Rosuvastatin preconditioning provides neuroprotection against spinal cord ischemia in rats through modulating nitric oxide synthase expressions

New rat model of spinal cord infarction with long-lasting functional disabilities generated by intraspinal injection of endothelin-1

BACKGROUND

The current method for generating an animal model of spinal cord (SC) infarction is highly invasive and permits only short-term observation, typically limited to 28 days.

OBJECTIVE

We aimed to establish a rat model characterised by long-term survival and enduring SC dysfunction by inducing selective ischaemic SC damage.

METHODS

In 8-week-old male Wistar rats, a convection-enhanced delivery technique was applied to selectively deliver endothelin-1 (ET-1) to the anterior horn of the SC at the Th13 level, leading to SC infarction. The Basso, Beattie and Bresnahan (BBB) locomotor score was assessed for 56 days. The SC was examined by a laser tissue blood flowmeter, MRI, immunohistochemistry, triphenyl tetrazolium chloride (TTC) staining, Western blots and TUNEL staining.

RESULTS

The puncture method was used to bilaterally inject 0.7 µL ET-1 (2.5 mg/mL) from the lateral SC into the anterior horns (40° angle, 1.5 mm depth) near the posterior root origin. Animals survived until day 56 and the BBB score was stably maintained (5.5±1.0 at day 14 and 6.2±1.0 at day 56). Rats with BBB scores ≤1 on day 1 showed stable scores of 5-6 after day 14 until day 56 while rats with BBB scores >1 on day 1 exhibited only minor dysfunction with BBB scores >12 after day 14. TTC staining, immunostaining and TUNEL staining revealed selective ischaemia and neuronal cell death in the anterior horn. T2-weighted MR images showed increasing signal intensity at the SC infarction site over time. Western blots revealed apoptosis and subsequent inflammation in SC tissue after ET-1 administration.

CONCLUSIONS

Selective delivery of ET-1 into the SC allows for more precise localisation of the infarcted area at the targeted site and generates a rat SC infarction model with stable neurological dysfunction lasting 56 days.

Memantine/Rosuvastatin Therapy Abrogates Cognitive and Hippocampal Injury in an Experimental Model of Alzheimer's Disease in Rats: Role of TGF-β1/Smad Signaling Pathway and Amyloid-β Clearance

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder of complex pathogenesis and multiple interacting signaling pathways where amyloidal-β protein (Aβ) clearance plays a crucial role in cognitive decline. Herein, the current study investigated the possible modulatory effects of memantine/ rosuvastatin therapy on TGF-β1/p-Smad/p21 signaling pathway and their correlation to the blood brain barrier transporters involved in Aβ-clearance and microRNAs as a novel molecular mechanism in AD treatment. AD was induced by a single intracerebroventricular streptozotocin injection (ICV-STZ, 3 mg/kg) in rats and drug therapy was continued for 28 days after AD induction. Efficacy was monitored by applying a battery of behavioral assessments, as well as biochemical, histopathological, molecular and gene expression techniques. The upregulated TGF-β1-signaling in the untreated rats was found to be highly correlated to transporters and microRNAs governing Aβ-efflux; ABCA1/miRNA-26 and LRP1/miRNA-205 expressions, rather than RAGE/miRNA-185 controlling Aβ-influx; an effect that was opposed by the tested drugs and was found to be correlated with the abolished TGF-β1-signaling as well. Combined memantine/rosuvastatin therapy ameliorated the STZ evoked decreases in escape latency and number of crossovers in the Morris water maze test, % spontaneous alternation in the Y-maze test, and discrimination and recognition indices in the object recognition test. The evoked behavioral responses were directly related to the β-amyloid accumulation and the alteration in its clearance. Additionally, drug treatment increased brain glutathione and decreased malondialdehyde levels. These findings were histopathologically confirmed by a marked reduction of gliosis and restoration of neuronal integrity in the CA1 region of the hippocampus of the AD rats. These findings implicated that the memantine/rosuvastatin combination could offer a new therapeutic potential for AD management by abrogating the TGF-β1/p-Smad2/p21 pathway and regulating Aβ-clearance.

