• The Korean Journal of Physiology and Pharmacology
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• v.19 no.2
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• pp.89-97
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• 2015

The aim of this study was to investigate the involvement of dopaminergic receptors (DR) in behavioral sensitization, as measured by locomotor activity, and the over-expression of cocaine- and amphetamine-regulated transcript (CART) peptides after repeated administration of cocaine in mice. Repeated administrations of cocaine induced behavioral sensitization and CART over-expression in mice. The levels of striatal CART mRNA were significantly increased on the $3^{rd}$ day. CART peptides were over-expressed on the $5^{th}$ day in the striata of behaviorally sensitized mice. A higher proportion of $CART^+$ cells in the cocaine-treated mice were present in the nucleus accumbens (NAc) shell than in the dorsolateral (DL) part of caudate putamen (CP). The concomitant administration of both $D_1R$ and $D_2R$ antagonists, SCH 23390 ($D_1R$ selective) and raclopride ($D_2R$ selective), blocked cocaine induced-behavioral sensitization, CART over-expression, and cyclic adenosine 5'-monophosphate (cAMP)/ protein kinase A (PKA)/phospho-cAMP response element-binding protein (pCREB) signal pathways. SCH 23390 more predominantly inhibited the locomotor activity, CART over-expression, pCREB and PKA activity than raclopride. Cocaine induced-behavioral sensitization was also attenuated in the both $D_1R$ and $D_2R$ knockout (KO) mice, respectively. CART over-expression and activated cAMP/PKA/pCREB signal pathways were inhibited in the $D_1R$-KO mice, but not in the $D_2R$-KO mice. It is suggested that behavioral sensitization, CART over-expression and activated cAMP/PKA/pCREB signal pathways induced by repeated administration of cocaine could be more predominantly mediated by $D_1R$.

• Journal of Ginseng Research
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• v.42 no.2
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• pp.123-132
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• 2018

Ginseng has gained its popularity as an adaptogen since ancient days because of its triterpenoid saponins, known as ginsenosides. These triterpenoid saponins are unique and classified as protopanaxatriol and protopanaxadiol saponins based on their glycosylation patterns. They play many protective roles in humans and are under intense research as various groups continue to study their efficacy at the molecular level in various disorders. Ginsenosides Rb1 and Rg1 are the most abundant ginsenosides present in ginseng roots, and they confer the pharmacological properties of the plant, whereas ginsenoside Rg3 is abundantly present in Korean Red Ginseng preparation, which is highly known for its anticancer effects. These ginsenosides have a unique mode of action in modulating various signaling cascades and networks in different tissues. Their effect depends on the bioavailability and the physiological status of the cell. Mostly they amplify the response by stimulating phosphotidylinositol-4,5-bisphosphate 3-kinase/protein kinase B pathway, caspase-3/caspase-9-mediated apoptotic pathway, adenosine monophosphate-activated protein kinase, and nuclear factor kappa-light-chain-enhancer of activated B cells signaling. Furthermore, they trigger receptors such as estrogen receptor, glucocorticoid receptor, and N-methyl-$\text\tiny{D}$-aspartate receptor. This review critically evaluates the signaling pathways attenuated by ginsenosides Rb1, Rg1, and Rg3 in various tissues with emphasis on cancer, diabetes, cardiovascular diseases, and neurodegenerative disorders.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.2
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• pp.677-682
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• 2014

Resveratrol has been examined in several model systems for potential effects against cancer. Adenosine monophosphate-activated protein kinase (AMPK) is reported to suppress proliferation in most eukaryocyte cells. Whether resveratrol via AMPK inhibits proliferation of oesophageal adenocarcinoma cells (OAC) is unknown. The aim of this study was to determine the roles of AMPK in the protective effects of resveratrol in OAC proliferation and to elucidate the underlying mechanisms. Treatment of cultured OAC derived from human subjects or cell lines with resveratrol resulted in decreased cell proliferation. Further, inhibition of AMPK by pharmacological reagent or genetical approach abolished resveratrol-suppressed OAC proliferation, reduced the level of $p27^{Kip1}$, a cyclin-dependent kinase inhibitor, and increased the levels of S-phase kinase-associated protein 2 (Skp2) of $p27^{Kip1}$-E3 ubiquitin ligase and 26S proteasome activity reduced by resveratrol. Furthermore, gene silencing of $p27^{Kip1}$ reversed resveratrol-suppressed OAC proliferation. In conclusion, these findings indicate that resveratrol inhibits Skp2-mediated ubiquitylation and 26S proteasome-dependent degradation of $p27^{Kip1}$ via AMPK activation to suppress OAC proliferation.

