Effects of atorvastatin therapy on hypercholesterolemic rabbits with respect to oxidative stress, nitric oxide pathway and homocysteine

The Oxidative Stress Markers' Protective Influence of Sea Buckthorn and Grape Extracts in Atorvastatin-Treated Hyperlipidemic Rats

Free radicals and reactive oxygen species initiate when the oxidative stress arises. (1) Background: The effect of natural molecules on oxidative stress in hyperlipidemic rats, taking statins, was observed. (2) Methods: One hundred and twelve white Wistar rats, males and females, were divided into seven: Group I received 20 mg of atorvastatin while groups II and III received a combination of 20 mg of atorvastatin and 100 mg of Sea buckthorn and grape extract. Groups IV and V received 100 mg of Sea buckthorn and grape extract, while groups VI and VII received only high-fat diet (HFD) and normal rodents' fodder. After two and six months, rats were euthanized, and blood was gathered to measure the main paraclinical values and total antioxidant capacity (TAC). Also, the liver and kidney were stored for the organs' cytoarchitecture. For statistics, two-way analysis of variance (ANOVA), was performed. (3) Results: HFD produced hyperlipidemia, accompanied by augmented serum and hepatic oxidative stress markers, in addition to a reduction in antioxidant enzyme activities and glutathione levels. Polyphenolic substances proven efficient against HFD caused oxidative stress. (4) Conclusions: Atorvastatin heightened the histological injuries caused by the fatty diet, but these were diminished by taking atorvastatin in combination with 100 mg/kg of plant extracts.

Grape seed extract improved the fertility-enhancing effect of atorvastatin in high-fat diet-induced testicular injury in rats: involvement of antioxidant and anti-apoptotic effects

Objectives

Reduced male fertility is highly prevalent with hypercholesterolaemia. Though statins are drugs of choice for hypercholesterolaemia, their effect on male fertility is still controversial and dose-dependent. Grape seed extract (GSE) possess hypocholesterolemic and testicular protective effects. Thus, this study aimed to investigate the effects of low-dose atorvastatin (ATV) on male infertility in hypercholesterolaemic rats and assess the additional value of combining ATV with GSE.

Methods

Male rats were randomized into four groups. The normal group was fed a standard diet. The remaining groups were fed a high-fat diet (HFD) for 1 month to induce hypercholesterolaemia. Two HFD groups were administered either ATV (1 mg/kg) alone or combined with GSE (200 mg/kg) orally for 65 days, while the third group served as HFD control.

Key findings

Treatment with ATV or ATV/GSE attenuated dyslipidemia-induced alteration in serum HDL-cholesterol, LDL-cholesterol, and total cholesterol. ATV enhanced serum testosterone, sperm count and motility and fertility index. The effect on testosterone and sperm count was more pronounced by ATV/GSE. Moreover, ATV reduced testicular malondialdehyde, nitric oxide, caspase-9 and caspase-3 while elevated reduced glutathione and superoxide dismutase along with catalase activity. Noteworthy, GSE/ATV induced more powerful antioxidant and anti-apoptotic effects.

Conclusion

GSE enhanced ATV’s protective effect against hypercholesterolaemia-induced infertility via antioxidant and anti-apoptotic mechanisms.

Hepatoprotective Effects of a Novel Trihoney against Nonalcoholic Fatty Liver Disease: A Comparative Study with Atorvastatin

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disorder worldwide with no curative therapy. The aim of this study was to investigate the hepatoprotective effects of a novel Trihoney against biochemical and histological manifestations of NAFLD in hypercholesterolemic rabbits. Methodology. Forty-eight male New Zealand white (NZW) rabbits were grouped into normal diet (C), normal diet with 0.6 g/kg/day of Trihoney (C + H), 1% cholesterol diet (HCD), 1% cholesterol diet with 0.3 g/kg/day of Trihoney (HCD + H₁), 1% cholesterol diet with 0.6 g/kg/day of Trihoney (HCD + H₂), and 1% cholesterol diet with 2 mg/kg/day of atorvastatin (HCD + At.). Animals were sacrificed after 12 weeks of treatment. Serum lipids and liver function test (LFT) were measured prior to and at the endpoint of the experiment for total cholesterol (TC), low-density lipoprotein (LDL-c), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), and total bilirubin (T. Bil.). Liver was processed for histopathology study. Liver homogenate was analysed for oxidative stress parameters: superoxide dismutase (SOD), glutathione peroxidase (GPx), and malondialdehyde (MDA). Results. Lipid analysis approved the induction of hypercholesterolemia. A significant elevation (p < 0.01) of serum AST and ALT levels showed by the HCD group was compared to C and C + H groups. Trihoney exhibited a significant reduction (p < 0.001) of AST and ALT compared to the HCD group. Likewise, AST and ALT reduced significantly in the HCD + At. group (p < 0.001). Trihoney supplementation induced significant (p < 0.05) enhancement of SOD and GPx activities. Atorvastatin treatment was associated with significant (p < 0.05) reduction of SOD and GPx activities in the liver. Trihoney and atorvastatin showed marked (p < 0.001) reduction of hepatic lipid peroxidation. Trihoney showed histological protection against progression of NAFLD to nonalcoholic steatohepatitis (NASH). Atorvastatin exhibited no beneficial impact on hepatic architecture. Conclusion. Trihoney was able to maintain normal liver function and showed hepatoprotection against progression of NAFLD to NASH probably through hypocholesterolaemic and antioxidant functions.

