• Preventive Nutrition and Food Science
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• 제22권3호
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• pp.172-183
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• 2017

Vitamin A and its metabolites modulate insulin resistance and regulate stearoyl-CoA desaturase 1 (SCD1), which are also known to affect insulin resistance. Here, we tested, whether vitamin A-mediated changes in insulin resistance markers are associated with SCD1 regulation or not. For this purpose, 30-week old male lean and glucose-intolerant obese rats of WNIN/GR-Ob strain were given either a stock or vitamin A-enriched diet, i.e. 2.6 mg or 129 mg vitamin A/kg diet, for 14 weeks. Compared to the stock diet, vitamin A-enriched diet feeding improved hyperglycemia and glucose-clearance rate in obese rats and no such changes were seen in lean rats receiving identical diets. These changes were corroborated with concomitant increase in circulatory insulin and glycogen levels of liver and muscle (whose insulin signaling pathway genes were up-regulated) in obese rats. Further, the observed increase in muscle glycogen content in these obese rats could be explained by increased levels of the active form of glycogen synthase, the key regulator of glycogen synthesis pathway, possibly inactivated through increased phosphorylation of its upstream inhibitor, glycogen synthase kinase. However, the unaltered hepatic SCD1 protein expression (despite decreased mRNA level) and increased muscle-SCD1 expression (both at gene and protein levels) suggest that vitamin A-mediated changes on glucose metabolism are not associated with SCD1 regulation. Chronic consumption of vitamin A-enriched diet improved hyperglycemia and glucose-intolerance, possibly, through the regulation of intracellular signaling and glycogen synthesis pathways of muscle and liver, but not associated with SCD1.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 1988년도 학술대회지
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• pp.1-10
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• 1988

조사포닌을 복강내 투여하면 1) 핵내의 RNA polymerase의 활성도, 2) 핵내의 RNA합성, 3) 세포질의 RNA합성,4) 세포질내의 폴리리보좀 함량, 5) in vitro 상태에서의 쥐간의 polysome과 micro-some으로의 아미노산 유입율, 6) 방사능 표지된 아미노산의 혈청 단백질로의 유입율이 증가하였음을 과거에 보고 한 바 있으며 또한 4주간 조사포닌을 투여한 쥐에서 적출한 간세포를 전자 현미경으로 조사한 결과, 조면 소포체가 상당히 증가하였으며 초원심분리기로서 막에 결합한 ribosome에서의 polysome함량의 증가를 확인하였다. 최근 streptozotocin으로 유도한 단백질 결핍성 당뇨병 쥐에 $Rb_2$를 계속적으로 주사한 결과 blood urea nitrogen과 간내의 urea 농도가 현저히 감소하였으며 혈청내의 총단백질과 알부민의 농도가 대조군의 수치에 비하여 증가한 반면 간내의 RNA와 총 ribosome, 막에 결합된 ribosome의 함량이 증가하였다. 또한 $Rb_2$투여로 혈청내의 총단백질로의 방사능 표지 전구물질의 유입량이 증가하였으며 당뇨쥐에서의 질소균형을 개선시켰다. 이러한 실험적 결과에 근거하여 인삼 사포닌은 대사를 촉진시키고 RNA, 단백질 합성 등을 촉진하는 것으로 생각된다.

• Molecules and Cells
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• 제46권8호
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• pp.496-512
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• 2023

A fructose-enriched diet is thought to contribute to hepatic injury in developing non-alcoholic steatohepatitis (NASH). However, the cellular mechanism of fructose-induced hepatic damage remains poorly understood. This study aimed to determine whether fructose induces cell death in primary hepatocytes, and if so, to establish the underlying cellular mechanisms. Our results revealed that treatment with high fructose concentrations for 48 h induced mitochondria-mediated apoptotic death in mouse primary hepatocytes (MPHs). Endoplasmic reticulum stress responses were involved in fructose-induced death as the levels of phosho-eIF2α, phospho-C-Jun-N-terminal kinase (JNK), and C/EBP homologous protein (CHOP) increased, and a chemical chaperone tauroursodeoxycholic acid (TUDCA) prevented cell death. The impaired oxidation metabolism of fatty acids was also possibly involved in the fructose-induced toxicity as treatment with an AMP-activated kinase (AMPK) activator and a PPAR-α agonist significantly protected against fructose-induced death, while carnitine palmitoyl transferase I inhibitor exacerbated the toxicity. However, uric acid-mediated toxicity was not involved in fructose-induced death as uric acid was not toxic to MPHs, and the inhibition of xanthine oxidase (a key enzyme in uric acid synthesis) did not affect cell death. On the other hand, treatment with inhibitors of the nicotinamide adenine dinucleotide (NAD)⁺-consuming enzyme CD38 or CD38 gene knockdown significantly protected against fructose-induced toxicity in MPHs, and fructose treatment increased CD38 levels. These data suggest that CD38 upregulation plays a role in hepatic injury in the fructose-enriched diet-mediated NASH. Thus, CD38 inhibition may be a promising therapeutic strategy to prevent fructose-enriched diet-mediated NASH.

