Effects of bezafibrate, PPAR pan-agonist, and GW501516, PPARdelta agonist, on development of steatohepatitis in mice fed a methionine- and choline-deficient diet.
Nagasawa T, Inada Y, Nakano S, Tamura T, Takahashi T, Maruyama K, Yamazaki Y, Kuroda J, Shibata N.
Toxicology Research Laboratory, R&D, Kissei Pharmaceutical Co., Ltd., 2320-1 Maki, Hotaka, Azumino-city, Nagano-Pref., 399-8305, Japan. tatsuya_nagasawa@pharm.kissei.co.jp
We evaluated the effects of bezafibrate, a peroxisome proliferator-activated receptor (PPAR) pan-agonist, and GW501516, a PPARdelta agonist, on mice fed a methionine- and choline-deficient (MCD) diet, a model of non-alcholic steatohepatitis (NASH), to investigate (a) the efficacy of bezafibrate against non-alcholic steatohepatitis and ( the relation between non-alcholic steatohepatitis and the functional role of PPARdelta. Bezafibrate (50 or 100 mg/kg/day) and GW501516 (10 mg/kg/day) were administered by gavage once a day for 5 weeks. Hepatic lipid contents, plasma triglyceride, high density lipoprotein (HDL)-cholesterol and alanine aminotransferase (ALT) concentrations were evaluated, as were histopathological changes in the liver and hepatic mRNA expression levels. Bezafibrate and GW501516 inhibited the MCD-diet-induced elevations of hepatic triglyceride and thiobarbituric acid-reactants contents and the histopathological increases in fatty droplets within hepatocytes, liver inflammation and number of activated hepatic stellate cells. In this model, bezafibrate and GW501516 increased the levels of hepatic mRNAs associated with fatty acid beta-oxidation [acyl-CoA oxidase (ACO), carnitine palmitoyltransferase-1 (CPT-1), liver-fatty acid binding protein (L-FABP) and peroxisomal ketothiolase], and reduced the levels of those associated with inflammatory cytokines or chemokine [transforming growth factor (TGF)-beta1, interleukin (IL)-6, IL-1beta, monocyte chemoattractant protein (MCP)-1, tumor necrosis factor (TNF) alpha and nuclear factor (NF)-kappaB1]. In addition, bezafibrate characteristically reduced the elevation in the level of plasma ALT, but enhanced that in plasma adiponectin and increased the mRNA expression levels of its receptors (adiponectin receptors 1 and 2). These results suggest that (a) bezafibrate (especially) and GW501516 might improve hepatic steatosis via an improvement in fatty acid beta-oxidation and a direct prevention of inflammation, ( treatment with a PPARdelta agonist might improve non-alcholic steatohepatitis, © bezafibrate may improve non-alcholic steatohepatitis via activation not only of PPARalpha but also of PPARdelta, because bezafibrate is a PPAR pan-agonist.
Peroxisome proliferator-activated receptor-alpha selective ligand reduces adiposity, improves insulin sensitivity and inhibits atherosclerosis in LDL receptor-deficient mice.
Srivastava RA, Jahagirdar R, Azhar S, Sharma S, Bisgaier CL.
CloneGen Biotechnology, Ann Arbor, MI, USA.
Fenofibrate, a selective (1)PPAR-alpha activator, is prescribed to treat human dyslipidemia. The aim of this study was to delineate the mechanism of fenofibrate-mediated reductions in adiposity, improvements in insulin sensitivity, and lowering of triglycerides (TG) and free fatty acids (FFA) and to investigate if these favorable changes are related to the inhibition of lipid deposition in the aorta. To test this hypothesis we used male LDLr deficient mice that exhibit the clinical features of metabolic syndrome X when fed a high fat high cholesterol (HF) diet. LDLr deficient mice fed HF diet and simultaneously treated with fenofibrate (100 mg/kg body weight) prevented development of obesity, lowered serum triglycerides and cholesterol, improved insulin sensitivity, and prevented accumulation of lipids in the aorta. Lowering of circulating lipids occurred via down-regulation of lipogenic genes, including fatty acid synthase, acetyl CoA carboxylase and diacyl glycerol acyl transferase-2, concomitant with decreased liver TG and cholesterol, and TG output rate. Fenofibrate also suppressed liver apoCIII mRNA levels and markedly increased lipoprotein lipase mRNA levels, known to enhance serum TG catabolism. In addition, fenofibrate profoundly reduced epididymal fat and mesenteric fat mass to the levels seen in lean mice. The reductions in body weight were associated with elevation of hepatic uncoupling protein 2 (UCP2) mRNA, a concomitant increase in the ketone body formation, and improved insulin sensitivity associated with tumor necrosis factor-alpha reductions and phosphoenol pyruvate carboxykinase down-regulation. These results demonstrate that fenofibrate improves lipid abnormalities partly via inhibition of TG production and partly via clearance of TG-rich apoB particles by elevating LPL and reduced apoCIII. The prevention of obesity development occurred via energy expenditure. Fenofibrate-mediated hypolipidemic effects together with improved insulin sensitivity and loss of adiposity led to the reductions in the aortic lipid deposition by inhibiting early stages of atherosclerosis possibly via vascular cell adhesion molecule-1 (VCAM-1) modulation. These results suggest that potent PPAR-alpha activators may be useful in the treatment of syndrome X. (Mol Cell Biochem xxx: 1-16, 2005).