Clopidogrel or prasugrel reduces mortality and lessens cardiovascular damage from acute myocardial infarction in hypercholesterolemic male rats

AIMS

Hypercholesterolemia is a hazard for increasing susceptibility of the heart to myocardial infarction (MI) by inducing platelet hyperaggregability. Clopidogrel and prasugrel have documented cardioprotective effects in clinical studies. Herein, we investigated whether clopidogrel and prasugrel could protect against isoproterenol-induced acute MI (A-MI) under hypercholesterolemic conditions in rats.

MAIN METHODS

Dietary hypercholesterolemic rats were subjected to acute doses of isoproterenol. Serum lipids, inflammatory markers, aortic endothelin1 and endothelial nitric oxide synthase (eNOS) mRNAs expression and immunexpression of BCL2 were determined.

KEY FINDINGS

Hypercholesterolemic rats showed infiltration of inflammatory cells and reduction in aortic wall thickness, deposition of fibrous tissue between cardiac muscle fibers. Protective doses of prasugrel or clopidogrel for 28 days before A-MI increased survival, amended the ECG parameters -including ST segment elevation- and improved the histopathological picture in hypercholesterolemic rats. This was coupled with reductions in platelet aggregation, creatine kinase-MB activity, endothelin 1, systemic inflammation and cardiac lipid peroxidation and increment in aortic eNOS expression. Clopidogrel and prasugrel groups showed enhanced BCL2 expression in cardiac fibers and aortic wall.

SIGNIFICANCE

Prasugrel and clopidogrel protected against A-MI via anti-aggregatory and anti-inflammatory effects. These results add to the value of these drugs in correcting cardiovascular dysfunction in patients vulnerable to A-MI after confirmation by appropriate human studies.

Mutual Influences between Nitric Oxide and Paraoxonase 1

One of the best consolidated paradigms in vascular pharmacology is that an uncontrolled excess of oxidizing chemical species causes tissue damage and loss of function in the endothelial and subendothelial layers. The fact that high-density lipoproteins play an important role in preventing such an imbalance is integrated into that concept, for which the expression and activity of paraoxonases is certainly crucial. The term paraoxonase (aryldialkyl phosphatase, EC 3.1.8.1) encompasses at least three distinct isoforms, with a wide variation in substrate affinity, cell and fluid localization, and biased expression of polymorphism. The purpose of this review is to determine the interactions that paraoxonase 1 has with nitric oxide synthase, its reaction product, nitric oxide (nitrogen monoxide, NO), and its derived reactive species generated in an oxidative medium, with a special focus on its pathological implications.

Effect of febuxostat on biochemical parameters of hyperlipidemia induced by a high-fat diet in rabbits

Febuxostat, a highly potent xanthine oxidase inhibitor with an antioxidant effect, inhibits elevated xanthine oxidase, leading to reduction of reactive oxygen species and oxidative stress, the main causes of vascular inflammation in hyperlipidemia. The aim of this study was to test the potential antioxidant and anti-inflammatory effects of febuxostat and (or) stopping a high-fat diet on the biochemical parameters in rabbits with hyperlipidemia induced by a high-fat diet. Male New Zealand rabbits were distributed into 3 groups: a normal control group fed standard chow for 12 weeks and 2 other groups fed a high-fat diet with 1% cholesterol for 8 weeks, and then shifted to standard chow for 4 weeks. During the last 4 weeks, one high-fat diet group received 0.5% carboxymethyl cellulose, whereas the other group was treated with febuxostat (2 mg/kg per day p.o.). Febuxostat significantly lowered low-density lipoprotein cholesterol (“bad” cholesterol) compared to the untreated group (high-fat diet group). Febuxostat also displayed a potent anti-inflammatory and antioxidant activity by decreasing serum levels of lipid peroxidation index, proinflammatory cytokines, and enhancing antioxidant enzyme activity. Stopping the hyperlipidemic diet in the high-fat diet group did not show improvement. These findings indicate the antioxidant and anti-inflammatory effects of febuxostat that may be common mechanisms of the anti-hyperlipidemic effect of this drug. Stopping a hyperlipidemic diet without treatment is not sufficient once injury has occurred.