• 대한유전성대사질환학회지
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• 제23권2호
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• pp.8-14
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• 2023

간 당원축적병 0형은 glycogen synthase 2 유전자에 부호화되어 있는 간 당원 합성효소의 결핍으로 비정상적으로 당원 생성이 되는 상염색체 열성 유전 질환이다. 당원축적병 0형의 임상 양상은 공복시에 고케톤혈증 저혈당증을 나타내고 식사후 고혈당과 고젖산혈증을 보인다. 당원축적병 0형은 현재까지 적은 수만 보고되었는데 증상이 경하거나 심한 저혈당이 드물고 또는 무증상이거나 나이가 듦에 따라 점차 증상이 사라지는 양상을 보이기 때문에 진단을 놓치는 경우가 있을 것으로 생각된다. 필수적 치료 전략은 포도당신생성을 자극하기 위해 고단백 식사, 낮동안 저혈당을 방지하기 위해서 잦은 식사 횟수, 밤 동안 천천히 포도당을 방출하기 위해 생옥수수전분가루 같은 복합 탄수화물을 먹는 것이다. 당원축적병 0형은 예후는 좋고 적절한 치료를 하면 정상적으로 성장하며 합병증도 발생하지 않는다. 성인이 될수록 심한 저혈당은 보이지 않게 되지만 지속적인 식사 관리는 필요하다.

• 생명과학회지
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• 제25권3호
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• pp.317-322
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• 2015

알코올에 의한 지방간(지방변성증)은 에탄올 대사에 의해 감소되는 당량의 과도한 발생에 의해 유발된다. 일반적으로 만성적인 에탄올 투여는 간 지질의 합성을 증가시키는 sterol regulatory element-binding protein 1c (SREBP-1c)를 조절함으로써 지방변성증을 유발시킨다. SPEBP-1c에서 에탄올의 영향은 간에서의 지방대사를 조절하는 NAD⁺ 의존적 단백질 탈아세틸화효소인 mammalian sirtuin-1 (SIRT-1)에 의해 조정된다. 홍삼은 항당뇨와 항비만 효과를 위해 아시아에서 광범위하게 사용되는 한약재이다. 홍삼의 약리학적 치료학적인 효과는 진세노사이드와 같은 생물활성 성분에 의해 주로 일어난다. 따라서 우리는 마우스 간세포주인 AML-12 세포에서 SREBP-1과 SIRT-1에대한 한국홍삼 추출물의 조절효과를 평가하였다. 알코올과 홍삼추출물(0-1,000 μg/ml)을 AML-12 세포주에 처리하고, 지방소립을 Oil red O 염색법으로 확인하고, western blots을 사용해 SIRT-1과 SREBP-1의 발현을 확인하였다. 에탄올을 처리한 세포에서 홍삼추출물은 SIRT-1과 SREBP-1c의 발현을 회복시켰다. 또한 에탄올이 처리된 세포에서 홍삼추출물과 진세노사이드 Rb₂와 Rd가 SREBP-1을 유의적으로 감소시키는 것으로 확인 되었다. 결과적으로 홍삼과 활성 진세노사이드 성분인 Rb₂와 Rd가 SIRT-1과 간 지질대사를 변화시키는 SREBP-1c의 아세틸화의 조절을 통해 알코올에 의한 간지방변성을 억제하는 것을 확인하였다.

