Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, reduces delayed neuronal death following transient forebrain ischemia in the adult rat hippocampus

Neuroprotective effects of pravastatin in cerebral venous infarction in a rat model

Objectives

Pravastatin sodium is reported to have multiple beneficial effects in cerebral atherosclerosis and neuronal injury; however, the preventive effects on cerebral venous ischemia are still unknown. Herein, we aimed to examine the neuroprotective effects of transoral prior administration of pravastatin sodium against cerebral cortical venous ischemia with suppression of apoptosis.

Methods

Thirty 8-week-old male Wistar rats were divided equally into two study groups (n = 15 vs. n = 15); the pravastatin group was fed 1% pravastatin sodium with their usual diet for 2 weeks, while the control group only received the usual diet. Two-vein occlusion (2VO) model was applied for this study, and two adjacent cortical veins in each animal were permanently occluded photochemically with rose bengal dye. During photo-thrombosis, regional changes of the cerebral blood flow (CBF) in area of the venous ischemia were recorded. At 48-h after 2VO, animals were euthanized using perfusion fixation, and we histologically measured ratios of infarcted area to contralateral hemisphere, and counted Bax- and Bcl-2-positive cells in the penumbra to investigate the implications for apoptosis.

Results

The ratio of infarcted area was significantly decreased in the pravastatin group compared to the control group (P < 0.01). The number of Bax-positive cells also decreased significantly in the pravastatin group (P < 0.01). In contrast, immunolabeling for Bcl-2 was essentially negative in all areas in both groups. There were also no significant differences in regional CBF changes after 2VO between the two groups (P = 0.13).

Conclusions

Pre-emptive administration of pravastatin sodium mixed in the food has neuroprotective effects against cerebral cortical venous ischemia with suppression of apoptosis associated with inhibition of Bax expression but has little influence on regional CBF.

Atorvastatin ameliorates early brain injury through inhibition of apoptosis and ER stress in a rat model of subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a severe cerebrovascular disease with very poor prognosis. The aim of the present study was to evaluate the protective effects of atorvastatin on early brain injury (EBI) after SAH using a perforation SAH model. Male Sprague-Dawley rats were randomly divided into four groups: the sham group, the SAH group (model group), SAH + 10 mg.kg-1day-1 atorvastatin (low atorvastatin group), and SAH + 20 mg.kg-1day-1 atorvastatin (high atorvastatin group). Atorvastatin was administered orally by gastric gavage for 15 days before operation. At 24 h after SAH, we evaluated the effects of atorvastatin on brain water content, apoptosis by TUNEL assay and scanning electron microscope (SEM), and the expression of apoptosis-related proteins by immunofluorescence and Western blotting analysis. Compared with the sham group, we observed increased brain water content, significant apoptosis, and elevated levels of apoptosis-related proteins including caspase-3, CCAAT enhancer-binding protein homologous protein (CHOP), the 78-kDa glucose-regulated protein (GRP78), and aquaporin-4 (AQP4) in the SAH group. Atorvastatin administration under all doses could significantly reduce brain water content, apoptosis, and the expression levels of caspase-3, CHOP, GRP78, and AQP4 at 24 h after SAH. Our data show that early treatment with atorvastatin effectively ameliorates EBI after SAH through anti-apoptotic effects and the effects might be associated inhibition of caspase-3 and endoplasmic reticulum (ER) stress related proteins CHOP and GRP78.

Post-ischemic administration of pravastatin reduces neuronal injury by inhibiting Bax protein expression after transient forebrain ischemia in rats

