Effects of handholding and providing information on anxiety in patients undergoing percutaneous vertebroplasty.

AIMS AND OBJECTIVES: This study evaluated the effects of handholding and spoken information provided on the anxiety of patients undergoing percutaneous vertebroplasty under local anaesthesia. BACKGROUND: A surgical intervention usually entails physical discomfort and psychological burden. Furthermore, patients under local anaesthesia are conscious during the surgical intervention, which leads to more anxiety, as patients are aware of their surroundings in the operating theatre. DESIGN: A quasi-experimental design with a nonequivalent control group was utilised. METHODS: Amsterdam preoperative anxiety scale assessed psychological anxiety, while blood pressure and pulse were measured to evaluate physiological anxiety. Participants were 94 patients undergoing percutaneous vertebroplasty in a spine hospital in Gwangju Metropolitan City, South Korea. Thirty patients were assigned to Experimental Group I, 34 to the Experimental Group II and 30 to the control group. During a surgical intervention, nurses held the hands of those in Experimental Group I and provided them with spoken information. Patients in Experimental Group II experienced only handholding. RESULTS: Psychological anxiety in Experimental Group I was low compared to those in Experimental Group II and the control group. In addition, there were significant decreases in systolic blood pressure in both Experimental Groups compared to the control group. CONCLUSIONS: Handholding and spoken information provided during a surgical intervention to mitigate psychological anxiety, and handholding to mitigate physiological anxiety can be used in nursing interventions with patients undergoing percutaneous vertebroplasty. RELEVANCE TO CLINICAL PRACTICE: Handholding and providing nursing information are possibly very useful interventions that are easily implemented by circulating nurses during a surgical intervention. In particular, handholding is a simple, economical and appropriate way to help patient in the operating theatre.

Plasma homocysteine level and hepatic sulfur amino acid metabolism in mice fed a high-fat diet.

PURPOSE: Obesity, a feature of metabolic syndrome, is a risk factor for cardiovascular disease, and elevated plasma homocysteine is associated with increased cardiovascular risk. However, little published information is available concerning the effect of obesity on homocysteine metabolism. METHODS: Hepatic homocysteine metabolism was determined in male C57BL/6 mice fed a high-fat diet for 12 weeks. RESULTS: High-fat diet increased plasma homocysteine but decreased hepatic homocysteine levels. Hepatic S-adenosylhomocysteine hydrolase levels were down-regulated in the obese mice, which was in part responsible for the decrease in hepatic S-adenosylmethionine/S-adenosylhomocysteine, which served as an index of transmethylation potential. Despite the decrease in hepatic cysteine, hepatic taurine synthesis was activated via up-regulation of cysteine dioxygenase. Hepatic levels of methionine adenosyltransferase I/III, methionine synthase, methylene tetrahydrofolate reductase, and gamma-glutamylcysteine ligase catalytic subunit were unchanged. Obese mice showed elevated betaine-homocysteine methyltransferase and decreased cystathionine beta-synthase activities, although the quantities of these enzymes were unchanged. CONCLUSION: This study suggests that plasma homocysteine level is increased in obesity-associated hepatic steatosis, possibly as a result of increased hepatic homocysteine efflux along with an altered sulfur amino acid metabolism.

Preformulation and formulation of newly synthesized QNT3-18 for development of a skin whitening agent.

New molecules having the structure of (E)-2-(4-tert-butylbenzylidene) hydrazinecarbothioamide (QNT3-18) or 4-tert-butylphenylthiourea (QNT3-20) was synthesized and presupposed to inhibit melanogenesis through the inhibition of tyrosinase, which is involved in melanin formation. Therefore, we seek to develop these new molecules as skin whitening agents in topical formulations based on preformulation studies. QNT3-18 or QNT3-20 showed a strong single endothermic peak at 159.34°C with 10.79 µm-sized or at 150.69°C with 9.0 µm-sized aggregated particles, respectively. Both QNT3-18 and QNT3-20 did not show cytotoxicity at effective concentration range (0.4 µM) against keratinocyte cells and QNT3-18 was more retained than QNT3-20 in the skin instead of permeating through the skin. QNT3-18 or QNT3-20 was practically insoluble in water; the aqueous solubility was 3.8 ± 0.37 or 130.6 ± 2.52 µg/mL, respectively. Also, the partition coefficient value (log P) corresponding to the quotient between aqueous and octanol concentration of the molecule was 3.9 or 2.6, respectively. The skin retention amount of QNT3-18 was 1.7-fold higher than that of QNT3-20. When the optimal SLN cream (J3 formulation) containing 4 µM QNT3-18 was applied on the backs of hairless rats for 4 days after UV irradiation for 7 days and the skin color was checked by reflectance spectrophotometer, the rat skin treated with SLN cream with QNT3-18 quickly recovered to normal compared to skin treated with SLN cream without QNT3-18. Taken together, this study suggests that topical formulations such as creams including SLNs with QNT3-18 might be appropriate carriers for skin whitening agents.

