Rosiglitazone Elicits an Adiponectin-Mediated Insulin-Sensitizing Action at the Adipose Tissue-Liver Axis in Otsuka Long-Evans Tokushima Fatty Rats.

Rosiglitazone is an agonist of peroxisome proliferator-activated receptor- (PPAR-) γ that is principally associated with insulin action. The exact mechanisms underlying its insulin-sensitizing action are still not fully elucidated. It is well known that adiponectin mostly secreted in adipose tissue is an insulin sensitizer. Here, we found that treatment of Otsuka Long-Evans Tokushima Fatty (OLETF) rats with rosiglitazone (3 mg/kg, once daily, by oral gavage for 33 weeks) attenuated the increase in fasting plasma insulin concentrations and the index of the homeostasis model assessment of insulin resistance along with the age growth and glucose concentrations during an oral glucose tolerance test. In addition, the increase in plasma alanine aminotransferase activity, concentrations of fasting plasma nonesterified fatty acids and triglyceride, and hepatic triglyceride content was also suppressed. The hepatic protein expression profile revealed that rosiglitazone increased the downregulated total protein expression of insulin receptor substrate 1 (IRS-1) and IRS-2. Furthermore, the treatment suppressed the upregulated phosphorylation of IRS-1 at Ser307 and IRS-2 at Ser731. The results indicate that rosiglitazone ameliorates hepatic and systemic insulin resistance, hepatic inflammation, and fatty liver. Mechanistically, rosiglitazone suppressed hepatic protein overexpression of both phosphorylated nuclear factor- (NF-) κBp65 and inhibitory-κB kinase-α/ß, a transcription factor that primarily regulates chronic inflammatory responses and the upstream NF-κB signal transduction cascades which are necessary for activating NF-κB, respectively. More importantly, rosiglitazone attenuated the decreases in adipose adiponectin mRNA level, plasma adiponectin concentrations, and hepatic protein expression of adiponectin receptor-1 and receptor-2. Thus, we can draw the conclusion that rosiglitazone elicits an adiponectin-mediated insulin-sensitizing action at the adipose tissue-liver axis in obese rats. Our findings may provide new insights into the mechanisms of action of rosiglitazone.

[Development of Tripterygium glycosides nano-carries based on "nanoemulsion-gels" and its pharmacodynamics].

The aim of this study is to develop the Tripterygium glycosides nanoemulsion gels and investigate its pharmacodynamics. Oleic acid was used as oil phase, polyoxyethylene castor oil as surfaetant, and 1,2-propanediol as cosurfactant to screen the formula of Tripterygium glycoside nanoemulsion using the pseudo-temary phase diagrams. Then the nanoemulsion gels was prepared. The ICR mouse ears were sensitazated by 7% DNCB, and then were excited by 0.3% DNCB to stimulate the model of mouse chronic dermatitis and eczema. The concentrations of IFN-γ, IL-4 and IL-8 in mouse blood were determined by ELISA. The results showed that Tripterygium glycosides nanoemulsion gels could significantly inhibit the swelling of mouse ears(P < 0.01) and ameliorate the edama and erythema of model mouse ears skin. Also it could significantly decrease the expression of IFN-γ and IL-4 in model mouse blood. Tripterygium glycosides nanoemulsion gels had a good therapeutic effect on mouse model of dermatitis and eczema. It was expected to provide a new and long-acting exterernal preparation for the treatment of dermatitis and eczema.

[Relationship between visceral fat depot and adiponectin mRNA level in the adipose tissue of OLETF rats].

OBJECTIVE: To investigate the relationship between visceral fat depot and adiponectin level in OLETF rats. METHODS: Twenty male OLETF rats and 10 male Long-Evans Tokushima Otsuka (LETO) rats were subjected to regular oral glucose tolerance test (OGTT). The rats were sacrificed at the ages of 8, 32 and 40 weeks for measurements of the body weight, blood glucose, blood lipid level, blood insulin, and weight of the visceral fat. RESULTS: Compared with LETO rats, OLETF rats had significantly higher body weight and visceral fat with impaired glucose tolerance (P<0.05). OLETF rats also had higher blood insulin, TG, FFA and CHOL levels (P<0.05). The plasma adiponectin level was significantly lower in OLETF rats than in LETO rats at different ages (P<0.05). The adiponectin mRNA level in the adipose tissue of OLETF rats was comparable with that in LETO rats, but significantly decreased at 32 and 40 weeks of age (P<0.01). CONCLUSION: Plasma adiponectin level is significantly correlated to insulin sensitivity and visceral fat depots in OLETF rats, but a lowered APN mRNA expression level is not the main reason for a decreased plasma adiponectin level in the early stage.

