Leptin induces hypertrophy through activating the peroxisome proliferator‐activated receptor α pathway in cultured neonatal rat cardiomyocytes

1. Our previous study has shown that leptin induces cardiomyocyte hypertrophy; however, the mechanisms are poorly understood. Recent studies have shown that peroxisome proliferator‐activated receptor α (PPARα) activation might be responsible for pathological remodeling and severe cardiomyopathy. Leptin, as an endogenous activator of PPARα, regulates energy metabolism through activating PPARα in many cells. Therefore, we hypothesized that leptin induces cardiomyocyte hypertrophy through activating the cardiac PPARα pathway. 2. Cultured neonatal rat cardiomyocytes were used to evaluate the effects of PPARα on hypertrophy. The selective PPARα antagonist GW6471 concentration‐dependently decreased atrial natriuretic factor mRNA expression by 23%, 36%, 44% and 59%, and significantly decreased total RNA levels, protein synthesis and cell surface areas, all of which were elevated by 72 h of leptin treatment. The augmentation of reactive oxygen species levels in leptin treated cardiomyocytes was reversed by 0.1–10 μmol/L GW6471 (40%, 52% and 58%). After 24 h of treatment, leptin concentration‐dependently enhanced mRNA expression by 7%, 93%, 100% and 256%, and protein expression by 31.2%, 64.2%, 143% and 199%, and the activity of PPARα. Meanwhile, cardiomycytes receiving 72 h of treatment with the PPARα agonist, fenofibrate, concentration‐dependently increased total RNA levels, atrial natriuretic factor mRNA expression, protein synthesis and cell surface area. Treatment of fenofibrate for 4 h also elevated oxygen species levels in a concentration‐dependent manner. 3. In conclusion, these findings show that leptin induces hypertrophy through the activation of the PPARα pathway in cultured neonatal rat cardiomyocytes.     

Peroxisome proliferator‐activated receptor‐γ coactivator‐1α in muscle links metabolism to inflammation

1. In higher eukaryotes, metabolism and immunity are tightly coupled. However, whereas in evolutionary terms a compromised immune response due to undernourishment has been the predominant problem, the inflammatory response to obesity and other lifestyle‐associated diseases has increased in relevance in Western societies in the past 100 years. 2. Traditionally, fat tissue has been considered as the major source of pro‐inflammatory secreted factors in these pathologies. However, in recent years the contribution of other tissues to disease‐causing chronic inflammation has been increasingly appreciated. 3. Peroxisome proliferator‐activated receptor‐γ coactivator‐1α (PGC‐1α) is one of the key regulatory factors in active skeletal muscle. Aberrant expression of PGC‐1α in inactive muscle fibres could be linked to a sedentary lifestyle, persistent systemic inflammation and a higher risk for many chronic diseases. Accordingly, modulation of PGC‐1α activity in skeletal muscle may have a broad range of therapeutic effects. Here, recent advances in the understanding of the role of muscle PGC‐1α in health and disease are reviewed.     

A role of peroxisome proliferator‐activated receptor γ in non‐alcoholic fatty liver disease

Non‐alcoholic fatty liver disease is becoming a major health burden, as prevalence increases and there are no approved treatment options. Thiazolidinediones target the nuclear receptor peroxisome proliferator‐activated receptor γ (PPARγ) and have been investigated in several clinical trials for their potential in treating non‐alcoholic fatty liver disease (NAFLD) and non‐alcoholic steatohepatitis (NASH). PPARγ has specialized roles in distinct tissues and cell types, and although the primary function of PPARγ is in adipose tissue, where the highest expression levels are observed, hepatic expression levels of PPARγ are significantly increased in patients with NAFLD. Thus, NAFLD patients receiving treatment with PPARγ agonists might have a liver response apart from the one in adipose tissue. Owing to the different roles of PPARγ, new treatment strategies include development of compounds harnessing the beneficial effects of PPARγ while restricting PPARγ unwanted effects such as adipogenesis resulting in weight gain. Furthermore, dual or pan agonists targeting two or more of the PPARs have shown promising results in pre‐clinical research and some are currently proceeding to clinical trials. This MiniReview explores adipose‐ and liver‐specific actions of PPARγ, and how this knowledge may contribute in the search for new treatment modalities in NAFLD/NASH.     