Nilotinib attenuates endothelial dysfunction and liver damage in high-cholesterol-fed rabbits

Nilotinib is an oral potent tyrosine kinase inhibitor that has diverse biological activities. However, its effects on hypercholesterolemia and associated disorders have not been studied yet. The present study explored the effect of nilotinib on atherosclerosis progression, endothelial dysfunction, and hyperlipidemia-associated hepatic injury in high-cholesterol (HC)-fed rabbits. Rabbits were classified into four groups: control, nilotinib, HC, and HC + nilotinib groups. Rabbits were fed either a regular diet or an HC-enriched diet for 8 weeks. By the end of the eighth week, blood and tissue samples were obtained for biochemical, histological, immunohistochemical, and in vitro analyses. Results indicated that the HC diet induced a significant elevation in the serum lipid parameters (triglycerides, total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol), lactate dehydrogenase, and nitric oxide content. Endothelial dysfunction was evident through the impairment of acetylcholine-induced relaxation of isolated aortas and the histopathological lesions of the aortic specimen. Moreover, HC significantly increased serum malondialdehyde. Liver damage was clear through increase in serum transaminases and alkaline phosphatase, and it was further supported by histopathological examination. HC increased the expression of platelet-derived growth factor receptor (PDGFR)-B in both aorta and liver tissues. Interestingly, nilotinib administration retarded atherosclerosis progression and attenuated all of the aforementioned parameters. These data suggest that nilotinib may counteract atherosclerosis development, vascular dysfunction, and hepatic damage in HC-fed rabbits through interfering with PDGF-B.

The association between atorvastatin administration and plasma total homocysteine levels in renal transplant recipients

BACKGROUND

Statins improve prognosis in patients with coronary heart diseases by decreasing the incidence of vascular events. Excess prevalence of hyperhomocysteinemia, an independent risk factor of cardiovascular diseases, has been observed in stable renal transplant recipients (RTRs).

OBJECTIVES

The objective of our study was to evaluate the association between atorvastatin administration and plasma total homocysteine (tHcy) levels in RTRs.

PATIENTS AND METHODS

We performed a retrospective cross-sectional study in 148 cyclosporine A (CsA) treated stable RTRs. We compared tHcy level and other demographic and clinical variables in RTRs with and without atorvastatin.

RESULTS

58.1% of the 148 RTRs were treated with atorvastatin (20-40 mg/day). Mean tHcy levels were lower in patients treated with atorvastatin compared to nonusers (14.80 ± 5.13 µmol/l versus 16.95 ± 7.87 µmol/l, P = 0.04). The comparison of 85 patients treated with atorvastatin and 61 non-users revealed that those subjects with atorvastatin were older, with higher estimated creatinine clearance and elevated body mass index (BMI). They were more likely to have higher systolic blood pressure and CsA trough level (C0). The association between lower tHcy levels and atorvastatin use was confirmed in the multivariate regression model (P = 0.004). However tHcy levels were independently and negatively associated with serum folate (P = 0.0001) and vitamin B12 levels (P = 0.001) and positively with serum BUN (P = 0.001) and diastolic blood pressure (P = 0.024) as well.

CONCLUSIONS

These data support the association between lower tHcy levels and atorvastatin administration in RTRs. Further clinical trials are recommended to clarify homocysteine lowering effect of atorvastatin.

Ameliorative effect of statin therapy on oxidative damage in heart tissue of hypercholesterolemic rabbits

The aim of this study was to investigate the effects of a high-cholesterol diet in the presence and absence of statin on Cu-Zn-superoxide dismutase (Cu,Zn-SOD), malondialdehyde (MDA), protein carbonyl (PCO), and nitric oxide (NO) of blood and heart tissue, the antioxidant activity of serum paraoxonase-1 (PON-1), and on the blood lipid profile of rabbits. The animals were divided into four groups each of which included 10 rabbits. Rabbits in group 1 received a regular rabbit chow diet (normal diet) for 8 weeks; those in group 2 received atorvastatin (0.3 mg atorvastatin per day/kg body weight) for 8 weeks; those in group 3 received high-cholesterol diet for 8 weeks; and those in group 4 received high-cholesterol diet for 4 weeks, a high-cholesterol diet + atorvastatin (0.3 mg atorvastatin per day/kg body weight) for 8 weeks. The parameters were measured by spectrophotometric methods. As expected, the atherogenic diet caused a pronounced increase in lipid profile (not HDL) parameters. Rabbits in group 3 showed higher PCO, MDA, and NO levels in circulating and heart tissue compared to the rabbits in group 1. Atorvastatin has prevented or limited LDL oxidation and has showed constitutively beneficial effects in group 4. Increased LDL-C, PCO, MDA, and NO levels leading to decreasing PON-1 activity thus create a predisposition to atherogenesis in this model. But atorvastatin administration partly ameliorated oxidative damage in heart injury of hypercholesterolemic rabbits. Atorvastatin which functions as a potent antioxidant agent may inhibit this LDL-C oxidation by increasing PON-1 activity in atherogenesis.