• Journal of Korean Medicine for Obesity Research
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• v.14 no.1
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• pp.13-23
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• 2014

Objectives: This study was performed to evaluate the effects of Metformin and Lonicerae Flos, Agrobacterium Rhizogenes, Coptidis Rhizoma, Atractylodis Rhizoma Alba, Houttuyniae Herba extracs combinations on hypoglycemia in RAW 264.7 cells. Methods: Expressions of Sirt1, p-adenosine monophosphate-activated kinase (p-AMPK), AMPK-alpha, peroxisome proliferator activated receptor (PPAR)-alpha, PPAR-gamma, X-box binding protein 1 (XBP-1), tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 were analyzed by real time polymerase chain reaction and Western blotting analysis. Results: The level of gene expression of Sirt1, p-AMPK, AMPK-alpha, PPAR-alpha and XBP-1 in relation to that of beta-actin were increased or decreased significantly with the Metformin and Lonicerae Flos, Agrobacterium Rhizogenes extracts combination groups. The level of gene expression of TNF-alpha and IL-6 were increased significantly with the Metformin and Houttuyniae Herba, Coptidis Rhizoma extracts combination groups. Conclusions: Metformin and Lonicerae Flos, Agrobacterium Rhizogenes extracts combination groups showed synergistic hypoglycemic effects by increasing AMPK and PPAR gene expression in RAW 264.7 cells.

• Journal of Korean Medicine for Obesity Research
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• v.19 no.2
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• pp.89-96
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• 2019

Objectives: We investigated whether membrane free stem cell extract from adipose tissue (MFSCE) has anti-diabetic effect. Methods: To determine glucose uptake effect of MFSCE, we carried out glucose uptake assay in 3T3-L1 adipocytes. The regulatory mechanisms of MFSCE on glucose uptake were examined by Western blot analysis. Results: When MFSCE was treated to adipocytes at the concentration of 0.5, 1, 2.5, and 5 ㎍/mL, 2-deoxyglucose-6-phosphate uptake was elevated approximately 1.8-fold compared to cells not treated with MFSCE. It indicated that MFSCE enhances glucose uptake in 3T3-L1 adipocytes. In addition, MFSCE reduced phosphorylation of insulin receptor substrate-1 at serine 307 and induced Akt and glucose transporter 4 protein expressions that were related to insulin signaling. Furthermore, MFSCE regulated adenosine monophosphate-activated protein kinase (AMPK) pathway by increases of increase phosphorylation of AMPK and acetyl-CoA carboxylase that were related to AMPK pathway. Conclusions: These results indicated that MFSCE promotes glucose uptake via modulation of insulin signaling and AMPK pathway. Therefore, MFSCE could be a promising agent for treatment of diabetes mellitus.

• Journal of Microbiology and Biotechnology
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• v.34 no.3
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• pp.495-505
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• 2024

Gromwell (Lithospermum erythrorhizon, LE) can mitigate obesity-induced skeletal muscle atrophy in C2C12 myotubes and high-fat diet (HFD)-induced obese mice. The purpose of this study was to investigate the anti-skeletal muscle atrophy effects of LE and the underlying molecular mechanism. C2C12 myotubes were pretreated with LE or shikonin, and active component of LE, for 24 h and then treated with 500 μM palmitic acid (PA) for an additional 24 h. Additionally, mice were fed a HFD for 8 weeks to induced obesity, and then fed either the same diet or a version containing 0.25% LE for 10 weeks. LE attenuated PA-induced myotubes atrophy in differentiated C2C12 myotubes. The supplementation of LE to obese mice significantly increased skeletal muscle weight, lean body mass, muscle strength, and exercise performance compared with those in the HFD group. LE supplementation not only suppressed obesity-induced skeletal muscle lipid accumulation, but also downregulated TNF-α and atrophic genes. LE increased protein synthesis in the skeletal muscle via the mTOR pathway. We observed LE induced increase of mitochondrial biogenesis and upregulation of oxidative phosphorylation related genes in the skeletal muscles. Furthermore, LE increased the expression of peroxisome proliferator-activated receptor-gamma coactivator-1 alpha and the phosphorylation of adenosine monophosphate-activated protein kinase. Collectively, LE may be useful in ameliorating the detrimental effects of obesity-induced skeletal muscle atrophy through the increase of protein synthesis and mitochondrial biogenesis of skeletal muscle.

• Journal of Ginseng Research
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• v.42 no.3
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• pp.389-399
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• 2018

