• 대한의생명과학회지
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• 제17권4호
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• pp.273-281
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• 2011

Our previous study demonstrated that the Korean traditional medicine Gyeongshingangjeehwan (GGEx) inhibits obesity and insulin resistance in obese type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. We investigated whether GGEx may affect AMP-activated protein kinase ${\alpha}$ ($AMPK{\alpha}$) since $AMPK{\alpha}$ activation is known to stimulate fatty acid oxidation in skeletal muscle of obese rodents. After OLETF rats were treated with GGEx, we studied the effects of GGEx on $AMPK{\alpha}$ and acetyl-CoA carboxylase (ACC) phosphorylation, and the expression of $AMPK{\alpha}$, $PPAR{\alpha}$, and $PPAR{\alpha}$ target genes. The effects of GGEx on mRNA expression of the above genes were also measured in C2C12 skeletal muscle cells. Administration of GGEx to OLETF rats for 8 weeks increased phosphorylation of $AMPK{\alpha}$ and ACC in skeletal muscle. GGEx also elevated skeletal muscle mRNA levels of $AMPK{\alpha}1$ and $AMPK{\alpha}2$ as well as $PPAR{\alpha}$ and its target genes. Consistent with the in vivo data, similar activation of genes was observed in GGEx-treated C2C12 cells. These results suggest that GGEx stimulates skeletal muscle $AMPK{\alpha}$ and $PPAR{\alpha}$ activation, leading to alleviation of obesity and related disorders.

• 대한의생명과학회지
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• 제17권4호
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• pp.283-289
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• 2011

Our previous study demonstrated that the Korean traditional medicine Gyeongshingangjeehwan (GGEx) activates AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor ${\alpha}$ ($PPAR{\alpha}$) critical for fatty acid oxidation in skeletal muscle and C2C12 skeletal muscle cells. Thus, we examined whether GGEx can reduce lipid accumulation in these cells and tissues. After obese and type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats were treated with GGEx, we studied the effects of GGEx on skeletal muscle lipid accumulation. The effects of GGEx and/or the AMPK inhibitor compound C on lipid accumulation and expression of AMPK and $PPAR{\alpha}$ were measured in C2C12 skeletal muscle cells. Compared with lean Long-Evans Tokushima Otsuka rats, obese OLETF rats had increased triglyceride droplets. However, administration of GGEx to OLETF rats for 8 weeks significantly decreased triglyceride droplets in skeletal muscle. Consistent with the $in$ $vivo$ data, GGEx inhibited lipid accumulation, the degree of which was comparable to Wy14,643, the potent activator of $PPAR{\alpha}$. GGEx also increased skeletal muscle mRNA levels of AMPK${\alpha}1$, AMPK${\alpha}2$, and $PPAR{\alpha}$. However, compound C inhibited these effects in C2C12 cells. These results suggest that GGEx suppresses skeletal muscle lipid accumulation and this process may be mediated by AMPK and $PPAR{\alpha}$ activation.

• Asian-Australasian Journal of Animal Sciences
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• 제25권9호
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• pp.1300-1308
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• 2012

The 5'-adenosine monophosphate-activated protein kinase (AMPK) is a key part of a kinase-signaling cascade that acts to maintain energy homeostasis. The objective of this experiment was to investigate the possible effects of fasting and refeeding on the gene expression of hypothalamic AMPK, some appetitive regulating peptides and lipid metabolism related enzymes. Seven-day-old male broiler (Arbor Acres) chicks were allocated into three equal treatments: fed ad libitum (control); fasted for 24 h; fasted for 24 h and then refed for 24 h. Compared with the control, the hypothalamic gene expression of $AMPK{\alpha}2$, $AMPK{\beta}1$, $AMPK{\beta}2$, $AMPK{\gamma}1$, Ste20-related adaptor protein ${\beta}$ ($STRAD{\beta}$), mouse protein $25{\alpha}$ ($MO25{\alpha}$) and agouti-related peptide (AgRP) were increased after fasting for 24 h. No significant difference among treatments was observed in mRNA levels of $AMPK{\alpha}1$, $AMPK{\gamma}2$, LKB1 and neuropeptide Y (NPY). However, the expression of $MO25{\beta}$, pro-opiomelanocortin (POMC), corticotropin-releasing hormone (CRH), ghrelin, fatty acid synthase (FAS), acetyl-CoA carboxylase ${\alpha}$ ($ACC{\alpha}$), carnitine palmitoyltransferase 1 (CPT-1) and sterol regulatory element binding protein-1 (SREBP-1) were significantly decreased. The present results indicated that 24 h fasting altered gene expression of AMPK subunits, appetite regulation peptides and lipometabolism related factors in chick's hypothalamus; the hypothalamic FAS signaling pathway might be involved in the AMPK regulated energy homeostasis and/or appetite regulation in poultry.

