Peroxisome proliferator-activated receptor gamma inhibits hepatic fibrosis in rats

BACKGROUND:Hepatic fibrosis is a necessary step in the development of hepatic cirrhosis.In this study we used lentiviral vector-mediated transfection technology to evaluate the effect of peroxisome proliferator-activated receptor gamma(PPAR-γ) on rat hepatic fibrosis. METHODS:Hepatic fibrosis in rats was induced by CCl4 for 2 weeks(early fibrosis)and 8 weeks(sustained fibrosis).The rats were randomly divided into four groups:normal control, fibrosis,blank vector,and PPAR-γ.They were infected with the recombinant lentiviral expression vector carrying the rat PPAR-γgene by portal vein injection.The liver of the rats was examined histologically and hydroxyproline was assessed.In vitro primary hepatic stellate cells(HSCs)were infected with the recombinant lentiviral expression vector carrying the rat PPAR-γgene.The status of HSC proliferation was measured by the MTT assay.The protein levels of PPAR-γ,α-smooth muscle actin(α-SMA)and type I collagen expression were evaluated by the Western blotting method. RESULTS:In vitro studies revealed that expression of PPAR-γ inhibited expression ofα-SMA and type I collagen in activated HSCs(P<0.01)as well as HSC proliferation(P<0.01).In vivo experiments indicated that in the early hepatic fibrosis group,the hydroxyproline content and the level of collagen I protein in the liver in the PPAR-γtransfected group were not significantly different compared to the hepatic fibrosis group and the blank vector group;whereas the expressions of PPAR-γ andα-SMA were different compared to the hepatic fibrosis group(P<0.01).In the sustained hepatic fibrosis group,there were significant differences in the hydroxyproline content and the expression of PPAR-γ,α-SMA,and type I collagen between each group.CONCLUSION:PPAR-γcan inhibit HSC proliferation and hepatic fibrosis,and suppressα-SMA and type I collagen expression.

Association of β3 Adrenergic Receptor and Peroxisome Proliferator-activated Receptor Gamma 2 Polymorphisms With Insulin Sensitivity:A Twin Study

Objective To study the effect of β3 adrenergic receptor （β3AR） Trp64Arg and peroxisome proliferator activated receptor gamma 2 （PPAR72） Prol2Ala polymorphisms on insulin resistance. Methods One hundred and eight dizygotic twin pairs were enrolled in this study. Microsatellite polymorphism was used to diagnose zygosity of twins. Insulin sensitivity was estimated with logarithm transformed homeostasis model assessment （HOMA）. PCR-RFLP analysis was performed to detect the variants. As a supplement to the sib-pair method, identity by state （IBS） was used to analyze the association of polymorphisms with insulin sensitivity. Results The genotype frequencies of Trp64Trg, Trp64Arg, and Arg64Arg were 72.3%, 23.8%, and 3.9%, respectively, while the genotype frequencies of Pro12Pro, Pro12Ala, and Ala12Ala were 89.9%, 9.6%, and 0.5%, respectively. For β3AR Trp64Arg the interclass co-twin correlations of Waist-to-hip ratio （WHR）, blood glucose （GLU）, and insulin （INS）, homeostasis model assessment insulin resistance index （HOMA-IR） of the twin pairs sharing 2 alleles of IBS were greater than those sharing 0-1 allele of IBS, and HOMA4R had statistic significance. For PPAR3t2 Prol2Ala most traits of twin pairs sharing 2 alleles of IBS had greater correlations and statistic significance in body mass index （BMI）, WHR, percent of body fat （PBF） and GLU, but there were low correlations of either insulin or HOMA-IR of twin pairs sharing 1 or 2 alleles of IBS. The combined effects of the two variations showed less squared significant twin-pair differences of INS and HOMA-IR among twins sharing 4 alleles of IBS. Condusions β3AR Trp64Arg and PPAR）,2 Pro 12Ala polymorphisms might be associated with insulin resistance and obesity, and there might be slight synergistic effects between this two gene loci, and further studies are necessary to confirm this finding.