[Hypoadiponectinemia leads to insulin resistance in OLETF rats: a preliminary study].

OBJECTIVE: To investigate the association between plasma adiponectin and insulin resistance in OLETF rats. METHODS: Twenty male Otsuka Long-Evans Tokushima Fatty (OLETF) rats and 10 male Long-evans Tokushima Otsuka (LETO) rats underwent oral glucose tolerance test (OGTT) at 13 and 40 weeks of age. At 8, 32 and 40 weeks of age, the rats were sacrificed to measure the blood glucose, plasma insulin and adiponectin levels, and serum levels of TG, CHOL and FFA. RESULTS: The plasma adiponectin level was significantly decreased in 8-week-old OLETF rats compared with that of LETO rats (P<0.05). The plasma insulin level, TG, CHOL, and FFA were significantly higher in OLETF rats than in LETO rats at 32 and 40 weeks of age. CONCLUSION: A decreased plasma level of adiponectin preludes insulin resistance and is inversely correlated to insulin sensitivity. Hypoadiponectinemia may be an important reason leading to insulin resistance.

[Adiponectin decreases insulin receptor substrate-1 phosphorylation in the liver of OLETF rats possibly through nuclear factor-κB signaling pathway].

OBJECTIVE: To investigate the effect of adiponectin (APN) on the insulin pathway in the liver of OLETF rats and explore its molecular mechanism. METHODS: Twenty male OLETF rats and 10 male LETO rats were sacrificed at 8 and 32 weeks of age to examine the fasting blood glucose, serum insulin, adiponectin and blood lipid profiles. The APN, phosphotyrosine of insulin receptor substrate-1 (IRS-1), IKKß and nuclear-κB (NF-κB) in the liver tissue were determined using ELISA, Western blotting or immunohistochemistry. RESULTS: The plasma adiponectin level in OLETF rats was significantly lower than that of LETO rats since 8 weeks of age (P<0.01). At 32 weeks of age, the blood lipid levels of OLETF rats increased significantly (P<0.05) with inverse correlations to plasma adiponectin (P<0.01). The liver APN, py-IRS-1, IKKß and NF-κB levels in OLETF rats differed significantly from those of LETO rats at both 8 and 32 weeks. At 32 weeks of age, the APN level of both rats were correlated to the levels of NF-κB and py-IRS-1 (P<0.01). CONCLUSION: APN may decrease tyrosine phosphorylation of IRS-1 via the IKK/NFκB pathway and inhibit insulin signaling pathway in the liver, which contributes to hyperlipidemia, hyperglycemia and development of type 2 diabetes.

[Regulation of hepatic lipid metabolism by adiponectin via IRS-2 phosphorylation in OLETF rats].