Effect of fenofibrate on fatty liver in rats treated with alcohol.
Tsutsumi And M, Takase S.
Division of Gastroenterology, Department of Internal Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan.
BACKGROUND: Although fatty liver and hyperlipemia are common in chronic alcoholics, there is no practical approach to prevent alcoholic fatty liver. Recently, it has been reported that fibrates bind to peroxisome proliferator-activated receptor-alpha and induce beta-oxidation enzymes of fatty acid in mitochondria. In this study, we investigated the effect of fenofibrate, one of the fibrates, on fatty liver in rats induced by chronic alcohol feeding. Furthermore, we studied the effect of fenofibrate on hyperlipemia in patients with alcoholic fatty liver. METHODS: Male Wistar rats were treated with liquid diet that contained ethanol (36% of total calories) or an isocaloric carbohydrate instead of ethanol for 4 weeks. Fenofibrate was administered orally with the liquid diets for 4 weeks at a concentration of either 0, 5, or 30 mg/kg body weight/day. As a pilot study, eight patients with alcoholic fatty liver were treated with 200 mg/day of fenofibrate for 4 weeks. RESULTS: After fenofibrate administration, fatty degeneration of liver was not observed in three of the five rats treated with 5 mg and in all rats treated with 30 mg of fenofibrate. Hepatic triglyceride content was decreased significantly in rats treated with 30 mg of fenofibrate compared with the rats not treated with fenofibrate. Serum triglyceride and total cholesterol levels also were decreased after treatment with fenofibrate. In eight alcoholic patients treated with 200 mg of fenofibrate for 4 weeks, serum triglyceride level decreased significantly compared with the levels before treatment. All patients continued alcohol consumption during fenofibrate administration. CONCLUSION: The results of the present investigation suggest that fenofibrate may be useful to prevent alcoholic fatty liver. Further studies with larger numbers of patients are necessary to obtain definitive results.
[Systemic lupus erythematosus with steroid induced non-alcoholic steatohepatitis: a case report]
[Article in Japanese]
Kamata Y, Kamimura T, Yoshio T, Hirata D, Masuyama J, Isoda N, Kanai N, Minota S.
A 56-year old Japanese female was admitted to our hospital because of the increased levels of serum AST, ALT, and gamma-GTP. She was diagnosed with systemic lupus erythematosus in September, 1996 and had been on a regular glucocorticoid therapy since then. Abdominal ultrasonography showed the mild fatty liver, and hepatic histopathology revealed a typical and remarkable steatohepatitis, a remarkable neutrophil infiltration, and Mallory bodies. Because she had no history of alcohol-drinking, diagnosis of non-alcoholic steatohepatitis (NASH) was made. Treatment was started with a low-calorie diet, bed-rest, and an oral administration of alpha-tocopherol and Bezafibrate with favorable effects on her serum levels of AST, ALT, gamma-GTP, and LDH. When a patient on a glucocorticoid therapy shows signs of fatty liver, diabetes mellitus, hyperlipidemia, an insulin resistance, NASH should be considered as one of the differential diagnosis. This is particularly important since proper therapy with a low-calorie diet and drugs with anti-oxidant activities improve this potentially progressive disease before resulting in liver cirrhosis and hepatic carcinoma
PPARalpha activators may be good candidates as antiaging agents.
Erol A.