Expression for peroxisome proliferator-activated receptor gamma in pituitary adenomas 38 cases for semi-quantitative immunohistochemical analysis

BACKGROUND： It has been reported that peroxisome proliferator-activated receptor γ （PPAR γ ） is highly expressed in lung cancer, colon cancer, and gastric cancer, as well as other tumors.OBJECTIVE： To study expression of PPAR γ in pituitary adenomas and analyze the role of PPAR γ in hormonal typing of pituitary adenomas. DESIGN, TIME AND SETTING： Semi-quantitative immunohistochemistry of pathological specimens. The experiment was conducted at the Department of Neurosurgery, Wuxi Second Hospital Affiliated to Nanjing Medical University between January 2002 and May 2005. MATERIALS： Surgical resection samples of pituitary adenomas from 38 cases （18 male and 20 female） were analyzed. Eight cases were determined to be invasive pituitary adenomas and 30 cases were non-invasive pituitary adenomas. Hormonal classification of the types of pituitary adenomas revealed somatotrophic adenomas in six cases, corticotrophic adenoma in five cases, prolactinomas in 13 cases, multi-hormone secreting adenomas in six cases, and eight cases of adenoma without altered endocrine function. Five autopsy specimens were collected during the same period from patients of matching age that died from unrelated diseases and were included as normal anterior pituitar3, controls. METHODS： Cell counts for positive immunohistochemical signals were recorded from histopathological sections. The percentage of positive cells was reported as a semi-quantitative analysis. MAIN OUTCOME MEASURES： The rate of PPAR γ positive cells in different types of adenoma was based on hormonal levels and invasiveness of pituitary tumor cells. RESULTS： All tumor biopsies were determined to express PPAR γ. The rate of PPAR γ -positive cells ranged between 8%-65% in the pituitary adenomas. According to hormonal type, PPAR γ expression did not vary between the groups. In addition, there was no significant difference in PPAR γ expression between the non-invasive and invasive pituitary adenomas. CONCLUSIONS： Human pituitary adenomas express PPAR γ, and this expression is unrelated to hormonal type and invasiveness.

Inhibitory roles of protein kinase B and peroxisome proliferator-activated receptor gamma coactivator on hepatic HMG-CoA reductase promoter activity

Since we had previously demonstrated that siRNAs to tristetraprolin (TTP) markedly inhibited insulin stimulation of hepatic HMG-CoA reductase (HMGR) transcription, we investigated the effects of transfecting rat liver with TTP constructs. We found that transfecting diabetic rats with TTP did not increase HMGR transcription but rather led to modest inhibition. We then investigated whether co-transfection with protein kinase B, hepatic form (AKT2), might lead to phosphorylation and result in activation of HMGR transcription. We found that this treatment resulted in near complete inhibition of transcription. Transfection with peroxisome proliferator-activated receptor g coactivator (PGC-1a) also inhibited HMGR transcription. These results show that although TTP is needed for activation of HMGR transcription, it cannot by itself activate this process. AKT2 and PGC-1a, which mediate the activation of gluconeogenic genes by insulin, exert the opposite effect on HMGR.

Protective effect of ghrelin on left ventricular remodeling in spontaneously hypertensive rats is associated with the peroxisome proliferator-activated receptor gamma-dependent pathway

Background Studies suggested that exogenous ghrelin administration could prevent early left ventricular remodeling in rats with myocardial infarction. We investigated herein whether ghrelin attenuated left ventricular remodeling induced by hypertension and whether ghrelin＇s effect was mediated through the peroxisome proliferator-activated receptor gamma （PPAR-y）-dependent pathway. Methods Spontaneously hypertensive rats （8-week-old males） were randomly divided into three groups with 12 rats in each： ghrelin group （received ghrelin 100 IJg/kg subcutaneously （sc） twice daily）; ghrelin＋GW9662 group （received the PPAR-y antagonist GW9662 at 2 mg/kg sc, and then ghrelin as above）; saline controls. Normal male Wistar Kyoto rats （n=-12） served as normal controls. Four weeks later, the effects of ghrelin on cardiac remodeling were evaluated by echocardiographic, hemodynamic, and histopathological examination, and gene expression analysis （PPAR-y protein and mRNA expression）. The serum levels of C-reactive protein （CRP） and tumor necrosis factor （TNF）-a were detected by enzyme linked immunosorbent assay. Results Ghrelin prevented ventricular remodeling, increased PPAR-y expression in the myocardium, suppressed collagen I and collagen Ill mRNA expression, and also decreased the serum levels of TNF-a, but not CRP. All abovementioned effects of ghrelin were inhibited by GW9662. Conclusion Ghrelin inhibited ventricular remodeling induced by hypertension, and the preventive effects of ghrelin may be mediated by the anti-inflammatory actions of the PPAR-y-dependent pathway.