Attenuation of oxidative stress, inflammation, and endothelial dysfunction in hypercholesterolemic rabbits by allicin

Allicin, the active substance of garlic, exerts a broad spectrum of pharmacological activities and is considered to have potential therapeutic applications. The present study was designed to investigate the possible beneficial effects of allicin against oxidative stress, inflammation, and endothelial dysfunction in hypercholesterolemic rabbits. Male New Zealand white rabbits were used in this study. Rabbits randomly received 1 of the following treatments: normal chow diet for 4 weeks, 1% high cholesterol diet (HCD), HCD plus allicin (10 mg/kg/day), or HCD plus atorvastatin (10 mg/kg/day). Blood samples were collected at the end of experimental diets for measurement of serum total cholesterol (TC), triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C), C-reactive protein (CRP), malondialdehyde (MDA), reduced glutathione (GSH), and superoxide dismutase (SOD). In addition, the aorta was removed for measurement of vascular reactivity, histopathological changes, intima/media (I/M) ratio, and immunohistochemical staining of both tumor necrosis-alpha (TNF-α) and nuclear factor (NF)-κB. HCD induced significant increases in serum TC, TGs, low-density lipoprotein cholesterol (LDL-C), CRP, and MDA. Moreover, HCD caused significant decrease in serum GSH and SOD. In addition, aortic relaxation response to acetylcholine (ACh) was impaired. Immunohistochemical staining of aortic specimens from HCD-fed rabbits revealed high expression levels of both TNF-α and the oxidant-induced transcription factor, NF-κB. Allicin supplementation significantly decreased serum MDA and CRP, increased serum HDL-C, GSH, and SOD levels while nonsignificantly affecting HCD-induced elevations in serum TC and LDL-C. Additionally, allicin significantly protected against HCD-induced attenuation of rabbit aortic endothelium-dependent relaxation to ACh and elevation in I/M ratio. This effect was confirmed by histopathological examination of the aorta. Moreover, allicin has substantially beneficial effects on aortic expression of TNF-α and NF-κB compared with HCD-fed rabbits. In conclusion, these findings demonstrate that allicin may be useful in reducing oxidative stress, inflammation, vascular dysfunction, and the aortic pathology in hypercholesterolemic rabbits.

Atherosclerotic process in taxi drivers occupationally exposed to air pollution and co-morbidities

Consistent evidence has indicated that the exposure to environmental air pollution increases the risk of cardiovascular disease. This study aimed to evaluate the possible effects of occupational exposure to air pollution, especially to polycyclic aromatic hydrocarbons (PAHs), and the influence of co-morbidities on the atherosclerotic process and inflammation. For that, biomarkers of exposure such as 1-hydroxypyrene urinary, oxidative damage and markers of cardiovascular risk were determined in plasma, serum and blood. In addition, inflammation models such as carotid intima-media thickness and serum inflammatory cytokines were analyzed in 58 taxi drivers with and without co-morbidity. The results demonstrated that considering only taxi drivers without co-morbidities, 15% presented carotid intima-media thickness above reference values. For the first time it has been demonstrated that urinary 1-hydroxypyrene levels were associated with carotid intima-media thickness and with serum homocysteine levels. The multiple linear regression analysis showed that several factors may contribute to the increased carotid intima-media thickness, among which age, interleukin-6, fibrinogen and exposure to PAHs stand out. In summary, our results suggest that chronic occupational exposure to atmospheric pollution could be an additional contributor to the atherogenesis process, leading to impaired vascular health. Moreover, carotid intima-media thickness, serum homocysteine levels, fibrinogen and the total cholesterol/HDL-c ratio could be suggested as preventive measures to monitor drivers' health.

Comparision of Effects of Rosuvastatin Versus Atorvastatin Treatment on Plasma Levels of Asymmetric Dimethylarginine in Patients With Hyperlipidemia Having Coronary Artery Disease

Elevated plasma levels of asymmetric dimethylarginine (ADMA) are prevalent in patients with hypercholesterolemia and coronary artery disease. A total of 83 patients with hypercholesterolemia and angiographically documented mild coronary artery stenosis were randomized to rosuvastatin treatment (20 mg) or atorvastatin treatment (40 mg) once daily for 6 weeks after a 4-week dietary lead-in phase. Both statins decreased total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglyceride levels effectively. Only rosuvastatin increased high-density lipoprotein cholesterol (HDL-C) levels. Both rosuvastatin and atorvastatin decreased plasma ADMA levels; rosuvastatin had a significantly greater effect. The reduction in ADMA levels were correlated with the reduction in TC and LDL-C levels as well as LDL-C–HDL-C ratio. Treatment with rosuvastatin or atorvastatin in patients with hyperlipidemia with mild coronary artery stenosis may lead to a decrease in ADMA levels, which may contribute to improved endothelial function.

Cholesterol and copper affect learning and memory in the rabbit

A rabbit model of Alzheimer's disease based on feeding a cholesterol diet for eight weeks shows sixteen hallmarks of the disease including beta amyloid accumulation and learning and memory changes. Although we have shown that feeding 2% cholesterol and adding copper to the drinking water can retard learning, other studies have shown that feeding dietary cholesterol before learning can improve acquisition and feeding cholesterol after learning can degrade long-term memory. We explore the development of this model, the issues surrounding the role of copper, and the particular contributions of the late D. Larry Sparks.