Rodent Models of Spinal Cord Injury: From Pathology to Application

Spinal cord injury (SCI) often has devastating consequences for the patient's physical, mental and occupational health. At present, there is no effective treatment for SCI, and appropriate animal models are very important for studying the pathological manifestations, injury mechanisms, and corresponding treatment. However, the pathological changes in each injury model are different, which creates difficulties in selecting appropriate models for different research purposes. In this article, we analyze various SCI models and introduce their pathological features, including inflammation, glial scar formation, axon regeneration, ischemia-reperfusion injury, and oxidative stress, and evaluate the advantages and disadvantages of each model, which is convenient for selecting suitable models for different injury mechanisms to study therapeutic methods.

Effect of L-carnitine and atorvastatin on a rat model of ischemia-reperfusion injury of spinal cord

Pro-inflammatory cytokines and reactive oxygen species (ROS) are produced in acute spinal cord injury, leading to myelin breakdown, inflammation, mitochondrial dysfunction, and apoptosis of neurons and glial cells. The aim of the present study was to investigate possible protective effects of L-carnitine (carn) or atorvastatin (ator) on spinal cord ischemia-reperfusion injury (IRI). Rats were randomized into nine equal groups (n = 8): control and control taking carn (100 mg/kg BW), ator (2.5 mg/kg BW) or both, as well as sham-operation, IRI and IRI taking same doses of carn, ator or both. Neurological assessments were done 48 hours after IRI, and serum nitrite/nitrate was measured. Finally, lumbar segments of spinal cord were excised, and part was homogenized and prepared for measuring tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), malondialdehyde (MDA), advanced oxidation protein products (AOPP), reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase. The other part was sectioned for evaluation of histopathological changes and for immunostaining by glial fibrillary acidic protein (GFAP), Bax and Bcl-2. The IRI increased ROS (nitrite/nitrate, MDA, AOPP) and pro-inflammatory cytokines (TNF-α, IL-1β), and decreased antioxidants (GSH, GPx, SOD, catalase) with impaired sensory and motor functions. Astrogliosis was detected by GFAP, and increased apoptosis was demonstrated by increasing Bax and decreasing Bcl-2. Treatment with carn or ator alone decreased TNF-α, IL-1β, nitrite/nitrate, MDA and AOPP, and increased GSH, GPx, SOD, and catalase with improvement of neurological functions and histological studies. Combination of carn and ator improved most of measured IRI-affected parameters better than isolated carn or ator administration.

Rosuvastatin enhanced functional recovery after sciatic nerve injury in the rat

Posttraumatic nerve recovery remains a challenge in regenerative medicine. As such, there is a need for agents that limit nerve damage and enhance nerve regeneration. Here we investigate rosuvastatin, a 3-hydroxy-3-methylglutaryl coenzyme (HMG-CoA) reductase inhibitor, with anti-inflammatory and antioxidant properties. We explore its neuroprotective properties on sciatic nerve crush injury in male Wistar Rats. Rats were subjected to crush injury to the left sciatic nerve using a vessel clamp for 30 s. Rosuvastatin or vehicle was prepared daily and administrated by oral gavage for seven days post-injury. In rosuvastatin treatment groups, rosuvastatin was administrated at the doses of (5 or 10 mg/kg) in the treatment group. The control group was given a vehicle in the same manner. Behavioral, electrophysiological, morphological and molecular parameters were examined during the recovery process. Chronic administration of rosuvastatin at all doses after sciatic nerve crush markedly promoted nerve regeneration and significantly accelerated motor function recovery (P < 0.05). Electrophysiological, morphological and molecular parameters also improved in the rosuvastatin treatment groups compared to the controls. These findings suggest that neuroprotective effects of rosuvastatin could be due to its antioxidant and anti-inflammatory activity. It is clear that more research is needed to confirm these findings.

