Fluoxetine-induced hepatic lipid accumulation is mediated by prostaglandin endoperoxide synthase 1 and is linked to elevated 15-deoxy-Δ12,14PGJ2

Major depressive disorder and other neuropsychiatric disorders are often managed with long-term use of antidepressant medication. Fluoxetine, an SSRI antidepressant, is widely used as a first-line treatment for neuropsychiatric disorders. However, fluoxetine has also been shown to increase the risk of metabolic diseases such as non-alcoholic fatty liver disease. Fluoxetine has been shown to increase hepatic lipid accumulation in vivo and in vitro. In addition, fluoxetine has been shown to alter the production of prostaglandins which have also been implicated in the development of non-alcoholic fatty liver disease. The goal of this study was to assess the effect of fluoxetine exposure on the prostaglandin biosynthetic pathway and lipid accumulation in a hepatic cell line (H4-II-E-C3 cells). Fluoxetine treatment increased mRNA expression of prostaglandin biosynthetic enzymes (Ptgs1, Ptgs2, and Ptgds), PPAR gamma (Pparg), and PPAR gamma downstream targets involved in fatty acid uptake (Cd36, Fatp2, and Fatp5) as well as production of 15-deoxy-Δ^12,14PGJ₂ a PPAR gamma ligand. The effects of fluoxetine to induce lipid accumulation were attenuated with a PTGS1 specific inhibitor (SC-560), whereas inhibition of PTGS2 had no effect. Moreover, SC-560 attenuated 15-deoxy-Δ^12,14PGJ₂ production and expression of PPAR gamma downstream target genes. Taken together these results suggest that fluoxetine-induced lipid abnormalities appear to be mediated via PTGS1 and its downstream product 15d-PGJ₂ and suggest a novel therapeutic target to prevent some of the adverse effects of fluoxetine treatment.     

Inadequate dietary magnesium intake increases atherosclerotic plaque development in rabbits

Epidemiological studies have shown dietary magnesium (Mg) intake and serum Mg levels to be inversely correlated with the development of atherosclerosis. We hypothesized that low levels of Mg would promote atherosclerotic plaque development in rabbits. New Zealand white rabbits (4 months old, n = 22) were fed an atherogenic diet containing 0.12% (−Mg), 0.27% (control), or 0.43% (+Mg) Mg for 8 weeks. Blood samples were obtained at baseline, 2, 4, 6, and 8 weeks and were assayed for total cholesterol, high-density lipoprotein (HDL), non-HDL, triglycerides (TG), C-reactive protein, serum Mg, and erythrocyte Mg. Aortas from −Mg had significantly more plaque, with an intima thickness 42% greater than control and 36% greater than +Mg. Serum cholesterol levels rose over time, and at 8 weeks, −Mg had the highest and +Mg the lowest total and non-HDL cholesterol and TG levels, although these results did not reach significance. Over time, serum Mg levels increased, and erythrocyte Mg levels decreased. C-reactive protein significantly increased in all groups at 4 and 6 weeks but returned to baseline levels by 8 weeks. This study supports the hypothesis that inadequate intake of Mg results in an increase in atherosclerotic plaque development in rabbits.     

胰岛素增敏剂曲格列酮对人卵巢颗粒细胞芳香化酶活性的抑制作用

为探讨曲格列酮(troglitazone,TGZ)对人卵巢颗粒细胞芳香化酶(P450arom)活性的调节作用，以不同剂量的TGZ和(或)维甲酸类X受体(RXR)激动剂(LG100268，LG)处理来源于体外受精患者的卵巢颗粒细胞24h，然后测定细胞的芳香化酶活性和P450arom mRNA水平。结果发现，TGZ处理颗粒细胞24h可引起剂量依赖性的芳香化酶活性下降；LG单独作用可以抑制芳香化酶活性，但与TGZ合用对芳香化酶的抑制作用更明显；RT-PCR结果显示，随着芳香化酶活性的下降，P450arom mRNA表达水平也降低。表明TGZ可能是通过过氧化物酶体增殖物激活受体γ(PPARγ)：RXR异二聚体组成的核受体系统直接抑制卵巢颗粒细胞芳香化酶活性。     