Expression of hepatic and ovarian cytochrome P450 during estrous cycle in rats.

It is known that gender differences in drug metabolism are largely attributed to changes in sex and growth hormones. Serum concentrations of estradiol, progesterone, prolactin, follicle-stimulating hormone, and luteinizing hormone change markedly during the human menstrual cycle and the rat estrous cycle. However, little information is available regarding the effects of the human menstrual cycle or the rat estrous cycle on expression and activity of cytochrome P450 (CYP) isoforms. The present study was carried out to determine the expression and activity of CYP-dependent drug-metabolizing enzymes in the liver and ovary during the estrous cycle. The expression and activity of microsomal CYP isoforms (CYP1A1, CYP1A2, CYP1B1, CYP2B1, CYP2C11, CYP2C12, CYP2E1, CYP3A1, CYP3A2, and CYP4A), cytochrome b(5) and NADPH-dependent CYP reductase in the liver and ovary were measured in female rats in diestrus and proestrus. Our results indicated that hepatic and ovarian expression and activity of CYP isoforms, cytochrome b(5), and NADPH-dependent CYP reductase were not different between diestrus and proestrus, although serum estradiol concentration and uterus weight were markedly increased in the proestrus phase. These results suggest that the cytochrome P450-dependent system is not sensitive to changes in the estrous cycle, and further studies are warranted to determine the effects of the estrous cycle on in vivo metabolism of xenobiotics.

A novel family VII esterase with industrial potential from compost metagenomic library.

BACKGROUND: Among the vast microbial genomic resources now available, most microbes are unculturable in the laboratory. A culture-independent metagenomic approach is a novel technique that circumvents this culture limitation. For the screening of novel lipolytic enzymes, a metagenomic library was constructed from compost, and the clone of estCS2 was selected for lipolytic properties on a tributyrin-containing medium. RESULTS: The estCS2 sequence encodes a protein of 570 amino acid residues, with a predicted molecular mass of 63 kDa, and based on amino acid identity it most closely matches (45%) the carboxylesterase from Haliangium ochraceum DSM 14365. EstCS2 belong to family VII, according to the lipolytic enzyme classification proposed by Arpigny and Jaeger, and it retains the catalytic triad Ser245-Glu363-His466 that is typical of an α/ß hydrolase. The Ser245 residue in the catalytic triad of EstCS2 is located in the consensus active site motif GXSXG. The EstCS2 exhibits strong activity toward p-nitrophenyl caproate (C6), and it is stable up to 60°C with an optimal enzymatic activity at 55°C. The maximal activity is observed at pH 9, and it remains active between pH 6-10. EstCS2 shows remarkable stability in up to 50% (v/v) dimethyl sulfoxide (DMSO) or dimethylformamide (DMF). The enzyme has the ability to cleave sterically hindered esters of tertiary alcohol, as well as to degrade polyurethanes, which are widely used in various industries. CONCLUSIONS: The high stability of EstCS2 in organic solvents and its activity towards esters of ketoprofen and tertiary alcohols, and in polyurethane suggests that it has potential uses for many applications in biotransformation and bioremediation.

Age-related changes in hepatic expression and activity of cytochrome P450 in male rats.

