Olanzapine causes non-alcoholic fatty liver disease via inhibiting the secretion of apolipoprotein A5 / 中南大学学报(医学版)

OBJECTIVES@#Long-term treatment of olanzapine, the most widely-prescribed second-generation antipsychotic, remarkably increases the risk of non-alcoholic fatty liver disease (NAFLD), whereas the mechanism for olanzapine-induced NAFLD remains unknown. Excessive hepatic fat accumulation is the basis for the pathogenesis of NAFLD, which results from the disturbance of TG metabolism in the liver. Apolipoprotein A5 (ApoA5) is a key regulator for TG metabolism in vivo that promotes TG accumulation in hepatocytes, thereby resulting in the development of NAFLD. However, there are no data indicating the role of apoA5 in olanzapine-induced NAFLD. Therefore, this study aims to investigate the role of apoA5 in olanzapine-induced NAFLD.@*METHODS@#This study was carried out via animal studies, cell experiment, and ApoA5 gene knockdown experiment. Six-week-old male C57BL/6J mice were randomized into a control group, a low-dose group, and a high-dose group, which were treated by 10% DMSO, 3 mg/(kg·d) olanzapine, and 6 mg/(kg·d) olanzapine, respectively for 8 weeks. The lipid levels in plasma, liver function indexes, and expression levels of ApoA5 were detected. HepG2 cells were treated with 0.1% DMSO (control group), 25 μmol/L olanzapine (low-dose group), 50 μmol/L olanzapine (medium-dose group), and 100 μmol/L olanzapine (high-dose group) for 24 h. HepG2 cells pretreated with 100 μmol/L olanzapine were transfected with siRNA and scrambled siRNA (negative control), respectively. We observed the changes in lipid droplets within liver tissues and cells using oil red O staining and fat deposition in liver tissues using HE staining. The mRNA and protein levels of ApoA5 were determined by real-time PCR and Western blotting, respectively.@*RESULTS@#After intervention with 3 and 6 mg/(kg·d) olanzapine for 8 weeks, there was no significant difference in body weight among the 3 groups (P>0.05). Olanzapine dose-dependently increased the plasma TG, ALT and AST levels, and reduced plasma ApoA5 levels (all P<0.05), whereas there was no significant difference in plasma cholesterol (HDL-C, LDL-C, and TC) levels among the 3 groups (all P>0.05). Olanzapine dose-dependently up-regulated ApoA5 protein levels in liver tissues (all P<0.05), but there was no significant change in ApoA5 mRNA expression among groups (P>0.05). In the control group, the structure of liver tissues was intact, the morphology of liver cells was regular, and only a few scattered lipid droplets were found in the cells. In the olanzapine-treated group, there was a large amount of lipid deposition in hepatocytes, and cells were balloon-like and filled with lipid droplet vacuoles. The nucleus located at the edge of cell, and the number of lipid droplets was increased significantly, especially in the high-dose group. Likewise, when HepG2 cells were treated with olanzapine for 24 h, the number and size of lipid droplets were significantly elevated in a dose-dependent manner. Moreover, olanzapine dose-dependently up-regulated ApoA5 protein levels in HepG2 cells (all P<0.05), but there was no significant difference in ApoA5 mRNA expression among groups (P>0.05). Compared with the HepG2 cells transfected with scrambled siRNA, the number and size of lipid droplets in HepG2 cells transfected with ApoA5 siRNA were significantly reduced.@*CONCLUSIONS@#The short-term intervention of olanzapine does not significantly increase body weight of mice, but it can directly induce hypertriglyceridemia and NAFLD in mice. Olanzapine inhibits hepatic apoA5 secretion but does not affect hepatic apoA5 synthesis, resulting in the pathogenesis of NAFLD. Inhibition of apoA5 secretion plays a key role in the development of olanzapine-related NAFLD, which may serve as an intervention target for this disease.

Remineralization of demineralized dentin induced by bioactive glass NovaMin / 中南大学学报(医学版)

To explore the remineralization effect of bioactive glass NovaMin on demineralized dentin specimens, and to study the physical and chemical properties of formed structure at dentin surface.
 Methods: One mm-thickness coronal dentin slices were soaked in ethylene diamine tetraacetic acid (EDTA) for 48 h to prepare the completely demineralized dentin specimens and they were divided into 2 groups: an artificial saliva group (control group) and a NovaMin powder group. The specimens were treated with artificial saliva or NovaMin powder for 2 min (2 times every day), and the interval was 8 hours. Then, the specimens were soaked in the remineralization solution. After 7 days, the scanning electron microscope (SEM), energy dispersive X-ray (EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) were used to detect dentin morphology, the physical and chemical properties of the formed structure at dentin surface.
 Results: The results of SEM showed that a defined surface layer in the NovaMin powder group could be observed in the SEM imaging at the 7th day, which completely occluded dentinal tubules; the EDX, ATR-FTIR and XRD analysis found that the mineralized layer formed at dentin surface was mainly composed of calcium and phosphate elements, which was similar to the hydroxyapatite-like crystal. However, there were no materials formed at the dentin surface in the control group, and the dentinal tubules were still open.
 Conclusion: NovaMin can remineralize the demineralized dentin specimens and occlude the dentinal tubules in hydroxyapatite-like crystal structure.