The synthesis of three isotopomers of 2‐methyl‐2‐(4‐[3‐[1‐(4‐methylbenzyl)‐5‐oxo‐4,5‐dihydro‐1H‐[1,2,4]triazol‐3‐yl]propyl]phenoxy)propionic acid,a potent and selective peroxisome proliferator‐activated receptor alpha agonist

Although fenofibrate ( 1a ) is commercially available and clinically effective in lowering serum triglycerides, its activity and sub‐type selectivity at the PPARα receptors are only moderate; therefore, there exists a need for more potent and sub‐type selective PPARα agonists. To that end, discovery efforts have identified 2‐methyl‐2‐(4‐[3‐[1‐(4‐methylbenzyl)‐5‐oxo‐4,5‐dihydro‐1H‐[1,2,4]triazol‐3‐yl]propyl]phenoxy)propionic acid ( 2 ), a potent and selective human PPARα receptor agonist. In support of pre‐clinical ADME studies and bioanalysis, three isotopomers of 2 have been synthesized. The results of these efforts are described below. Copyright © 2007 John Wiley & Sons, Ltd.     

Antihypertensive methyldopa,labetalol, hydralazine,and clonidine reversed tumour necrosis factor‐α inhibited endothelial nitric oxide synthase expression in endothelial‐trophoblast cellular networks

Medications used to control hypertension in pregnancy also improve trophoblast and endothelial cellular interaction in vitro. Tumour necrosis factor‐α (TNF‐α) inhibits trophoblast and endothelial cellular interactions and simultaneously decreases endothelial nitric oxide synthase (eNOS) expression. This study investigated whether antihypertensive medications improved these cellular interactions by modulating eNOS and inducible nitric oxide synthase (iNOS) expression. Human uterine myometrial microvascular endothelial cells (UtMVECs) were pre‐incubated with (or without) low dose TNF‐α (0.5 ng/mL) or TNF‐α plus soluble fms‐like tyrosine kinase‐1 (sFlt‐1) (100 ng/mL). The endothelial cells were cultured on Matrigel. After endothelial cellular networks appeared, trophoblast derived HTR‐8/SVneo cells were co‐cultured in the presence of clinically relevant doses of methyldopa, labetalol, hydralazine or clonidine for 24 hours. Cells were retrieved from the Matrigel to extract mRNA and eNOS and iNOS expression were examined by quantitative PCR. Methyldopa, labetalol, hydralazine and clonidine reversed the inhibitory effect of TNF‐α on eNOS mRNA expression. After pre‐incubating endothelial cells with TNF‐α and sFlt‐1, all the medications except methyldopa lost their effect on eNOS mRNA expression. In the absence of TNF‐α, antihypertensive medications did not change eNOS expression. The mRNA expression of iNOS was not affected by TNF‐α or any medications. This study shows that selected antihypertensive medications used in the treatment of hypertension in pregnancy increase eNOS expression in vitro when induced by the inflammatory TNF‐α. The anti‐angiogenic molecule sFlt‐1 may antagonise the potential benefit of these medications by interfering with the NOS pathway.     