Silivri City Hospital, Internal medicine, Ali Cetinkaya Cad, 34930 Silivri, Istanbul, Turkey. eroladnan@hotmail.com
Aging is associated with a metabolic decline characterized by the development of changes in fat distribution, obesity, and insulin resistance. Dysfunctional humoral and cell-mediated immune responses occur with age, and these aberrations have been implicated in the increased incidence of infectious diseases, hyporesponsiveness to vaccination, and the etiology of numerous chronic degenerative diseases. All these metabolic and immune alterations are associated with a variety of age-related diseases that subsequently result in increased mortality. Leptin can modulate many of the metabolic alterations characteristic of aging. Leptin resistance has been implicated in the pathogenesis of obesity-related complications involving abnormalities of lipid metabolism that resemble those of old age. Increased plasma leptin levels with aging suggest resistance to leptin action and may explain why elderly subjects have abdominal obesity and insulin resistance. Leptin's failure may be considered for the metabolic decline seen with aging. Peroxisome proliferator-activated receptor (PPAR)-alpha, the transcription factor for the mitochondrial and peroxisomal enzymes of beta-oxidation, and its target enzymes, are upregulated by hyperleptinemia. PPARalpha has been shown to mediate the action of the hypolipidemic drugs of the fibrate class on lipid and lipoprotein metabolism. PPARalpha activators furthermore improve glucose homeostasis and influence body weight and energy homeostasis. The administration of agents capable of activating the PPARalpha was found to restore the cellular redox balance, evidenced by a lowering of tissue lipid peroxidation, an elimination of constitutively active NF-kappaB, loss in spontaneous inflammatory cytokine production, and ailing in the aging immunity.
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Now lets talk about side effects...... LIBIDO:
we have hypothised that the LIBIDO side effects caused by fibrates/sesathin were correlated to LESS inflamtion resulting in less prostagandin E2 decreasing NO2 avaibility and we talked about i´ts efects on testosterone production....Less NO2 avaiability is a proven factor sinse renal problems caused by fibrates correlate with less NO2 + more creatinine.......but maybe it´s not the main factor for libido problems sinse i don´t think it blunts No2 to such a degree....
testosterone production also don´t seem to be hihgly effected by this drugs........not to a significant degree...
now i have a new theory for the libido side effects caused by sesathin/fibrates and i think this new theory is right on spot...it seems to be the most rational one i could come up with...
PROLACTIN !!!
PPAR-a increases PROLACTIN gene...this would result in more prolactin wich would probably be the main reason people get LIBIDO side effects on this drugs......
--------------------------------------------------------------------------------------Activation of the prolactin gene by peroxisome proliferator-activated receptor-alpha appears to be DNA binding-independent.
Tolon RM, Castillo AI, Aranda A.
Instituto de Investigaciones Biomedicas, Consejo Superior de Investigaciones Cientificas, 28029 Madrid, Spain.
Although the effects of the peroxisome proliferator-activated receptors (PPARs) have been studied primarily in adipocytes and liver, the wide distribution of these receptors suggests that they might also play a role in other cell types. We present evidence that PPAR activators stimulate the expression of the prolactin gene in pituitary GH4C1 cells. Transfection assays in non-pituitary HeLa cells showed that stimulation of the prolactin promoter by PPARalpha requires the presence of the transcription factor GHF-1 (or Pit-1). Proximal promoter sequences confer responsiveness to PPARalpha, and activation by this receptor is lost concomitantly with the response to GHF-1. Surprisingly, expression of the retinoid X receptor (RXR) abolishes stimulation by PPARalpha. Furthermore, the promoter region that confers PPARalpha responsiveness does not contain a PPAR response element. This suggests that the transcriptional effect of PPARalpha might be mediated by protein-protein interactions rather than by binding of PPAR/RXR to the promoter. A direct interaction between PPARalpha and GHF-1 was confirmed by in vitro binding studies. Expression of the coactivators SRC-1 and CREB-binding protein, which bind to PPAR, also enhanced the responsiveness of the prolactin promoter to PPARalpha. Furthermore, CREB-binding protein also significantly increased activation by GHF-1, and both proteins associated in vitro. Thus, PPARalpha, a receptor that normally acts as a ligand-dependent transcription factor by binding to specific DNA sequences in one context, can also stimulate the prolactin promoter by association with GHF-1 and coactivator proteins.