• International Journal of Oral Biology
• /
• v.31 no.4
• /
• pp.141-148
• /
• 2006

The effects of adenosine triphosphate(ATP) on salivary glands have been recognized since 1982. The presence of purinergic recepetors(P2Rs) that mediate the effects of ATP in various tissues, including parotid and submandibular salivary gland, has been supported by the cloning of receptor cDNAs and the expression of the receptor proteins. P2Rs have many subtypes, and the activation of these receptor subtypes increase intracellular $Ca^{2+}$, a key ion in the regulation of the secretion in the salivary gland. The apical pores of taste buds in circumvallate and foliate papillae are surrounded by the saliva from von Ebner salivary gland(vEG). Thus, it is important how the secretion of vEG is controlled. This study was designed to elucidate the roles of P2Rs on salivary secretion of vEG. Male Sprague-Dawley rats (about 200 g) were used for this experiment. vEG-rich tissues were obtained from dissecting $500-1,000\;{\mu}m$ thick posterior tongue slices under stereomicroscope view. P2Rs mRNA in vEG acinar cells were identified with RT-PCR. To observe the change in intracellular $Ca^{2+}$ activity, we employed $Ca^{2+}-ion$ specific fluorescence analysis with fura-2. Single acinar cells and cell clusters were isolated by a sequential trypsin/collagenase treatment and were loaded with $10\;{\mu}M$ fura -2 AM for 60 minutes at room temperature. Several agonists and antagonists were used to test a receptor specificity. RT-PCR revealed that the mRNAs of $P2X_4$, $P2Y_1$, $P2Y_2$ and $P2Y_3$ are expressed in vEG acinar cells. The intracellular calcium activity was increased in response to $10\;{\mu}M$ ATP, a P2Rs agonist, and 2-MeSATP, a $P2Y_1$ and $P2Y_2R$ agonist. However, $300\;{\mu}M\;{\alpha}{\beta}-MeATP$, a $P2X_1$ and $P2X_3R$ agonist, did not elicit the response. The responses elicited by $10\;{\mu}M$ ATP and UTP, a $P2Y_2R$ agonists, were maintained when extracellular calcium was removed. $10\;{\mu}M$ suramin, a P2XR antagonist, and reactive blue 2, a P2YR antagonist, partially blocked ATP-induced response. However, when extracellular calciums were removed, suramin did not abolish the responses elicited by ATP. These results suggest that P2Rs play an important role in salivary secretion of vEG acinar cells and the effects of ATP on vEG salivary secretion may be mediated by $P2X_4$, $P2Y_1$, $P2Y_2$, and/or $P2Y_3$.

• Biomedical Science Letters
• /
• v.29 no.4
• /
• pp.242-248
• /
• 2023

Platelets are activated at the sites of vascular injury by a number of molecules, including adenosine diphosphate, collagen and thrombin. The full platelet aggregation is absolutely essential for the normal hemostasis. Glycyrrhiza glabra is a well-known medicinal herb that grows in various parts of the world and is known to have various effects such as antioxidant, anti-inflammatory, anti-atherogenic, anti-osteoporotic and skin-whitening. However, the platelet inhibitory effect of Glycyrrhiza glabra extract (GGE) has not been identified. In this study, we investigated if GGE inhibited platelet aggregation. We observed that GGE inhibited collagen-induced platelet aggregation, Ca²⁺ mobilization, and thromboxane A2 generation. In addition, GGE suppressed phosphorylation of phosphatidylinositol-3 kinase (PI3K), Akt and elevated phosphorylation of inositol 1,4,5-trisphosphate receptor (IP3R), vasodilator stimulated phosphoprotein (VASP). Taken together, GGE showed strong antiplatelet effects and may be used to block platelet-mediated cardiovascular diseases.

• Biomedical Science Letters
• /
• v.27 no.4
• /
• pp.270-276
• /
• 2021

Physiological agents trigger a signaling process called "inside-out signaling" and activated platelets promote adhesion, granule release, and conformational changes of glycoprotein IIb/IIIa (αIIb/β₃). Activated αIIb/β₃ interacts with fibrinogen and initiates a second signaling step called "external signaling". These two signaling pathways can cause hemostasis or thrombosis, and thrombosis is a possible medical problem in arterial and venous vessels, and platelet-mediated thrombosis is a major cause of cardiovascular disease (CVD). Therefore, modulating platelet activity is important for platelet-mediated thrombosis and cardiovascular disease. Esculetin is a coumarin-based physiologically active 6,7-dihydroxy derivative known to have pharmacological activity against obesity, diabetes, renal failure and CVD. Although some studies have confirmed the effects of esculetin in human platelet activation and experimental mouse models, it is not clear how esculetin has antiplatelet and antithrombotic effects. We confirmed the effect and mechanism of action of escultein on human platelets induced by collagen. As a result, esculetin decreased Ca²⁺ recruitment through upregulation of inositol 1, 4, 5-triphosphate receptor. In addition, esculetin upregulates cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP)-dependent pathways and inhibits fibrinogen binding and thrombus contraction. Our results demonstrate the antiplatelet effect and antithrombotic effect of esculetin in human platelets. Therefore, we suggest that esculetin could be a potential phytochemical for the prevention of thrombus-mediated CVD.