RNAi Silencing of IL‐1β and TNF‐α in the Treatment of Post‐traumatic Arthritis in Rabbits

Post‐traumatic arthritis is a secondary complication to severe joint trauma. With the disease progression, it may eventually lead to osteoarthritis in patients whose age is considerably younger than patients with traditional bone arthritis. The main objective of this study was to explore the feasibility of using lentiviral‐mediated RNA interference silencing of IL‐1β and TNF‐α to treat post‐traumatic arthritis in rabbits. About 48 New Zealand rabbits underwent bilateral knee joint surgery to stimulate traumatic arthritis. They were then randomly divided into four groups of 12 rabbits each. The histopathology of the cartilage was observed, and the changes were assessed by Mankin scoring. ELISA was used to detect the expression of IL‐1β and TNF‐α in the synovial fluid. (i) Compared with the control group, the transfection and co‐transfected groups displayed reduced cartilage damage and speed of degeneration. The co‐transfected group showed the greatest alleviation of symptoms. The Mankin score was statistically different (p < 0.01). (ii) Compared with the control group, the expression of IL‐1β or TNF‐α was reduced in the respective transfection groups (p < 0.01 in both groups) and IL‐1β and TNF‐α were reduced in the co‐transfected group (p < 0.01). The co‐transfected group showed the lowest expression of the three experimental groups of both IL‐1β and TNF‐α (p < 0.01). Lentivirus‐mediated RNA interference can knock down the expression of IL‐1β and TNF‐α in joint fluids and, in a synergistic effect when two siRNAs are co‐transfected, ease cartilage degeneration.     

Synthesis,Hypoglycaemic, Hypolipidemic and PPARγ Agonist Activities of 5‐(2‐Alkyl/aryl‐6‐Arylimidazo[2,1‐b][1,3,4]thiadiazol‐5‐yl)methylene‐1,3‐Thiazolidinediones

A novel series of 5‐(2‐alkyl/aryl‐6‐arylimidazo[2,1‐b][1,3,4]thiadiazol‐5‐yl)methylene‐1,3‐thiazolidinediones were synthesized as possible PPARγ agonists. The structures of these target molecules were established by spectral and analytical data. All the newly synthesized compounds were screened for their in vivo hypoglycaemic and hypolipidemic activity in male Wistar rats. Further, compounds with good activity were screened for PPARγ agonist activity. Among the screened compounds, 5‐{[2‐Cyclohexyl‐6‐(4‐methoxyphenyl)imidazo[2,1‐b] [1,3,4]thiadiazol‐5‐yl]methylene}‐1,3‐thiazolidine‐2,4‐dione (3i) exhibits promising hypoglycaemic and hypolipidemic activity via potential PPARγ agonist activity.     

Effects of thalidomide and 3‐phthalimido‐3‐(3,4‐dimethoxyphenyl)‐propanamide on bile duct obstruction‐induced cirrhosis in the rat

Tumor necrosis factor‐alpha (TNF‐α) plays a central role in cellular necrosis, apoptosis, organ failure, tissue damage, inflammation, and fibrosis. These processes, occurring in liver injury, may lead to cirrhosis. Thalidomide and its analogs have shown to be effective TNF‐α inhibitors. The aim of this work was to synthesize a thalidomide analog, the 3‐phthalimido‐3‐(3,4‐dimethoxyphenyl)‐propanamide (PDP) and to evaluate its hepatoprotective properties on bile duct obstruction‐induced cirrhosis. Synthesis, purification, and spectroscopic characterization of PDP were carried out. Thalidomide (200 mg/kg) or PDP (15 mg/kg) were administered to sham (Sh) or bile duct ligated (BDL) rats. The animals were sacrificed 28 days after treatments. Alkaline phosphatase (Alk. Phosph.), γ‐glutamyl transpeptidase (γ‐GTP) and alanine aminotransferase (ALT) enzyme activities, bilirubins, and TNF‐α concentrations were evaluated in plasma. Collagen was estimated by the liver hydroxyproline content and histopathology was performed. Both drugs showed partial amelioration of cirrhosis. However, the hepatoprotective effects of thalidomide were poor when compared to those afforded by PDP. While PDP improved the majority of the biochemical markers of liver injury and prevented partial but significantly collagen accumulation, thalidomide showed only modest beneficial effects on bilirubins and ALT. PDP was effective in preventing the increase in plasma TNF‐α levels, while thalidomide not only failed to inhibit TNF‐α, but increased it. Differences between thalidomide and PDP effectiveness may be due to their stability and different mechanism of action, as reported by others. Inhibition of proinflamatory cytokines is an interesting pharmacological aim to treat cirrhosis. Drug Dev. Res. 54:209–218, 2001. © 2002 Wiley‐Liss, Inc.     