Peroxisome proliferator-activated receptor gamma signaling in human sperm physiology

Peroxisome proliferator-activated receptor gamma （PPARy） is a member of the PPARs, which are transcription factors of the steroid receptor superfamily. PPARy acts as an important molecule for regulating energy homeostasis, modulates the hypothalamic-pituitary-gonadal （HPG） axis, and is reciprocally regulated by HPG. In the human, PPARγprotein is highly expressed in ejaculated spermatozoa, implying a possible role of PPARγ signaling in regulating sperm energy dissipation. PPARγ protein is also expressed in Sertoli cells and germ cells （spermatocytes）. Its activation can be induced during capacitation and the acrosome reaction. This mini-review will focus on how PPARy signaling may affect fertility and sperm quality and the potential reversibility of these adverse effects.

Peroxisome proliferator-activated receptors as targets to treat metabolic diseases:Focus on the adipose tissue,liver,and pancreas

The world is experiencing reflections of the intersection of two pandemics:Obesity and coronavirus disease 2019.The prevalence of obesity has tripled since 1975 worldwide,representing substantial public health costs due to its comorbidities.The adipose tissue is the initial site of obesity impairments.During excessive energy intake,it undergoes hyperplasia and hypertrophy until overt inflammation and insulin resistance turn adipocytes into dysfunctional cells that send lipotoxic signals to other organs.The pancreas is one of the organs most affected by obesity.Once lipotoxicity becomes chronic,there is an increase in insulin secretion by pancreatic beta cells,a surrogate for type 2 diabetes mellitus(T2DM).These alterations threaten the survival of the pancreatic islets,which tend to become dysfunctional,reaching exhaustion in the long term.As for the liver,lipotoxicity favors lipogenesis and impairs beta-oxidation,resulting in hepatic steatosis.This silent disease affects around 30%of the worldwide population and can evolve into end-stage liver disease.Although therapy for hepatic steatosis remains to be defined,peroxisome proliferator-activated receptors(PPARs)activation copes with T2DM management.Peroxisome PPARs are transcription factors found at the intersection of several metabolic pathways,leading to insulin resistance relief,improved thermogenesis,and expressive hepatic steatosis mitigation by increasing mitochondrial beta-oxidation.This review aimed to update the potential of PPAR agonists as targets to treat metabolic diseases,focusing on adipose tissue plasticity and hepatic and pancreatic remodeling.

Hepatic lipid homeostasis by peroxisome proliferator-activated receptor gamma 2

Peroxisome proliferator-activated receptor gamma(PPARγor PPARG)is a ligand-activated transcription factor belonging to the nuclear hormone receptor superfamily.It plays a master role in the differentiation and proliferation of adipose tissues.It has two major isoforms,PPARγ1 and PPARγ2,encoded from a single gene using two separate promoters and alternative splicing.Among them,PPARγ2 is most abundantly expressed in adipocytes and plays major adipogenic and lipogenic roles in the tissue.Furthermore,it has been shown that PPARγ2 is also expressed in the liver,specifically in hepatocytes,and its expression level positively correlates with fat accumulation induced by pathological conditions such as obesity and diabetes.Knockout of the hepatic Pparg gene ameliorates hepatic steatosis induced by diet or genetic manipulations.Transcriptional activation of Pparg in the liver induces the adipogenic program to store fatty acids in lipid droplets as observed in adipocytes.Understanding how the hepatic Pparg gene expression is regulated will help develop preventative and therapeutic treatments for non-alcoholic fatty liver disease(NAFLD).Due to the potential adverse effect of hepatic Pparg gene deletion on peripheral tissue functions,therapeutic interventions that target PPAR g for fatty liver diseases require fine-tuning of this gene's expression and transcriptional activity。