• Biomolecules & Therapeutics
• /
• v.26 no.2
• /
• pp.201-209
• /
• 2018

G protein-coupled receptor 119 (GPR119) is expressed in the pancreas and gastrointestinal tract, and its activation promotes insulin secretion in the beta cells of the pancreatic islets as well as the secretion of glucagon-like peptide-1 (GLP-1) in intestinal L cells, consequently improving glucose-stimulated insulin secretion. Due to this dual mechanism of action, the development of small-molecule GPR119 agonists has received significant interest for the treatment of type 2 diabetes. We newly synthesized 1,2,4-triazolone derivatives of GPR119 agonists, which demonstrated excellent outcomes in a cyclic adenosine monophosphate (cAMP) assay. Among the synthesized derivatives, YH18968 showed cAMP=2.8 nM; in GLUTag cell, GLP-1secretion=2.3 fold; in the HIT-T15 cell, and insulin secretion=1.9 fold. Single oral administration of YH18968 improved glucose tolerance and combined treatment with a dipeptidyl peptidase 4 (DPP-4) inhibitor augmented the glucose lowering effect as well as the plasma level of active GLP-1 in normal mice. Single oral administration of YH18968 improved glucose tolerance in a diet induced obese mice model. This effect was maintained after repeated dosing for 4 weeks. The results indicate that YH18968 combined with a DPP-4 inhibitor may be an effective therapeutic candidate for the treatment of type 2 diabetes.

• International Journal of Molecular Medicine
• /
• v.44 no.3
• /
• pp.1161-1171
• /
• 2019

The present study investigated whether glucagon like peptide-1 (GLP-1) improves glucose uptake through glucose transporter type 4 (GLUT4), mediated by the activation of sirtuin 1 (SIRT1), in skeletal muscle cells with palmitate induced-insulin resistance. The levels of glucose uptake, GLUT4, protein kinase A (PKA), and cyclic adenosine monophosphate (cAMP) were determined in human skeletal muscle myotubes (HSMMs) exposed to palmitate and GLP-1. Then, to determine whether PKA/cAMP were downstream signals of GLP-1, a PKA inhibitor was used. To determine whether SIRT-1 contributes to GLP-1 action in HSMMs with palmitate-induced insulin resistance, the levels of peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) deacetylation and SIRT-1 activity were assessed using a SIRT1 inhibitor and small interfering RNA (siRNA). The phosphorylation levels of protein kinase B (Akt) and insulin receptor substrate 1 (IRS-1) as insulin signaling pathways, were assessed in GLP-1-treated HSMMs exposed to palmitate. The influence of SIRT1 on the GLP-1-induced activation of insulin signaling pathway was determined using a SIRT1 inhibitor. GLP-1 restored the palmitate-induced reductions in the levels of glucose uptake, GLUT4 mRNA, GLUT4 promoter activity, and GLUT4 protein in HSMMs. PKA and cAMP, as GLP-1 downstream signals, played a role in this process. GLP-1 increased the deacetylation levels of PGC1α, and stimulated SIRT1 in HSMMs. Moreover, the SIRT1 inhibitor and siRNA of SIRT1 suppressed the effect of GLP-1 on GLUT4 expression in HSMMs exposed to palmitate. The SIRT1 inhibitor also prevented the GLP-1-induced phosphorylation of IRS-1 and Akt in palmitate-treated HSMMs. The present findings suggest that in palmitate-induced insulin-resistant HSMM, GLP-1 activates SIRT1 through the PKA/cAMP pathway, which in turn enhances glucose uptake through GLUT4 and the insulin signaling pathway.