OBJECTIVE: To explore the effect and mechanism of adiponectin on hepatic lipid metabolism in Otsuka Long Evans Tokushima fatty (OLETF) rats. METHODS: Twenty male OLETF rats and 10 male Long-Evans Tokushima (LETO) rats were sacrificed at 8, 32 or 40-week old to examine the fasting blood glucose, plasma insulin, adiponectin and blood lipid profile. The levels of triglyceride, cholesterol, adiponectin, phosphotyrosine of IRS-2, acetyl-coenzyme A carboxylase and sterol regulatory element-binding protein 1 (SREBP-1) mRNA in liver tissue were determined by chemical enzymatic assay, enzyme-linked immunosorbent assay (ELISA) or Western blot. RESULTS: Higher insulin level, lower insulin sensitivity index and deteriorated lipid metabolism was observed in OLETF rats since 32-week age. ACC (acetyl coenzyme A carboxylase) and SREBP-1 mRNA expression, lowered plasma adiponectin (OLETF vs LETO: 8 weeks age, 2.38 ± 0.23 vs 3.1 ± 0.17, P < 0.05; 32 weeks age, 1.51 ± 0.05 vs 2.84 ± 0.34, P < 0.01; 40 weeks age, 1.24 ± 0.04 vs 2.64 ± 0.49 ng/ml, P < 0.01) and liver tissue (8, 32 or 40 weeks age, 2.24 ± 0.18 vs 2.68 ± 0.13, 2.04 ± 0.19 vs 2.51 ± 0.14, 1.76 ± 0.12 vs 2.47 ± 0.21 µg/g respectively, P < 0.05) as well as elevated triglyceride (TG) (40 weeks age, TG 1.88 ± 0.11 vs 0.51 ± 0.07 mmol/L, P < 0.01) and cholesterol (40 weeks age, total cholesterol 0.94 ± 0.17 vs 0.69 ± 0.14 mmol/L, P < 0.01) and lowered IRS-1 (insulin receptor substrate 1) tyrosine phosphorylation in liver tissue in OLETF rats were observed. The hepatic adiponectin was positively correlated with the level of py-IRS2 and inversely with those of hepatic ACC, SREBP-1 mRNA, triglyceride and cholesterol (r = -0.431, -0.396, -0.353, -0.349, P < 0.05). CONCLUSION: Adiponectin may affect the signaling pathway of hepatic insulin via tyrosine phosphorylation of IRS-2. It is involved in the regulation of hepatic lipid metabolism.

Cetirizine dihydrochloride loaded microparticles design using ionotropic cross-linked chitosan nanoparticles by spray-drying method.

To control the release rate and mask the bitter taste, cetirizine dihydrochloride (CedH) was entrapped within chitosan nanoparticles (CS-NPs) using an ionotropic gelation process, followed by microencapsulation to produce CS matrix microparticles using a spray-drying method. The aqueous colloidal CS-NPs dispersions with a drug encapsulation efficiency (EE) of <15%, were then spray dried to produce a powdered nanoparticles-in-microparticles system with an EE of >70%. The resultant spherical CS microparticles had a smooth surface, were free of organic solvent residue and showed a diameter range of 0.5~5 µm. The in vitro drug release properties of CedH encapsulated microparticles showed an initial burst effect during the first 2 h. Drug release from the matrix CS microparticles could be retarded by the crosslinking agent pentasodium tripolyphosphate or the wall material. The technique of 'ionotropic gelation' combined with 'spray-drying' could be applicable for preparation of CS nanoparticlesin-microparticles drug delivery systems. CS-NPs based microparticles might provide a potential micro-carrier for oral administration of the freely water-soluble drug--CedH.

[Effects of Liuweidihuang pills on pancreatic islet structure in OLETF rats].

OBJECTIVE: To study the effects of Liuweidihuang pills on pancreatic islet structure in OLETF (Otsuka Long-Evans Tokushima Fatty) rats. METHODS: Forty male OLETF rats were divided randomly into Liuweidihuang pills group (Liuwei group) and control group (n=20). Ten male LETO rats were used as normal control group (LETO group). The rats in Liuwei group were given Liuweidihuang pills at the daily dose of 2.4 mg/kg intragastrically since the age of 8 weeks. Blood glucose was determined by OGTT. The rats were sacrificed at 8, 32 and 40 weeks and the pancreatic tissue was isolated to examine the morphological changes of the pancreas by HE staining and Masson trichrome staining. RESULTS: As the age of the rats increased, the pancreatic islets in the control group gradually showed fibrosis and islet atrophy, which were not found in Liuwei group. Masson staining visualized no fibrosis in Liuwei group. No significant pathological change occurred in the pancreatic islet of LETO rats. The rats in Liuwei group developed diabetes since 30 weeks of age and the incidence was 28.6% at 40 weeks, significantly lower than that in the control group (P<0.01). CONCLUSION: Liuweidihuang pills can prevent degeneration of the pancreatic islets in spontaneous OLETF rats.

[Effect of Liuweidihuang pills in preventing diabetes mellitus in OLETF rats].