Role of peroxisome proliferator-activated receptors alpha and gamma in gastric ulcer: An overview of experimental evidences

Peroxisome proliferator-activated receptors(PPARs) are ligand-activated transcription factors belonging to the nuclear hormone receptor superfamily. Three subtypes, PPARα, PPARβ/δ, and PPARγ, have been identifiedso far. PPARα is expressed in the liver, kidney, small intestine, heart, and muscle, where it activates the fatty acid catabolism and control lipoprotein assembly in response to long-chain unsaturated fatty acids, eicosanoids, and hypolipidemic drugs(e.g., fenofibrate). PPARβ/δ is more broadly expressed and is implicated in fatty acid oxidation, keratinocyte differentiation, wound healing, and macrophage response to very low density lipoprotein metabolism. This isoform has been implicated in transcriptional-repression functions and has been shown to repress the activity of PPARα or PPARγ target genes. PPARγ1 and γ2 are generated from a single-gene peroxisome proliferator-activated receptors gamma by differential promoter usage and alternative splicing. PPARγ1 is expressed in colon, immune system(e.g., monocytes and macrophages), and other tissues where it participates in the modulation of inflammation, cell proliferation, and differentiation. PPARs regulate gene expression through distinct mechanisms: Liganddependent transactivation, ligand-independent repression, and ligand-dependent transrepression. Studies in animals have demonstrated the gastric antisecretory activity of PPARα agonists like ciprofibrate, bezafibrate and clofibrate. Study by Pathak et al also demonstrated the effect of PPARα agonist, bezafibrate, on gastric secretion and gastric cytoprotection in various gastric ulcer models in rats. The majority of the experimental studies is on pioglitazone and rosiglitazone, which are PPARγ activators. In all the studies, both the PPARγ activators showed protection against the gastric ulcer and also accelerate the ulcer healing in gastric ulcer model in rats. Therefore, PPARα and PPARγ may be a target for gastric ulcer therapy. Finally, more studies are also needed to confirm the involvement of PPARs α and γ in gastric ulcer.

Peroxisome proliferator-activated receptors for hypertension

Peroxisome proliferator-activated receptors(PPARs) are ligand-activated transcription factors belonging to the nuclear receptor superfamily, which is composed of four members encoded by distinct genes(α, β, γ, and δ). The genes undergo transactivation or transrepression under specific mechanisms that lead to the induction or repression of target gene expression. As is the case with other nuclear receptors, all four PPAR isoforms contain five or six structural regions in four functional domains; namely, A/B, C, D, and E/F. PPARs have many functions, particularly functions involving control of vascular tone, inflammation, and energy homeostasis, and are, therefore, important targets for hypertension, obesity, obesity-induced inflammation, and metabolic syndrome in general. Hence, PPARs also represent drug targets, and PPARα and PPARγ agonists are used clinically in the treatment of dyslipidemia and type 2 diabetes mellitus, respectively. Because of their pleiotropic effects, they have been identified as active in a number of diseases and are targets for the development of a broad range of therapies for a variety of diseases. It is likely that the range of PPARγ agonist therapeutic actions will result in novel approaches to lifestyle and other diseases. The combination of PPARs with reagents or with other cardiovascular drugs, such as diuretics and angiotensin Ⅱ receptor blockers, should be studied.This article provides a review of PPAR isoform characteristics, a discussion of progress in our understanding of the biological actions of PPARs, and a summary of PPAR agonist development for patient management. We also include a summary of the experimental and clinical evidence obtained from animal studies and clinical trials conducted to evaluate the usefulness and effectiveness of PPAR agonists in the treatment of lifestyle-related diseases.

