Comparative toxicity of high doses of vastatins currently used by clinicians, in CD-1 male mice fed with a hypercholesterolemic diet

Effects of high rosuvastatin doses on hepatocyte mitochondria of hypercholesterolemic mice

Statins are the cornerstone of therapy for individuals with hyperlipidemia. The aim of this study was to analyze the undesirable effects of mild, moderate and high doses of rosuvastatin in CD-1 male mice who received a cholesterol-rich diet, focusing on the morphological and functional changes on hepatocyte mitochondria. In a mouse model we studied the combined administration of a cholesterol-rich diet along with mild and moderate doses of rosuvastatin (1, 2.5 or 5 mg/kg/day) during several days. After the animals were sacrificed, liver mitochondria were isolated for microscopic studies and to analyze the respiratory function. The respiratory control (state-3/state-4) was evaluated in mice who received high doses of rosuvastatin. Rosuvastatin doses higher than 20 mg/kg/day induced premature death in mice with a hypercholesterolemic diet, but not in mice with a cholesterol-free diet. Doses from 2.5 to 5 mg/kg/day also induced morphological and functional alterations in mitochondria but these hypercholesterolemic animals survived longer. Giving 1 mg/kg/day, which is close to the maximal therapeutic dose for humans, did not affect mitochondrial architecture or respiratory function after two months of treatment. We analyzed the effect of rosuvastatin on hepatic tissue because it is where statins are mainly accumulated and it is the main site of endogenous cholesterol synthesis. Our results contribute to understand the side effects of rosuvastatin in hypercholesterolemic mice, effects that could also affect humans who are intolerant to statins.

Antioxidant and antihyperlipidemic activity of Costus speciosus against atherogenic diet-induced hyperlipidemia in rabbits

OBJECTIVE

An extract of Costus speciosus (CSE), a herb widely used in folk medicine, was evaluated for its antioxidant, antihyperlipidemic and ameliorating effects on histopathological changes in atherogenic rabbits.

METHODS

Twenty-four male rabbits (Oryctolagus cuniculus) were divided into 4 groups. Three groups were fed a diet containing 3% saturated fat and 1.3% cholesterol for 40 d. One of these was sacrificed on the 40th day and was called the pathogenic (P) group; the other two groups received treatment for another 30 d as follows: one received 0.8 g/(kg·d) of CSE and the other was given 0.01 g/(kg·d) of simvastatin. The normal group was sacrificed on the 70th day and used as a control.

RESULTS

CSE showed radical-scavenging ability. Administration of CSE for a 30-day period resulted in a significant decrease in total cholesterol, triacylglycerol, low-density lipoprotein and aspartate aminotransferase compared to the P group, while levels of hemoglobin, packed corpuscular volume and red blood cells were elevated. With respect to studies performed on the heart, a decrease in malondialdehyde and an increase in reduced glutathione were noted. Total protein increased in the liver, heart and aorta after treatment with CSE and also a marked improvement in histopathological parameters was demonstrated.

CONCLUSION

The present findings indicate that the C. speciosus rhizome possesses antiatherogenic and antioxidant properties which may provide protective effects against oxidative stress in atherosclerotic rabbits.

Coenzyme Q10 supplementation improves metabolic parameters, liver function and mitochondrial respiration in rats with high doses of atorvastatin and a cholesterol-rich diet

Background

The aim of this study was to evaluate the actions of coenzyme Q₁₀ (CoQ₁₀) on rats with a cholesterol-rich diet (HD) and high doses of atorvastatin (ATV, 0.2, 0.56 or 1.42 mg/day).

Methods

Two experiments were done, the first one without coenzyme Q₁₀ supplementation. On the second experiment all groups received coenzyme Q₁₀ 0.57 mg/day as supplement. After a 6-week treatment animals were sacrificed, blood and liver were analyzed and liver mitochondria were isolated and its oxygen consumption was evaluated in state 3 (phosphorylating state) and state 4 (resting state) in order to calculate the respiratory control (RC).

Results

HD increased serum and hepatic cholesterol levels in rats with or without CoQ₁₀. ATV reduced these values but CoQ₁₀ improved even more serum and liver cholesterol. Triacylglycerols (TAG) were also lower in blood and liver of rats with ATV + CoQ₁₀. HDL-C decreased in HD rats. Treatment with ATV maintained HDL-C levels. However, these values were lower in HD + CoQ₁₀ compared to control diet (CD) + CoQ₁₀. RC was lessened in liver mitochondria of HD. The administration of ATV increased RC. All groups supplemented with CoQ₁₀ showed an increment in RC. In conclusion, the combined administration of ATV and CoQ₁₀ improved biochemical parameters, liver function and mitochondrial respiration in hypercholesterolemic rats.

