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1.  A novel IRS-1-associated protein, DGKζ regulates GLUT4 translocation in 3T3-L1 adipocytes 
Scientific Reports  2016;6:35438.
Insulin receptor substrates (IRSs) are major targets of insulin receptor tyrosine kinases. Here we identified diacylglycerol kinase zeta (DGKζ) as an IRS-1-associated protein, and examined roles of DGKζ in glucose transporter 4 (GLUT4) translocation to the plasma membrane. When DGKζ was knocked-down in 3T3-L1 adipocytes, insulin-induced GLUT4 translocation was inhibited without affecting other mediators of insulin-dependent signaling. Similarly, knockdown of phosphatidylinositol 4-phosphate 5-kinase 1α (PIP5K1α), which had been reported to interact with DGKζ, also inhibited insulin-induced GLUT4 translocation. Moreover, DGKζ interacted with IRS-1 without insulin stimulation, but insulin stimulation decreased this interaction. Over-expression of sDGKζ (short-form DGKζ), which competed out DGKζ from IRS-1, enhanced GLUT4 translocation without insulin stimulation. Taking these results together with the data showing that cellular PIP5K activity was correlated with GLUT4 translocation ability, we concluded that IRS-1-associated DGKζ prevents GLUT4 translocation in the absence of insulin and that the DGKζ dissociated from IRS-1 by insulin stimulation enhances GLUT4 translocation through PIP5K1α activity.
PMCID: PMC5064357  PMID: 27739494
2.  The Effects of Brazilian Green Propolis against Excessive Light-Induced Cell Damage in Retina and Fibroblast Cells 
Background. We investigated the effects of Brazilian green propolis and its constituents against white light- or UVA-induced cell damage in mouse retinal cone-cell line 661W or human skin-derived fibroblast cells (NB1-RGB). Methods. Cell damage was induced by 3,000lx white light for 24 h or 4/10 J/cm2 UVA exposure. Cell viability was assessed by Hoechst33342 and propidium iodide staining or by tetrazolium salt (WST-8) cell viability assay. The radical scavenging activity of propolis induced by UVA irradiation in NB1-RGB cells was measured using a reactive-oxygen-species- (ROS-) sensitive probe CM-H2DCFDA. Moreover, the effects of propolis on the UVA-induced activation of p38 and extracellular signal-regulated kinase (ERK) were examined by immunoblotting. Results. Treatment with propolis and two dicaffeoylquinic acids significantly inhibited the decrease in cell viability induced by white light in 661W. Propolis and its constituents inhibited the decrease in cell viability induced by UVA in NB1-RGB. Moreover, propolis suppressed the intracellular ROS production by UVA irradiation. Propolis also inhibited the levels of phosphorylated-p38 and ERK by UVA irradiation. Conclusion. Brazilian green propolis may become a major therapeutic candidate for the treatment of AMD and skin damage induced by UV irradiation.
PMCID: PMC3876711  PMID: 24416064
3.  Laxative effects and mechanism of action of Brazilian green propolis 
Brazilian green propolis is reported to have wide range of biological properties including antibacterial, anti-inflammatory, anti-influenza, and antioxidant activities. In the digestive system, a protective effect of propolis on gastric ulcer has been reported, but a laxative effect has not yet been reported. We investigated the effect and the mechanism of action of water and ethanol extracts of Brazilian green propolis.
We examined the laxative effect of propolis on stool frequency by administering orally an ethanol extract of propolis (EEP) or a water extract of propolis (WEP) at 10, 50, 100, or 500 mg/kg to normal mice. We then investigated the effects of propolis using constipation model mice induced by two types of drugs, loperamide (a μ opioid receptor agonist) and clonidine (an α-2 adrenergic receptor agonist). We also investigated the effects of WEP on gastrointestinal transit and contractional tension of the ileum to uncover the mechanism of action of WEP.