This study investigated the neuroprotective effect of pravastatin administration after forebrain ischemia in rats. Forebrain ischemia was induced by bilateral common carotid artery occlusion and systemic hypotension for 8min. Pravastatin at 1mg/kg (pravastatin group, n=10), or an identical volume of normal saline (control group, n=10), was injected 10min, and 1-4 days after reperfusion. Arterial blood gas was analyzed 10min before ischemia onset and 10min after ischemia completion. Viable and apoptotic neuronal cells were evaluated 7 days after ischemia by hematoxylin and eosin (H&E) staining and terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuracil triphosphate biotin in situ nick-end labeling (TUNEL) staining of the hippocampal Cornu Ammonis area (CA1). Expression of Bcl-2 and Bax proteins was quantified by Western blot analysis. The proportion of viable neuronal cells after ischemia was greater in the pravastatin vs. control group (p<0.01), with greater expression of apoptotic cells in the control vs. pravastatin group (p<0.05). Bax protein expression was significantly decreased in the pravastatin group (p<0.05), whereas, Bcl-2 expression was increased, but not significantly (p>0.05). Our findings suggest that pravastatin administration after forebrain ischemia confers neuroprotection in rats by inhibiting Bax protein expression.

Low-dosage statins reduce choroidal damage in hypercholesterolemic rabbits

PURPOSE

To describe the ultrastructural changes in the choroid of long-term hypercholesterolemic rabbits after a low-dosage statin treatment and to evaluate some pleiotropic effects of these drugs on the morphology of endothelial cells (EC) and vascular smooth-muscle cells (VSMC).

METHODS

New Zealand rabbits were divided into three groups: G0, fed a standard diet; G1, fed a 0.5% cholesterol-enriched diet for 8 months and G2, fed a 0.5% cholesterol-enriched diet for 8 months plus administration of fluvastatin sodium or pravastatin sodium at a dose of 2 mg/Kg/day each. Eyes were processed for transmission-electron microscopy.

RESULTS

G1 had a lipid build-up at the suprachoroidea that compressed the vascular layers with the lumens of the vessels to the point of collapse in some instances. By contrast, G2 underwent a substantial decrease in suprachoroidal foam cells and of lipids in the vascular layers while the vascular lumens were normal. The preservation of cytoplasmic organelles, caveolar system and other ultrastructural features of EC and VSMC in G2 contrasted with the numerous signs of necrosis observed in G1. Bruch's membrane (BM) in G2 contained fewer lipids and more collagen than in G1.

CONCLUSION

Treatment with a low dosage of fluvastatin sodium or pravastatin sodium reduced the lipid build-up as well as the macrophages in the choroid and restored the vascular lumens of choroidal vessels independently of the cholesterol effect. The normal ultrastructural features of choroidal EC and VSMC in statin-treated animals suggest that the endothelial function is preserved and the ischaemia reduced.

Reduction of spinal cord ischemia/reperfusion injury with simvastatin in rats

BACKGROUND

Surgery of the thoracic or thoracoabdominal aorta may cause spinal cord ischemia and subsequent paraplegia. However, conventional strategies for preventing paraplegia due to spinal cord ischemia provide insufficient protection and cause additional side effects. We hypothesized that simvastatin, a drug recently shown to be neuroprotective against brain ischemia/reperfusion, would be neuroprotective in a rat spinal cord ischemia/reperfusion model.

METHODS

Rats were randomly assigned to simvastatin, vehicle, or sham-surgery (sham) groups (n = 6 per group). Simvastatin (10 mg/kg) or vehicle was administered subcutaneously once daily for 7 days before aortic balloon occlusion, and once at 24 hours after reperfusion. Spinal cord ischemia was induced by balloon inflation of a 2F Fogarty catheter in the thoracic aorta, and the proximal mean arterial blood pressure was maintained at 40 mm Hg for 12 minutes. The sham group received the same operation without inflation of the balloon. Ischemic injury was assessed by hindlimb motor function using the Motor Deficit Index score at 6 to 48 hours after ischemic reperfusion, and histological assessment of the spinal cord was performed 48 hours after reperfusion.

RESULTS

The Motor Deficit Index scores at 24 and 48 hours after reperfusion were significantly improved in the simvastatin group compared with the vehicle group (P = 0.021 and P = 0.023, respectively). Furthermore, there were significantly more normal motor neurons in the simvastatin group than in the vehicle group (P = 0.037). The percentage area of white matter vacuolation was significantly smaller in the simvastatin group than in the vehicle group (P = 0.030).

CONCLUSIONS

Simvastatin treatment can attenuate hindlimb motor dysfunction and histopathological changes in spinal cord ischemia/reperfusion injury in rats.

