Most cited article - PubMed ID 9329783
Increased lipoprotein oxidability and aortic lipid peroxidation in an experimental model of insulin resistance syndrome
Metabolic syndrome (MetS) is a cluster of risk factors that increase the likelihood of developing cardiovascular, metabolic and other diseases. The pharmacological management of MetS often involves polypharmacy, making it essential to understand how drug-metabolising enzymes, transporters, transcription factors and other proteins involved are affected under different metabolic conditions. This study investigated the relative mRNA expression of key hepatic and intestinal genes involved in drug metabolism, including Cyp1a2, Cyp3a23, Cyp2d1, Cyp2c11, Cyp2c6, Cyp2e1, Cyp7a1, Cyp2b1, Cyp2a1, Abcg5, Abcg8, Abcb1, Nr1i3, Nr1i2, Ahr, Gsta1 and Comt, in four nonobese rat models of MetS: hereditary hypertriglyceridaemic (HHTg), spontaneously hypertensive rat (SHR), SHR expressing transgenic human C-reactive protein (SHR-CRP), and bilaterally ovariectomised Wistar (W-OVX), compared to Wistar controls. Gene expression was quantified by RT-PCR with data normalised using the ΔΔCt method. Between the models studied, measurements showed significant differences in the liver. The upregulation of Cyp2c6 and Cyp3a23 was observed only in SHR; upregulated Cyp2d1 was found in SHR as well as in HHTg rats. The downregulated Cyp1a2 was measured in a condition of hypertriglyceridemia, postmenopause or hypertension. These findings highlight model-specific alterations in gene expression that may affect drug metabolism and interactions. The HHTg may be, in particular, a suitable model for preclinical studies focusing on intestinal drug-drug interactions in MetS-related conditions.
- Keywords
- drug metabolism, metabolic syndrome, rat model,
- MeSH
- Liver metabolism enzymology MeSH
- Rats MeSH
- Humans MeSH
- Membrane Transport Proteins * genetics metabolism MeSH
- RNA, Messenger * metabolism genetics MeSH
- Metabolic Syndrome * genetics metabolism MeSH
- Disease Models, Animal MeSH
- Rats, Inbred SHR MeSH
- Rats, Wistar MeSH
- Receptors, Cytoplasmic and Nuclear * genetics metabolism MeSH
- Cytochrome P-450 Enzyme System * genetics metabolism MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Membrane Transport Proteins * MeSH
- RNA, Messenger * MeSH
- Receptors, Cytoplasmic and Nuclear * MeSH
- Cytochrome P-450 Enzyme System * MeSH
Background: Hypertriglyceridemia has serious health risks such as cardiovascular disease, type 2 diabetes mellitus, nephropathy, and others. Fenofibrate is an effective hypolipidemic drug, but its benefits for ameliorating disorders associated with hypertriglyceridemia failed to be proven in clinical trials. Methods: To search for possible causes of this situation and possibilities of their favorable influence, we tested the effect of FF monotherapy and the combination of fenofibrate with silymarin on metabolic disorders in a unique model of hereditary hypertriglyceridemic rats (HHTg). Results: Fenofibrate treatment (100 mg/kg BW/day for four weeks) significantly decreased serum levels of triglyceride, (-77%) and free fatty acids (-29%), the hepatic accumulation of triglycerides, and the expression of genes encoding transcription factors involved in lipid metabolism (Srebf2, Nr1h4. Rxrα, and Slco1a1). In contrast, the hypertriglyceridemia-induced ectopic storage of lipids in muscles, the heart, and kidneys reduced glucose utilization in muscles and was not affected. In addition, fenofibrate reduced the activity of the antioxidant system, including Nrf2 expression (-35%) and increased lipoperoxidation in the liver and, to a lesser extent, in the kidneys and heart. Adding silymarin (micronized form, 600 mg/kg BW/day) to fenofibrate therapy increased the synthesis of glycogen in muscles, (+36%) and reduced hyperinsulinemia (-34%). In the liver, it increased the activity of the antioxidant system, including PON-1 activity and Nrf2 expression, and reduced the formation of lipoperoxides. The beneficial effect of combination therapy on the parameters of oxidative stress and lipoperoxidation was also observed, to a lesser extent, in the heart and kidneys. Conclusions: Our results suggest the potential beneficial use of the combination of FF with SLM in the treatment of hypertriglyceridemia-induced metabolic disorders.