• The Korean Journal of Physiology and Pharmacology
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• 제13권6호
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• pp.449-454
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• 2009

5'-AMP-activated protein kinase (AMPK) is a heterotrimeric complex consisting of a catalytic ($\alpha$) and two regulatory ($\beta$ and $\gamma$) subunits. Two isoforms are known for catalytic subunit (${\alpha}1$, ${\alpha}2$) and are encoded by different genes. To assess the metabolic effects of $AMPK{\alpha}1$, we examined the effects of overexpression of adenoviral-mediated $AMPK{\alpha}1$ in hyperlipidemic type 2 diabetic rats. The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an established animal model of type 2 diabetes that exhibits chronic and slowly progressive hyperglycemia and hyperlipidemia. Thirty five-week-old overt type 2 diabetic rats (n=10) were administered intravenously with Ad.$AMPK{\alpha}1$. AMPK activity was measured by phosphorylation of acetyl CoA carboxlyase (ACC). To investigate the changes of gene expression related glucose and lipid metabolism, quantitative real-time PCR was performed with liver tissues. Overexpression of $AMPK{\alpha}1$ showed that blood glucose concentration was decreased but that glucose tolerance was not completely recovered on 7th day after treatment. Plasma triglyceride concentration was decreased slightly, and hepatic triglyceride content was markedly reduced by decreasing expression of hepatic lipogenic genes. Overexpression of $AMPK{\alpha}1$ markedly improved hepatic steatosis and it may have effective role for improving hepatic lipid metabolism in hyperlipidemic state.

• Journal of Yeungnam Medical Science
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• 제29권2호
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• pp.77-82
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• 2012

AMP-activated protein kinase (AMPK) is an important cellular fuel sensor. Its activation requires phosphorylation at Thr-172, which resides in the activation loop of the ${\alpha}1$ and ${\alpha}2$ subunits. Several AMPK upstream kinases are capable of phosphorylating AMPK at Thr-172, including LKB1 and CaMKK${\beta}$ ($Ca^{2+}$/calmodulin-dependent protein kinase kinase${\beta}$). AMPK has been implicated in the regulation of physiological signals, such as in the inhibition of cholesterol fatty acid, and protein synthesis, and enhancement of glucose uptake and blood flow. AMPK activation also exhibits several salutary effects on the vascular function and improves vascular abnormalities. AMPK is modulated by numerous hormones and cytokines that regulate the energy balance in the whole body. These hormone and cytokines include leptin, adiponectin, ghrelin, and even thyroid hormones. Moreover, AMPK is activated by several drugs and xenobiotics. Some of these are in being clinically used to treat type 2 diabetes (e.g., metformin and thiazolidinediones), hypertension (e.g., nifedipine and losartan), and impaired blood flow (e.g., aspirin, statins, and cilostazol). I reviewed the precise mechanisms of the AMPK activation pathway and AMPK-modulating drugs.

• The Korean Journal of Physiology and Pharmacology
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• 제21권5호
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• pp.495-507
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• 2017

