Neuroprotective Effects Of Simvastatin Research Articles

Repurposing of cholesterol-lowering agents in status epilepticus: A neuroprotective effect of simvastatin

The increase of cholesterol synthesis after a status epilepticus may lead to excitotoxic processes, neuronal loss and favor the appearance of spontaneous epileptic seizures. Lowering cholesterol content could be a neuroprotective strategy.Here, we evaluated the protective effect of simvastatin administrated daily for 14 days, after the induction of a status epilepticus by intrahippocampal injection of kainic acid in mice. The results were compared to those obtained from mice showing a kainic acid-induced status epilepticus, treated daily with a saline solution, and from mice injected with a control phosphate-buffered solution without any status epilepticus. We first assessed the antiseizure effects of simvastatin by performing video-electroencephalographic recordings during the first three hours after kainic acid injection and continuously between the fifteenth and the thirty-first days. Mice treated with simvastatin had significantly fewer generalized seizures during the first three hours without a significant effect on generalized seizures after two weeks. There was a trend for fewer hippocampal electrographic seizures after two weeks. Secondly, we evaluated the neuroprotective and anti-inflammatory effects of simvastatin by measuring the fluorescence of neuronal and astrocyte markers on the thirtieth day after status onset. We found that simvastatin reduced CA1 reactive astrocytosis, demonstrated by a significant 37% decrease in GFAP-positive cells, and that simvastatin prevented the neuronal loss in CA1, demonstrated by a significant 42% increase in the NeuN-positive cells, as compared to the findings in mice with kainic acid-induced status epilepticus treated by a saline solution.Our study confirms the interest of cholesterol-lowering agents, and in particular simvastatin, in status epilepticus and paves the way for a clinical pilot study to prevent neurological sequelae after status epilepticus. This paper was presented at the 8th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in September 2022.

The Effect of Simvastatin on Acute Phase Functional Outcome of Ischemic Stroke

Introduction: Stroke is one of the leading causes of death and disability worldwide, and especially in Indonesia. Several studies showed the pleiotropic and neuroprotective effect of simvastatin in addition to lowering blood cholesterol levels. Objective: This trial was conducted to investigate if the administration of simvastatin in acute ischemic stroke management can improve functional outcomes. Methods: This randomized, double-blind, placebo-controlled trial of simvastatin was conducted in patients with acute ischemic stroke with an NIHSS score of 4-14. Participants were randomly assigned to receive 40 mg of simvastatin or placebo for seven days. The NIHSS scale was compared on admission day, 4th and 8th day after administration of simvastatin between the two groups. Results: 52 individuals were randomized: 28 to simvastatin and 24 to placebo. There was no significant improvement of functional outcome between the two groups (p > 0.05). Conclusion: Administration of simvastatin had no significant effect on outcome (measured by NIHSS) in patients with acute ischemic stroke.

Simvastatin attenuates spatial memory impairment via inhibiting microgliosis and apoptotic cell death against ethanol induced neurotoxicity in the developing rat hippocampus

Ethanol is associated with oxidative stress. Exposure to ethanol during childhood may lead to neurological disorders. Congenital disorders induced by alcohol are mainly caused by an oxidative-inflammatory cascade due to extensive apoptotic neurodegeneration in the brain, particularly in the hippocampus. Simvastatin, which acts as an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA), is widely used to manage cardiovascular diseases. Recently, the neuroprotective effects of simvastatin against nervous system disorders have been introduced. In this study, we examined the protective effects of simvastatin on ethanol-related neurotoxicity in the hippocampus of rat pups. Ethanol (5.27 g/kg) in a milk solution (27.8 mL/kg) was administered to male rat pups via intragastric intubation at 2–10 days after birth. Also, 10 and 20 mg/kg of simvastatin were injected to the animals. By using Morris water maze task, the hippocampus-dependent memory and spatial learning was evaluated 36 days after birth. An ELISA assay was performed to investigate the antioxidant and anti-inflammatory effects of simvastatin by measuring the levels of tumor necrosis factor-α (TNF-α), and antioxidant enzymes. To assess the expression levels of Iba1 immunohistochemical staining and caspase-3 immunofluorescence staining was performed. The current study demonstrated that administration of simvastatin significantly attenuates spatial memory impairment (P < 0.01) after ethanol neurotoxicity. Also simvastatin could considerably increase the total superoxide dismutaseand glutathione levels (P < 0.01). Moreover, it was associated with a greater reduction in malondialdehyde (P < 0.05) and TNF-α levels, compared to the ethanol group (P < 0.01). Furthermore, in the simvastatin group, the hippocampal level of caspase-3 and the level of Iba1-positive cells, reduced (P < 0.01).This study demonstrated that apoptotic signaling, mediated by the oxidative-inflammatory cascade, could be inhibited by simvastatin in rat pups with ethanol exposure in the postnatal period.