Imbalance in superoxide dismutase/thioredoxin reductase activities in hypercholesterolemic subjects: relationship with low density lipoprotein oxidation

BACKGROUND

There is a relationship among hypercholesterolemia, oxidative stress and inflammation in the atherogenesis. Thus, the objective of the present study was to assess paraoxonase (PON1), superoxide dismutase (SOD) and thioredoxin reductase (TrxR-1) activities and their relationship with lipids, oxidative stress and inflammation in subjects with different low density lipoprotein-cholesterol (LDL) levels.

METHODS

Serum lipids, highly sensitive C-reactive protein (hs-CRP), lipid and protein oxidation, oxidized LDL (LDLox) and LDLox autoantibodies (LDLoxAB) levels and enzymes activities were measured in a total of 116 subjects that were divided into the following groups according to their LDL levels: low-LDL group (LDL < 100 mg/dL, n = 23), intermediate-LDL group (LDL 100-160 mg/dL, n = 50) and high-LDL group (LDL > 160 mg/dL, n = 43).

RESULTS

The LDLox and hs-CRP levels increased in the high-LDL group (2.7- and 3.7- fold, respectively), whereas the intermediate and high-LDL groups had higher LDLoxAB (2.2- and 3.1-fold) when compared to low-LDL group (p < 0.05). Similarly, SOD activity, the atherogenic index (AI) and protein oxidation were also higher in the intermediate (1.3-, 1.3- and 1.2-fold) and high-LDL (1.6-, 2.3- and 1.6-fold) groups when compared to the low-LDL group (p < 0.05). Lipid oxidation and SOD/TrxR-1 ratio increased only in the high-LDL group (1.3- and 1.6-fold) when compared to the low-LDL group (p < 0.05). The SOD/TrxR-1 ratio was positively correlated to TBARS (r = 0.23, p < 0.05), LDLox (r = 0.18, p < 0.05), LDLoxAB (r = 0.21, p < 0.05), LDL (r = 0.19, p < 0.05) and AI (r = 0.22, p < 0.05). PON1 and TrxR-1 activities were similar among groups.

CONCLUSIONS

Some oxidative events initiate when LDL levels are clinically acceptable. Moreover, hypercholesterolemic patients have an imbalance in SOD and TrxR-1 activities that is positively associated to LDL oxidation.

Astaxanthin prevents changes in the activities of thioredoxin reductase and paraoxonase in hypercholesterolemic rabbits

This study explored the effects of the antioxidant astaxanthin on paraoxonase and thioredoxin reductase activities as well as on other oxidative stress parameters and on the lipid profile in hypercholesterolemic rabbits. Rabbits were fed a standard or a hypercholesterolemic diet alone or supplemented with 50, 100 and 500 mg/100 g of astaxanthin for 60 days. Antioxidant enzymes activities, lipid profile and oxidative stress markers were evaluated in the serum. The hypercholesterolemic diet increased lipids, including unsaturated fatty acids level, whereas it decreased saturated fatty acids level. These changes were accompanied by increased levels of oxidized low-density lipoprotein and oxidized low-density lipoprotein antibodies, as well as lipid and protein oxidation. Astaxanthin (100 and 500 mg/100 g) prevented hypercholesterolemia-induced protein oxidation, whereas 500 mg/100 g of astaxanthin decreased protein oxidation per se. The activities of superoxide dismutase and thioredoxin reductase were enhanced, whereas paraoxonase activity was inhibited in hypercholesterolemic rabbits. All astaxanthin doses prevented changes in thioredoxin reductase and paraoxonase activities. This effect was not related to a direct effect of astaxanthin on these enzymes, because in vitro astaxanthin enhanced thioredoxin reductase and had no effect on paraoxonase activity. Astaxanthin could be helpful in cardiovascular diseases by restoring thioredoxin reductase and paraoxonase activities.

Relationship between paraoxonase and homocysteine: crossroads of oxidative diseases

Homocysteine (Hcy) is an accepted independent risk factor for several major pathologies including cardiovascular disease, birth defects, osteoporosis, Alzheimer's disease, and renal failure. Interestingly, many of the pathologies associated with homocysteine are also linked to oxidative stress. The enzyme paraoxonase (PON1) - so named because of its ability to hydrolyse the toxic metabolite of parathion, paraoxon - was also shown early after its identification to manifest arylesterase activity. Although the preferred endogenous substrate of PON1 remains unknown, lactones comprise one possible candidate class. Homocysteine-thiolactone can be disposed of by enzymatic hydrolysis by the serum Hcy-thiolactonase/paraoxonase carried on high-density lipoprotein (HDL). In this review, Hcy and the PON1 enzyme family were scrutinized from different points of view in the literature and the recent articles on these subjects were examined to determine whether these two molecular groups are related to each other like a coin with two different sides, so close and yet so different and so opposite.

PPARs in Regulation of Paraoxonases: Control of Oxidative Stress and Inflammation Pathways

The paraoxonase (PON) group of enzymes, composed of PON1, PON2, and PON3, play an important role in decreasing oxidative stress by degrading lipid peroxides. PON1 synthesis is upregulated by PPAR. Several pharmacological compounds (acting as antioxidants and, hence, atheroprotective) stimulate both PPAR activity and PON1 expression. Recent evidence suggests that PON1 and the monocyte chemoattractant protein-1 (MCP-1) are involved in coordinating the inflammatory response in damaged tissues; PPAR may be central in the regulation of these biochemical pathways. This article reviews the state of knowledge on PON1 biochemistry and function, the influence of genetic variation, and the regulation of PON1 expression by pharmaceutical compounds that increase PPAR activity. We also describe recent lines of evidence suggesting links between PON1 and MCP-1 and how their production may be regulated by PPAR.