Unfolding the pleiotropic facades of rosuvastatin in therapeutic intervention of myriads of neurodegenerative disorders

Rosuvastatin, a 3-hydroxy-3-methylglutaryl-coenzyme (HMG-CoA) reductase inhibitor, and one of the most popular antihyperlipidemic medications have been found to possess pharmacodynamic activities much different from its usual indication. Recent research studies have revealed the efficacy of rosuvastatin in attenuating neuroinflammation, reducing the progression of Alzheimer's disease, providing protection against cerebral ischaemia and spinal cord injury as well as ameliorating epilepsy. Mechanisms behind the neuroprotective potential of rosuvastatin can be attributed to its pleiotropic effects, independent of its ability to inhibit HMG-CoA reductase. These processes include modulation of several cellular pathways, isoprenylation, effects on oxidative stress, nitrosative levels, inflammation, and immune response. This review aims to assimilate and summarize recent findings on the pharmacological actions of rosuvastatin in attenuating neurological disorders in order to guide future research in this space.

Remote Limb Ischemic Conditioning and Motor Learning: Evaluation of Factors Influencing Response in Older Adults

Remote limb ischemic conditioning (RLIC) is a clinically feasible method of promoting tissue protection against subsequent ischemic insult. Recent findings from our lab demonstrated that RLIC robustly enhances motor learning in young, healthy humans. The next step is to determine which individuals would receive maximum benefit from RLIC before applying these findings to clinical rehabilitation populations such as stroke. Numerous factors, such as age, sex, body mass index (BMI), and cardiovascular comorbidities may influence the response. Sixty-nine participants aged 40-80 were randomized to receive either RLIC (n = 33) or sham (n = 36) conditioning. Participants underwent seven consecutive sessions consisting of RLIC or sham conditioning with a blood pressure cuff on the upper extremity and motor training on a stability platform balance task, with two follow-up sessions. Balance change (post-test-pre-test) was compared across participants, groups, and the factors of age, sex, BMI, and comorbidities. Participants in both groups improved their performance on the balance task from pre- to post-test. Overall balance change was independently associated with age and BMI. There was no difference in balance change between RLIC and Sham groups. However, RLIC significantly enhanced balance performance in participants with no comorbidities. Compared with our previous study in young adults, middle-aged and older adults demonstrated smaller improvements on the balance task. RLIC enhanced learning in middle-aged and older adults only in the absence of pre-defined comorbidities. RLIC may be a promising tool for enhancing motor recovery, but the accumulation of comorbidity with age may decrease its effectiveness.

The Antinociceptive Effects of Rosuvastatin in Chronic Constriction Injury Model of Male Rats

Introduction:

According to studies, statins possess analgesics and anti-inflammatory properties. In the present study, we examined the antinociceptive, anti-inflammatory and antioxidative effects of rosuvastatin in an experimental model of Chronic Constriction Injury (CCI).

Methods:

Our study was conducted on four groups; sham, CCI (the control group), CCI+rosuvastatin (i.p. 5 mg/kg), and CCI+rosuvastatin (i.p. 10 mg/kg). We performed heat hyperalgesia, cold and mechanical allodynia tests on the 3^rd, 7^th, 14^th, and 21^st after inducing CCI. Blood samples were collected to measure the serum levels of Tumor Necrosis Factor (TNF)-α, and Interleukin (IL)-6. Rats’ spinal cords were also examined to measure tissue concentration of Malondialdehyde (MDA), Superoxide Dismutase (SOD), and Glutathione Peroxidase (GPx) enzymes.

Results:

Our findings showed that CCI resulted in significant increase in heat hyperalgesia, cold and mechanical allodynia on the 7^th, 14^th and 21^st day. Rosuvastatin use attenuated the CCI-induced hyperalgesia and allodynia. Rosuvastatin use also resulted in reduction of TNF-α, IL-6, and MDA levels. However, rosuvastatin therapy increased the concentration of SOD and GPx in the CCI+Ros (5 mg/kg) and the CCI+Ros (10 mg/kg) groups compared to the CCI group.