Intravenous administration of pravastatin immediately after middle cerebral artery occlusion reduces cerebral oedema in spontaneously hypertensive rats

3-hydroxy-3-methyl-glutaryl-coenzyme-A (HMG-CoA) reductase inhibitors (statins) have been shown to protect against ischemic stroke by mechanisms that are independent of lowering serum cholesterol levels. In this study we investigated the potential neuroprotective effect of a single i.v. treatment with four increasing doses of pravastatin on permanent occlusion of middle cerebral artery (MCAo) in spontaneously hypertensive rats. Pravastatin was given 10 min after MCAo and its effect was determined 24 h later. Treatment results were evaluated in terms of infarct volume, homolateral hemisphere oedema, glial fibrillary acid (GFAP), vimentin (Vim) and endothelial NO synthase (eNOS) immunoreactivity and TUNEL positivity. Cerebral levels of eNOS were measured by western blot analysis. Pravastatin did not reduce cerebral infarct while it mitigated homolateral hemisphere oedema in a dose-dependent manner with respect to controls. No differences among groups were found regarding GFAP and Vim immunoreactivity and TUNEL positivity. Instead, pravastatin-treated animals presented a more marked cerebral eNOS immunoreactivity as compared with controls. In agreement with immunohistochemistry, immunoblot revealed dose-dependent increases in cerebral levels of eNOS in pravastatin rats. Our data confirm statin neuroprotection in cerebral ischemia. In particular, it is of great interest that a single i.v. Pravastatin administration reduced cerebral oedema by upregulating eNOS expression/activity. This, by increasing vascular NO bioavailability, could have produced proximal vasodilation and contributed to reducing perfusional deficit. It is worthy stressing how important the anti-oedema action is that pravastatin seems to exert. Indeed, cerebral oedema, when widespread and beyond limits of physiological compensation, causes endocranic hypertension and additional cerebral damage over time.

Pravastatin treatment causes a shift in the balance of hippocampal neurotransmitter binding densities towards inhibition

Since pravastatin, a HMG-CoA reductase inhibitor, has recently been shown to reduce infarct volumes and glutamate release in a rat model of ischemic stroke, the aim of the present study was to investigate whether this neuroprotective effect may be due to a modulation of excitatory and inhibitory neurotransmitter receptors. Therefore, Wistar rats were treated six times in 4 days with pravastatin or saline and allowed to survive for 6 hours or 5 days (n=10 per time point and group), respectively. Using quantitative receptor autoradiography, ligand binding densities of [(3)H]MK-801, [(3)H]AMPA, and [(3)H]muscimol for labeling of NMDA, AMPA, and GABA(A) receptors were analyzed in sensorimotor cortices Par1 and Par2, the striatum, and the hippocampus. Statin therapy induced complex alterations of ligand binding densities in different brain regions. Labeling of NMDA receptors was significantly increased in Par2, both after 6 hours and 5 days, respectively. Within the striatum, AMPA as well as GABA(A) receptor binding values were significantly increased on day 5. Furthermore, a marked and significant increase of [(3)H]muscimol ligand binding to GABA(A) receptors throughout all hippocampal subfields was seen after 6 hours. This complexity could easily be unraveled when focusing on the balance between excitatory glutamate and inhibitory GABA(A) receptors, in which case only the increase of hippocampal [(3)H]muscimol ligand binding 6 hours after the first application of pravastatin was accompanied by a net shift towards inhibition. Consequently, our data suggest an additional regulatory pathway induced by statins, namely modification of the abundance of excitatory and inhibitory neurotransmitter receptors.

Atorvastatin ameliorates cerebral vasospasm and early brain injury after subarachnoid hemorrhage and inhibits caspase-dependent apoptosis pathway

Backgroud

Cerebral vasospasm (CVS) and early brain injury remain major causes of morbidity and mortality after aneurysmal subarachnoid hemorrhage (SAH). Hydroxymethylglutaryl coenzyme A reductase inhibitors, also known as statins, has the neuroprotective effects and ameliorating CVS after SAH. This study was designed to explore apoptosis inhibiting effects of atorvastatin and its potential apoptotic signal pathway after SAH.