OBJECTIVE: To study the effects of Liuweidihuang pills in preventing diabetes in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. METHODS: Forty male OLETF rats were randomized equally into Liuweidihuang pill group and control group, with 10 male LETO rats as the normal control group. In Liuweidihuang pill group, the rats were given the pills intragastrically at the daily dose of 2.4 mg/kg since 8 weeks of age, and the rats in the other two groups received water instead. Blood glucose of the rats was determined by oral glucose tolerance test (OGTT), and the body weight and food intake were monitored on a weekly basis. At 8, 32 and 40 weeks, the rats were sacrificed and the expression level of adiponectin mRNA in the adipose tissue was detected using RT-PCR. RESULTS: Treatment with Liuweidihuang pills significantly lowered the increment of the blood glucose and postponed the onset of hyperglycemia in the rats. Compared with the control group, the rats in Liuweidihuang pill group showed significantly increased expression of adiponectin mRNA in the adipose tissue. The rats receiving Liuweidihuang pills developed diabetes at 30 weeks of age with an incidence of 28.6% at 40 weeks, significantly lower than that in the control group (P<0.01). CONCLUSION: Liuweidihuang pills can significantly increase the expression of adiponectin mRNA in the adipose tissue and decrease the incidence of type 2 diabetes in OLETF rats.

Induction of leukotriene B(4) and prostaglandin E(2) release from keratinocytes by protease-activated receptor-2-activating peptide in ICR mice.

Protease-activated receptor-2 (PAR2) has been shown to play a key role in the pathophysiology of itch. However, the precise mechanism of PAR2-mediated itch remains largely unknown. In the present study, we investigated the effects of several agents on the scratching behavior induced by PAR2-activating peptide (SLIGRL-NH2). Pretreatment of experimental animals with tacrolimus or the 5-lipoxygenase inhibitor zileuton significantly reduced SLIGRL-NH2-induced scratching behavior, whereas histamine H(1) receptor antagonist cetirizine or the cyclooxygenase inhibitor indomethacin had little effect. Furthermore, intradermal injection of SLIGRL-NH2 increased cutaneous levels of LTB(4) and PGE(2). In vitro, SLIGRL-NH2 treatment enhanced LTB(4) and PGE(2) release from primary keratinocytes in a concentration-dependent manner. Preincubation of keratinocytes with zileuton resulted in a significant decrease of LTB(4) release and treatment of indomethacin led to a significant decrease of PGE(2) in response to SLIGRL-NH2 stimulation. In addition, SLIGRL-NH2-induced secretion of LTB(4) and PGE(2) was significantly inhibited by tacrolimus, whereas cetirizine had no effect. These results indicate that SLIGRL-NH2 stimulates LTB(4) and PGE(2) release from mouse keratinocytes and that enhancement of LTB(4) and PGE(2) secretion contributes to SLIGRL-NH2-induced scratching behavior in ICR mice.

Preparation and characterization of sodium ferulate entrapped bovine serum albumin nanoparticles for liver targeting.

Sodium ferulate (SF) loaded nanoparticles were prepared by desolvation procedure and subsequent cross-linking of the wall material of bovine serum albumin (BSA). Several factors in the nanoencapsulation process, such as the addition rate of the desolvation agent, composition of BSA and SF solution, amount of the cross-linker glutaraldehyde, were investigated to elucidate their influences on the particle size, zeta potential, drug loading and encapsulation efficiency of the resulted nanoparticles. The obtained spherical nanoparticles were negative charged with zeta potential from -20 to -40 mV, and characterized between 100 and 200 nm with a narrow size distribution. In the condition of introducing 1.0 mL 8% glutareldehyde per mg of BSA, the drug entrapment efficiency (EE) of 80% (w/w) and loading capacity of about 16% (w/w) could be achieved for the cross-linked BSA nanoparticles with SF encapsulated (SF-BSA-NP). And the drug EE was decreased along with the increasing amount of glutareldehyde used for cross-linking. The in vitro drug release properties of SF-BSA-NP behaved with an initial burst effect and then sustained-release stage. To some extent, the drug release rate could be adjusted by cross-linking with different amount of glutaraldehyde. Compared with SF solution, SF-BSA-NP showed a much higher drug distribution into liver and a lower drug concentration in other tissues, after intravenously injected to mice. So, BSA based nanoparticles might be a suitable controlled released carrier for the freely water-soluble drug SF and further hepatic targeted drug delivery.