The neuroprotective effect of simvastatin on the cerebellum of experimentally-induced diabetic rats through klotho upregulation: An immunohistochemical study

BackgroundDiabetes mellitus is a multifactorial metabolic disorder that is complicated by multi-organ dysfunction including CNS. Klotho is an anti-aging protein expressed in Purkinje cells of the cerebellum. Klotho protects against the development of several neurodegenerative diseases. Simvastatin is a lipophilic statin that can enhance klotho expression. Aim of the studyThis study was designed to investigate cerebellar structural changes in diabetes, klotho expression in the cerebellum of diabetic rats and the neuroprotective effect of simvastatin. Materials & methods24 adult albino rats were divided into 4 groups; control, simvastatin, diabetic (induced by single intraperitoneal injection of STZ 45 mg/kg) and diabetic treated by simvastatin (10 mg/kg once daily) after confirmation of diabetes. Rotarod test was performed for evaluation of motor coordination. Blood glucose and insulin levels were estimated for confirmation of diabetes. Reduced glutathione (GSH) and malonaldehyde (MDA) in cerebellar tissues were evaluated. The cerebellar samples were prepared for histological and immunohistochemical staining. ResultsThe latency time on the rotarod was reduced in diabetic rats. Cerebellar structure was disturbed in diabetic group. Oxidative stress was evidenced by increased MDA and reduced GSH. Klotho expression was downregulated and caspase-3 was increased in diabetes. Simvastatin increased the latency time. Simvastatin diminished the changes in oxidative stress markers and succeeded to ameliorate the diabetic induced cerebellar changes. Simvastatin enhanced Klotho and diminished Caspase-3 expression. ConclusionSimvastatin can ameliorate diabetic induced cerebellar changes through minimizing oxidative stress, enhancement of Klotho expression and reduction of apoptosis.

Simvastatin in an experimental spinal cord injury model: a histopathological and biochemical evidence based study.

In this study we tried to determine the possible neuroprotective effects of simvastatin in a rat model of Spinal Cord Injury (SCI) with the help of biochemical and histopathological tests. Rats were divided into 5 groups:1) SCI control, 2) Sham operated, 3) SCI with 10 mg/kg intraperitoneal simvastatin, 4) SCI with 10 mg/kg oral simvastatin, 5) SCI with 10 mg/kg subcutaneous simvastatin. After the treatment period, all rats were sacrificed; their blood and spinal cord samples were taken for biochemical and histopathological assessment. When the groups were compared in terms of oedema and inflammation status, the scores of groups receiving simvastatin were better than the control and sham groups (p = 0.001 and p = 0.038 respectively). When the 3 treatment groups (oral, intraperitoneal and subcutaneous simvastatin groups) were compared with each other in terms of inflammation, haemorrhage and oedema, there were no significant differences between groups (p = 0.112, p = 0.797 and p = 0.188, respectively). NSE and S100B levels were significantly lower in the treatment groups compared to the sham group (p = 0.039 and p = 0.004 respectively). According to our biochemical and histopathological findings, simvastatin 10 mg/kg has a positive impact in the spinal cord injury model in rats, regardless of route of application (Tab. 1, Fig. 5, Ref. 26).

