Anti-lipid deposition effect of HMG-CoA reductase inhibitor, pitavastatin, in a rat model of hypertension and hypercholesterolemia

[Doctor, Do You Know Red Yeast Rice?]

Doctor, Do You Know Red Yeast Rice? Abstract. We present cases of patients with high total cholesterol who wanted to use an alternative therapy for lowering cholesterol. An improvement in the lipid profile was found in all patients, and all tolerated the product made from red rice yeast very well. No side effects were observed. The patients who take red fermented rice consciously choose an alternative agent in the field of phytotherapy because they already have to take several conventional medicines and are no longer willing to use an additional drug of this kind. Another reason is that they no longer want to put up with the side effects they suffered from when using a common lipid-lowering drug.

Most appropriate animal models to study the efficacy of statins: a systematic review

BACKGROUND

In animal models and clinical trials, statins are reported as effective in reducing cholesterol levels and lowering the risk of cardiovascular diseases. We have aggregated the findings in animal models - mice, rats and rabbits - using the technique of systematic review and meta-analysis to highlight differences in the efficacy of statins.

MATERIALS AND METHODS

We searched Medline and Embase. After examining all eligible articles, we extracted results about total cholesterol and other blood parameters, blood pressure, myocardial infarction and survival. Weighted and standard mean difference random effects meta-analysis was used to measure overall efficacy in prespecified species, strains and subgroups.

RESULTS

We included in systematic review 161 animal studies and we analysed 120 studies, accounting for 2432 animals. Statins lowered the total cholesterol across all species, although with large differences in the effect size: -30% in rabbits, -20% in mice and -10% in rats. The reduction was larger in animals fed on a high-cholesterol diet. Statins reduced infarct volume but did not consistently reduce the blood pressure or effect the overall survival. Few studies considered strains at high risk of cardiovascular diseases or hard outcomes.

CONCLUSIONS

Although statins showed substantial efficacy in animal models, few preclinical data considered conditions mimicking human pathologies for which the drugs are clinically indicated and utilized. The empirical finding that statins are more effective in lowering cholesterol derived from an external source (i.e. diet) conflicts with statin's supposed primary mechanism of action.

Gene expression in the vascular wall of the aortic arch in spontaneously hypertensive hyperlipidemic model rats using DNA microarray analysis

AIMS

In recent years, there has been an increase in patients with arteriosclerosis and the risk of lifestyle-related diseases. However, the pathogenesis and medication of atherosclerosis have not been elucidated. We developed a rat model of lifestyle-related diseases by feeding a high-fat diet and 30% sucrose solution (HFDS) to spontaneously hypertensive hyperlipidemic rats (SHHR) and reported that this model is a useful model of early atherosclerosis. In order to elucidate the pathogenesis of early atherosclerosis, we searched for atherosclerosis-related genes by microarray analysis using the aortic arch rat model of lifestyle-related diseases.

MAIN METHODS

Four-month-old male Sprague-Dawley rats and SHHR were each divided into two normal diet (ND) groups and two HFDS groups. After a four-month treatment, the expression of mRNA in the aortic arch was detected using the oligo DNA microarray one-color method and quantified using real-time PCR.

KEY FINDINGS

In this study, we detected 39 genes in microarray analysis. Esm1, Retnlb Mkks, and Grem2 showed particularly marked changes in gene expression in the SHHR-HFDS group. Compared with the SD-ND group, the SHHR-HFDS group had an increase in Mkks gene expression of about 26-fold and an approximately 22-fold increase in the expression of Grem2. Similarly, the expression of Esm1 increased by about 12-fold and that of Retnlg by about 10-fold as shown by quantitative real-time PCR.

SIGNIFICANCE

This study suggested that these four genes might be important in early atherosclerosis development.

High fat diets and pathology in the guinea pig. Atherosclerosis or liver damage?

Animal models have been widely used to investigate the relationship between diet and atherosclerosis and also to study disease etiology and possible interventions. Guinea pigs have been suggested to be a more "realistic" model for atherosclerosis due to their many similarities to humans. However, few published studies actually reported observations of characteristic atherosclerotic lesions and even fewer of advanced lesions. Studies, by our group, of guinea pigs fed on a high-fat diet revealed similar observations, with indications primarily of fatty streaks but little evidence of atherosclerotic plaques. This review discusses the feasibility of the guinea pig as a model for dietary-induced atherosclerosis. As it stands, current evidence raises doubt as to whether guinea pigs could serve as a realistic model for atherosclerosis. However, our own data and the literature suggest that they could be useful models for studying lipoprotein metabolism, non-alcoholic fatty liver disease, and dietary interventions which may help regulate these conditions.

Enhancement of antioxidant defense mechanism by pitavastatin and rosuvastatin on obesity-induced oxidative stress in Wistar rats

CONTEXT

There has been a steady increase in the epidemiology of obesity over the last 30 years with developed countries leading the way. Oxidative stress was believed to be the principle contributor to the development of cardiovascular disorders that linked with obesity.

OBJECTIVE

To evaluate the enhancement of antioxidant defense mechanism by Pitavastatin (PTV) and Rosuvastatin (RSV) on obesity-induced oxidative stress in Wistar rats.

METHODS

Fifty Wistar albino rats were divided into five groups. High fat diet (HFD, 20 g/day/rat) pellets were given for 28 days to produce obesity-induced oxidative stress in Wistar rats. Oral administration of HFD along with PTV, RSV and Orlistat [(HFD for 28 days + from 8th day PTV (1 mg/kg), RSV (5 mg/kg) and Orlistat (10 mg/kg) to 28th day] were given respectively.