Peroxisome proliferator-activated receptors as targets to treat non-alcoholic fatty liver disease

Lately, the world has faced tremendous progress in the understanding of non-alcoholic fatty liver disease(NAFLD) pathogenesis due to rising obesity rates. Peroxisome proliferator-activated receptors(PPARs) are transcription factors that modulate the expression of genes involved in lipid metabolism, energy homeostasis and inflammation, being altered in diet-induced obesity. Experimental evidences show that PPAR-alpha is the master regulator of hepatic beta-oxidation(mitochondrial and peroxisomal)and microsomal omega-oxidation, being markedly decreased by high-fat(HF) intake. PPAR-beta/delta is crucial to the regulation of forkhead box-containing protein O subfamily-1 expression and, hence, the modulation of enzymes that trigger hepatic gluconeogenesis. In addition, PPAR-beta/delta can activate hepatic stellate cells aiming to the hepatic recovery from chronic insult. On the contrary, PPAR-gamma upregulation by HF diets maximizes NAFLD through the induction of lipogenic factors, which are implicated in the fatty acid synthesis. Excessive dietary sugars also upregulate PPAR-gamma, triggering de novo lipogenesis and the consequent lipid droplets deposition within hepatocytes. Targeting PPARs to treat NAFLD seems a fruitful approach as PPAR-alpha agonist elicits expressive decrease in hepatic steatosis by increasing mitochondrial beta-oxidation, besides reduced lipogenesis. PPAR-beta/delta ameliorates hepatic insulin resistance by decreasing hepatic gluconeogenesis at postprandial stage. Total PPAR-gamma activation can exert noxious effects by stimulating hepatic lipogenesis. However, partial PPAR-gamma activation leads to benefits, mainly mediated by increased adiponectin expression and decreased insulin resistance. Further studies are necessary aiming at translational approaches useful to treat NAFLD in humans worldwide by targeting PPARs.

Effect of insulin and metformin on methylation and glycolipid metabolism of peroxisome proliferator-activated receptor γcoactivator-1A of rat offspring with gestational diabetes mellitus

Objective:To discuss the effect of insulin and metformin on amethylation and glycolipid metabolism of peroxisome proliferator-activated receptor γ coactivator-1A(PPARGC1A) of rat offspring with gestational diabetes mellitus(GDM).Methods:A total of 45 pregnant rats received the intraperitoneal injection of streptozotocin to establish the pregnant rat model of GDM.A total of 21 pregnant rats with GDM were randomly divided into three groups,with 7ruts in each group,namely the insulin group,metformin group and control group.Rats in the insulin group received the abdominal subcutaneous injection of 1 mL/kg recombinant insulin glargine at 18:00 every day.Rats in the metformin group received the intragastric infusion of metformin hydrochloride at 18:00 every day,with the first dose of 300 mg/kg.The doses of two groups were adjusted every 3 d to maintain the blood glucose level at 2.65-7.62 mmol/L.Rats in the control group received the intragastric infusion of 1 mL normal saline at 18:00 every day.After the natural delivery of pregnant rats.10 offspring rats were randomly selected from each group.At birth,4 wk and 8 wk after the birth of offspring rats,the weight of offspring rats was measured.The blood glucose level of offspring rats was measured at 4wk and 8 wk,while the level of serum insulin,triglyceride and leptin was measured at 8 wk.Results:The weight of offspring rats at birth in the insulin group and metformin group was significantly lower than the one in the control group(P<0.05),and there was no significant difference at 4 wk and 8 wk among three groups(P>0.05).The fasting blood glucose and random blood glucose in the insulin group and metformin group at 4 wk and 8 wk were all significantly lower than ones in the control group(P<0.05);there was no significant difference between the insulin group and metformin group(P>0.05).The expression of PPARGC1 A mRNA in the insulin group and metformin group was significantly higher and the methylation level of PPARGC1 A was significantly lower than the one in the control group(P<0.05),but there was no significant difference between the insulin group and metformin group(P>0.05).Insulin and leptin at 8 wk in the insulin group and metformin group were significantly higher,while triglyceride was significantly lower than the one in the control group(P<0.05);triglyceride level of rats in the insulin group was significantly higher than the one in the metformin group(P<0.05).There was no significant difference in insulin and leptin level of offspring rats between the insulin group and metformin group(P>0.05).Conclusions:GDM can induce the methylation of PPARGC1 A of offspring rats to reduce the expression of PPARGC1 A mRNA and then cause the disorder of glycolipid metabolism when the offspring rats grow up;the insulin or metformin in the treatment of pregnant rats with GDM can reduce the methylation level of PPARGC1 A and thus improve the abnormal glycolipid metabolism of offspring rats.

