酢酸摂取と運動が脂肪代謝と運動耐久性に及ぼす影響

Previously, we found that acetic acid had effects on lipid metabolism in skeletal muscles and has functions that work against obesity and obesity-linked type 2 diabetes through the activation of AMPactivated protein kinase (AMPK). During exercise, AMPK is activated in skeletal muscle according to exercise intensity and it increases fatty acid oxidation. The purpose of this study was to investigate the interactive effects of chronic intake of acetic acid and exercise training on lipid metabolism and endurance performance. Six-week-old SD rats were randomly assigned to four groups: water-injected (rest-water), acetic acid-injected (rest-ace), exercise-trained after injection of water (water-ex), and exercise-trained after injection of acetic acid (ace-ex) for 4 weeks. Body weight (BW) in rest-ace and ace-ex groups was significantly lower than rest-water group. Exercise-training groups showed an increase of exercise capacity, by the addition of intake of acetic acid, lipid oxidation was promoted during exercise tolerance test. Skeletal muscle of rats treated with acetic acid and exercise training led to higher expressions of cytochrome c (cycs), and tended to stimulate expressions of peroxisome proliferator-activated receptor coactivator 1-α (PGC1-α ) and MHC1 genes than those of rest-water group. Those results indicate that treatments both of exercise training and intake of acetic acid contribute to enhancement of lipid metabolism and improvement of exercise capacity.これまで我々は、酢酸の摂取が骨格筋内のAMP活性化プロテインキナーゼ（AMPK）の活性化を介して脂質代謝と肥満、肥満に関連した2型糖尿病の予防に効果があることを示唆してきた。AMPKは運動によって骨格筋で活性化し、脂肪酸酸化を促進する。この研究は、4週間の継続的な酢酸摂取と運動トレーニングが運動中の脂肪代謝と運動耐久性に及ぼす影響について調べることを目的とした。　6週齢のSD系雄ラットを安静期に水を摂取するrest-water群、酢酸を摂取するrest-ace群、運動前に水を摂取するwater-ex群、運動前に酢酸を摂取するace-ex群に無作為に分け実験を行った。酢酸を継続的に摂取すると水摂取に比較して腹腔内脂肪量の減少と体重増加の抑制がみられた。また継続的な酢酸摂取および運動トレーニングにより、耐久性運動下でのグルコース利用の抑制および脂肪酸酸化の促進が見られた。酢酸摂取および運動トレーニング群の腓腹筋では、MHCIおよびcytochrome c等の遅筋線維マーカー遺伝子が増加していた。継続的な酢酸摂取と運動トレーニングにより、脂肪代謝と運動耐久性の向上が示唆された

A multicentric consortium study demonstrates that dimethylarginine dimethylaminohydrolase 2 is not a dimethylarginine dimethylaminohydrolase

Dimethylarginine dimethylaminohydrolase 1 (DDAH1) protects against cardiovascular disease by metabolising the risk factor asymmetric dimethylarginine (ADMA). However, the question whether the second DDAH isoform, DDAH2, directly metabolises ADMA has remained unanswered. Consequently, it is still unclear if DDAH2 may be a potential target for ADMA-lowering therapies or if drug development efforts should focus on DDAH2's known physiological functions in mitochondrial fission, angiogenesis, vascular remodelling, insulin secretion, and immune responses. Here, an international consortium of research groups set out to address this question using in silico, in vitro, cell culture, and murine models. The findings uniformly demonstrate that DDAH2 is incapable of metabolising ADMA, thus resolving a 20-year controversy and providing a starting point for the investigation of alternative, ADMA-independent functions of DDAH2

Activation of AMP-Activated Protein Kinase and Stimulation of Energy Metabolism by Acetic Acid in L6 Myotube Cells.

Previously, we found that orally administered acetic acid decreased lipogenesis in the liver and suppressed lipid accumulation in adipose tissue of Otsuka Long-Evans Tokushima Fatty rats, which exhibit hyperglycemic obesity with hyperinsulinemia and insulin resistance. Administered acetic acid led to increased phosphorylation of AMP-activated protein kinase (AMPK) in both liver and skeletal muscle cells, and increased transcripts of myoglobin and glucose transporter 4 (GLUT4) genes in skeletal muscle of the rats. It was suggested that acetic acid improved the lipid metabolism in skeletal muscles. In this study, we examined the activation of AMPK and the stimulation of GLUT4 and myoglobin expression by acetic acid in skeletal muscle cells to clarify the physiological function of acetic acid in skeletal muscle cells. Acetic acid added to culture medium was taken up rapidly by L6 cells, and AMPK was phosphorylated upon treatment with acetic acid. We observed increased gene and protein expression of GLUT4 and myoglobin. Uptake of glucose and fatty acids by L6 cells were increased, while triglyceride accumulation was lower in treated cells compared to untreated cells. Furthermore, treated cells also showed increased gene and protein expression of myocyte enhancer factor 2A (MEF2A), which is a well-known transcription factor involved in the expression of myoglobin and GLUT4 genes. These results indicate that acetic acid enhances glucose uptake and fatty acid metabolism through the activation of AMPK, and increases expression of GLUT4 and myoglobin

Effect of acetic acid on the expression of PGC-1α in L6 myotube cells.