Stevioside protects against rhabdomyolysis‐induced acute kidney injury through PPAR‐γ agonism in rats

We explored the potential role of peroxisome proliferator activated receptor‐γ (PPAR‐γ) in stevioside‐mediated renoprotection using rhabdomyolysis‐induced acute kidney injury (AKI) model in rats. Rhabdomyolysis refers to intense skeletal muscle damage, which further causes AKI. Glycerol (50% w/v, 8 ml/kg) was injected intramuscularly in rats to induce rhabdomyolysis. After 24 hr, AKI was demonstrated by quantifying serum creatinine, urea, creatinine clearance, microproteinuria, and electrolytes in rats. Further, oxidative stress was measured by assaying thiobarbituric acid reactive substances, generation of superoxide anion, and reduced glutathione levels. Additionally, serum creatine kinase (CK) level was assayed to determine glycerol‐induced muscle damage in rats. Pathological changes in rat kidneys were studied using hematoxylin–eosin and periodic acid Schiff staining. Moreover, the expression of apoptotic markers (Bcl‐2, Bax) in rat kidneys was demonstrated by immunohistochemistry. Stevioside (10, 25, and 50 mg/kg) was administered to rats, prior to the induction of AKI. In a separate group, bisphenol A diglycidyl ether (BADGE, 30 mg/kg), a PPAR‐γ receptor antagonist was given prior to stevioside administration, which was followed by rhabdomyolysis‐induced AKI in rats. The significant alteration in biochemical and histological parameters in rats indicated AKI, which was attenuated by stevioside treatment. Pretreatment with BADGE abrogated stevioside‐mediated renoprotection, which is suggestive of the involvement of PPAR‐γ in its renoprotective effect. In conclusion, stevioside protects against rhabdomyolysis‐induced AKI, which may be attributed to modulation of PPAR‐γ expression.     

The peroxisome proliferator‐activated receptor‐γ agonist pioglitazone protects against cisplatin‐induced renal damage in mice

Peroxisome proliferator‐activated receptor‐γ (PPAR‐γ) agonists not only improve metabolic abnormalities of diabetes and consequent diabetic nephropathy, but they also protect against non‐diabetic kidney disease in experimental models. Here, we investigated the effect of PPAR‐γ agonist pioglitazone against acute renal injury on a cisplatin model in mice. Nephrotoxicity was induced by a single intraperitoneal (i.p.) injection of cisplatin (10 mg kg^–1). Pioglitazone was administered for six consecutive days in doses of 15 or 30 mg kg^–1 day^–1, per os (p.o.), starting 3 days before cisplatin injection. Cisplatin treatment to mice induced a marked renal failure, characterized by a significant increase in serum urea and creatinine levels and alterations in renal tissue architecture. Cisplatin exposure induced oxidative stress as indicated by decreased levels of non‐enzymatic antioxidant defenses [glutathione (GSH) and ascorbic acid levels] and components of the enzymatic antioxidant defenses [superoxide dismutase (SOD), catalase (CAT) glutathione peroxidase (GPx), glutathione reductase (GR) and and glutathione S‐transferase(GST) activities)] in renal tissue. Administration of pioglitazone markedly protected against the increase in urea and creatinine levels and histological alterations in kidney induced by cisplatin treatment. Pioglitazone administration ameliorated GSH and ascorbic acid levels decreased by cisplatin exposure in mice. Pioglitazone protected against the inhibition of CAT, SOD, GPx, GR and GST activities induced by cisplatin in the kidneys of mice. These results indicated that pioglitazone has a protective effect against cisplatin‐induced renal damage in mice. The protection is mediated by preventing the decline of antioxidant status. The results have implications in use of PPAR‐γ agonists in human application for protecting against drugs‐induced nephrotoxicity. Copyright © 2012 John Wiley & Sons, Ltd.     