The Neuroprotective Effects of Simvastatin on High Cholesterol Following Traumatic Brain Injury in Rats

High cholesterol has been correlated with a greater risk of cerebrovascular diseases. Whether pre-existing high cholesterol exacerbates traumatic brain injury (TBI), and whether treatment with the cholesterol-lowering agent simvastatin has neuroprotective effects, especially anti-neuroinflammatory effects, after TBI are not well investigated. Five-week-old male Sprague-Dawley rats were fed a high-fat diet for 8 weeks to induce hypercholesterolemia. Anesthetized male Sprague-Dawley rats were divided into 5 groups, including the sham-operated control, TBI control, and TBI with simvastatin treatment (4 mg/kg, 10 mg/kg, or 20 mg/kg) groups. Simvastatin was intraperitoneally injected at 0, 24, and 48 hours after TBI. Motor function was measured using an inclined plane. Neuronal apoptosis (maker Neu-N, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling), tumor necrosis factor-α expression in microglia (marker OX42) and astrocytes (marker glial fibrillary acidic protein), and Tumor necrosis factor-alpha receptor (TNFR) 1 and TNFR2 expression in neurons in the ischemic cortex were investigated using an immunofluorescence assay. All of the parameters were measured on the third day after TBI. TBI significantly increased the serum levels of cholesterol. The TBI-induced motor deficit was significantly attenuated by 4, 10, and 20 mg/kg simvastatin therapy on the third day after TBI. TBI-induced neuronal TNFR1 activation and apoptosis, as well as tumor necrosis factor-α expression in astrocytes in the ischemic cortex, were significantly attenuated by simvastatin, particularly when 20 mg/kg was administered. Simultaneously, the serum cholesterol remained high despite simvastatin treatment. The neuroprotection effects of simvastatin on the pre-existing hypercholesterolemia during TBI in rats may be related to its anti-neuroinflammatory effects but not to its cholesterol-lowing effects.

Brain Oxidative Stress During Experimental Sepsis Is Attenuated by Simvastatin Administration.

During sepsis, brain damage is associated with oxidative stress due to overproduction of reactive oxygen species (ROS). Although there are recent reports about the benefits of statins in experimental sepsis and endotoxemia in peripheral organs, little is known about their effects in the CNS. Here, we investigated the antioxidant properties of simvastatin and its possible neuroprotective role during experimental sepsis. Male Wistar rats (250-300g) were submitted to cecal ligation and puncture (CLP, n=34) or remained as non-manipulated (naive, n=34). Both groups were treated by gavage with simvastatin (20mg/kg) or an equivalent volume of saline. The animals submitted to CLP were treated 4days before and 48h after surgery. One animal group was decapitated and the blood and brain were collected to quantify plasma levels of cytokines and assess astrogliosis and apoptosis in the prefrontal cortex and hippocampus. Another group was perfused with PBS (0.01M), and the same brain structures were dissected to analyze oxidative damage. The CLP rats treated with simvastatin showed a reduction in nitric oxide (P<0.05), IL1-β (P<0.001), IL-6 (P<0.01), and TBARS levels (P<0.001) and an increase in catalase activity (P<0.01), citrate synthase enzyme (P<0.05), and normalized GSH/GSSG ratio. In addition, the histopathological analysis showed a reduction (P<0.001) in reactive astrocytes and caspase 3-positive apoptotic cells. The results suggest a possible neuroprotective effect of simvastatin in structures responsible for spatial learning and memory and indicate the need for behavioral studies evaluating the impact on cognitive damage, as frequently seen in patients surviving sepsis.