The effect of clonidine administered intrathecally (i.t.) on the mortality and the blood glucose level induced by sepsis was examined in mice. To produce sepsis, the mixture of D-galactosamine (GaLN; 0.6 g/10 ml)/lipopolysaccharide (LPS; $27{\mu}g/27{\mu}l$) was treated intraperitoneally (i.p.). The i.t. pretreatment with clonidine ($5{\mu}g/5{\mu}l$) increased the blood glucose level and attenuated mortality induced by sepsis in a dose-dependent manner. The i.t. post-treatment with clonidine up to 3 h caused an elevation of the blood glucose level and protected sepsis-induced mortality, whereas clonidine post-treated at 6, 9, or 12 h did not affect. The pre-treatment with oral D-glucose for 30 min prior to i.t. post-treatment (6 h) with clonidine did not rescue sepsis-induced mortality. In addition, i.t. pretreatment with pertussis toxin (PTX) reduced clonidine-induced protection against mortality and clonidine-induced hyperglycemia, suggesting that protective effect against sepsis-induced mortality seems to be mediated via activating PTX-sensitive G-proteins in the spinal cord. Moreover, pretreatment with clonidine attenuated the plasma tumor necrosis factor ${\alpha}$ ($TNF-{\alpha}$) induced by sepsis. Clonidine administered i.t. or i.p. increased $p-AMPK{\alpha}1$ and $p-AMPK{\alpha}2$, but decreased p-Tyk2 and p-mTOR levels in both control and sepsis groups, suggesting that the up-regulations of $p-AMPK{\alpha}1$ and $p-AMPK{\alpha}2$, or down-regulations of p-mTOR and p-Tyk2 may play critical roles for the protective effect of clonidine against sepsis-induced mortality.

• 한방비만학회지
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• 제14권2호
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• pp.55-62
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• 2014

Objective: The prevalence of metabolic syndrome and type 2 diabetes is increasing worldwide. Mitochondrial dysfunction is known to be involved in insulin resistance and obesity, researches have been increasing highly. Astragali Radix extract (ARE) or its main components have been shown to perform comparably to insulin by significantly reducing blood glucose levels in animal models however, the influence on mitochondrial dysfunction are not well understood. Methods: ARE (0.2, 0.5 and 1.0 mg/ml) or metformin (2.5 mM) were treated in C2C12 after 6 day-differentiation. The expressions of adenosine monophosphate (AMP)-activated protein kinase (AMPK) and phosphorylation AMPK, peroxisome proliferators-activated receptror ${\gamma}$ coactivator $1{\alpha}$ ($PGC1{\alpha}$), nuclear respiratory factors 1 (NRF1), mitochondrial transcription factor (Tfam) and myosin heavy chain were detected with western blotting or polymerase chain reaction analysis. The morphological changes were also investigated. Results: ARE dose dependently increased phosphorylation of AMPK and respectively activated mRNA expressions of $PGC1{\alpha}$, NRF1 and Tfam which are mitochondrial biogenesis regulators. Furthermore, there were some morphologic differences of differentiated cells between ARE treatment and control. Conclusions: This study suggests that ARE has the potential to increase muscle mitochondrial function by activating AMPK and $PGC1{\alpha}$.

• The Korean Journal of Physiology and Pharmacology
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• 제16권2호
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• pp.131-138
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• 2012

Alcoholic hepatitis is a leading cause of liver failure in which the increased production of tumor necrosis factor ${\alpha}$ (TNF${\alpha}$) plays a critical role in progression of alcoholic liver disease. In the present study, we investigated the effects of cilostazol, a selective inhibitor of type III phosphodiesterase on ethanol-mediated TNF${\alpha}$ production in vitro and $in$ $vivo$, and the effect of cilostazol was compared with that of pentoxifylline, which is currently used in clinical trial. RAW264.7 murine macrophages were pretreated with ethanol in the presence or absence of cilostazol then, stimulated with lipopolysacchride (LPS). Cilostazol significantly suppressed the level of LPS-stimulated TNF${\alpha}$ mRNA and protein with a similar degree to that by pentoxifylline. Cilostazol increased the basal AMP- activated protein kinase (AMPK) activity as well as normalized the decreased AMPK by LPS. AICAR, an AMPK activator and db-cAMP also significantly decreased TNF${\alpha}$ production in RAW264.7 cells, but cilostazol did not affect the levels of intracellular cAMP and reactive oxygen species (ROS) production. The $in$ $vivo$ effect of cilostazol was examined using ethanol binge drinking (6 g/kg) mice model. TNF${\alpha}$ mRNA and protein decreased in liver from ethanol gavaged mice compared to that from control mice. Pretreatment of mice with cilostazol or pentoxifylline further reduced the TNF${\alpha}$ production in liver. These results demonstrated that cilostazol effectively decrease the ethanol-mediated TNF${\alpha}$ production both in murine macrophage and in liver from binge drinking mice and AMPK may be responsible for the inhibition of TNF${\alpha}$ production by cilostazol.