• Animal Bioscience
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• 제36권11호
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• pp.1693-1699
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• 2023

Objective: Cows that are nursing get around 80% of their glucose from liver gluconeogenesis. Propionate, a significant precursor of liver gluconeogenesis, can regulate the key genes involved in hepatic gluconeogenesis expression, but its precise effects on the activity of enzymes have not yet been fully elucidated. Therefore, the aim of this study was to investigate the effects of propionate on the activity, gene expression, and protein abundance of the key enzymes involved in the gluconeogenesis of dairy cow hepatocytes. Methods: The hepatocytes were cultured and treated with various concentrations of sodium propionate (0, 1.25, 2.50, 3.75, and 5.00 mM) for 12 h. Glucose content in the culture media was determined by an enzymatic coloring method. The activities of gluconeogenesis related enzymes were determined by enzyme linked immunosorbent assay kits, and the levels of gene expression and protein abundance of the enzymes were detected by real-time quantitative polymerase chain reaction and Western blot, respectively. Results: Propionate supplementation considerably increased the amount of glucose in the culture medium compared to the control (p<0.05); while there was no discernible difference among the various treatment concentrations (p>0.05). The activities of cytoplasmic phosphoenolpyruvate carboxylase (PEPCK1), mitochondrial phosphoenolpyruvate carboxylase (PEPCK2), pyruvate carboxylase (PC), and glucose-6-phosphatase (G6PC) were increased with the addition of 2.50 and 3.75 mM propionate; the gene expressions and protein abundances of PEPCK1, PEPCK2, PC, and G6PC were increased by 3.75 mM propionate addition. Conclusion: Propionate encouraged glucose synthesis in bovine hepatocytes, and 3.75 mM propionate directly increased the activities, gene expressions and protein abundances of PC, PEPCK1, PEPCK2, and G6PC in bovine hepatocytes, providing a theoretical basis of propionate-regulating gluconeogenesis in bovine hepatocytes.

• Nutrition Research and Practice
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• 제11권5호
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• pp.365-372
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• 2017

BACKGROUND/OBJECTIVES: Owing to health concerns related to the consumption of traditional snacks high in sugars and fats, much effort has been made to develop functional snacks with low calorie content. In this study, a new recipe for Korean rice cookie, dasik, was developed and its antioxidative, lipid-lowering, and anti-inflammatory effects and related mechanisms were elucidated. The effects were compared with those of traditional rice cake dasik (RCD), the lipid-lowering effect of which is greater than that of traditional western-style cookies. MATERIALS/METHODS: Ginseng-added brown rice dasik (GBRD) was prepared with brown rice flour, fructooligosaccharide, red ginseng extract, and propolis. Mice were grouped (n = 7 per group) into those fed a normal AIN-76 diet, a high-fat diet (HFD), and HFD supplemented with RCD or GBRD. Dasik in the HFD accounted for 7% of the total calories. The lipid, reactive oxygen species, and peroxynitrite levels, and degree of lipid peroxidation in the plasma or liver were determined. The expression levels of proteins involved in lipid metabolism and inflammation, and those of antioxidant enzymes were determined by western blot analysis. RESULTS: The plasma and hepatic total cholesterol concentrations in the GBRD group were significantly decreased via downregulation of sterol regulatory element-binding protein-2 and 3-hydroxy-3-methylglutaryl-CoA reductase (P < 0.05). The hepatic peroxynitrite level was significantly lower, whereas glutathione was higher, in the GBRD group than in the RCD group. Among the antioxidant enzymes, catalase (CAT) and glutathione peroxidase (GPx) were significantly upregulated in the GBRD group (P < 0.05). In addition, nuclear factor-kappaB (NF-${\kappa}B$) expression in the GBRD group was significantly lower than that in the RCD group. CONCLUSIONS: GBRD decreases the plasma and hepatic cholesterol levels by downregulating cholesterol synthesis. This new dasik recipe also improves the antioxidative and anti-inflammatory status in HFD-fed mice via CAT and GPx upregulation and NF-${\kappa}B$ downregulation. These effects were significantly higher than those of RCD.

• Asian-Australasian Journal of Animal Sciences
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• 제21권7호
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• pp.1003-1010
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• 2008