Age-related changes in hepatic expression and activity of cytochrome P450 (CYP) were investigated in male rats aged 3 (weanling), 12 (young), 26 (adult), and 104 (old) weeks. Levels of microsomal protein, total CYP, and cytochrome b(5) increased fully after puberty. CYP1A1 was detected only in 3-week-old rats, and CYP1A2, CYP2B1, and CYP2E1 were maximally expressed at 3 weeks but decreased at 12 and 26 weeks. CYP2C11 and CYP3A2 increased markedly after puberty and decreased with aging. Ethoxyresorufin-O-deethylase, methoxyresorufin-O-demethylase, pentoxyresorufin-O-depenthylase, and p-nitrophenol hydroxylase activities were at their highest in 3-week-old rats, and midazolam hydroxylase activity was at a maximum in 12-week-old rats but decreased with aging. The present results show that increasing age caused significant alterations in hepatic expression/activity of CYP isoforms in an isoform-specific manner. These results suggest that age-related changes in hepatic CYP isoforms may be an important factor for deciding the efficacy and safety of xenobiotics.

Glabridin inhibits lipopolysaccharide-induced activation of a microglial cell line, BV-2, by blocking NF-kappaB and AP-1.

Glabridin, a flavonoid present in licorice root, is known to have antiinflammatory and cardiovascular protective activities. The present study reports an inhibitory effect of glabridin on microglial activation. Glabridin dose-dependently attenuated lipopolysaccharide (LPS)-induced production of inflammatory mediators, including nitric oxide, tumor necrosis factor-alpha and interleukin-1beta, in BV-2 cells, a murine microglia cell line. Moreover, mRNA expression of these inflammatory mediators was also suppressed by glabridin in LPS-stimulated BV-2 cells. Further study demonstrated that glabridin inhibited LPS-induced DNA binding activity of NF-kappaB and AP-1 in BV-2 cells. Collectively, the results presented in this report demonstrate that glabridin inhibits the production of inflammatory mediators in BV-2 cells and this is mediated, at least in part, by blocking NF-kappaB and AP-1 activation. The results suggest that glabridin might be a potential therapeutic agent for the treatment of neuroinflammatory and neurodegenerative diseases.

Preparation and evaluation of solid lipid nanoparticles with JSH18 for skin-whitening efficacy.

A new molecule having the structure of 6-methyl-3-phenethyl-3,4-dihydro-1H-quinazoline-2-thione (JSH18) was synthesized and it was possibly presupposed to show depigmentation through the inhibition of tyrosinase which is involved in the formation of melanin. Therefore, we are going to develop JSH18 as an inhibitor of melanin synthesis with topical formulations to show its optimal efficiency for skin whitening. Solid lipid nanoparticles (SLNs) play an important role as drug delivery systems for intravenous, peroral, parenteral, or ocular administration and for topical delivery. The particle size of prepared SLNs of JSH18 was variable from 59.8-919.6 nm. When the optimal SLNs cream (PU3) including 4 uM of JSH18 was applied to the backs of hairless rats for four days after the backs were irradiated by UV ray for seven days and the skin color was checked by reflectance spectrophotometer, the rat skin applied with PU3 cream quickly recovered to normal compared to SLNs cream without JSH18. Taken together, this study suggests topical formulations such as creams including SLNs with JSH18 might be an appropriate carrier for skin-whitening agents.

Immunosuppressive effect of silibinin in experimental autoimmune encephalomyelitis.

Silibinin is the major pharmacologically active compound of silymarin, the Silybum marianum fruit extract. Hepatoprotective activities of silibinin/silymarin are well-known, and recent studies demonstrated their anti-inflammatory and anti-carcinogenic effects which are due to inhibition of the transcription factor NF-kappaB. Based on this knowledge, we hypothesized that silibinin could be effective in the treatment of multiple sclerosis (MS) and so we tested its immunosuppressive effect in experimental autoimmune encephalomyelitis (EAE), the MS animal model. The process of spinal cord demyelination and inflammation were observed and T cell migration was determined by FACS analysis. The results showed that silibinin significantly reduced the histological signs of demyelination and inflammation in EAE. Since cytokines play an important role in inflammatory disease, the proliferative response and cytokine production were examined in lymphocytes from spleens and lymph nodes. We demonstrated that silibinin Ag-nonspecifically down-regulated the secretion of pro-inflammatory Th1 cytokines and up-regulated the anti-inflammatory Th2 cytokines in vitro. Silibinin also dose-dependently inhibited the production of Th1 cytokines ex vivo. These results indicate that silibinin is both immunosuppressive and immunomodulatory.