亚油酸对纤溶酶原激活物抑制剂-1表达的影响及其机制

目的探讨过氧化体增殖物激活型受体α（PPARα）的特异性激活物亚油酸对HepG2细胞1型纤溶酶原激活物抑制剂（PAI-1）mRNA表达及其活性的影响和在该基因转录调控中的作用机制.方法用不同浓度亚油酸为诱导因素刺激HepG2细胞,采用半定量RT-PCR法检测PAI-1mRNA水平,发色底物法检测PAI-1的活性变化.构建四个含PAI-1启动子序列从-804～＋17间不同长度片段驱动的荧光素酶报告基因质粒,体外瞬时转染HepG2细胞,检测荧光素酶的活性.结果与对照组相比,亚油酸组能使HepG2细胞PAI-1mRNA表达及蛋白活性显著升高（P＜0.05,P＜0.01）,且呈一定剂量依赖性;亚油酸诱导可使PAI-1转录活性显著升高（P＜0.01）;与转染质粒PAI-pGL3-A（-804/＋17）相比较,当转染质粒含有PAI-pGL3-B（-636/＋17）、PAI-pGL3-C（-449/＋17）时,荧光素酶活性显著降低（P＜0.01）;共转染PPARα表达质粒（PPARα-pSG5）的细胞在亚油酸诱导下PAI-1转录活性显著升高（P＜0.01）.结论亚油酸可以增加HepG2细胞PAI-1mRNA表达及其蛋白活性,调节PAI-1的基因转录,PPARα参与亚油酸对PAI-1基因的表达调控;在PAI-1启动子-804～-636、-449～-276区域内存在亚油酸作用的调控PAI-1基因表达的序列.     

Human multiple myeloma cells express peroxisome proliferator-activated receptor gamma and undergo apoptosis upon exposure to PPARgamma ligands

Multiple myeloma is essentially an incurable malignancy and it is therefore of great interest to develop new therapeutic approaches. We previously reported that human B cell-lymphomas express the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) and are killed by PPARgamma ligands. Herein, we investigate the therapeutic potential of PPARgamma ligands for multiple myeloma. The human multiple myeloma cell lines ANBL6 and 8226 express PPARgamma mRNA and protein. The PPARgamma ligands, 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2) and ciglitazone, induced multiple myeloma cell apoptosis as determined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay, loss of mitochondrial membrane potential, and caspase activation. Importantly, the ability of PPARgamma ligands to kill both multiple myeloma cell lines was not abrogated by Interleukin-6 (IL-6), a multiple myeloma growth survival factor. Finally, the RXR ligand 9-cis retinoic acid (9-cis RA) in combination with PPARgamma ligands greatly enhanced multiple myeloma cell killing. These new findings support that PPARgamma ligands may represent a novel therapy for multiple myeloma.     

Mutation analysis of PEX7 in 60 probands with rhizomelic chondrodysplasia punctata and functional correlations of genotype with phenotype

PEX7 encodes the cytosolic receptor for the set of peroxisomal matrix enzymes targeted to the organelle by the peroxisome targeting signal 2 (PTS2). Mutations in PEX7 cause rhizomelic chondrodysplasia punctata (RCDP), a distinct peroxisome biogenesis disorder. In previous work we described three novel PEX7 mutant alleles, including one, L292X, with a high frequency due to a founder effect. We have now extended our analysis to 60 RCDP probands and identified a total of 24 PEX7 alleles, accounting for 95% of the mutant PEX7 genes in our sample. Of these, 50% are L292X, 13% are IVS9+1G>C, and the remainder are mostly private. IVS9+1G>C occurs on at least three different haplotypes and thus appears to result from recurrent mutation. The phenotypic spectrum of RCDP is broader than commonly recognized and includes minimally affected individuals at the mild end of the spectrum. To relate PEX7 genotype and phenotype, we evaluated the consequence of the disease mutation on PEX7 RNA by Northern analysis and RT/PCR. We evaluated the function of the encoded Pex7 protein (Pex7p) by expressing selected alleles in fibroblasts from RCDP patients and assaying their ability to restore import of a PTS2 marker protein. We find that residual activity of mutant Pex7p and reduced amounts of normal Pex7p are associated with milder and variant phenotypes.     