Conclusions

Our results suggest a potential beneficial effect of CoQ₁₀ supplementation in hypercholesterolemic rats that also receive atorvastatin. This beneficial effect of CoQ₁₀ must be combined with statin treatment in patient with high levels of cholesterol.

Antiatherogenic Potential of Nigella sativa Seeds and Oil in Diet-Induced Hypercholesterolemia in Rabbits

Nigella sativa or Black seed (N. sativa L.) is traditionally used for several ailments in many Middle Eastern countries. It is an annual herbaceous plant that belongs to the Ranuculacea family with many beneficial properties as antitumor, antidiabetic, antihypertensive, antioxidative and antibacterial. This work attempted to study the effect of N. sativa seeds powder and oil on atherosclerosis in diet-induced hypercholesterolemic (HC) rabbits in comparison with simvastatin (ST). Twenty-five adult New Zealand male white rabbits, weighing 1.5-2.5 kg, were divided into five groups; normal group (NC, n = 5) and four hypercholesterolemic groups (n = 20): a positive control (PC) and three HC groups force fed diet supplemented with 1000 mg Kg(-1) body weight of N. sativa powder (NSP), 500 mg Kg(-1) body N. sativa oil (NSO) and 10 mg Kg(-1) ST for 8 weeks. Feeding HC rabbits with N. sativa either in powder or oil forms was shown to significantly reduce (P < .05) total cholesterol (TC) and low-density lipoprotein cholesterol (LDLC) levels and enhance high-density lipoprotein cholesterol (HDL) levels after treatment for 2, 4, 6 and 8 weeks compared to the PC group. Plaque formation was significantly inhibited while the intima: media ratio was significantly reduced in the NSP and NSO supplemented groups compared to the PC group. In conclusion, treatment of HC rabbits with N. sativa seeds powder or oil showed hypocholesterolemic and antiatherogenic cardioprotective properties.

Using pravastatin to improve the vascular reactivity in a mouse model of soluble fms-like tyrosine kinase-1-induced preeclampsia

OBJECTIVE

To estimate the effects of pravastatin on the altered vascular function in a mouse model of preeclampsia induced by overexpression of soluble fms-like tyrosine kinase-1 (sFlt-1).

METHODS

Pregnant CD1 mice, at day 8 of gestation, were randomly allocated to injection using the tail vein of the adenovirus carrying sFlt-1 (10 plaque-forming units in 100 microliters; sFlt-1 group) or mFc (10 plaque-forming units) as virus control, and then to receive pravastatin (Pra; 5 mg/kg/d) dissolved in drinking water or control. The mice in four groups (sFlt-1, sFlt-1-pravastatin, mFc, and mFc-pravastatin; n=4-6 per group) were killed at day 18 of gestation and 2-mm segments of carotid artery were used for vascular reactivity studies. Serum sFlt-1 levels were also measured by enzyme-linked immunosorbent assay.

RESULTS

Mice in the sFlt-1 group had the highest responses to phenylephrine. Treatment with pravastatin decreased the contractile responses to phenylephrine (maximal effect [mean+/-standard error of the mean] 137.35+/- 27.70 compared with 42.24+/-8.76; P=.006) for sFlt-1 compared with sFlt-1-pravastatin, respectively. There were no differences in the contractile responses to thromboxane A2. The vasorelaxant responses to acetylcholine were significantly highest in the mFc-pravastatin group, with a maximal effect of 108.37+/-5.25 compared with 89.77+/-3.96 in the mFc group (P=.008), and those with sodium nitroprusside were not different across the four groups. Serum sFlt-1 levels were not different at baseline (day 8) but were significantly lower in sFlt-1-pravastatin compared with sFlt-1 at day 18 (59.42+/-5.31 compared with 102.59+/-15.15 ng/mL; P=.01).

CONCLUSION

Pravastatin improved the vascular reactivity in this murine model of preeclampsia by decreasing sFlt-1 levels. Statins should be evaluated for the prevention of the vascular abnormalities of preeclampsia.

The effect of statin on the aortic gene expression profiling

BACKGROUND

Beyond lipid lowering, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin) has been found to have anti-inflammatory and anti-thrombotic effects. However, the genetic expression pattern changes in atherosclerotic lesions produced by statin are rarely studied.

METHODS

Cholesterol-fed apolipoprotein (Apo) E-deficient mice were examined for the treatment effect of statin on aortic gene expression. ApoE-deficient mice were fed with a hypercholesterolemic diet started at 8 weeks of age for a total of 22 weeks. In the statin treatment group (n=25), the ApoE-deficient mice were treated with pravastatin (80 mg/kg/day) dissolved in water by daily oral inoculation from 25 to 30 weeks of age. For the control group (n=25), the ApoE-deficient mice were orally inoculated with water only for the same period of time. The aortic gene expression affected by pravastatin was identified using oligonucleotide microarray technology with Agilent gene chips.