Results

Preserving blood-brain-barrier permeability, decreasing brain edema, increasing neurological scores and ameliorating cerebral vasospasm were obtained after prophylactic use of atorvastatin. TUNEL-positive cells were reduced markedly both in basilar artery and in brain cortex by atorvastatin. Apoptosis-related proteins P53, AIF and Cytochrome C were up-regulated after SAH, while they were not affected by atorvastatin. In addition, up-regulation of caspase-3 and caspase-8 after SAH was decreased by atorvastatin treatment both in mRNA and in protein levels.

Conclusion

The neuroprotective effects of atorvastatin after SAH may be related to its inhibition of caspase-dependent proapoptotic pathway based on the present results.

Lovastatin improves histological and functional outcomes and reduces inflammation after experimental traumatic brain injury

Traumatic brain injury (TBI) triggers a complex sequence of inflammatory responses that contribute to secondary injury. Statins have demonstrated neuroprotective effects against brain injury, but the underlying mechanisms remain unclear. This study evaluated the effects of lovastatin on a rat model of controlled cortical impact (CCI) injury. Our two hypotheses were that pre-administration of lovastatin would reduce functional deficits and extent of anatomical brain damage and that lovastatin would attenuate levels of pro-inflammatory cytokines. Rats were injected with lovastatin (4 mg/kg) or vehicle for 5 days and subjected to CCI. Neurological status was evaluated using rotarod and adhesive removal tests. Contusion volume and neuronal degeneration were examined using cresyl violet and FluoroJade B (FJB) histochemistry. Levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) mRNA and protein were assessed by real-time quantitative reverse transcriptase polymerase chain reaction, enzyme-linked immunosorbent assay, and immunohistochemistry. Lovastatin significantly improved performance on both the rotarod and adhesive removal tests before post-injury day 7. Lovastatin also significantly reduced contusion volume (20%) and number of FJB-positive degenerating neurons (35%) at 4 days. These changes were associated with a significant decrease in levels of TNF-alpha and IL-1beta mRNA and protein at the contusion site at 6 h and 4 days, respectively. Our results show that pre-administration of lovastatin improved functional outcomes and reduced extent of brain damage, with a concomitant decrease in tissue levels of TNF-alpha and IL-1beta mRNA and protein. These findings suggest that lovastatin's protective mechanisms may be partly attributed to a dampening of the inflammatory response.

Pitavastatin prevents NMDA-induced retinal ganglion cell death by suppressing leukocyte recruitment

Excitotoxicity is a major cause of retinal ganglion cell (RGC) death during ischemic diseases such as vessel occlusion and diabetic retinopathy. However, the underlying mechanisms are not well understood. Statins, inhibitors of the HMG-CoA reductase, have neuroprotective effects in addition to their original role in lowering cholesterol. We hypothesize that pitavastatin, a recently introduced potent statin, is protective against N-methyl-d-aspartic acid (NMDA)-induced RGC death. Pitavastatin, administered by gavage, abolished NMDA-induced loss of RGCs. To elucidate the mechanisms underlying the neuroprotective effect of pitavastatin, we investigated its impact on inflammation. NMDA increased the expression of interleukin-1beta and TNF-alpha, and endothelial adhesion molecules, including ICAM-1, and induced leukocyte accumulation in the retinal vessels. Pitavastatin significantly reduced NMDA-induced leukocyte accumulation and up-regulation of endothelial adhesion molecules, whereas cytokine expression was unaffected. Systemic blockade of ICAM-1 in wild-type mice or absence of CD18 in gene-deficient (CD18(-/-)) mice significantly suppressed NMDA-induced leukocyte accumulation and RGC death. These findings suggest a novel and causative role for inflammatory leukocyte recruitment in NMDA-induced excitotoxicity. Furthermore, we show the novel neuroprotective effect of statins against excitotoxicity-induced RGC death. Statins or other anti-inflammatory agents may thus have therapeutic benefits in excitotoxicity-associated neuronal diseases through blockade of leukocyte recruitment.