6,7-di-O-acetylsinococuline (FK-3000) induces G2/M phase arrest in breast carcinomas through p38 MAPK phosphorylation and CDC25B dephosphorylation.

We evaluated the cytostatic effect of 6,7-di-O-acetyl-sinococuline (FK-3000) isolated from Stephania delavayi Diels. against breast carcinoma cell lines MDA-MB­231 and MCF-7. FK-3000 suppressed CDC25B phosphorylation directly and indirectly via p38 MAPK phosphorylation. CDC25B dephosphorylation decreased levels of cyclin B and phospho-CDC-2, and ultimately induced cell cycle arrest at the G2/M phase. The p38 MAPK inhibitor, SB 239063 blocked FK-3000-induced p38 MAPK phosphorylation and nuclear accumulation, but did not completely rescue cell death. Conclusively FK-3000 exerts its antiproliferative effect through two pathways: i) G2/M cell cycle arrest via downregulation of cyclin B and phospho-CDC2 by p38 MAPK phosphorylation and CDC25B dephosphorylation, and ii) p38 MAPK-independent induction of apoptosis.

Role of NADPH oxidase-4 in saturated fatty acid-induced insulin resistance in SK-Hep-1 cells.

We aimed to develop a cell culture model of type 2 diabetes by treating SK-Hep-1 cells with four free fatty acids [i.e., palmitic acid, stearic acid (SA), linoleic acid and oleic acid]. The results showed that Akt phosphorylation was increased in SK-Hep-1 cells treated with insulin in a time- and concentration-dependent manner, which was inhibited by saturated fatty acids, but not by unsaturated fatty acids. Moreover, protein levels of NADPH oxidase (NOX) 4 but not NOX2 were increased following SA treatment and, consequently, increased reactive oxygen species production and decreased cellular glutathione were observed. Apocynin, a NOX4 inhibitor, restored the SA-induced inhibition of Akt phosphorylation, suggesting the role of NOX4 in insulin resistance induced by SA. Neither phosphorylation level nor protein level of the stress signaling kinases, such as c-Jun N-terminal kinase or p38 mitogen activated protein kinase, was changed by SA treatment. Although binding immunoglobulin protein, a marker of endoplasmic reticulum stress, was transiently increased in SKHep-1 cells treated with SA, 4-phenyl butyric acid, a chemical chaperone, had no effect on the insulin-mediated Akt phosphorylation inhibited by SA. The present study provides a useful model for screening anti-insulin resistance drugs and finding new drug targets for treatment of diabetes.

Expression of hepatic antioxidant enzymes in non-obese type-2 diabetic Goto-Kakizaki rats.

Diabetes mellitus and its complications have been attributed in part to oxidative stress, against which antioxidant enzymes constitute a major protective mechanism. The present study was performed to investigate the effects of early stage type 2 diabetes in the absence of obesity and liver damage on hepatic antioxidant enzyme expression and oxidative stress using 9-week-old Goto-Kakizaki (GK) rats. Hepatic total antioxidant capacity determined by total oxygen radical scavenging capacity and lipid peroxidation determined by malondialdehyde in plasma and liver were not significantly different between normal Wistar rats and GK rats. These results indicated that oxidative stress is not evident in these type 2 diabetic rats. Hepatic expression levels of antioxidant enzymes, including superoxide dismutase-1, catalase, glutathione peroxidase and reductase, thioredoxin-1, mu- and pi-class glutathione S-transferase (GST), and the gamma-glutamylcysteine ligase catalytic subunit, were not different between normal rats and GK rats. But, hepatic level and activity of alpha-class GST were decreased and peroxiredoxin-1 level was increased in GK rats, suggesting that upregulation of peroxiredoxin-1 compensates for downregulation of alpha-class GST. These results suggest that alpha-class GST and peroxiredoxin-1 in liver can be altered during the early stages of type 2 diabetes in the absence of obesity and severe oxidative stress.

Hepatic metabolism of sulfur amino acids in db/db mice.