5‐Amino‐3‐methyl‐4‐isoxazolecarboxylic acid hydrazide derivatives with in vitro immunomodulatory activities

Isoxazoles are an important class of compounds of potential therapeutic value. The aim of this study was to determine immunotropic effects of 5‐amino‐3‐methyl‐4‐isoxazolecarboxylic acid hydrazide derivatives on spontaneous and mitogen‐induced lymphocyte proliferation in young and old mice, cytokine production by peritoneal cells as well as possible mechanism of action in a model of Jurkat cells. Three‐month‐old and 13‐month‐old BALB/c mice were used as donors of the cells from a thymus, a spleen, mesenteric lymph nodes, and a peritoneal cavity. Spontaneous and concanavalin A or lipopolysaccharide (LPS)‐induced cell proliferation was measured by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide colorimetric method. IL‐1β and TNF‐α production induced by LPS in macrophage‐enriched peritoneal cell cultures was measured by enzyme‐linked immunoassay. 5‐amino‐3‐methyl‐4‐isoxazolecarboxylic acid hydrazide, 01K (4‐phenyl‐1‐(5‐amino‐3‐methylisoxazole‐4‐carbonyl)‐thiosemicarbazide), and 06K (4‐(4‐chlorophenyl)‐1‐(5‐amino‐3‐methylisoxazole‐4‐carbonyl)‐thiosemicarbazide) exhibited regulatory activity in the proliferation tests. Prevailing stimulatory activity of the hydrazide and inhibitory activity of 01K and 06K was observed. Those effects were connected with different influence of the compounds on signaling proteins expression in Jurkat cells. The regulatory effects of the compounds on IL‐1β production were more profound than those on TNF‐α. Differences in the compound activity in young versus old mice were mainly restricted to 01K. Immunosuppressive isoxazole leflunomide and a stimulatory RM‐11 (1,7‐dimethyl‐8‐oxo‐1,2H‐isoxazole [5,4‐e]triazepine) were applied as reference drugs.     

Synthesis of 1,4‐Anthracene‐9,10‐dione Derivatives and Their Regulation of Nitric Oxide,IL‐1β and TNF‐α in Activated RAW264.7 Cells

Mitoxantrone is an anthracenedione antineoplastic and immunosuppressive agent approved for multiple sclerosis treatment. Novel mono‐ and disubstituted anthraquinone derivatives, analogues of mitoxantrone, were synthesized through the addition of lipophilic amino alcohols and evaluated for their effect on IL‐1β, TNF‐α and nitric oxide production by LPS/IFN‐γ‐stimulated RAW264.7 cells. The disubstituted 1,4‐anthracene‐9,10‐dione 10 showed significant inhibition of nitric oxide, TNF‐α and IL‐1β production at the concentration of 5 μg/mL, with a much lower cytotoxicity than mitoxantrone. The monosubstituted 3 , 4 , 11, 12 and 13 also displayed a moderate to good inhibitory capacity on IL‐1β production. However, the methylated compounds 11, 12 and 13 failed to inhibit the TNF‐α production, and compound 13 was the only one to decrease the production of nitric oxide. None of these derivatives was toxic at the tested concentrations. Compounds 10 and 13 had better inhibitory capacity of the inflammatory mediators analyzed, with reliable viability of the cells.     