<p>Total RNA was extracted from untreated L6 myotube cells or cells treated with 0.5 mM acetic acid for the indicated time period (A). L6 cells were treated with 0.5 mM acetic acid for 5 min, 0.5 mM AICAR for 12 hours, and pre-treated with 10 μM compound C for 30 min (B) or 2 mM araA for 20 min (C), and total RNA were isolated. Real-time PCR analysis was carried out for the determination of <i>ppargc1a</i> mRNA level in L6 myotube cells. PGC-1α protein level was analyzed by western blotting in 5 min treatment with 0.5 mM acetic acid, 0.5 mM AICAR for 12 hours, and 10 μM compound C for 30 min (D) or 2 mM araA for 20 min (E). Each bar represents the mean ±SE (n = 3–6). Results were analyzed with one-way ANOVA followed by the Tukey-Kramer post hoc test for multiple comparisons. Groups without the same letter are significantly different (p<0.05).</p

Effects of acetic acid treatment on glucose, fatty acid uptake and triglyceride accumulation in L6 myotube cells.

<p>(A)Glucose uptake by L6 cells. Differentiated L6 myotube cells were treated with 0.5 mM acetic acid and 100 nM insulin for 24 and 48 hrs in the medium (50μmol/2ml). Each conditioned medium was collected and measured the concentration of glucose. Amount of glucose uptake was calculated by using the amount of glucose remaining in the medium. (B) Fatty acid uptake by L6 cells. (C) TG accumulation in L6 cells. Differentiated L6 myotube cells were incubated with the medium containing 0.6 μmol palmitic acid (300 μmol/L) for 24 and 48 hrs in the presence or absence of 0.5 mM acetic acid or 0.5 mM AICAR. After the incubation, mediums and cells were collected separately and the concentration of NEFA in the mediums and the concentration of TG in the cells were determined. Each bar represents the mean ±SE (n = 3–4). Results were analyzed with one-way ANOVA followed by the Tukey-Kramer post hoc test for multiple comparisons. Groups without the same letter are significantly different (p<0.05).</p

Effects of acetic acid on the expression of myoglobin and GLUT4 in L6 myotube cells.

<p>Total RNA was extracted from untreated L6 myotube cells or those treated with 0.5 mM acetic acid for the indicated time period (A; <i>Mb</i>, B; <i>Slc2a4</i>) or for 5 min after the addition of acetic acid (C; <i>Mb</i>, D; <i>Slc2a4</i>) or 0.5 mM AICAR for 12 hr, and 10 μM compound C for 30 min or 2mM araA for 20min. Real-time PCR analysis was carried out for determination of <i>Mb</i> (A, C, E) and <i>Slc2a4</i> (B, D, F) mRNA levels in L6 myotube cells. Myoglobin or GLUT4 proteins were analyzed by western blotting on the treatment of 0.5 mM acetic acid for 10 min, 0.5 mM AICAR for 12 hours, and 10 μM compound C for 30 min (G, H) or 2 mM araA for 20 min (I, J). Each bar represents the mean ±SE (n = 3–6). Results were analyzed with one-way ANOVA followed by the Tukey-Kramer post hoc test for multiple comparisons. Groups without the same letter are significantly different (p<0.05).</p

Uptake of acetic acid by L6 myotube cells.

<p>After treatment with acetic acid (0.5 mM), acetic acid content in the medium was determined at each indicated time point and the amount of uptake by the cells was calculated. Each value is shown as the mean ± SE (n = 3–6).</p

Effect of acetic acid on the expression of MEF2A in L6 myotube cells.

<p>Total RNA was extracted from untreated L6 myotube cells or cells treated with 0.5 mM acetic acid for the indicated time period (A). L6 cells were treated with 0.5 mM acetic acid for 5 min, 0.5 mM AICAR for 12 hours, and pre-treated with 10 μM compound C for 30 min (B), and pre-treated with 2 mM araA for 20 min (C). Real-time PCR analysis was carried out for the determination of <i>mef2A</i> mRNA level in L6 myotube cells. MEF2A protein was analyzed by western blotting in 10 min treatment of 0.5 mM acetic acid, 0.5 mM AICAR for 12 hours, and 10 μM compound C for 30 min (D) or 2 mM araA for 20 min (E). Each bar represents the mean ±SE (n = 3–6). Results were analyzed with one-way ANOVA followed by the Tukey-Kramer post hoc test for multiple comparisons. Groups without the same letter are significantly different (p<0.05).</p