Pro12Ala polymorphism of the peroxisome proliferator-activated receptor γ2 in patients with fatty liver diseases

AIM:To test the occurrence of the Pro12Ala mutation of the peroxisome proliferator-activated receptor-γ (PPARγ)2-gene in patients with non-alcoholic fatty liver disease (NAFLD) or alcoholic fatty liver disease (AFLD).METHODS:DNA from a total of 622 specimens including 259 blood samples of healthy blood donors and 363 histologically categorized liver biopsies of patients with NAFLD (n=263) and AFLD (n=100) were analyzed by Real-time polymerase chain reaction using allele-specific probes.RESULTS:In the NAFLD and the AFLD collective,3% of the patients showed homozygous occurrence of the Ala12 PPARγ2-allele,differing from only 1.5% cases in the healthy population.In NAFLD patients,a high incidence of the Ala12 mutant was not associated with the progression of fatty liver disease.However,we observed a significantly higher risk (odds ratio=2.50,CI:1.05-5.90,P=0.028) in AFLD patients carrying the mutated Ala12 allele to develop inflammatory alterations.The linkage of the malfunctioning Ala12-positive PPARγ2 isoform to an increased risk in patients with AFLD to develop severe steatohepatitis and fibrosis indicates a more prominent anti-inflammatory impact of PPARγ2 in progression of AFLD than of NAFLD.CONCLUSION:In AFLD patients,the Pro12Ala single nuclear polymorphism should be studied more extensively in order to serve as a novel candidate in biomarker screening for improved prognosis.

Peroxisome proliferator-activated receptor γ and colorectal cancer

Peroxisome proliferator-activated receptors(PPARs) are members of the nuclear hormone receptor superfamily and ligand-activated transcription factors.PPARγ plays an important role in adipocyte differentiation,lipid storage and energy dissipation in adipose tissue,and is involved in the control of inflammatory reactions as well as in glucose metabolism through the improvement of insulin sensitivity.Growing evidence has demonstrated that activation of PPARγ has an antineoplastic effect in tumors,including colorectal cancer.High expression of PPARγ is detected in human colon cancer cell lines and adenocarcinoma.This review describes the molecular mechanisms by which PPARγ regulates tumorigenesis in colorectal cancer,and examines current clinical trials evaluating PPARγ agonists as therapeutic agents for colorectal cancer.

Effect of ligand of peroxisome proliferator-activated receptor γ on the biological characters of hepatic stellate cells

AIM: To study the effect of rosiglitazone, which is a ligand of peroxisome proliferator-activated receptor gamma (PPARγ), on the expression of PPARγ in hepatic stellate cells (HSCs) and on the biological characteristics of HSCs.METHODS: The activated HSCs were divided into three groups: control group, 3 μmol/L rosiglitazone group, and 10 μmol/L rosiglitazone group. The expression of PPARγ,α-smooth muscle actin (α-SMA), and type Ⅰ and Ⅲ collagen was detected by RT-PCR, Western blot and immunocytochemical staining, respectively. Cell proliferation was determined with methylthiazolyltetrazolium (MTT) colorimetric assay. Cell apoptosis was demonstrated with flow cytometry.RESULTS: The expression of PPARγ at mRNA and protein level markedly increased in HSCs of 10 μmol/L rosiglitazone group (tvalue was 10.870 and 4.627 respectively, P<0.01in both). The proliferation of HSCs in 10 μmol/L rosiglitazone group decreased significantly (t = 5.542, P<0.01), α-SMA expression level and type Ⅰ collagen synthesis ability were also reduced vs controls (tvalue= 10.256 and 14.627respectively, P<0.01 in both). The apoptotic rate of HSCs significantly increased in 10 μmol/L rosiglitazone group vs control (x2= 16.682, P<0.01).CONCLUSION: By increasing expression of PPARγ in activated HSCs, rosiglitazone, an agonist of PPARγ,decreases α-SMA expression and type Ⅰ collagen synthesis,inhibits cell proliferation, and induces cell apoptosis.