Role of atorvastatin in improving the inflammation-induced adipokine imbalance in mice with acute myocardial infarction / 中南大学学报(医学版)

Objective:To investigate the effect of acute myocardial infarction (AMI)-activated inflammation on adipokine imbalance and the therapeutic effects of statin.Methods:A total of 32 C57BL/6 mice were divided into 4 groups:a sham group,an AMI group,a low-dose atorvastatin [2 mg/(kg.d)] group and a high-dose atorvastatin [20 mg/(kg.d)] group.AMI models were established by surgical coronary artery ligation.Plasma levels of high sensitive C reaction protein (hs-CRP),adiponectin and resistin were measured.Adiponectin and resistin expressions were determined.In addition,mouse 3T3-L1 preadipocytes in vitro were differentiated and they were stimulated by oxidized low density lipoprotein (ox-LDL).The protein expressions of adiponectin and resistin in adipocytes were detected.The effects of atorvastatin on ox-LDL-induced adipokine imbalance in adipocytes were identified.Results:The plasma levels of hs-CRP and resistin in AMI mice were significantly increased,whereas the plasma levels of adiponectin were remarkably decreased.However,atorvastatin treatment blocked the changes in the plasma levels of hs-CRP,resistin and adiponectin in AMI mice in a dose-dependent manner.Consistent findings regarding the adipose expressions of the two adipokines were obtained.The plasma levels of hs-CRP were positively correlated with resistin but negatively with adiponectin.In vitro study,ox-LDL increased resistin protein and adiponectin expressions in adipocytes,which were dose-dependently reversed by atorvastatin.Conclusion:Inflammation activation in AMI mice leads to adipokine imbalance.Atorvastatin ameliorates the AMI-induced adipokine imbalance via anti-inflammation.

Metformin reduces plasma triglycerides in ob/ob obese mice via inhibiting the hepatic apoA5 expression / 中南大学学报(医学版)

Objective:To investigate the role of apolipoprotein A5 (apoA5) in the pathogenesis of obesityrelated hypertriglyceridemia and the related therapeutic effects of metformin.Methods:The ob/ob mice were treated with regular chow diet and metformin for 4 weeks,and the levels of hepatic triglyceride (TG) and apoA5 were measured.Hepatic IAR20 cells were treated with metformin and/or apoA5 siRNAs,and then cellular TG contents and apoA5 expression were determined.Results:High plasma and hepatic levels of apoA5 and TG were found in ob/ob mice.The plasma levels of apoA5 were positively correlated with plasma TG in these mice.Metformin could dosedependently decrease the plasma and hepatic levels of apoA5 and TG in ob/ob mice.Metformin could also dose-dependently reduce cellular TG contents and apoA5 expression,these effects were attenuated by knockdown of apoA5.Conclusion:Hepatic apoA5 is up-regulated in ob/ob mice,which contributes to the elevation of plasma TG.Metformin could inhibit hepatic apoA5 expression,leading to the reduction of the plasma level of TG.

Effect of apocynum venetum extract on expression of TNF-αin early atherosclerosis / 重庆医学

Objective To investigate the anti-atherosclerosis effect of apocynum venetum(AV)by observing the influence of AV extract on early inflammatory factor TNF-αexpression.Methods Human U937 monocytes were differentiated to macrophages by the phorbol myristate acetate(PMA)induction and acted with 100 mg/L ox-LDL to form the foam cells for establishing the early atherosclerosis model(ox-LDL group).The different concentrations(0.2,0.4,0.8 mg/L)of AV were added to co-culture for 48 h (AV1,AV2,AV3 groups).The expression level of TNF-αin the supernate was detected by ELISA and RT-PCR respectively.Re-sults Compared with control group,the expression level of TNF-αin the ox-LDL group was significantly increased,the expression level of TNF-αin various AV medication groups(AV1,AV2,AV3 groups)was significantly decreased compared with the ox-LDL group(P<0.05).The AV concentration increase was negatively correlated with the TNF-αexpression level(P<0.05).Conclusion TNF-αis an important inflammatory factor in early atherosclerosis,AV could play the anti-atherosclerosis role by inhibiting the inflammatory factors.

Statin reduces triglyceride level via activating PPARα and upregulating apolipoprotein A5 in hypertriglyceridemic rats / 中华内分泌代谢杂志

Objective To explore the potential role of apolipoprotein A5 (ApoA5) on the hypertriglyceridemia (HTG)-lowering effects of statin. Methods Twenty-four Sprague-Dawley rats were assigned to 3 groups:(1)control group, with no special treatment. (2) HTG group, treated with 10% fructose water for 6 weeks. (3) statin 4 weeks. Body weight, fasting plasma lipids, and the hepatic expressions of ApoA5 and PPARα were determined. In separate in vitro experiments, the effects of atorvastatin on triglyceride (TG) and the expressions of ApoA5 and PPARα in HepG2 cells were tested. Results (1) Plasma TG was higher in HTG group than in controls group, which was significantly reduced in statin group (both P ＜ 0. 05). (2) Rat hepatic ApoA5expression in HTG group was significantly lower than in control group and it was significantly higher in statin group than in HTG group (both P＜0. 05). (3) Similarly, rat PPARα mRNA expression in HTG group was lower than in control group and it was higher in statin group than in HTG group (both P ＜ 0.05). (4) Statin significantly upregulated the expressions of ApoA5 and PPARα and decreased TG in HepG2 cells, which was blocked in the presence of PPARα inhibitor. Conclusion Upregulation of ApoA5 expression contributes to TG lowering effect of statin via PPARα signaling pathway.