Regulation of paraoxonase 1 (PON1) in PCB 126-exposed male Sprague Dawley rats

3,3',4,4',5-Pentachlorobiphenyl (PCB 126), an aryl hydrocarbon receptor (AhR) agonist and most potent dioxin-like PCB congener, significantly alters gene expression, lipid metabolism, and oxidative stress in the liver. PON1, an antioxidant and anti-atherogenic enzyme, is produced in the liver and secreted into the blood where it is incorporated into high density lipoprotein (HDL) and protects LDL and cellular membranes against lipid peroxidation. To explore the regulation of PON1, male Sprague-Dawley rats were treated with ip injections of corn oil or 1 μmol/kg or 5 μmol/kg PCB 126 and euthanized up to two weeks afterwards. Serum total and HDL-cholesterol were increased by low dose and decreased by high dose exposure, while LDL-cholesterol was unchanged. PCB 126 significantly increased hepatic PON1 gene expression and liver and serum PON1 activities. Liver and serum thiobarbituric acid reactive substances levels were not elevated except for high dose and long exposure times. Serum antioxidant capacity was unchanged across all exposure doses and time points. This study, the first describing the regulation of gene expression of PON1 by a PCB congener, raises interesting questions whether elevated PON1 is able to ameliorate PCB 126-induced lipid peroxidation and whether serum PON1 levels may serve as a new biomarker of exposure to dioxin-like compounds.

The effects of hypercaloric diets on glucose homeostasis in the rat: influence of saturated and monounsaturated dietary lipids

Consumption of energy-dense/high-fat diets is strongly and positively associated with overweight and obesity, which are associated with increase in the prevalence of certain chronic diseases. We evaluated the effect of hypercaloric/fat or normocaloric diets on some biochemical parameters in rats. Seventy-two rats were divided into four groups that were fed for 16 weeks with diets: normocaloric [9.12% soy oil, normocaloric soy oil (NSO)], hypercaloric olive oil [43.8% olive oil, hypercaloric olive oil (HOO)], hypercaloric saturated fat [43.8% saturated fat, hypercaloric saturated fat (HSF)] and normocaloric saturated fat [43.8% saturated fat, normocaloric saturated fat (NSF)]. HSF rats consumed more calories daily than the others and gained more retroperitoneal fat, although HSF and HOO rats had higher body weight. In liver, glycogen synthesis and concentration were higher in rats HSF and NSF. In plasma, total cholesterol (TC) levels were higher in HSF rats than in the others, and triacylglycerol (TAG) levels were lower in HOO and higher in HSF rats in relation to the others. In liver, TC and TAG were elevated in HSF, NSF and HOO rats. Paraoxonase 1 activity, which is related to high-density lipoprotein cholesterol and has anti-atherogenic role was lower in rats HSF. In HOO rats, glucose tolerance test was altered, but insulin tolerance test was normal. These results suggest that consumption of energy-dense/high-fat diets, both saturated or monounsaturated, causes damaging effects. However, more studies are necessary to understand the mechanisms by which these diets cause the metabolic alterations observed.

The effects of atorvastatin and rosuvastatin on oxidative stress in diabetic patients

AIM

Diabetes is associated with abnormalities in lipid profile and increased oxidative stress. Statins are preferred agents in diabetic patients due to their antioxidant and LDL-C lowering effects. This study is designed to compare the effects of atorvastatin and rosuvastatin on low density lipoprotein cholesterol (LDL-C), lipid hydroperoxide (LOOH), total oxidant status (TOS) and total antioxidant capacity (TAC) in diabetic patients with hyperlipidemia.

MATERIALS AND METHODS

Sixty two patients who have type 2 diabetes mellitus with serum LDL levels more than 100mg/dL were randomly assigned to receive atorvastatin 20mg (n=31) or rosuvastatin 10mg (n=31). Blood tests were performed at the beginning of the study and after three months.

RESULTS

There were no statistically significant differences in the pre- and after treatment levels of the LDL-C between groups. TAC values were increased in both groups and statistically significant in the former group (p=0.007). There was no difference between the change percentages ((after treatment TAC-pretreatment TAC)/pretreatment level) of TAC between two treatment groups. The effects of two drugs on the other oxidative parameters were not significantly different.

CONCLUSION

Both atorvastatin and rosuvastatin may be helpful in reducing increased oxidative stress in diabetic patients with hyperlipidemia.