- Keywords
- fenofibrate, glycogen synthesis, insulin resistance, metabolic syndrome, oxidative stress, reesterification of fatty acids, silymarin, triglycerides,
- Publication type
- Journal Article MeSH
Activation of nuclear factor-κB (NF-κB) by increased production of reactive oxygen species (ROS) might induce transcription and expression of different antioxidant enzymes and also of nitric oxide synthase (NOS) isoforms. Thus, we aimed at studying the effect of NF-κB inhibition, caused by JSH-23 (4-methyl-N (1)-(3-phenyl-propyl)-benzene-1,2-diamine) injection, on ROS and NO generation in hereditary hypertriglyceridemic (HTG) rats. 12-week-old, male Wistar and HTG rats were treated with JSH-23 (bolus, 10 μmol, i.v.). After one week, blood pressure (BP), superoxide dismutase (SOD) activity, SOD1, endothelial NOS (eNOS), and NF-κB (p65) protein expressions were higher in the heart of HTG rats compared to control rats. On the other hand, NOS activity was decreased. In HTG rats, JSH-23 treatment increased BP and heart conjugated dienes (CD) concentration (measured as the marker of tissue oxidative damage). Concomitantly, SOD activity together with SOD1 expression was decreased, while NOS activity and eNOS protein expression were increased significantly. In conclusion, NF-κB inhibition in HTG rats led to decreased ROS degradation by SOD followed by increased oxidative damage in the heart and BP elevation. In these conditions, increased NO generation may represent rather a counterregulatory mechanism activated by ROS. Nevertheless, this mechanism was not sufficient enough to compensate BP increase in HTG rats.
- MeSH
- Gene Expression drug effects MeSH
- Phenylenediamines pharmacology MeSH
- Glutathione analysis MeSH
- Hyperlipoproteinemia Type IV pathology veterinary MeSH
- Blood Pressure drug effects MeSH
- Rats MeSH
- Myocardium metabolism MeSH
- Nitric Oxide metabolism MeSH
- Oxidative Stress drug effects MeSH
- Rats, Wistar MeSH
- Reactive Oxygen Species metabolism MeSH
- Heart Ventricles metabolism MeSH
- Superoxide Dismutase genetics metabolism MeSH
- Nitric Oxide Synthase Type III genetics metabolism MeSH
- Nitric Oxide Synthase genetics metabolism MeSH
- Body Weight drug effects MeSH
- Transcription Factor RelA genetics metabolism MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- 4-methyl-N1-(3-phenylpropyl)benzene-1,2-diamine MeSH Browser
- Phenylenediamines MeSH
- Glutathione MeSH
- Nitric Oxide MeSH
- Reactive Oxygen Species MeSH
- Superoxide Dismutase MeSH
- Nitric Oxide Synthase Type III MeSH
- Nitric Oxide Synthase MeSH
- Transcription Factor RelA MeSH
While metabolic syndrome is often associated with obesity, 25% of humans suffering from it are not obese and the effect of physical activity remains unclear in such cases. Therefore, we used hereditary hypertriaclyglycerolemic (HHTg) rats as a unique model for studying the effect of spontaneous physical activity [voluntary running (VR)] on metabolic syndrome-related disorders, such as dyslipidemia, in non-obese subjects. Adult HHTg males were fed standard (CD) or high-sucrose (HSD) diets ad libitum for four weeks. Within both dietary groups, some of the rats had free access to a running wheel (CD+VR, HSD+VR), whereas the controls (CD, HSD) had no possibility of extra physical activity. At the end of the four weeks, we measured the effects of VR on various metabolic syndrome-associated parameters: (i) biochemical parameters, (ii) the content and composition of triacylglycerols (TAG), diacylglycerols (DAG), ceramides and membrane phospholipids, and (iii) substrate utilization in brown adipose tissue. In both dietary groups, VR led to various positive effects: reduced epididymal and perirenal fat depots; increased epididymal adipose tissue lipolysis; decreased amounts of serum TAG, non-esterified fatty acids and insulin; a higher insulin sensitivity index. While tissue ceramide content was not affected, decreased TAG accumulation resulted in reduced and modified liver, heart and skeletal muscle DAG. VR also had a beneficial effect on muscle membrane phospholipid composition. In addition, compared with the CD group, the CD+VR rats exhibited increased fatty acid oxidation and protein content in brown adipose tissue. Our results confirm that physical activity in a non-obese model of severe dyslipidemia has many beneficial effects and can even counteract the negative effects of sucrose consumption. Furthermore, they suggest that the mechanism by which these effects are modulated involves a combination of several positive changes in lipid metabolism.