• 한국식품영양과학회지
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• 제42권8호
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• pp.1197-1203
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• 2013

본 연구는 2주간의 지구성 운동과 ginsenoside $Rb_1$이 쥐골격근의 AMPK insulin signaling($tAMPK{\alpha}$, $pAMPK{\alpha}$ $Thr^{172}$)과 PI3K insulin signaling pathway(pIRS-1 $Tyr^{612}$, PI3K $p^{85}$, pAkt $Ser^{473}$) 발현 및 glucose uptake에 미치는 영향을 분석하였다. 골격근내 glucose uptake에서는 비교집단과 비교하여 운동집단(59.4%), $Rb_1$집단(70.5%) $Rb_1/Ex$집단(58.6%)에서 유의하게 증가하였다. 2주간의 지구성 운동과 ginsenoside $Rb_1$이 AMPK insulin signaling pathway에 미치는 효과를 조사한 결과 비교집단에 비해 $AMPK{\alpha}$(Ex, 28.6%; $Rb_1$, 28.5%; $Rb_1/Ex$, 29.8%), $pAMPK{\alpha}$ $Thr^{172}$(Ex, 35.1%; $Rb_1$, 35.3%; $Rb_1/Ex$, 30.9%)의 발현이 유의하게 증가한 것을 알 수 있었다. 2주간의 지구성 운동과 ginsenoside $Rb_1$이 PI3K insulin signaling pathway에 미치는 효과를 알아본 결과 비교집단과 비교하여 IRS-1, PI3K $p^{85}$에서는 유의한 차이가 없었으나 pAkt $Ser^{473}$은 $Rb_1$ 집단에서 유의하게 증가한 것을 알 수 있었다. 이상의 결과를 종합해 볼 때, ginsenoside $Rb_1$은 운동과 더불어 근육 세포내 AMPK의 활성화와 근육 내 glucose uptake를 증가시켜 제2형 당뇨병 예방과 치료에 효과가 있을 것으로 생각된다. 그러나 본 연구의 결과로 PI3K insulin signaling pathway의 항당뇨 효과는 설명하기는 부족하다고 판단되며 추후 본 연구의 결과를 기초로 ginsenoside $Rb_1$의 농도, 처치시간, 처치방법을 고려한 후속 연구가 필요할 것으로 생각된다.

• 생명과학회지
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• 제21권2호
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• pp.251-256
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• 2011

파이토케미컬의 일종인 EGCG는 녹차의 카테킨 성분으로, 세포 내 신호 경로 조절을 통하여 항산화, 항암효과를 나타내는 것으로 알려져 있다. 본 연구에서는 hypoxia 상태인 B16F10 피부암 세포에서 HIF-$1{\alpha}$를 포함한 AMPK의 신호경로를 통하여 EGCG의 apoptosis 유도 효과를 규명하였다. AMPK는 hypoxia, 영양분 결핍, 운동, heat shock 등, 세포 내 ATP의 결핍에 의해서 활성화되며 암세포의 증식을 억제하고 apoptosis를 유도한다. 세포에서 중요한 에너지 센서로서 작용하는 AMPK가 hypoxia 상태의 암세포 내에서는 HIF-$1{\alpha}$의 전사 활성을 유도하는데, HIF-$1{\alpha}$는 hypoxia 상태에서 산소 결핍에 반응하는 첫 번째 전사 조절인자로서 암세포의 생존을 위한 세포내 산소공급과 혈관신생형성을 조절한다. Hypoxia 상태가 아닌 B16F10 세포에서와 hypoxia 상태에서의 B16F10 세포에서 EGCG에 의한 apoptosis 효과를 관찰하였다. 실험 결과, hypoxia 상태에서 EGCG는 더 강한 apoptosis를 유도하며, 혈관신생형성을 조절할 수 있는 HIF-$1{\alpha}$의 전사 활성을 억제시킨다. 이러한 관찰을 통해 EGCG가 hypoxia 상태의 피부암 세포에서 암의 성장과 신생혈관형성을 저해하는 것으로 보인다. 이와 같은 연구는 향후 식품에 첨가된 파이토케미컬을 이용하여 암을 예방하는 연구에서 있어서, 도움이 될 것으로 여겨진다.