Long-term high-dose atorvastatin decreases brain oxidative and nitrosative stress in a preclinical model of Alzheimer disease: a novel mechanism of action

Alzheimer disease (AD) is an age-related neurodegenerative disorder characterized by progressive memory loss, inability to perform the activities of daily living and personality changes. Unfortunately, drugs effective for this disease are limited to acetylcholinesterase inhibitors that do not impact disease pathogenesis. Statins, which belong to the class of cholesterol-reducing drugs, were proposed as novel agents useful in AD therapy, but the mechanism underlying their neuroprotective effect is still unknown. In this study, we show that atorvastatin may have antioxidant effects, in aged beagles, that represent a natural higher mammalian model of AD. Atorvastatin (80 mg/day for 14.5 months) significantly reduced lipoperoxidation, protein oxidation and nitration, and increased GSH levels in parietal cortex of aged beagles. This effect was specific for brain because it was not paralleled by a concomitant reduction in all these parameters in serum. In addition, atorvastatin slightly reduced the formation of cholesterol oxidation products in cortex but increased the 7-ketocholesterol/total cholesterol ratio in serum. We also found that increased oxidative damage in the parietal cortex was associated with poorer learning (visual discrimination task). Thus, a novel pharmacological effect of atorvastatin mediated by reducing oxidative damage may be one mechanism underlying benefits of this drug in AD.

The three-gene paraoxonase family: physiologic roles, actions and regulation

The paraoxonase (PON) gene family is composed of three members (PON1, PON2, PON3) that share considerable structural homology and are located adjacently on chromosome 7 in humans. By far the most-studied member is PON1, a high-density lipoprotein-associated esterase/lactonase, also endowed with the capacity to hydrolyze organophosphates, but all the three proteins prevent oxidative stress and fight inflammation. They therefore seem central to a wide variety of human illnesses, including atherosclerosis, diabetes mellitus, mental disorders and inflammatory bowel disease. The major goal of this review is to highlight the regulation of each of the paraoxonase components by diverse nutritional molecules and pharmacological agents as well as a number of pathophysiological events, such as oxidative stress and inflammation. Considerable and detailed cell-based studies and animal model experiments have been provided to allow a thorough scrutiny of PON modulation, which will increase our understanding and ability to target these genes in order to efficiently increase their transcriptional activity and decrease the risks of developing different disorders.

Ezetimibe therapy and its influence on oxidative stress and fibrinolytic activity

OBJECTIVE

The effect of ezetimibe on blood lipids, oxidative stress, and fibrinolytic activity in hyperlipidemic patients was investigated after three months of therapy.

METHODS

Thirty hyperlipidemic patients were treated for twelve weeks with ezetimibe 10 mg/day. A healthy control group with matching age and gender was also included. Fasting blood glucose, lipid parameters, paraoxonase (PON1), protein carbonyl (PCO), oxidized LDL (oxLDL), 8-isoprostane (ISOPR), total antioxidant capacity (TAC) levels, tissue-type plasminogen activator (tPA), plasminogen activator inhibitor type-1 (PAI-1), and PAI-1/t-PA levels were evaluated.

RESULTS

Ezetimibe therapy for twelve weeks led to changes in lipid profile in accordance with the literature. Fibrinolytic activity parameters, PAI-1/tPA and tPA-1 decreased, whereas PAI-1 levels did not change significantly. Antioxidant parameters, serum PON1 activity, and TAC levels increased significantly compared with the basal values. Oxidant parameters, oxLDL, ISOPR, and PCO (which is an indicator of oxidative protein damage) decreased significantly after therapy.

CONCLUSIONS

Ezetimibe therapy has beneficial effects on fibrinolytic activity and homeostasis between oxidant and antioxidant activity in hyperlipidemic patients This may be through lowering lipid levels or other mechanisms such as decreasing insulin resistance and the pleiotropic effects of the drug.

Countervailing vascular effects of rosiglitazone in high cardiovascular risk mice: role of oxidative stress and PRMT-1

In the present study, we tested the hypothesis that the PPARγ (peroxisome-proliferator-activated receptor γ) activator rosiglitazone improves vascular structure and function in aged hyperhomocysteinaemic MTHFR (methylene tetrahydrofolate reductase) gene heterozygous knockout (mthfr+/−) mice fed a HCD (high-cholesterol diet), a model of high cardiovascular risk. One-year-old mthfr+/− mice were fed or not HCD (6 mg·kg−1 of body weight·day−1) and treated or not with rosiglitazone (20 mg·kg−1 of body weight·day−1) for 90 days and compared with wild-type mice. Endothelium-dependent relaxation of carotid arteries was significantly impaired (−40%) only in rosiglitazone-treated HCD-fed mthfr+/− mice. Carotid M/L (media-to-lumen ratio) and CSA (cross-sectional area) were increased (2-fold) in mthfr+/− mice fed or not HCD compared with wild-type mice (P<0.05). Rosiglitazone reduced M/L and CSA only in mthfr+/− mice fed a normal diet. Superoxide production was increased in mthfr+/− mice fed HCD treated or not with rosiglitazone, whereas plasma nitrite was decreased by rosiglitazone in mice fed or not HCD. PRMT-1 (protein arginine methyltransferase-1), involved in synthesis of the NO (nitric oxide) synthase inhibitor ADMA (asymmetric ω-NG,NG-dimethylarginine), and ADMA were increased only in rosiglitazone-treated HCD-fed mthfr+/− mice. Rosiglitazone had both beneficial and deleterious vascular effects in this animal model of high cardiovascular risk: it prevented carotid remodelling, but impaired endothelial function in part through enhanced oxidative stress and increased ADMA production in mice at high cardiovascular risk.