RESULTS

The total cholesterol and atherosclerotic lesion/total aortic area were significantly lower in the pravastatin treatment group. Microarray analysis of the expression of 20,281 murine genes in the aortas between the two groups indicated that 94 genes were significantly regulated. Thirty genes were up-regulated and 64 genes were down-regulated. The most up-regulated genes were troponin T3, actin alpha1, tubulin alpha1, regulator of G-protein signaling 5 (Rgs5), stathmin-like 2 and myosin light chain kinase. Most of them are related with cytoskeleton organization, while Rgs5 is a G-protein signal transduction molecule. The most down-regulated genes were adenosine deaminase, atrial natriuretic peptide, troponin T2, FXYD domain-containing ion transport regulator 3, and glutathione S-transferase alpha4.

CONCLUSIONS

The beneficial effect of the 6-week statin treatment in ApoE-deficient mice is largely dependent on its influence on the cytoskeleton organization. Our study results might provide insight into the clinical benefits of chronic statin treatment.

Ultrastructure of mouse striated muscle fibers following pravastatin administration

To examine the effect of pravastatin administration on striated muscle ultrastructure, 10 BalbC mice were given pravastatin 40 mg/kg/day for 3 weeks. At the end of the study, blood was withdrawn for evaluation of the serum creatine phospho-kinase (CPK) level and the muscles of the hind legs, as well as the heart and liver of the animals were examined with a light and transmission electron microscope. After treatment with pravastatin the results showed a 101% increase in serum CPK level in comparison to untreated controls. Hematoxillin-eosin stained tissues of pravastatin treated mice did not show any abnormal findings. While the ultrastructure of the heart and liver of the treated animals appeared normal, the muscle fibers showed a marked alterations of the mitochondria, which were increased in size compared to those of the controls. The cristae were heavily damaged and even completely destructed, giving the mitochondria appearance of empty vacuoles. The findings are in favor of a specificity of pravastatin for striated muscles.

Statin effects on cholesterol micro-domains in brain plasma membranes

Recent epidemiological studies revealed inhibitors of the hydroxymethylglutaryl-coenzyme A reductase, so-called statins, to be effective in lowering the prevalence of Alzheimer's disease (AD). In vitro, statins strongly reduced the cellular amyloid beta-protein load by modulating the processing of the amyloid beta precursor protein. Both observations are probably linked to cellular cholesterol homeostasis in brain. So far, little is known about brain effects of statins. Recently, we could demonstrate that treatment of mice with the lipophilic compound lovastatin resulted in a discrete reduction of brain membrane cholesterol levels. To follow up these findings, we subsequently carried out a further in vivo study including lovastatin and simvastatin as lipophilic agents, as well as pravastatin as a hydrophilic compound, focussing on their efficiency to affect subcellular membrane cholesterol pools in synaptosomal plasma membranes of mice. In contrast to the hydrophilic pravastatin, the lipophilic lovastatin and simvastatin strongly reduced the levels of free cholesterol in SPM. Interestingly, lovastatin and pravastatin but not simvastatin significantly reduced cholesterol levels in the exofacial membrane leaflet. These changes were accompanied by modified membrane bulk fluidity. All three statins reduced the expression of the raft marker protein flotillin. Alterations in transbilayer cholesterol distribution have been suggested as the underlying mechanism that forces amyloidogenic processing of APP in AD. Thus, our data give some first insight in the mode of action of statins to reduce the prevalence of AD in clinical trials.

Arthrospira maxima prevents the acute fatty liver induced by the administration of simvastatin, ethanol and a hypercholesterolemic diet to mice

An evident fatty liver, corroborated morphologically and chemically, was produced in CD-1 mice after five daily doses of simvastatin 75 mg/Kg body weight, a hypercholesterolemic diet and 20 percent ethanol in the drinking water. After treating the animals, they presented serum triacylglycerols levels five times higher than the control mice, total lipids, cholesterol and triacylglycerols in the liver were 2, 2 and 1.5 times higher, respectively, than in control animals. When Arthrospira maxima was given with diet two weeks prior the onset of fatty liver induction, there was a decrement of liver total lipids (40%), liver triacylglycerols (50%) and serum triacylglycerols (50%) compared to the animals with the same treatment but without Arthrospira maxima. In addition to the mentioned protective effect, the administration of this algae, produced a significant increase (45%) in serum high density lipoproteins. The mechanism for this protective effect was not established in these experiments.