Effects of simvastatin on the expression of inducible nitric oxide synthase and brain-derived neurotrophic factor in a lipopolysaccharide-induced rat model of Parkinson disease

Objective: To investigate the effects of simvastatin on the expression of inducible nitric oxide synthase (iNOS) and brain-derived neurotrophic factor (BDNF) in the substantia nigra in a lipopolysaccharide (LPS)-induced rat model of Parkinson disease (PD), and to study the mechanisms underlying the neuroprotective effects of simvastatin in PD. Methods: The LPS-PD model was established by injection of LPS (5 mg/mL, 2.0 μL) into the right substantia nigra compacta (SNC). Rats in the sham-operated group received saline. The simvastatin treatment group was intraperitoneally administered simvastatin (5 mg/kg, 2.0 μL) at 1 h before, and daily for 14 days after surgery, while the sham-operated and LPS-model groups received saline. Iba-1-positive cells and tyrosine hydroxylase (TH), as well as iNOS and BDNF in the SNC were detected by immunohistochemistry and Western blotting, respectively. The effect of simvastatin in the PD model was also examined in behavioral tests. Results: The LPS-model group exhibited typical animal PD behaviors. Compared with the control group, the LPS-model group exhibited a decreased number of DA neurons (p < 0.01) in the SNC, as well as increases in the Iba-1-positive cell number and iNOS expression (p < 0.05), while BDNF expression was downregulated (p < 0.01). These effects were inhibited by simvastatin treatment (p < 0.05). Conclusion: Simvastatin mediates a protective effect on dopaminergic neurons in the SNC in the LPS-PD model, possibly by promoting neuronal repair and regeneration, and by inhibiting oxidative stress, thus improving substantia nigra function.

Neuroprotective Effect of Simvastatin via Inducing the Autophagy on Spinal Cord Injury in the Rat Model.

Simvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, is invariably used to treat cardiovascular diseases. Simvastatin has been recently demonstrated to have a neuroprotective effect in nervous system diseases. The present study aimed to further verify the neuroprotection and molecular mechanism of simvastatin on rats after spinal cord injury (SCI). The expression of Beclin-1 and LC3-B was evidently enhanced at postoperation days 3 and 5, respectively. However, the reduction of the mTOR protein and ribosomal protein S6 kinase p70 subtype (p70S6K) phosphorylation level occurred at the same time after SCI. Simvastatin significantly increased the expression of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF). Meanwhile, immunofluorescence results indicated that the expression of chondroitin sulfate proteoglycan (CSPG) and caspase-3 protein was obviously reduced by simvastatin. Furthermore, Nissl staining and Basso, Beattie, and Bresnahan (BBB) scores showed that the quantity and function of motor neurons were visibly preserved by simvastatin after SCI. The findings of this study showed that simvastatin induced autophagy by inhibiting the mTOR signaling pathway and contributed to neuroprotection after SCI.

Simvastatin activates Akt/glycogen synthase kinase-3 β signal and inhibits caspase-3 activation after experimental subarachnoid hemorrhage

This study was designed to explore the role of simvastatin and its effects on the Akt/GSK3β survival signal and apoptosis pathway after experimental subarachnoid hemorrhage (SAH). SAH was induced by blood injection into the cisterna magna in New Zealand white rabbits. Increased expression of phospho-Akt and phospho-GSK3β was observed in brain tissue after SAH. Apoptosis and related proteins, including P53, apoptosis-inducing factor (AIF), cytochrome C, and cleaved caspase-3, were also activated. Simvastatin, at both low dose (10 mg/kg) and high dose (40 mg/kg), further increased expression of phospho-Akt and phospho-GSK3β, decreased activation of caspase-3, and inhibited apoptosis. Preserved blood-brain barrier and attenuated brain edema were observed following simvastatin treatment. In addition, the neuroprotective effects of simvastatin were blocked by wortmannin (2.5 µg/kg/min), an irreversible PIK3 inhibitor. P53, AIF, and cytochrome C were not affected by simvastatin treatment. Findings from the present study suggest that simvastatin ameliorates acute brain injury after SAH. The potential mechanisms of action include activation of the Akt/GSK3β survival signal and inhibition of caspase-dependent apoptosis pathway.