Effect of preoperative atorvastatin therapy on paraoxonase activity and oxidative stress after coronary artery bypass grafting

The aim of this study was to examine the influence of preoperative atorvastatin therapy on oxidative stress in coronary artery bypass grafting (CABG) patients. Forty patients who underwent elective CABG were enrolled into the study. Of these patients, 20 received atorvastatin (Group I) for 15 days prior to surgery and 20 patients did not use any antihyperlipidemic agents preoperatively (Group II). Serum paraoxonase 1 (PON1) and arylesterase activities, and total antioxidant status (TAS) and total oxidant status (TOS) were measured before surgery and at 1, 6 and 24 hours after the operation. Paraoxonase 1 and arylesterase activities (p<0.001) and TAS levels (p<0.001 for 1st hour and p<0.05 for 6th hour) in Group II were significantly reduced at the 1 st and 6th hours after the operation, whereas the activities of the enzymes (p<0.01) and TAS levels (p<0.05) were significantly reduced only at the 1st hour after the operation in Group I. The total oxidant status of both groups was significantly increased at the 1 st hour after operation (p<0.05 for Group I and p<0.01 for Group II). In conclusion, 15 days of preoperative atorvastatin therapy does not significantly change either the serum PON1 activity or the oxidative stress after CABG.

Thyroid hormone beta receptor activation has additive cholesterol lowering activity in combination with atorvastatin in rabbits, dogs and monkeys

BACKGROUND AND PURPOSE

Thyroid hormone receptor (TR) agonists are in clinical trials for the treatment of hypercholesterolaemia. As statins are the standard of clinical care, any new therapies must have adjunctive activity, when given in combination with statins. As already known for the statins, the cholesterol lowering effect of TR activation involves increased expression of the low-density lipoprotein receptor. Using animal models, we tested whether TR activation would have additive cholesterol lowering activity in the presence of effective doses of a statin.

EXPERIMENTAL APPROACH

We evaluated the activity of a liver-targeted prodrug, MB07811, of a novel TH receptor beta agonist, MB07344, as monotherapy and in combination with atorvastatin in rabbits, dogs and monkeys.

KEY RESULTS

In rabbits, MB07344 (i.v.) decreased total plasma cholesterol (TPC) comparable to that achieved with a maximally effective dose of atorvastatin (p.o.). The addition of MB07344 to atorvastatin resulted in a further decrease in TPC. Similarly, the addition of MB07811 (p.o.) to atorvastatin treatment decreased TPC beyond the level achieved with either agent as monotherapy. In dogs and monkeys, atorvastatin and MB07811 were administered as monotherapy or in combination. Consistent with the rabbit studies, the combination treatment caused a greater decrease in TPC than either MB07811 or atorvastatin administered as monotherapy.

CONCLUSIONS AND IMPLICATIONS

We conclude that the effects of MB07811 and atorvastatin in lowering cholesterol are additive in animals. These results would encourage and support the demonstration of similarly improved efficacy of combination versus monotherapy with such agents in the clinic.

[Vascular endothelial dysfunction, oxidative stress--a new topic within the referral section of Orvosi Hetilap]

The author describes some of the numerous domains regarding the new topic called "Vascular endothelial dysfunction, oxidative stress". The endothelium is responsible for the constancy and integrity of the milieu interieur by producing various substances. Endothelial dysfunction occurs when there is imbalance between vasodilators and vasoconstrictors, growth factors and their inhibitors, proinflammatory and antiinflammatory agents, prothrombotic and fibrinolytic activities. The reason for this imbalance may be response to vascular endothelial or intimal injury caused by mechanical, physical, chemical, microbiological, immunologic, genetic damage or any of their combination. Endothelial dysfunction occurring on the huge inner surface of the vessels (the endothelium) is responsible for the triggering of atherosclerosis, which is a chronic vascular disease. All the risk factors of vascular pathology are leading to chronic (cardio)vascular diseases by causing endothelial dysfunction. Decreased endogenous antioxidative capacity leads to oxidative stress by free radical reactions of physiological oxidative metabolic processes, ending as the ultimate reason for endothelial dysfunction induced by risk factors. The therapeutic and preventive effects of causal antioxidant treatments having intracellular and mitochondrial effects (statins, angiotensin-converting-enzyme inhibitors, angiotensin-receptor-blockers, acetylsalicylic acid, and third generation beta-blockers) should be emphasized. It is also important to underline the physiological-pathophysiological-therapeutic consubstantiality and systemic nature of human vasculature and to emphasize the preventive-therapeutic significance of the vascular consequence cascade. And finally, there has been large process in the assessment of oxidative stress and consecutive endothelial dysfunction which revolutionized our clinical point of view.