Pravastatin reduces microvascular basal lamina damage following focal cerebral ischemia and reperfusion

Transient ischemia has been shown to damage the basal lamina of the cerebral microvasculature. Other studies proved statins to be beneficial to non-cerebral microvessels. The aim of this study was to determine whether pravastatin pretreatment ameliorates microvascular basal lamina damage following transient ischemia. Using the suture model, we subjected 15 rats to focal ischemia (3 h) and reperfusion (24 h). Rats received pravastatin (20 mg/kg/day) or saline for 4 weeks prior to the experiment. The outcome was determined by a behavior test and the infarct size. Collagen type IV, a marker for an intact basal lamina, and hemoglobin extravasation were measured by Western blot analysis. A ratio (in percentage) between ischemic and contralateral hemispheres was calculated. Pravastatin pretreatment resulted in a significantly better neurological outcome and reduced infarct size (15 +/- 0.5 and 59 +/- 10 mm(3), respectively) compared with controls (12.25 +/- 0.4 and 167 +/- 13 mm(3), respectively, P < 0.01 for both). In controls, loss of collagen type IV was seen in the basal ganglia and in the cortex (43 +/- 4 and 64 +/- 5%, respectively). Pravastatin prevented significant collagen loss (basal ganglia: 106 +/- 17%; cortex: 112 +/- 14%, P < 0.01 for both) and significantly reduced the hemoglobin extravasation compared with controls in the basal ganglia (198 +/- 49 vs. 553 +/- 47%, P < 0.01). Pravastatin pretreatment resulted in a reduction of microvascular basal lamina damage and hemoglobin extravasation following transient ischemia. Pravastatin seems to protect the cerebral microvascular system.

Treatment with statins in the acute phase of ischemic stroke

Although statins are being used for the secondary prevention of ischemic stroke, recent experimental data have shown new pleiotropic effects of these drugs independent of their lipid-lowering properties that might be responsible for their role in neuroprotection. In fact, statins have been successfully tested in animal models of acute cerebral ischemia. In humans, the possibility that statins could be used for the treatment of acute ischemic stroke has not yet been addressed, however, a pilot trial and observational studies testing this approach showed promising results for a disease in which tissue plasminogen activator is the only available treatment for a reduced number of patients. The aim of this review is to answer the basic question of whether treatment with statins initiated in the acute phase of ischemic stroke is feasible and if it can improve neurologic outcome. The possible benefits of this scenario will be discussed.

Simvastatin reduces caspase-3 activation and inflammatory markers induced by hypoxia–ischemia in the newborn rat

The present study was undertaken to evaluate whether in a neonatal model of stroke a prophylactic neuroprotective treatment with simvastatin modulates hypoxia-ischemia-induced inflammatory and apoptotic signaling. Procaspase-3 and cleaved caspase-3 expression showed a peak at 24 h and returned to control values after 5 days. Caspase-3 activity followed the same pattern of caspase-3 proteolytic cleavage. In simvastatin-treated ischemic animals, the expression of these proteins and caspase-3 activity were significantly lower when compared to that of ischemic animals. alpha-Spectrin and protein kinase C-alpha (PKCalpha) cleavages were not affected by the treatment. Poly (ADP-ribose) polymerase fragmentation, caspase-1 activation, and IL-1beta and ICAM-1 mRNA expression were increased by hypoxia-ischemia and significantly reduced in simvastatin-treated animals. The results indicate that simvastatin-induced attenuation of hypoxia-ischemia brain injury in the newborn rat occurs through reduction of the inflammatory response, caspase-3 activation, and apoptotic cell death.