• Journal of Life Science
• /
• v.25 no.3
• /
• pp.299-306
• /
• 2015

Chrysanthemum zawadskii, a herbaceous perennial plant belonging to the Compositae, grows wild in Asian countries, including Japan, China, and Korea. The biological, antioxidative, anti-inflammatory, and antibacterial activities of C. zawadskii have been reported, its antiobesity activity has not been elucidated. In the present study, the effect of C. zawadskii methanol extract (CZME) on pancreatic lipase enzyme activity, adipocyte differentiation, and adipogenesis was investigated using an in vitro assay and a cell model system. CZME effectively suppressed lipase enzyme activity in a dose-dependent manner. CZME also inhibited insulin, dexamethasone, 3-isobutyl-1-methylxanthine (MDI)-induced adipocyte differentiation, lipid accumulation, and the level of triglyceride in 3T3-L1 preadipocytes in a dose-dependent manner, without cytotoxicity. The antiobesity effect of CZME might be modulated by gene and protein expression of cytidine-cytidine-adenosine-adenosine-thymidine (CCAAT)/enhancer binding proteins (C/EBP) α, C/EBPβ, and the peroxisome proliferator-activated receptor γ (PPAR γ). CZME also triggered lipolysis in a dose-dependent manner in MDI-induced 3T3-L1 preadipocytes. Taken together, these results provide important new insights into the antiobesity activities of C. zawadskii, showing that they involve pancreatic lipase inhibition, as well as antiadipogenic and lipolysis effects. CZME might be a promising source in the field of nutraceuticals. However, the active compounds that confer the antiobesity activities of CZME need to be identified.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.17 no.2
• /
• pp.529-541
• /
• 2003

Yukmijihwang-tang has been widely used as an and-aging herbal medicine for hundred years in Asian countries. Numerous studies show that Yukmijihwangtang has anti-oxidative effect both in vivo and in vitro. It has been reported that Moutan Cortex Radicis extract (MCR) was the most effective herb in Yukmijihwang-tang on undifferentiated PC12 cells upon oxidative-stressed with hydrogen peroxide. The purpose of this study is to; 1) evaluate the recovery of neuronal damage by assessing the anti-oxidant effect of MCR on PC12 cells differentiated with nerve growth factor (NGF), 2) identify candidate genes responsible for anti-oxidative effect on differentiated PC12 cells by oligonucleotide chip microarray. PC12 cells, which were differentiated by treating with NGF, were treated without or with hydrogen peroxide in the presence or absence of various concentration of MCR. Cell survival was determined by using MTS assay. Measurement of intracellular reactive oxygen species (ROS) generation was determined using the H2DCFDA assay The viability of cells treated with MCR was significantly recovered from stressed PC12 cell. In addition, wide rage of concentrations of MCR shows dose-dependent inhibitory effect on ROS production in oxidative-stressed cells. Total RNAs of cells without treatment(Control group), only treated with H₂O₂ (stressed group) and treated with both H₂O₂ and of MCR (MCR group) were isolated, and cDNAs was synthesized using oligoT7(dT) primer. The fragmented cRNAs, synthesized from cDNAs, were applied to Affymetrix GeneChip Rat Neurobiology U34 Array. mRNA of Calcium/calmodulin-dependent protein kinase II delta subunit(CaMKII), neuron glucose transporter (GLUT3) and myelin/oligodendrocyte glycoprotein(MOG) were downregulated in Stressed group comparing to Control group. P2X2-5 receptor (P2X2R-5), P2X2-4 receptor (P2X2R-4), c-fos, 25 kDa synaptosomal attachment protein(SNAP-25a) and GLUT3 were downregulated, whereas A2 adenosine receptor (A2AR), cathechol-O-methyltransferase(COMT), glucose transporter 1 (GLUT1), EST223333, heme oxygenase (HO), VGF, UI-R-CO-ja-a-07-0-Ul.s1 and macrophage migration inhibitory factor (MIF) were upregulated in MCA group comparing to Control group. Expression of Putative potassium channel subunit protein (ACK4), P2X2A-5, P2X2A-4, Interferon-gamma inducing factor isoform alpha precursor (IL-18α), EST199031, P2XR, P2X2 purinoceptor isoform e (P2X2R-e), Precursor interleukin 18 (IL-18) were downregulated, whereas MOO, EST223333, GLUT-1, MIF, Neuronatin alpha, UI-R-C0-ja-a-07-0-Ul.s1, A2. adenosine receptor, COMT, neuron-specific enolase (NSE), HO, VGF, A rat novel protein which is expressed with nerve injury (E12625) were upregulated in MCR group comparing to Stressed group. The results suggest that decreased viability and AOS production of PC12 cell by H₂O₂ may be, at lease, mediated by impaired glucose transporter expression. It is implicated that the MCR treatment protect PC12 cell from oxidative stress via following mechanisms; improving glucose transport into the cell, enhancing expression of anti-oxidative genes and protecting from dopamine cytotoxicity by increment of COMT and MIF expression. The list of differentially expressed genes may implicate further insight on the action and mechanism behind the anti-oxidative effects of herbal extract Moutan Cortex Radicis.