Peroxisome proliferator-activated receptor δ (PPARδ), a novel target site for drug discovery in metabolic syndrome

The development of new treatments for metabolic syndrome is urgent project for decreasing the prevalence of coronary heart disease and diabetes mellitus in the advanced countries. Peroxisome proliferator-activated receptor (PPAR)α and γ agonists have shed light on the treatment of hypertriglyceridemia and type 2 diabetes mellitus, respectively. Among PPARs, analysis of the PPARδ functions is lagging behind because specific PPARδ agonists have not been developed. The appearance of new PPARδ agonists is brightening the prospects for elucidating the physiological role of PPARδ. PPARδ is a new target for the treatment of metabolic syndrome. In particular, the fact that fatty acid oxidation and energy dissipation in skeletal muscle and adipose tissue by PPARδ agonists lead to improved lipid profile, reduced adiposity and insulin sensitivity is a breakthrough. It seems that treatment of PPARδ agonists operate similarly to the caloric restriction and prolonged exercise. We suggest that the physiological role of PPARδ may be an indicator for switching from glucose metabolism to fatty acid metabolism. To receive new benefits of PPARδ agonists against metabolic syndrome by increasing fatty acid consumption in skeletal muscle and adipose tissue, we need to unveil more details on the functions of PPARδ itself and its agonists in the future.     

Inflammatory cytokines tumour necrosis factor‐α and interleukin‐8 enhance airway smooth muscle contraction by increasing L‐type Ca2+ channel expression

Inflammation elevates intracellular calcium concentrations ([Ca²⁺]_i) in airway smooth muscle (ASM). The L‐type Ca²⁺ channel (L‐VDCC) plays an important role in regulating Ca²⁺ influx in ASM. However, the role of L‐VDCC in the inflammatory cytokine‐induced pathology of ASM remains unclear. In the present study, we used calcium imaging and isometric tension measurements to assess the role of L‐VDCC in agonist‐induced [Ca²⁺]_i rise and the associated contractions in mouse ASM, and we used immunoblotting to identify L‐VDCC protein expression levels in mouse ASM after exposure to tumour necrosis factor alpha (TNF‐α) or interleukin‐8 (IL‐8). Our results showed that high‐K⁺‐ or carbachol‐induced contractions of mouse ASM were significantly greater after pretreatment with TNF‐α or IL‐8 for 24 hours. Both verapamil and nifedipine, L‐VDCC inhibitors, abolished this increased contraction induced by TNF‐α or IL‐8 pretreatment. Moreover, TNF‐α treatment enhanced carbachol‐induced Ca²⁺ influx in ASM cells, and this effect was abrogated by verapamil. Additionally, immunoblotting results showed that preincubation of mouse ASM with TNF‐α or IL‐8 also enhanced L‐VDCC protein expression. On the basis of these findings, we concluded that proinflammatory cytokines, such as TNF‐α and IL‐8, increase the expression level of L‐VDCC, which in turn contributes to augmented agonist‐induced ASM contractions. This effect of inflammation on L‐VDCC expression in ASM may be associated with airway hyper‐responsiveness and involved in the development of asthma.     

Acute effect of β‐sitosterol on calcium uptake mediates anti‐inflammatory effect in murine activated neutrophils

Objectives To evaluate the effect of β‐sitosterol on ⁴⁵Ca²⁺ uptake in activated murine neutrophils, and upon myeloperoxidase and adenosine deaminase activity, and interleukin‐1β (IL‐1β) and tumour necrosis factor‐α (TNF‐α) levels, in carrageenan‐induced inflammation in the mouse air pouch model. Methods Dried Esenbeckia leiocarpa bark was macerated and extracted resulting in a crude hydroalcoholic extract (CHE) that was partitioned to obtain an alkaloid fraction. The alkaloid was then partitioned in polar and nonpolar subfractions. β‐Sitosterol was isolated from the nonpolar subfraction and identified by comparison with the literature. The effect of β‐sitosterol on ⁴⁵Ca²⁺ uptake in activated murine neutrophils, and upon myeloperoxidase and adenosine deaminase activity, IL‐1β and TNF‐α levels in carrageenan‐induced inflammation in mice were evaluated. Key findings β‐Sitosterol promoted a time‐ and dose‐dependent increase of the calcium uptake in activated neutrophils that was promptly reversed by nifedipine, BAPTA‐AM, LY294002, and colchicine. β‐Sitosterol inhibited myeloperoxidase and adenosine deaminase activity, and IL‐1β and TNF‐α levels. Conclusions β‐Sitosterol inhibited either myeloperoxidase and adenosine deaminase activity or IL‐1β and TNF‐α levels. This effect seemed to be mediated by the calcium uptake in activated neutrophils in a time‐ and concentration‐dependent manner through L‐type voltage dependent calcium channels, intracellular calcium, phosphoinositide kinase‐3, and microtubule modulation.     