Effects of simvastatin on neuroprotection and modulation of Bcl-2 and BAX in the rat quinolinic acid model of Huntington's disease

A possible neuroprotective role has been recently suggested for 3H3MGCoA reductase inhibitors. Here, we sought to determine whether simvastatin exerts a neuroprotective effect in our rat model of HD. Rats were surgically administered quinolinic acid and treated with simvastatin 1mg/kg intraperitoneally (i.p.) once daily up to 2 or 8 weeks. Two more groups of animals received a pretreatment with 1mg/kg simvastatin i.p. for 2 weeks before the QA lesion and then were treated with simvastatin for the following 2 weeks or 8 weeks, respectively. In the simvastatin treated groups (both pretreated and non-pretreated), striatal lesion size was about 36% smaller while neuronal counts where higher than in the vehicle treated ones at 2 weeks. The neuroprotective effects of simvastatin was still evident at 8 weeks post lesion, where the non-pretreated group had a 8% smaller lesion size than the saline group, and the pretreated group had an 11% smaller lesion size than the saline group. Simvastatin also induced immunoreactivity for Bcl-2, an anti-apoptotic factor, on one hand, and down-regulated immunoreactivity for Bax, a proapoptotic factor. Bcl-2/Bax modulation can account, at least partly, for the beneficial effect of simvastatin in our rodent model of striatal degeneration. Our findings show that statins could be explored as possible neuroprotective agents for neurodegenerative disorders such as HD.

Squalestatin protects neurons and reduces the activation of cytoplasmic phospholipase A 2 by Aβ 1–42

Alzheimer's disease is characterised by the loss of neurons and the production of Aβ peptides. We report that the addition of Aβ 1–42 to neurons resulted in activation of cytoplasmic phospholipase A 2 (cPLA 2), the production of prostaglandin E 2, synapse damage and reduced neuronal survival. Pre-treatment with simvastatin, a clinically relevant statin that penetrates the brain, protected against Aβ 1–42 induced synapse damage and neuronal death in vitro. The neuroprotective effects of simvastatin were shared by squalestatin, a squalene synthase inhibitor that reduces neuronal cholesterol production and crucially, does not affect isoprenoid formation. The protective effect of both these drugs was reversed by the addition of exogenous cholesterol. These drugs did not alter the amounts of extracellular Aβ 1–42 ingested by neurons; rather they reduced Aβ 1–42 induced activation of cPLA 2 and prostaglandin E 2 production. Treatment prevented the migration of Aβ 1–42 and cPLA 2 to caveolin-1 containing lipid rafts. We propose that critical concentrations of Aβ 1–42 trigger the amalgamation of individual micro-domains containing signalling molecules to form lipid raft platforms in which sustained activation of cPLA 2 leads to neuronal dysfunction and ultimately neuronal death. This process is dependent on the amounts of cholesterol in neuronal membranes and is susceptible to treatment with squalestatin or simvastatin.

Acute neurovascular unit protection by simvastatin in transient cerebral ischemia

Acute vascular- and neuroprotective effects of simvastatin were evaluated in a rat model of transient, focal cerebral ischemia. Male, Wistar rats (n=12) underwent transient middle cerebral artery (MCA) occlusion for 3 hours followed by 3 hours of reperfusion. After 30 minutes of MCA occlusion, four rats each were subcutaneously injected with either 20 or 40 mg/kg of simvastatin. At the end of 3 hours of reperfusion, tissue injury and blood–brain barrier (BBB) opening were quantified by histology and [14C]-alpha-aminoisobutyric acid (AIB)-based quantitative autoradiography (QAR), respectively. Compared with untreated rats, those treated with simvastatin (20 mg/kg) had reduced volumes of AIB leakage, tissue pallor and distribution space for AIB (p<0.05). No additional effects were seen with the higher drug dose (40 mg/kg). These data suggest that the acute neuroprotective effects of statins are in part owing to attenuation of stroke-induced changes in BBB permeability.