To determine the effect of type-2 diabetes and obesity on the hepatic metabolism of sulfur amino acids, hepatic sulfur amino acid metabolism was determined in db/db mice. Hepatic methionine was markedly decreased in db/db mice, although the hepatic activity of betaine homocysteine methyltransferase was increased. The decrease in hepatic methionine was reflected by decreased sulfur-containing methionine metabolites, including S-adenosylmethionine, homocysteine, cysteine, and hypotaurine in liver and plasma. In contrast, S-adenosylhomocysteine, putrescine, and spermidine were increased in db/db mice. The hepatic level and activity of methionine adenosyltransferase I/III, an S-adenosylmethionine synthesizing enzyme, were significantly increased. These results suggest that increased polyamine synthesis, in conjunction with decreased hepatic methionine levels, is partly responsible for the reduction in hepatic S-adenosylmethionine. Decreased homocysteine in liver and plasma may be attributable to the decrease in hepatic methionine and upregulation of hepatic betaine homocysteine methyltransferase. Glutathione in liver and plasma did not change despite decreased γ-glutamylcysteine ligase activity. The decreased hepatic hypotaurine may be attributable to the downregulation of cysteine dioxygenase. The major finding of this study is that db/db mice exhibited decreases in hepatic methionine and its sulfurcontaining metabolites.

Alterations in hepatic metabolism of sulfur amino acids in non-obese type-2 diabetic Goto-Kakizaki rats.

Elevated plasma homocysteine has been identified as a risk factor for cardiovascular disease and non-alcoholic liver disease, which are major complications of diabetes. Hence, hepatic homocysteine metabolism has become a major focus of diabetes research. However, little information is available regarding plasma homocysteine levels in non-obese diabetic animals. Therefore, we investigated the hepatic metabolism of sulfur-amino acids in non-obese type-2 diabetic Goto-Kakizaki rats. The experiments were performed using 9-week-old Goto-Kakizaki rats and age-matched Wistar rats. The major finding of this study is that homocysteine levels in the liver and plasma are maintained by a balance between the up-regulation of betaine homocysteine methyltransferase and the inhibition of cystathionine ß-synthase in non-obese type-2 diabetic rats. Hepatic levels of cysteine and its metabolites, such as hypotaurine, taurine, and glutathione, were increased despite inhibition of the transsulfuration of homocysteine to cysteine. The elevated hepatic taurine and glutathione levels may be attributed to the up-regulation of cysteine dioxygenase expression and increased cysteine availability for glutathione synthesis. Inhibition of hepatic methionine adenosyltransferase activity in Goto-Kakizaki rats was associated with a decrease in hepatic S-adenosylmethionine, which serves as an allosteric activator of cystathionine ß-synthase. The non-obese type-2 diabetic condition results in profound changes in hepatic sulfur-amino acid metabolism and raises the possibility that sulfur-amino acid metabolism may be regulated by obesity- as well as diabetes-associated factors. Further study to elucidate the pathological significance of sulfur-amino acid metabolism in chronic liver disease in type-2 diabetic animals is underway in this laboratory.

1'-Acetoxychavicol acetate isolated from Alpinia galanga ameliorates ovalbumin-induced asthma in mice.

The World Health Organization reports that 235 million people are currently affected by asthma. This disease is associated with an imbalance of Th1 and Th2 cells, which results in the upregulation of cytokines that promote chronic inflammation of the respiratory system. The inflammatory response causes airway obstruction and can ultimately result in death. In this study we evaluated the effect of 1'-acetoxychavicol acetate (ACA) isolated from Alpinia galanga rhizomes in a mouse model of ovalbumin (OVA)-induced asthma. To generate the mouse model, BALB/c mice were sensitized by intraperitoneal injection of OVA and then challenged with OVA inhalation for 5 days. Mice in the vehicle control group were sensitized with OVA but not challenged with OVA. Treatment groups received dexamethasone, 25 mg/kg/day ACA, or 50 mg/kg/day ACA for 5 days. Asthma-related inflammation was assessed by bronchoalveolar lavage fluid cell counts and histopathological and immunohistochemical analysis of lung tissues. Our results showed that ACA reduced the infiltration of white blood cells (especially eosinophils) and the level of IgE in the lungs of mice challenged with OVA and suppressed histopathological changes such as airway remodeling, goblet-cell hyperplasia, eosinophil infiltration, and glycoprotein secretion. In addition, ACA inhibited expression of the Th2 cytokines interleukin (IL)-4 and IL-13, and Th1 cytokines IL-12α and interferon-γ. Because asthmatic reactions are mediated by diverse immune and inflammatory pathways, ACA shows promise as an antiasthmatic drug candidate.