Molecular analysis of antilipemic effects of FR218944, a novel vasopressin V1a receptor antagonist,in genetically diabetic db/db mice in comparison with pioglitazone and fenofibrate

Arginine vasopressin V1a receptor is highly expressed in liver. The aim of this article is to perform a molecular analysis of the effects of a novel nonpeptide V1a receptor (V1aR) antagonist, FR218944 (2‐methoxy‐N‐(2‐methyl‐1H‐benzimidazol‐4‐yl)‐4‐(2,3,4,5‐tetrahydro‐1H‐1‐benzazepin‐1‐yl‐carbonyl)benzamide methanesulfonate), on plasma glucose (Glu) and triglyceride (TG) levels in diabetic db/db mice in comparison with those of a peroxisome proliferator‐activated receptor γ (PPARγ) agonist, pioglitazone, and a PPARα agonist, fenofibrate. FR218944 significantly lowered the plasma TG level but not plasma Glu level after oral administration at 32 mg/kg twice a day for 2 weeks. On the other hand, 10 mg/kg pioglitazone significantly lowered both TG and Glu levels, and 10 mg/kg fenofibrate significantly lowered only the TG level. Significant weight gain was observed only with pioglitazone treatment. db/db mice had lower levels of hepatic V1aR mRNA than normal +/+ mice. The three compounds lowered the mRNA level further. FR218944 significantly raised mRNA levels of β‐oxidation enzymes, Acyl‐CoA oxidase and bifunctional enzymes (BFE). Pioglitazone significantly increased mRNA levels of all the tested enzymes for β‐oxidation and fatty acid synthesis. Fenofibrate significantly increased mRNA levels of Acyl‐CoA synthase and BFE for β‐oxidation and decreased the mRNA level of sterol regulatory element‐binding protein 1, which transactivates many enzymes for fatty acid synthesis. In conclusion, chronic administration of FR218944, a V1aR antagonist, would lower the plasma TG level by increasing energy consumption via upregulation of β‐oxidation enzymes. Furthermore, the compound expresses its antilipemic effect via a different gene‐regulatory pathway from pioglitazone and fenofibrate. FR218944 has the potential to become a new drug for hyperlipemia. Drug. Dev. Res. 60:241–251, 2003. © 2003 Wiley‐Liss, Inc.     

Fenofibrate induced PPAR alpha expression was attenuated by oestrogen receptor alpha overexpression in Hep3B cells