Chronic oleoylethanolamide treatment attenuates diabetes-induced mice encephalopathyby activating peroxisome proliferator-activatedreceptor alpha in hippocampus

OBJECTIVE Oleoylethanolamide(OEA) is an endogenous peroxisome proliferatoractivated receptor alpha(PPARα) agonist that acts on the peripheral control of energy metabolism.Previous studies have shown that OEA exerts neuroprotection after cerebral ischemia.However,whether OEA affects the outcomes of diabetes-induced encephalopathy(DE) requires further study.METHODS The chronic effects of OEA on DE were evaluated in C57BL/6 and PPARαknockout mice,individually.The cognitive function was assessed with Morris water maze.The expression of receptor for advanced glycation end products(RAGE) and phosphorylation of Tau in mice hippocampus were determined using Western blotting.The influence of OEA in neuron loss and neuroplasticity were assessed with immunofluorescent staining and Western blotting.RESULTS OEA markedly ameliorated performance in the Morris water maze,which was correlated with its capabilities of suppressing glycometabolism and phosphorylation of Tau in the hippocampus.OEA offered protection from diabetes-induced impairments in hippocampal neuroplasticity.Furthermore,the changes in Morris water maze performance and neuron loss could not be observed in PPARα knockout mouse models with OEA administration.CONCLUSION The ability of OEA to control PPARα signaling can serve as a novel neuroprotective approach for the treatment of diabetes-induced encephalopathy.

Effect of Atorvastatin on Expression of Peroxisome Proliferator-activated Receptor Beta/delta in Angiotensin Ⅱ-induced Hypertrophic Myocardial Cells In Vitro

Objective To explore the effect of atorvastatin on cardiac hypertrophy and to determine the potential mechanism involved. Methods An in vitro cardiomyocyte hypertrophy from neonatal rats was induced with angiotensinⅡ(Ang Ⅱ) stimulation. Before AngⅡ stimulation, the cultured rat cardiac myocytes were pretreated with atorvastatin at different concentrations(0.1, 1, and 10 μmol/L). The following parameters were evaluated: the myocyte surface area, 3H-leucine incorporation into myocytes, m RNA expressions of atrial natriuretic peptide, brain natriuretic peptide, matrix metalloproteinase 9, matrix metalloproteinase 2, and interleukin-1β, m RNA and protein expressions of the δ/β peroxisome proliferator-activated receptor(PPAR) subtypes. Results It was shown that atorvastatin could ameliorate Ang Ⅱ-induced neonatal cardiomyocyte hypertrophy in the area of cardiomyocytes, 3H-leucine incorporation, and the expression of atrial natriuretic peptide and brain natriuretic peptide markedly. Meanwhile, atorvastatin also inhibited the augmented m RNA level of several cytokines in hypertrophic myocytes. Furthermore, the down-regulated expression of PPAR-δ/β at both the m RNA and protein levels in hypertrophic myocytes could be significantly reversed by atorvastatin treatment. Conclusions Atorvastatin could improve AngⅡ-induced cardiac hypertrophy and inhibit the expression of cytokines. Such effect might be partly achieved through activation of the PPAR-δ/β pathway.

Association between Cardiac Changes and Stress, and the Effect of Peroxisome Proliferator-activated Receptor-γ on Stress-induced Myocardial Injury in Mice

This study was aimed to investigate the effect of stress induced by high-intensity exercises on the cardiovascular system. In the epidemiological investigation, 200 subjects（test group） engaged in special high-intensity exercises, and 97 who lived and worked in the same environment and conditions as those in the test group, but did not participate in the exercises served as controls. In the second part of the study, 50 mice were randomly divided into control group, exhaustive swimming group, white noise group, exhaustive swimming plus white noise group, and pioglitazone intervention group. The results showed that the plasma concentrations of the myocardial injury markers heart fatty acid-binding protein（H-FABP）, C-reactive protein（CRP）, β-endorphin（β-EP） and levels of psychological stress were significantly increased in test group as compared with control group; special high-intensity exercises resulted in a significant elevation of the incidence of cardiac arrhythmias. Animal experiments showed that the plasma levels of corticosterone（CORT） and troponin I（Tn I） were raised while the level of SOD was reduced in exhaustive swimming group, white noise group, and exhaustive swimming plus white noise group. The expression levels of PPARγ m RNA and protein were decreased in myocardial tissues in these groups as well. HE staining showed no remarkable change in myocardial tissues in all the groups. Treatment with pioglitazone significantly decreased the plasma levels of Tn I and CORT, while increased the level of SOD and the expression levels of PPARγ m RNA and protein. It was concluded that the high-intensity exercises may induce a heavy physical and psychological stress and predispose the subjects to accumulated fatigue and sleep deprivation; high-intensity exercises also increases the incidence of arrhythmias and myocardial injury. PPARγ may be involved in the physical and psychological changes induced by high-intensity exercises.