The objective of the present study was to identify differences in the expression levels of liver proteins between healthy and ketotic cows, establish a liver metabolic interrelationship of ketosis and elucidate the metabolic characteristics of the liver during ketosis. Liver samples from 8 healthy multiparous Hostein cows and 8 ketotic cows were pooled by health status and the proteins were separated by two-dimensional-electrophoresis (2D-E). Statistical analysis of gels was performed using PDQuest software 8.0. The differences in the expression levels of liver proteins (p<0.05) between ketotic and healthy cows were identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF-TOF) tandem mass spectrometry. Five enzymes/proteins were identified as being differentially expressed in the livers of ketotic cows: expression of 3-hydroxyacyl-CoA dehydrogenase type-2 (HCDH), acetyl-coenzyme A acetyltransferase 2 (ACAT) and elongation factor Tu (EF-Tu) were down-regulated, whereas that of alpha-enolase and creatine kinase were up-regulated. On the basis of this evidence, it could be presumed that the decreased expression of HCDH, which is caused by high concentrations of acetyl-CoA in hepatic cells, in the livers of ketotic cows, implies reduced fatty acid ??oxidation. The resultant high concentrations of acetyl-CoA and acetoacetyl CoA would depress the level of ACAT and generate more ??hydroxybutyric acid; high concentrations of acetyl-CoA would also accelerate the Krebs Cycle and produce more ATP, which is stored as phosphocreatine, as a consequence of increased expression of creatine kinase. The low expression level of elongation factor Tu in the livers of ketotic cows indicates decreased levels of protein synthesis due to the limited availability of amino acids, because the most glucogenic amino acids sustain the glyconeogenesis pathway; thus increasing the level of alpha-enolase. Decreased protein synthesis also promotes the conversion of amino acids to oxaloacetate, which drives the Krebs Cycle under conditions of high levels of acetyl-CoA. It is concluded that the livers of ketotic cows possess high concentrations of acetyl-CoA, which through negative feedback inhibited fatty acid oxidation; show decreased fatty acid oxidation, ketogenesis and protein synthesis; and increased gluconeogenesis and energy production.

• Journal of Microbiology and Biotechnology
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• 제27권11호
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• pp.1925-1931
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• 2017

Korean red pine (Pinus densiflora) bark extract, PineXol (PX), was investigated for its potential antioxidant and anti-inflammation effects in vitro. It was hypothesized that PX treatment ($25-150{\mu}g/ml$) would reduce the lipid synthesis in HepG2 hepatocytes as well as lipid accumulation in 3T3-L1 adipocytes. Hepatocytes' intracellular triglycerides and cholesterol were decreased in the PX $150{\mu}g/ml$ treatment group compared with the control (p < 0.05). Consequently, de novo lipogenic proteins (acetyl-CoA carboxylase 1, stearoyl-CoA desaturase 1, elongase of very long chain fatty acids 6, glycerol-3-phosphate acyltransferase 1, and sterol regulatory element-binding protein 1) were significantly decreased in hepatocytes by PX $150{\mu}g/ml$ treatment compared with the control (p < 0.05). In differentiated 3T3-L1 adipocytes, the lipid accumulation was significantly attenuated by all PX treatments (p < 0.01). Regulators of adipogenesis, including CCAAT-enhancer-binding proteins alpha, peroxisome proliferatoractivated receptor gamma, and perilipin, were decreased in PX $100{\mu}g/ml$ treatment compared with the control (p < 0.05). In conclusion, PX might have anti-obesity effects by blocking hepatic lipogenesis and by inhibiting adipogenesis in adipocytes.

• Nutrition Research and Practice
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• 제13권4호
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• pp.286-294
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• 2019

BACKGROUND/OBJECTIVES: Docosahexaenoic acid (DHA), an n-3 long chain polyunsaturated fatty acid (LCPUFA), is acquired by dietary intake or the in vivo conversion of ${\alpha}$-linolenic acid. Many enzymes participating in LCPUFA synthesis are regulated by peroxisome proliferator-activated receptor alpha ($PPAR{\alpha}$). Therefore, it was hypothesized that the tissue accretion of endogenously synthesized DHA could be modified by $PPAR{\alpha}$. MATERIALS/METHODS: The tissue DHA concentrations and mRNA levels of genes participating in DHA biosynthesis were compared among $PPAR{\alpha}$ homozygous (KO), heterozygous (HZ), and wild type (WT) mice (Exp I), and between WT mice treated with clofibrate ($PPAR{\alpha}$ agonist) or those not treated (Exp II). In ExpII, the expression levels of the proteins associated with DHA function in the brain cortex and retina were also measured. An n3-PUFA depleted/replenished regimen was applied to mitigate the confounding effects of maternal DHA. RESULTS: $PPAR{\alpha}$ ablation reduced the hepatic Acox, Fads1, and Fads2 mRNA levels, as well as the DHA concentration in the liver, but not in the brain cortex. In contrast, $PPAR{\alpha}$ activation increased hepatic Acox, Fads1, Fads2, and Elovl5 mRNA levels, but reduced the DHA concentrations in the liver, retina, and phospholipid of brain cortex, and decreased mRNA and protein levels of the brain-derived neurotrophic factor in brain cortex. CONCLUSIONS: LCPUFA enzyme expression was altered by $PPAR{\alpha}$. Either $PPAR{\alpha}$ deficiency or activation-decreased tissue DHA concentration is a stimulus for further studies to determine the functional significance.