Background: The antioxidant effects of Panax ginseng have been reported in several articles; however, little is known about the antimelanogenesis effect, skin-protective effect, and cellular mechanism of Panax ginseng, especially of P. ginseng calyx. To understand how an ethanol extract of P. ginseng berry calyx (Pg-C-EE) exerts skin-protective effects, we studied its activities in activated melanocytes and reactive oxygen species (ROS)-induced keratinocytes. Methods: To confirm the antimelanogenesis effect of Pg-C-EE, we analyzed melanin synthesis and secretion and messenger RNA and protein expression levels of related genes. Ultraviolet B (UVB) and hydrogen peroxide ($H_2O_2$) were used to induce cell damage by ROS generation. To examine whether this damage is inhibited by Pg-C-EE, we performed cell viability assays and gene expression and transcriptional activation analyses. Results: Pg-C-EE inhibited melanin synthesis and secretion by blocking activator protein 1 regulatory enzymes such as p38, extracellular signal-regulated kinases (ERKs), and cyclic adenosine mono-phosphate response element-binding protein. Pg-C-EE also suppressed ROS generation induced by $H_2O_2$ and UVB. Treatment with Pg-C-EE decreased the expression of matrix metalloproteinases, mitogen-activated protein kinases, and hyaluronidases and increased the cell survival rate. Conclusion: These results suggest that Pg-C-EE may have antimelanogenesis properties and skin-protective properties through regulation of activator protein 1 and cyclic adenosine monophosphate response element-binding protein signaling. Pg-C-EE may be used as a skin-improving agent, with moisture retention and whitening effects.

• Journal of Nutrition and Health
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• v.55 no.4
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• pp.462-475
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• 2022

Purpose: Allomyrina dichotoma larvae are one of the approved edible insects with nutritional value and various functional and medicinal properties. Previously we have demonstrated that the Allomyrina dichotoma larval extract (ADLE) ameliorates hepatic insulin resistance in high-fat diet (HFD)-induced diabetic mice through the activation of adenosine monophosphate-activated protein kinase (AMPK). This study investigated the effects of ADLE on insulin resistance in the skeletal muscle and explored mechanisms for enhancing the glucose uptake in palmitate (PAL)-treated C2C12 myotubes. Methods: To induce insulin resistance, the differentiated C2C12 myotubes were treated with PAL (0.5 mM) for 24 hours, and then treated with a 0.5 mg/ml concentration of ADLE, and the resultant effects were measured. The expression levels of glucose transporter-4 (GLUT4), AMPK, and the mitochondrial metabolism-related proteins were analyzed by western blotting. The mRNA expression levels of lipogenesis- related genes were determined by quantitative reverse-transcriptase PCR. Results: The exposure of C2C12 myotubes to 0.5 mg/ml of ADLE increased cell viability significantly compared to PAL-treated cells. ADLE upregulated the protein expression of GLUT4 and enhanced glucose uptake in the PAL-treated cells. ADLE increased the phosphorylated AMPK in both the PAL-treated C2C12 myotubes and HFD-treated skeletal muscle. The reduced expression levels of peroxisome-proliferator-activated receptor gamma co-activator-1 alpha (PGC1α) and uncoupling protein 3 (UCP3) due to the PAL and HFD treatment were reversed by the ADLE treatment. The citrate synthase activity was also significantly increased with the PAL and ADLE co-treatment. Moreover, the mRNA and protein expressions of fatty acid synthesis-related factors were reduced in the PAL and HFD-treated muscle cells, and this effect was significantly attenuated by the ADLE treatment. Conclusion: ADLE activates AMPK, which in turn induces mitochondrial metabolism and reduces fatty acid synthesis in C2C12 myotubes. Therefore, ADLE could be useful for preventing or treating insulin resistance of skeletal muscles in diabetes.

• Journal of Korean Medicine for Obesity Research
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• v.22 no.2
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• pp.93-101
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• 2022

Objectives: This study aimed to observe the anti-diabetic effect and underlying mechanisms of Galgunhwanggumhwangryun-tang (GHH; Gegen-Qinlian-decoction) in the C2C12 myotubes. Methods: GHH (1.0 mg/ml) or metformin (0.75 mM) or insulin (100 nM) were treated in C2C12 myotubes after 4 days differentiation. The glucose uptake was assessed by 2-[N-(7-160 nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-d-glucose uptake by C2C12 cells. The expression of adenosine monophosphate-activated protein kinase (AMPK) and phosphorylation AMPK (pAMPK) were measured by western blot. We also evaluated gene expression of glucose transporter type 4 (Slc2a4, formerly known as GLUT4), glucokinase (Gk), carnitine palmitoyltransferase IA (Cpt1a), nuclear respiratory factors 1 (Nrf1), mitochondrial transcription factor A (Tfam), and peroxisome proliferator-activated receptor γ coactivator 1α (Ppargc1a) by quantitative real-time polymerase chain reaction. Results: GHH promoted glucose uptake in C2C12 myotubes. The expression of AMPK protein, which plays an essential role in glucose metabolism, was increased by treatment with GHH. GHH treatment tended to increase gene expression of Slc2a4, Gk, and Nrf1 but was not statistically significant. However, GHH significantly improved Tfam and Ppargc1a gene expression in C2C12 myotubes. Conclusions: In summary, GHH treatment promoted glucose uptake in C2C12 myotubes. We suggest that these effects are associated with increased gene expression involved in mitochondrial biosynthesis and oxidative phosphorylation, such as Tfam and Ppargc1a, and increased expression of AMPK protein.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.9
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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.