- MeSH
- Running physiology MeSH
- Adipose Tissue, White pathology MeSH
- Cell Membrane metabolism MeSH
- Ceramides metabolism MeSH
- Phospholipids metabolism MeSH
- Adipose Tissue, Brown metabolism pathology MeSH
- Hypertriglyceridemia blood MeSH
- Muscle, Skeletal metabolism pathology MeSH
- Rats MeSH
- Metabolic Syndrome blood MeSH
- Lipid Metabolism * MeSH
- Oxidative Stress MeSH
- Muscle Cells metabolism MeSH
- Triglycerides metabolism MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Ceramides MeSH
- Phospholipids MeSH
- Triglycerides MeSH
Disorders of carbohydrate and lipid metabolism have been reported to cluster in patients with essential hypertension and in spontaneously hypertensive rats (SHRs). A deletion in the Cd36 gene on chromosome 4 has recently been implicated in defective carbohydrate and lipid metabolism in isolated adipocytes from SHRs. However, the role of Cd36 and chromosome 4 in the control of blood pressure and systemic cardiovascular risk factors in SHRs is unknown. In the SHR. BN-Il6/Npy congenic strain, we have found that transfer of a segment of chromosome 4 (including Cd36) from the Brown Norway (BN) rat onto the SHR background induces reductions in blood pressure and ameliorates dietary-induced glucose intolerance, hyperinsulinemia, and hypertriglyceridemia. These results demonstrate that a single chromosome region can influence a broad spectrum of cardiovascular risk factors involved in the hypertension metabolic syndrome. However, analysis of Cd36 genotypes in the SHR and stroke-prone SHR strains indicates that the deletion variant of Cd36 was not critical to the initial selection for hypertension in the SHR model. Thus, the ability of chromosome 4 to influence multiple cardiovascular risk factors, including hypertension, may depend on linkage of Cd36 to other genes trapped within the differential segment of the SHR. BN-Il6/Npy strain.
- MeSH
- CD36 Antigens genetics MeSH
- Cerebrovascular Disorders genetics physiopathology MeSH
- Phenotype MeSH
- Genotype MeSH
- Hemodynamics genetics MeSH
- Hypertension genetics physiopathology MeSH
- Insulin blood genetics MeSH
- Blood Glucose genetics metabolism MeSH
- Rats MeSH
- Lipids blood genetics MeSH
- Rats, Inbred BN MeSH
- Rats, Inbred SHR MeSH
- Risk Factors MeSH
- Sequence Deletion MeSH
- Cluster Analysis MeSH
- Animals, Congenic MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, U.S. Gov't, P.H.S. MeSH
- Names of Substances
- CD36 Antigens MeSH
- Insulin MeSH
- Blood Glucose MeSH
- Lipids MeSH