Evaluation of hepatotoxicity and oxidative stress in rats treated with tert-butyl hydroperoxide.

Although tert-butyl hydroperoxide (t-BHP) is commonly used to induce oxidative stress, little is known about the time- or dose-dependence of its oxidative effects. In this study, we examined hepatotoxicity and oxidative stress in male rats at various times (0-24 h) after t-BHP (0, 0.2, 0.5, 1 or 3 mmol/kg, ip) treatment. Serum hepatotoxicity parameters were increased from 2 h following 1 mmol/kg t-BHP and reached their maximum values at 8 h. Plasma malondialdehyde levels were maximally elevated by 62% at 0.5 h and returned to control levels by 4 h. Hepatic glutathione levels were decreased between 0.5 and 2 h, and hepatic glutathione disulfide levels were increased at 2h. Interestingly, hepatic glutathione levels were increased at 24 h, which may be attributed to up-regulation of glutathione synthesis through induction of gamma-glutamylcysteine ligase expression. The elevation of hepatotoxic parameters and plasma MDA was observed from 0.5 to 1 mmol/kg t-BHP, respectively, in a dose-dependent manner. Considering that the maximal dose resulted in 20% lethality, 1 mmol/kg of t-BHP may be suitable for evaluating antioxidant activity of tested compounds. Our results provide essential information to characterize the t-BHP-induced oxidative stress and hepatotoxicity.

Effects of palmitic acid on TNF-α-induced cytotoxicity in SK-Hep-1 cells.

Non-alcoholic steatohepatitis (NASH) is an increasingly common cause of chronic liver disease; however, no specific pharmacologic therapy has been shown to be effective in its treatment. The present study was designed to develop an experimental cell culture model of NASH using four kinds of fatty acids - palmitic acid (PA), stearic acid (SA), linoleic acid (LA), and oleic acid (OA) - and TNF-α, according to the "two-hit" hypothesis. The saturated fatty acids PA and SA are more cytotoxic than the unsaturated fatty acids OA and LA. Cellular lipid accumulation without cytotoxicity was more easily induced with the unsaturated fatty acids than with the saturated fatty acids. PA augmented TNF-α-induced cytotoxicity, while the unsaturated fatty acids attenuated TNF-α-induced cytotoxicity. In a mechanistic study, PA enhanced TNF-α-mediated apoptosis in the absence of oxidative stress, as determined by measuring the cellular glutathione and malondialdehyde levels. Moreover, PA inhibited the TNF-α-induced phosphorylation of AKT, but not c-Jun N-terminal kinase, indicating that inhibition of survival signaling pathways activated by TNF-α may explain the effects of PA on TNF-α-induced cytotoxicity. The in vitro NASH model established in this study may be used to screen drug candidates for suitability for the treatment of NASH.

Evaluation of the total oxidant scavenging capacity of saponins isolated from Platycodon grandiflorum.

The antioxidant activity of saponins isolated from Platycodon grandiflorum (PG; Balloon flower) was determined using the total oxidant-scavenging capacity (TOSC) assay. Platycodigenin, polygalacic acid, platycodin D, platycoside E and deapioplatycoside E were isolated and their structures were characterised based on their physical and spectral properties and by comparison of these results with similar data in the literature. Platycodin D showed the greatest TOSC value against peroxyl radicals, followed (in decreasing order) by polygalacic acid, platycodigenin, deapioplatycosides E and platycoside E. Although the TOSC value of the saponins against peroxyl radicals was less than that of glutathione (GSH) and Trolox used as positive controls. However, TOSC value of platycodigenin, deapioplatycoside E, platycodin D or platycoside E against peroxynitrite was 2.35-, 1.27-, 1.02- or 0.75-fold of GSH, respectively, while polygalacic acid exhibited no scavenging capacity of peroxynitrites. These results suggest importance of the presence of hydroxyl group at carbon 24 in platycodigenin in peroxynitrite scavenging. As the number of attached sugar residues in the saponin glycosides is increased, the scavenging capacity of peroxyl radical, but not peroxynitrite was significantly decreased. These results showed that PG saponins have potent antioxidant activities, which is different according to the structure of aglycones and the number of attached sugar residues.