Simvastatin treatment does not protect retinal ganglion cells from degeneration in a rat model of autoimmune optic neuritis

In patients with multiple sclerosis (MS), non-remitting deficits are mainly caused by axonal and neuronal damage. We demonstrated previously that myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis in rats provokes severe axonal and neuronal injury even before clinical manifestation of the disease. In our present study, we investigated effects of simvastatin treatment on degeneration of retinal ganglion cell (RGC) bodies as well as their axons during MOG-induced optic neuritis. Electrophysiological functions of optic nerves and RGCs were analyzed in vivo. Although neuroprotective effects of simvastatin have been demonstrated before in other experimental settings, we did not observe an increase in RGC survival nor an improvement of visual functions. As we could not reproduce the anti-inflammatory effects that were observed under statin therapy in other EAE models, we hypothesize that patients suffering from optic neuritis might not take advantage of simvastatin applications.

Prophylactic but not delayed administration of simvastatin protects against long-lasting cognitive and morphological consequences of neonatal hypoxic-ischemic brain injury, reduces interleukin-1beta and tumor necrosis factor-alpha mRNA induction, and does not affect endothelial nitric oxide synthase expression.

Prophylactic administration of simvastatin has been shown to protect against brain damage and its long-lasting behavioral consequences in neonatal rats. To establish the drug treatment window, we evaluated the effectiveness of simvastatin administered at different intervals before and after stroke. Furthermore, we determined whether simvastatin affected endothelial nitric oxide synthase (eNOS) or inflammatory cytokines in brain tissue or cholesterol levels in serum. On postnatal day 7, male rats were subjected to hypoxia-ischemia (HI). The experiment included sham-operated controls and HI animals receiving daily saline or activated simvastatin (20 mg/kg) injections from postnatal day 1 to day 7 (HI-simvastatin 1-7 group), from postnatal day 4 to day 11 (HI-simvastatin 4-11 group), or from postnatal day 7 to day 14 (HI-simvastatin 7-14 group). The neuroprotective effect of simvastatin was evaluated at adulthood by means of behavioral and histological analyses. Cytokines and eNOS expression were assessed by reverse transcriptase-polymerase chain reaction and Western blotting. Animals in both the HI-simvastatin 1-7 and HI-simvastatin 4-11 groups performed better than HI rats in either the T-maze or the circular water maze and showed significantly attenuated brain damage. Expression of interleukin-1beta and tumor necrosis factor-alpha mRNA in cortex was significantly increased in HI but not in HI-simvastatin 1-7 animals. In the same brain area, simvastatin treatment did not affect the increase of eNOS expression observed after HI. These findings indicate that prophylactic but not delayed administration of simvastatin improves functional outcome in neonatal rat stroke. The reduced induction of cytokines suggests that the neuroprotective effect of simvastatin may be related to a dampening of the inflammatory response.

Treatment with statins after induction of focal ischemia in rats reduces the extent of brain damage.

In the present study, MRI has been used to investigate therapeutic intervention with statins in a model of permanent focal cerebral ischemia in rat. Brain ischemia was induced in rats by the permanent occlusion of middle cerebral artery (MCAO) and the brain infarct size followed up in alive animals 2, 24, and 48 hours after MCAO, using the trace of apparent diffusion coefficient [Tr(D)] maps and T2-weighted images. In vehicle-treated rats, the infarct volumes increased by 38.5% and 89% after 24 and 48 hours, respectively, compared with the damage detected at 2 hours after MCAO. Treatment with simvastatin (20 mg/kg) after MCAO prevented the increase in brain infarct volume occurring at 24 hours and induced a 46.6% reduction after 48 hours. This effect was similar to that observed when simvastatin was administered before the induction of focal ischemia. T2W-MRI images confirmed these findings. The neuroprotective effects of simvastatin were paralleled by an increase in endothelial NO synthase immunoreactivity, detectable in the brain of simvastatin-treated rats. Statins, in addition to their preventive effect on cerebral ischemia, exert a neuroprotective role in the attenuation of brain damage after acute stroke.