过氧化物酶增殖体激活受体α在急性肺损伤大鼠肺组织的表达及其意义

目的: 观察内毒素(LPS)复制的急性肺损伤（ALI）大鼠肺组织过氧化物酶增殖体激活受体α（PPARα）表达的变化,探讨PPARα在ALI中可能的作用。方法: 将40只雄性Wistar大鼠随机分为对照组、LPS致伤1 h组、2 h组、4 h组和8 h组。用LPS(5 mg/kg) 静脉注射复制大鼠ALI模型，分别在LPS致伤后1 h、2 h、4 h、8 h时处死大鼠，测定各组肺组织湿/干重比（W/D）及肺组织病理变化；采用RT-PCR法检测肺组织中PPARα mRNA的表达；采用免疫组化法检测肺组织中PPARα的表达。结果: LPS致伤后2 h、4 h、8 h肺组织W/D均显著高于对照组（均P< 0.01）；LPS致伤后2h、4h PPARα mRNA表达分别显著低于对照组（均P < 0.01）；而LPS致伤4h和8h组PPARα表达阳性细胞数显著低于对照组（均P< 0.05）。结论: PPARα在ALI大鼠肺组织表达降低。表明PPARα在急性肺损伤的发病机制中具有重要作用。     

Chronic Oleoylethanolamide Treatment Decreases Hepatic Triacylglycerol Level in Rat Liver by a PPARγ/SREBP-Mediated Suppression of Fatty Acid and Triacylglycerol Synthesis

Oleoylethanolamide (OEA) is a naturally occurring bioactive lipid belonging to the family of N-acylethanolamides. A variety of beneficial effects have been attributed to OEA, although the greater interest is due to its potential role in the treatment of obesity, fatty liver, and eating-related disorders. To better clarify the mechanism of the antiadipogenic effect of OEA in the liver, using a lipidomic study performed by ¹H-NMR, LC-MS/MS and thin-layer chromatography analyses we evaluated the whole lipid composition of rat liver, following a two-week daily treatment of OEA (10 mg kg⁻¹ i.p.). We found that OEA induced a significant reduction in hepatic triacylglycerol (TAG) content and significant changes in sphingolipid composition and ceramidase activity. We associated the antiadipogenic effect of OEA to decreased activity and expression of key enzymes involved in fatty acid and TAG syntheses, such as acetyl-CoA carboxylase, fatty acid synthase, diacylglycerol acyltransferase, and stearoyl-CoA desaturase 1. Moreover, we found that both SREBP-1 and PPARγ protein expression were significantly reduced in the liver of OEA-treated rats. Our findings add significant and important insights into the molecular mechanism of OEA on hepatic adipogenesis, and suggest a possible link between the OEA-induced changes in sphingolipid metabolism and suppression of hepatic TAG level.     

Peroxisome biogenesis occurs in late dorsal-anterior structures in the development of Xenopus laevis.

Metabolism and development are two important processes not often examined in the same context. The focus of the present study is the expression of specific peroxisomal genes, the subsequent biogenesis of peroxisomes, and their potential role in the metabolism associated with the development of Xenopus laevis embryos. The temporal and expression patterns of six peroxisomal genes (PEX5, ACO, PEX19, PMP70, PEX16, and catalase) were elucidated using RT-PCR. Functionally related peroxisomal genes exhibited similar expression patterns with their RNA levels elevated relatively late during embryogenesis. Using immunohistochemistry PMP70 and catalase protein was localized largely to dorsal-anterior structures. Peroxisomal function was assayed with peroxisomal targeted-GFP, which when microinjected, revealed peroxisomes in dorsal-anterior structures at stage 45. A requirement for peroxisomal function appears to be present only late in development as organogenesis is finishing, yolk stores are depleted, and ingestion commences.     

壳聚糖复方制剂对脂肪肝大鼠的治疗作用及其机制的探讨

目的 :进一步研究壳聚糖复方制剂对实验性脂肪肝大鼠的治疗作用及其机制。方法 :采用小剂量CCl4 致肝损伤并高脂饮食建立大鼠脂肪肝模型 ,给予模型大鼠壳聚糖复方制剂 0 .7g·kg- 1·d- 1灌服 8wk ,检测肝脏三酰甘油 (TG )、总胆固醇(TC)、血清及肝脏游离脂肪酸 (FFA)含量 ,检测肝脂变面积及肝脏过氧化物酶体增殖物激活受体α(PPARα)mRNA的表达情况。结果 :CCl4 损伤并高脂饮食可引起实验性大鼠肝脏明显脂肪变性 ,肝脏TG ,TC ,FFA及血清FFA含量升高 ,肝细胞PPARαmRNA表达减少。与模型组比较 ,壳聚糖复方制剂能明显降低肝脏TG ,TC ,FFA及血清FFA含量(P <0 .0 1) ,提高肝细胞PPARαmRNA的表达(P <0 .0 1)。结论 :壳聚糖复方制剂对实验性脂肪肝大鼠具有一定的治疗作用 ,其作用机制可能与其诱导PPARα表达 ,促进肝脏摄取、氧化脂肪酸有关。