Hepatic expression of cytochrome P450 in type 2 diabetic Goto-Kakizaki rats.

Although hepatic expression of cytochrome P450 (CYP) changes markedly in diabetes, the role of ketone bodies in the regulation of CYP in diabetes is controversial. The present study was performed to determine the expression and activity of CYP in non-obese type II diabetic Goto-Kakizaki (GK) rats with normal levels of ketone bodies. In the present study, basal serum glucose levels increased 1.95-fold in GK rats, but acetoacetate and ß-hydroxybutyrate levels were not significantly different. Hepatic expression of CYP reductase and CYP3A2 was up-regulated in the GK rats, and consequently, activities of CYP reductase and midazolam 4-hydroxylase, mainly catalyzed by CYP3A2, increased. In contrast, hepatic expression of CYP1A2 and CYP3A1 was down-regulated and the activities of 7-ethoxyresorufin-O-deethylase and 7-methoxyresorufin-O-demethylase, mainly catalyzed by CYP1A, also decreased in GK rats. Hepatic levels of microsomal protein and total CYP and hepatic expression of cytochrome b(5), CYP1B1, CYP2B1 and CYP2C11 were not significantly different between the GK rats and normal Wistar rats. Moreover, the expression and activity of CYP2E1, reported to be up-regulated in diabetes with hyperketonemia, were not significantly different between GK rats and control rats, suggesting that elevation of ketone bodies plays a critical role in the up-regulation of hepatic CYP2E1 in diabetic rats. Our results showed that the expression of hepatic CYP is regulated in an isoform-specific manner. The present results also show that the GK rat is a useful animal model for the pathophysiological study of non-obese type II diabetes with normal ketone body levels.

Metformin inhibits P-glycoprotein expression via the NF-κB pathway and CRE transcriptional activity through AMPK activation.

BACKGROUND AND PURPOSE: The expression of P-glycoprotein (P-gp), encoded by the multidrug resistance 1 (MDR1) gene, is associated with the emergence of the MDR phenotype in cancer cells. We investigated whether metformin (1,1-dimethylbiguanide hydrochloride) down-regulates MDR1 expression in MCF-7/adriamycin (MCF-7/adr) cells. EXPERIMENTAL APPROACH: MCF-7 and MCF-7/adr cells were incubated with metformin and changes in P-gp expression were determined at the mRNA, protein and functional level. Transient transfection assays were performed to assess its gene promoter activities, and immunoblot analysis to study its molecular mechanisms of action. KEY RESULTS: Metformin significantly inhibited MDR1 expression by blocking MDR1 gene transcription. Metformin also significantly increased the intracellular accumulation of the fluorescent P-gp substrate rhodamine-123. Nuclear factor-κB (NF-κB) activity and the level of IκB degradation were reduced by metformin treatment. Moreover, transduction of MCF-7/adr cells with the p65 subunit of NF-κB induced MDR1 promoter activity and expression, and this effect was attenuated by metformin. The suppression of MDR1 promoter activity and protein expression was mediated through metformin-induced activation of AMP-activated protein kinase (AMPK). Small interfering RNA methods confirmed that reduction of AMPK levels attenuates the inhibition of MDR1 activation associated with metformin exposure. Furthermore, the inhibitory effects of metformin on MDR1 expression and cAMP-responsive element binding protein (CREB) phosphorylation were reversed by overexpression of a dominant-negative mutant of AMPK. CONCLUSIONS AND IMPLICATIONS: These results suggest that metformin activates AMPK and suppresses MDR1 expression in MCF-7/adr cells by inhibiting the activation of NF-κB and CREB. This study reveals a novel function of metformin as an anticancer agent.