Treatment with WEP, but not with EEP, significantly increased the weight of stools (p<0.01 at 500 mg/kg). WEP treatment significantly restored stool frequency and stool weight in clonidine-induced constipation model mice, but not in loperamide-induced constipation model mice. WEP treatment did not affect gastro-intestinal transit, but significantly increased the contractional tension of the isolated ileum of guinea pigs. This increase was inhibited by an acetylcholine receptor antagonist (atropine), but not by a 5-HT receptor antagonist (GR113808).
These findings indicate that WEP has laxative effects both in normal mice and in clonidine-induced constipation model mice. The laxative effects of WEP might be mediated by increased contractional tension of the ileum exerted at least in part via activation of an acetylcholine receptor.
PMCID: PMC3487869  PMID: 23088672
Propolis; Laxative; Acetylcholine receptor; Water extract
4.  Laxative effects of agarwood on low-fiber diet-induced constipation in rats 
Agarwood (Aquilaria sinensis), well known as incense in Southeast Asia, has been used as a digestive in traditional medicine. We investigated the laxative effects of an ethanol extract of agarwood leaves (EEA) in a rat model of low-fiber diet-induced constipation.
A set of rats was bred on a normal diet while another set was placed on a low-fiber diet to induce constipation. The laxative effect of agarwood was then investigated on both sets of rats.
Pretreatment of normal rats with single dose of EEA (600 mg/kg, p.o.) significantly increased frequency and weight of stools. Also, treatments with EEA (300 and 600 mg/kg, p.o.) for 14 days caused a significant increase in stool frequency and weight. Feeding of the animals with a low-fiber diet resulted in a decrease in stool weight, frequency, and water content and also delayed carmine egestion. A single treatment with EEA (600 mg/kg) or senna (150 and 300 mg/kg) significantly increased stool frequency, weight, and water content and also accelerated carmine egestion in the model rats. Once daily administrations of EEA (150 mg/kg), for 14 days, caused a significant increase in water content of stools. The higher doses of EEA (300 and 600 mg/kg) significantly increased frequency, weight, and water content of the stools while accelerating carmine egestion in the constipated rats. Senna (150 and 300 mg/kg) produced similar effect as the higher doses of EEA but, in addition, induced severe diarrhea.
These findings indicate that EEA has a laxative effect, without causing diarrhea, in a rat model of low-fiber diet-induced constipation. These findings suggest that EEA may be highly effective on constipation as a complementary medicine in humans suffering from life style-induced constipation.
PMCID: PMC2995776  PMID: 21078136
5.  Protective effects of a gastrointestinal agent containing Korean red ginseng on gastric ulcer models in mice 
Korean red ginseng (KRG) is a ginseng that has been cultivated and aged for 4-6 years or more, and goes through an extensive cleaning, steaming and drying process. KRG contains more than 30 kinds of saponin components and has been reported as having various biological properties, such as anti-fatigue action, immune restoration, and neurovegetative effect. The purpose of this study was to assess the effects of a KRG-containing drug (KRGCD) on gastric ulcer models in mice.
Stomach ulcers were induced by oral ingestion of hydrochloride (HCl)/ethanol or indomethacin. Treatment with KRGCD (30, 100, and 300 mg/kg, p.o.) occurred 1 hr before the ulcer induction. Effect of KRGCD on anti-oxidant activity and gastric mucosal blood flow with a laser Doppler flowmeter in mice stomach tissue was evaluated.
KRGCD (100 and 300 mg/kg, p.o.) significantly decreased ethanol- and indomethacin-induced gastric ulcer compared with the vehicle-treated (control) group. KRGCD (100 and 300 mg/kg) also decreased the level of thiobarbituric acid reactive substance (TBARS) and increased gastric mucosal blood flow compared with the control group.
These results suggest that the gastroprotective effects of KRGCD on mice ulcer models can be attributed to its ameliorating effect on oxidative damage and improving effect of gastric mucosal blood flow.
PMCID: PMC2936409  PMID: 20718962

Results 1-5 (5)