[Liuweidihuang pills reduces visceral fat deposition in Otsuka Long-Evans Tokushima Fatty rats].

OBJECTIVE: To investigate the effects of Liuweidihuang pills (LP) on visceral fat deposition in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. METHODS: Forty male OLETF rats were randomly divided into LP group and control group (n=20 per group), and 10 male Long-evans Tokushima Otsuka (LETO) rats were used as normal controls. The rats in LP group were given LP(2.4 mg/kg) daily by intragastric administration since the age of 8 weeks, and those in the other two groups were given water of the same volume by intragastric administration. Blood glucose of all the rats was determined by oral glucose tolerance test (OGTT) and visceral fat deposition examined after the rats were sacrificed. RESULTS: OLETF rats had obviously greater amount of visceral fat than LETO rats (P<0.05) and administration of LP ameliorated the increment of visceral fat deposition in this type 2 diabetic model, producing significant effect at the age of 40 weeks (P<0.01). CONCLUSION: LP may effectively decrease visceral fat deposition in OLETF rats.

[Percutaneous penetration of ketoprofen and ketoprofen isopropyl ester through a tissue engineering skin reconstructed with HaCaT cells].

AIM: To reconstruct of a tissue engineering skin in vitro for the study of the use of drug percutaneous penetration and metabolism. METHODS: Dermal fibroblasts were embedded in collagen type I. HaCaT cells were seeded on the top of the gel. The skin was generated through air-liquid interface culture. Effects of various culture media on tissues morphology were investigated. Sections of the cultured skin were stained with hematoxylin and eosin and examined under microscope. Permeation and metabolism of ketoprofen and its isopropyl ester through the cultured skin were investigated. RESULTS: HaCaT cells initially developed a multilayer epithelium at the air-liquid interface, but it showed a parakeratotic stratum corneum. Vitamin C enhanced cell proliferation obviously. Vitamin D3 promoted cell differentiation. And estradiol showed little effect on the tissue engineering skin. Ketoprofen isopropyl ester was hydrolyzed into ketoprofen when penetrated through the cultured skin, which resembled in the skin cell homogenates metabolism. CONCLUSION: Cultured at the air-liquid interface, HaCaT cells developed a parakeratotic mutilayer epithelium. Enzyme activity was reserved. This cultured skin could serve as an appropriate model for drug percutaneous metabolism and skin irritation.

[Effects of liuwei dihuang pills on expressions of apoptosis-related genes bcl-2 and Bax in pancreas of OLETF rats].

OBJECTIVE: To investigate the effects of Liuwei Dihuang Pills (LWDHP) on expressions of apoptosis-related genes bcl-2 and Bax in pancreas of OLETF rats. METHODS: Forty male OLETF rats were randomly divided into LWDHP-treated group and untreated group. Another ten male LETO rats were included in normal control group. OLETF rats in the LWDHP-treated group were given LWDHP (2.4 g.kg(-1).d(-1)) orally since the age of 8 weeks and the rats in the other two groups were given distilled water orally. Body weights of rats were recorded weekly and blood glucose concentration was determined by oral glucose tolerance test (OGTT). Pancreas weights were recorded after rats were killed and the expression levels of bcl-2 mRNA and Bax mRNA were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: In the LWDHP-treated group, the expression of bcl-2 mRNA in the pancreas of rats at the age of 40 weeks (1.25+/-0.07) was much higher than that in the untreated group (1.01+/-0.16), P<0.01. Bax mRNA level in the LWDHP-treated group (0.57+/-0.11) was obviously lower than that in the untreated group (1.18+/-0.28), P<0.01. There was no significant difference of pancreas-to-body weight ratios between the LWDHP-treated group and the untreated group. The ability of glucose tolerance was improved in the LWDHP-treated group. CONCLUSION: LWDHP can up-regulate the expression of bcl-2 and down-regulate the expression of Bax at transcription level, which maybe contribute to the anti-apoptosis effects of LWDHP.