• Journal of Nutrition and Health
• /
• v.54 no.5
• /
• pp.448-458
• /
• 2021

Purpose: Mulberry (Morus alba L.) fruit is widely grown in Asia and consumed as fresh fruit, jam, and juices. The fruit has beneficial health effects, including anti-diabetic, anti-tumor, and anti-obesity properties. However, the mechanisms by which mulberry fruit juice powder (MJ) regulates inflammatory microRNAs (miRs) are not yet known. This study investigated the effect of mulberry fruit juice powder on the regulation of inflammation and miR-132/143 during 3T3-L1 adipocyte differentiation. Methods: The 3T3-L1 cells were induced to differentiate for 2 days and then treated with various concentrations of MJ for 7 days. Cytotoxicity was determined by evaluating cell viability using a water-soluble tetrazolium salt-8 assay kit. Intracellular lipid accumulation was evaluated by oil-red O staining. The levels of the expression of genes involved in adipogenesis and inflammation, and miR-132/143 were measured by quantitative real-time polymerase chain reactions. Results: MJ showed no cytotoxic effect on 3T3-L1 adipocytes at concentrations below 100 ng/mL. Intracellular lipid accumulation was reduced by MJ treatment at concentrations of 100 ng/mL. The messenger RNA (mRNA) levels of proliferator-activated receptor-γ, cytosine-cytosine-adenosine-adenosine-thymidine/enhancer-binding protein-α, and adipocyte protein 2, which are involved in adipogenesis, were suppressed by MJ. A reduction was also seen in mRNA levels of genes related to the inflammatory response, such as tumor necrosis factor-α, interleukin-6, monocyte chemoattractant protein-1, and inducible nitric oxide synthase. The expression of the inflammatory miR-132 and miR-143 was also decreased by MJ. Conclusion: These results suggest that MJ may suppress adipogenesis and inflammation through the regulation of miR-132/143 expression in 3T3-L1 adipocytes. Thus, MJ may be useful as a food agent that prevents obesity-associated inflammation.

• Integrative Medicine Research
• /
• v.3 no.1
• /
• pp.4-10
• /
• 2014

Green tea and coffee consumption have been widely popular worldwide. These beverages contain caffeine to activate the central nervous system by adenosine receptor blockade, and due to the caffeine, addiction or tolerance may occur. In addition to this caffeine effect, green tea and coffee consumption have always been at the center of discussions about human health, disease, and longevity. In particular, green tea catechins are involved in many biological activities such as antioxidation and modulation of various cellular lipid and proteins. Thus, they are beneficial against degenerative diseases, including obesity, cancer, cardiovascular diseases, and various inflammatory diseases. Some reports also suggest that daily consumption of tea catechins may help in controlling type 2 diabetes. However, other studies have reported that chronic consumption of green tea may result in hepatic failure, neuronal damage, and exacerbation of diabetes, suggesting that interindividual variations in the green tea effect are large. This review will focus on the effect of green tea catechins extracted from the Camellia sinensis plant on type 2 diabetes and obesity, and the possible mechanistic explanation for the experimental results mainly from our laboratory. It is hoped that green tea can be consumed in a suitable manner as a supplement to prevent the development of type 2 diabetes and obesity.

• Journal of Life Science
• /
• v.27 no.8
• /
• pp.888-895
• /
• 2017

Salsola collina (S. collina) is an annual plant widely distributed in drought and semi-drought areas, which has been used for a long time as a kind of folk remedy in traditional Chinese medicine for the treatment of hypertension. Previously, the anti-oxidative and anti-cancer activities of S. collina were elucidated in our research group. In this study, the anti-obesity activities of S. collina ethanol extract (SCEE) were evaluated using a pancreatic lipase enzyme inhibition assay and cell culture model. The results showed that SCEE effectively suppressed pancreatic lipase enzyme activity in a dose-dependent manner. Furthermore, SCEE significantly suppressed adipocyte differentiation, lipid accumulation, and triglyceride (TG) content, and triggered lipolysis on insulin, dexamethasone, and 3-isobutyl-l-methylxanthine-treated 3T3-L1 preadipocytes in a dose-dependent manner without cytotoxicity. Its anti-obesity effect was modulated by cytidine-cytidine-adenosine-adenosine-thymidine (CCAAT)/enhancer binding proteins ${\alpha}$ ($C/EBP{\alpha}$), $C/EBP{\beta}$, and the peroxisome proliferator-activated receptor ${\gamma}$ ($PPAR{\gamma}$) gene, as well as protein expressions. Taken together, these results offer the important new insight that S. collina possesses anti-obesity properties, such as pancreatic lipase inhibition and anti-adipogenic and lipolysis effects through the modulation of their upstream signaling pathway. It could become a promising source in the field of nutraceuticals, and the identification of active compounds that confer the biological activities of SCEE may be needed.