RESULTS

Both PTV and RSV produced significant (p < 0.01) reduction in serum apolipoprotein-B (Apo-B), total cholesterol (TC), triglycerides (TGs), cardiac-lipid peroxides (TBARS) levels and elevation in serum high density lipoprotein (HDL-C), cardiac antioxidant enzymes [glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catase (CAT)] levels.

DISCUSSION AND CONCLUSION

Results were comparable with Orlistat, a standard antiobesity drug and present initial evidence that Pitavastatin and Rosuvastatin are useful for the treatment of obesity by enhancing the antioxidant defense mechanism. However, the effects of PTV were more prominent than RSV. The present findings of Pitavastatin and Rosuvastatin raise the possibility of a new application as an antiobesity therapeutic modality.

Alterations of glucose-dependent and -independent bladder smooth muscle contraction in spontaneously hypertensive and hyperlipidemic rat

Alteration of bladder contractility was examined in the spontaneously hypertensive and hyperlipidemic rat (SHHR; age, 9 months; systolic blood pressure, >150 mm Hg; plasma cholesterol, >150 mg/dl). Carbachol (CCh) induced time- and dose-dependent contractions in Sprague-Dawley (age-matched control) rats and SHHR; however, maximal levels differed significantly (13.3 +/- 2.2 and 5.4 +/- 1.9 microN/mm(2) following 10 microM CCh treatment, respectively; n = 5). This difference, which was maintained in calcium-replaced physiological salt solution (PSS), was suppressed by pretreatment with rho kinase inhibitor, 1 microM Y27632 [(R)-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide]; moreover, total activity of rho kinase was also reduced in SHHR bladder. Pretreatment of bladders under high-glucose (HG) conditions (22.2 mM glucose-contained PSS for 30 min) led to enhancement of CCh-induced contraction solely in control animals. Under HG conditions, both protein kinase C (PKC) activity and production of diacylglycerol (DG) derived from incorporated glucose declined in SHHR bladder; however, sustained elevation of plasma glucose level was not detected in SHHR. These results suggested that bladder contractility dysfunction in SHHR is attributable to alteration of rho kinase activity and the DG-PKC pathway. This dysfunction may occur prior to chronic hyperglycemia onset in progressive hypertension and hyperlipidemia.

Development of Hyperfibrinogenemia in Spontaneously Hypertensive and Hyperlipidemic Rats: A Potentially Useful Animal Model as a Complication of Hypertension and Hyperlipidemia

According to current concepts, hypertension and hyperlipidemia cause vascular damage that leads to a hypercoagulative state. In this study, we investigated whether spontaneously hypertensive and hyperlipidemic rats (SHHR) can be a useful experimental model for complications in combined hypertension and hyperlipidemia, by comparing coagulative and fibrinolytic activities in SHHR with those in spontaneously hypertensive rats (SHR) and spontaneously hyperlipidemic rats (HLR). We measured coagulation and fibrinolysis markers in plasma and levels of fibrinogen and prothrombin mRNA in livers of eight-month-old male Wistar Kyoto rats (WKY), Sprague-Dawley rats (SD), SHR, HLR and SHHR. The plasma levels of fibrinogen in SHR, HLR and SHHR were significantly higher than those in WKY and SD, and were highest in SHHR. Higher plasma levels of antithrombin III and plasminogen were detected in increasing order in SHR, HLR and SHHR as compared to those in WKY and SD. Hepatic mRNA expressions of fibrinogen chains and prothrombin were enhanced in SHR, HLR and SHHR, resulting in increased plasma fibrinogen levels in SHHR. These results suggest that hypertension and hyperlipidemia can each cause hypercoagulation, with hyperlipidemia being a stronger factor than hypertension. Since a greater hypercoagulative state is a complication of combined hypertension and hyperlipidemia, the SHHR model is a good system for studying the early stage of atherosclerosis ensuing from hyperfibrinogenemia.

Pitavastatin improves cardiac function and survival in association with suppression of the myocardial endothelin system in a rat model of hypertensive heart failure

Statin therapy may be associated with lower mortality in patients with heart failure, but the underlying mechanism of such an association is unknown. We have evaluated the effects of pitavastatin on cardiac function and survival in a rat model of hypertensive heart failure and investigated the molecular mechanism of the observed effects. Dahl salt-sensitive rats fed with high-salt diet from 7 weeks of age developed compensatory left ventricular hypertrophy at 12 weeks and heart failure at 19 weeks. Dahl salt-sensitive rats were treated with either vehicle or pitavastatin (0.3 mg/kg per day) from 7 or 12 weeks. Both early-onset and late-onset pitavastatin treatment reduced left ventricular fibrosis, improved cardiac function, and increased the survival rate apparent at 19 weeks. The increases in the expression levels of hypertrophic, profibrotic, and metalloproteinase genes as well as in gelatinase activities in the heart induced by the high-salt diet were suppressed by pitavastatin treatment. Furthermore, the level of cardiac endothelin-1 was increased in association with the development of heart failure in a manner sensitive to treatment with pitavastatin. Both early and late pitavastatin treatment thus improved cardiac function and survival, with modulation of extracellular matrix remodeling and endothelin-1 signaling possibly contributing to these beneficial effects.