Lovastatin reduces neuronal cell death in hippocampal CA1 subfield after pilocarpine-induced status epilepticus: preliminary results

OBJECTIVE: To further characterize the capacity of lovastatin to prevent hippocampal neuronal loss after pilocarpine-induced status epilepticus (SE) METHOD: Adult male Wistar rats were divided into four groups: (A) control rats, received neither pilocarpine nor lovastatin (n=5); (B) control rats, received just lovastatin (n=5); (C) rats that received just pilocarpine (n=5); (D) rats that received pilocarpine and lovastatin (n=5). After pilocarpine injection (350mg/kg, i.p.), only rats that displayed continuous, convulsive seizure activity were included in our study. Seizure activity was monitored behaviorally and terminated with an injection of diazepam (10 mg/kg, i.p.) after 4 h of convulsive SE. The rats treated with lovastatin received two doses of 20mg/kg via an oesophagic probe immediately and 24 hours after SE induction. Seven days after pilocarpine-induced SE, all the animals were perfused and their brains were processed for histological analysis through Nissl method. RESULTS: The cell counts in the Nissl-stained sections performed within the hippocampal formation showed a significant cell loss in rats that received pilocarpine and presented SE (CA1= 26.8 ± 13.67; CA3= 38.1 ± 7.2; hilus= 43.8 ± 3.95) when compared with control group animals (Group A: CA1= 53.2 ± 9.63; CA3= 63.5 ± 13.35; hilus= 59.08 ± 10.24; Group B: CA1= 74.3 ± 8.16; CA3= 70.1 ± 3.83; hilus= 70.6 ± 5.10). The average neuronal cell number of CA1 subfield of rats that present SE and received lovastatin (44.4 ± 17.88) was statically significant increased when compared with animals that just presented SE. CONCLUSION: Lovastatin exert a neuroprotective role in the attenuation of brain damage after SE.

Evidence for a Role of Second Pathophysiological Stress in Prevention of Delayed Neuronal Death in the Hippocampal CA1 Region

In ischemic tolerance experiment, when we applied 5-min ischemia 2 days before 30-min ischemia, we achieved a remarkable (95.8%) survival of CA1 neurons. However, when we applied 5-min ischemia itself, without following lethal ischemia, we found out 45.8% degeneration of neurons in the CA1. This means that salvage of 40% CA1 neurons from postischemic degeneration was initiated by the second pathophysiological stress. These findings encouraged us to hypothesize that the second pathophysiological stress used 48 h after lethal ischemia can be efficient in prevention of delayed neuronal death. Our results demonstrate that whereas 8 min of lethal ischemia destroys 49.9% of CAI neurons, 10 min of ischemia destroys 71.6% of CA1 neurons, three different techniques of the second pathophysiological stress are able to protect against both: CA1 damage as well as spatial learning/memory dysfunction. Bolus of norepinephrine (3.1 micromol/kg i.p.) used two days after 8 min ischemia saved 94.2%, 6 min ischemia applied 2 days after 10 min ischemia rescued 89.9%, and an injection of 3-nitropropionic acid (20 mg/kg i.p.) applied two days after 10 min ischemia protected 77.5% of CA1 neurons. Thus, the second pathophysiological stress, if applied at a suitable time after lethal ischemia, represents a significant therapeutic window to opportunity for salvaging neurons in the hippocampal CA1 region against delayed neuronal death.

Statins and stroke

Inhibitors of HMG-CoA reductase (statins) are potent cholesterol-lowering drugs. Large clinical trials have shown that statins reduce the incidence of cerebrovascular events, which might be surprising because cholesterol is not an established risk factor for stroke. In addition to their cholesterol-lowering properties, statins exert a number of pleiotropic, vasculoprotective actions that include improvement of endothelial function, increased nitric oxide (NO) bioavailability, antioxidant properties, inhibition of inflammatory responses, immunomodulatory actions, regulation of progenitor cells, and stabilization of atherosclerotic plaques. In fact, statins augment cerebral blood flow and confer significant protection in animal models of stroke partly via mechanisms related to the upregulation of endothelial nitric oxide synthase. Retrospective clinical evidence suggests that long-term statin administration may not only reduce stroke risk but also improve outcome. Early secondary prevention trials are underway to test the hypothesis that statin treatment initiated immediately after an event improves short-term outcome. Lastly, recent evidence suggests that sudden discontinuation of statin treatment leads to a rebound effect with downregulation of NO production. Withdrawal of statin treatment may impair vascular function and increase morbidity and mortality in patients with vascular disease.