The physiological regulation of Oestrogen receptor α (ERα) and peroxisome proliferator‐activated receptor alpha (PPARα) in Hepatocellular carcinoma (HCC) remains unknown. The present study we first treat the cells with fenofibrate and further investigated the possible mechanisms of 17β‐estradiol (E₂) and/or ERα on regulating PPARα expression. We also found higher PPARα expression in the tumor area than adjacent areas and subsequently compared PPARα expression in four different hepatic cancer cell lines. Hep3B cells were found to express more PPARα than the other cell lines. Using the PPARα agonist fenofibrate, we found that fenofibrate increased Hep3B cell proliferation efficiency by increasing cell cycle proteins, such as cyclin D1 and PCNA, and inhibiting p27 and caspase 3 expressions. Next, we performed transient transfections and immuno‐precipitation studies using the pTRE2/ERα plasmid to evaluate the interaction between ERα and PPARα. ERα interacted directly with PPARα and negatively regulated its function. Moreover, in Tet‐on ERα over‐expressed Hep3B cells, E₂ treatment inhibited PPARα, its downstream gene acyl‐CoA oxidase (ACO), cyclin D1 and PCNA expression and further increased p27 and caspase 3 expressions. However, over‐expressed ERα plus 17‐β‐estradiol (10⁻⁸ M) reversed the fenofibrate effect and induced apoptosis, which was blocked in ICI/melatonin/fenofibrate‐treated cells. This study illustrates that PPARα expression and function were negatively regulated by ERα expression in Hep3B cells.     

TNF‐α level affects etanercept clearance: TNF‐α concentration as a new correction factor of allometric scaling to predict individual etanercept clearances in patients with ankylosing spondylitis

Etanercept (ETN) is a widely used anti‐tumour necrosis factor‐α (TNF‐α) agent, which relieves the symptoms of ankylosing spondylitis (AS) by binding to TNF‐α to inhibit its inflammation effects. In this study, the effect of TNF‐α level on ETN clearance (CL) was investigated, and the TNF‐α concentration was initially set as a correction factor for allometric scaling to improve the predictions of individual ETN CLs. Individual ETN CLs and TNF‐α concentrations in healthy volunteers and patients with AS were determined by performing ETN pharmacokinetic studies in the two cohorts. Accordingly, individual ETN CLs in both healthy volunteers and patients with AS were predicted from data of two animal species using different methods, including simple allometric scaling, scaling with a correction factor of maximum life span potential or brain weight, and scaling with a correction factor of the TNF‐α concentration. The accuracies of such predictions were evaluated by the percentage errors. Consequently, increased TNF‐α concentration was shown to improve ETN CL, by comparing both ETN CLs and TNF‐α concentrations between healthy volunteers and patients with AS. More importantly, better predictions of individual ETN CLs were achieved in patients with AS using allometric scaling with TNF‐α concentration as the correction factor. In conclusion, in vivo levels of TNF‐α can affect ETN CL, and allometric scaling corrected with the TNF‐α concentration can be used to estimate the individual CLs of anti‐TNF‐α monoclonal antibodies based on preclinical data.     

Metformin attenuates renal fibrosis in both AMPKα2‐dependent and independent manners

Metformin is a well‐known AMP ‐activated protein kinase (AMPK ) activator, and it has been shown to inhibit organ fibrosis. Whether AMPK α2 mediates metformin protection against renal fibrosis remains unknown. Here, we aimed to investigate the role of the AMPK α2 isoform in mediating the inhibitory effect of metformin on renal fibrosis. Unilateral ureteral obstruction (UUO ) was used to induce renal fibrosis in wild‐type (WT ) and AMPK α2 knockout (AMPK α2^?/?) mice. Metformin treatment was initiated 3 days before UUO and was continued until 7 days after UUO . In WT mice, metformin significantly inhibited UUO ‐induced renal fibrosis. In AMPK α2^?/? mice, metformin also tended to inhibit UUO ‐induced renal fibrosis. Specifically, metformin significantly reduced UUO ‐induced transforming growth factor β1 (TGF β1) mRNA and protein expression in WT mice but not in AMPK α2^?/? mice. In contrast, metformin reduced UUO ‐induced TGF β1 downstream Smad3 phosphorylation in both WT and AMPK α2^?/? mice, suggesting that this regulation occurs in an AMPK α2‐independent manner. In conclusion, the underlying mechanisms for the protective effects of metformin against renal fibrosis include AMPK α2‐dependent targeting of TGF β1 production and AMPK α2‐independent targeting of TGF β1 downstream signalling. In this regard, metformin has an advantage over other AMPK activators for the treatment of renal fibrosis.