The interplay between non-esterified fatty acids and bovine peroxisome proliferator-activated receptors: results of an in vitro hybrid approach

Background: In dairy cows circulating non-esterified fatty acids(NEFA) increase early post-partum while liver and other tissues undergo adaptation to greater lipid metabolism, mainly regulated by peroxisome proliferator-activated receptors(PPAR). PPAR are activated by fatty acids(FA), but it remains to be demonstrated that circulating NEFA or dietary FA activate bovine PPAR. We hypothesized that circulating NEFA and dietary FA activate PPAR in dairy cows.Methods: The dose-response activation of PPAR by NEFA or dietary FA was assessed using HP300 e digital dispenser and luciferase reporter in several bovine cell types. Cells were treated with blood plasma isolated from Jersey cows before and after parturition, NEFA isolated from the blood plasma, FA released from lipoproteins using milk lipoprotein lipase(LPL), and palmitic acid(C16:0). Effect on each PPAR isotype was assessed using specific synthetic inhibitors.Results: NEFA isolated from blood serum activate PPAR linearly up to ~ 4-fold at 400 μmol/L in MAC-T cells but had cytotoxic effect. Addition of albumin to the culture media decreases cytotoxic effects of NEFA but also PPAR activation by ~ 2-fold. Treating cells with serum from peripartum cows reveals that much of the PPAR activation can be explained by the amount of NEFA in the serum(R~2 = 0.91) and that the response to serum NEFA follows a quadratic tendency, with peak activation around 1.4 mmol/L. Analysis of PPAR activation by serum in MAC-T, BFH-12 and BPAEC cells revealed that most of the activation is explained by the activity of PPARδ and PPARγ, but not PPARα. Palmitic acid activated PPAR when added in culture media or blood serum but the activation was limited to PPARδ and PPARα and the response was nil in serum from post-partum cows. The addition of LPL to the serum increased > 1.5-fold PPAR activation.Conclusion: Our results support dose-dependent activation of PPAR by circulating NEFA in bovine, specifically δand γ isotypes. Data also support the possibility of increasing PPAR activation by dietary FA;however, this nutrigenomics approach maybe only effective in pre-partum but not post-partum cows.

Role of Neuropeptide Y and Peroxisome Proliferator-activated Receptor γ Coactivator-1α in Stress Cardiomyopathy

Death following situations of intense emotional stress has been linked to the cardiac pathology described as stress cardiomyopathy, whose pathomechanism is still not clear. In this study, we sought to determine, via an animal model, whether the transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator-1alpha (PGC-1α) and the amino peptide neuropeptide Y (NPY) play a role in the pathogenesis of this cardiac entity. Male Sprague-Dawley rats in the experimental group were subjected to immobilization in a plexy glass box for 1 h, which was followed by low voltage elec-tric foot shock for about 1h at 10s intervals in a cage fitted with metallic rods. After 25 days the rats were sacrificed and sections of their hearts were processed. Hematoxylin-eosin staining of cardiac tissues revealed the characteristic cardiac lesions of stress cardiomyopathy such as contraction band necrosis, inflammatory cell infiltration and fibrosis. The semi-quantitative RT-PCR analysis for PGC-1α mRNA expression showed significant overexpression of PGC1-α in the stress-subjected rats (P<0.05). Fluorescence immunohistochemistry revealed a higher production of NPY in the stress-subjected rats as compared to the control rats (P=0.0027). Thus, we are led to conclude that following periods of intense stress, an increased expression of PGC1-α in the heart and an overflow of NPY may lead to stress car-diomyopathy and even death in susceptible victims. Moreover, these markers can be used to identify stress cardiomyopathy as the cause of sudden death in specific cases.