルチコステロンの増加にともなう体タンパク質分解亢進、腸管微絨毛の損傷・免疫応答の変化ならびにミトコンドリア活性酸素(reactive oxygen species、ROS)の過剰産生による酸化ストレスが生じることが明らかにされている。このため、呼吸性アルカローシス発症を抑制するための重曹(重炭酸ナトリウム)の給与や、酸化ストレス発生抑制のためのビタミンCやビタミンE、ポリフェノール類、電解還元水といった抗酸化物質の給与による暑熱ストレス緩和の有効性が調べられてきている。しかしながら、これらはいずれも暑熱時の生産性を真に改善するまでには至っておらず、暑熱時の生体応答の一部改善を目的とした対策としては十分ではない。

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その他リンク： https://agriknowledge.affrc.go.jp/RN/2010873699

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