Conclusion:

Rosuvastatin attenuated the CCI-induced neuropathic pain and inflammation. Thus, antinociceptive effects of rosuvastatin might be channeled through inhibition of inflammatory biomarkers and antioxidant properties.

CoQ10 Augments Rosuvastatin Neuroprotective Effect in a Model of Global Ischemia via Inhibition of NF-κB/JNK3/Bax and Activation of Akt/FOXO3A/Bim Cues

Statins were reported to lower the Coenzyme Q10 (CoQ10) content upon their inhibition of HMG-CoA reductase enzyme and both are known to possess neuroprotective potentials; therefore, the aim is to assess the possible use of CoQ10 as an adds-on therapy to rosuvastatin to improve its effect using global I/R model. Rats were allocated into sham, I/R, rosuvastatin (10 mg/kg), CoQ10 (10 mg/kg) and their combination. Drugs were administered orally for 7 days before I/R. Pretreatment with rosuvastatin and/or CoQ10 inhibited the hippocampal content of malondialdehyde, nitric oxide, and boosted glutathione and superoxide dismutase. They also opposed the upregulation of gp91^phox, and p47^phox subunits of NADPH oxidase. Meanwhile, both agents reduced content/expression of TNF-α, iNOS, NF-κBp65, ICAM-1, and MPO. Besides, all regimens abated cytochrome c, caspase-3 and Bax, but increased Bcl-2 in favor of cell survival. On the molecular level, they increased p-Akt and its downstream target p-FOXO3A, with the inhibition of the nuclear content of FOXO3A to downregulate the expression of Bim, a pro-apoptotic gene. Additionally, both treatments downregulate the JNK3/c-Jun signaling pathway. The effect of the combination regimen overrides that of either treatment alone. These effects were reflected on the alleviation of the hippocampal damage in CA1 region inflicted by I/R. Together, these findings accentuate the neuroprotective potentials of both treatments against global I/R by virtue of their rigorous multi-pronged actions, including suppression of hippocampal oxidative stress, inflammation, and apoptosis with the involvement of the Akt/FOXO3A/Bim and JNK3/c-Jun/Bax signaling pathways. The study also nominates CoQ10 as an adds-on therapy with statins.

Impact of Heat Shock Protein A 12B Overexpression on Spinal Astrocyte Survival Against Oxygen-Glucose-Serum Deprivation/Restoration in Primary Cultured Astrocytes

Heat shock protein A 12B (HSPA12B) is a newly discovered member of the heat shock protein 70 family. Preclinical evidence indicates that HSPA12B helps protect the brain from ischemic injury, although its specific function remains unclear. The aim of this study is to investigate whether HSPA12B overexpression can protect astrocytes from oxygen-glucose-serum deprivation/restoration (OGD/R) injury. We analyzed the effects of HSPA12B overexpression on spinal cord ischemia-reperfusion injury and spinal astrocyte survival. After ischemia-reperfusion injury, we found that HSPA12B overexpression decreased spinal cord water content and infarct volume. MTT assay showed that HSPA12B overexpression increased astrocyte survival after OGD/R treatment. Flow cytometry results showed a marked inhibition of OGD/R-induced astrocyte apoptosis. Western blot assay showed that HSPA12B overexpression significantly increased regulatory protein B-cell lymphocyte 2 (Bcl-2) levels, whereas it decreased expression of the Bax protein, which forms a heterodimer with Bcl-2. Measurements of the level of activation of caspase-3 by Caspase-Glo®3/7 Assay kit showed that HSPA12B overexpression markedly inhibited caspase-3 activation. Notably, we demonstrated that the effects of HSPA12B on spinal astrocyte survival depended on activation of the PI3K/Akt signal pathway. These findings indicate that HSPA12B protects against spinal cord ischemia-reperfusion injury and may represent a potential treatment target.

Hyperlipidemia and statins affect neurological outcome in lumbar spine injury

The disabling pathophysiologic effects of lipid and neuroprotective effects of statins have recently been demonstrated for acute spinal cord injuries in animal models. This large scale population-based study aimed to investigate the effect hyperlipidemia and the use of statins in patients with lumbar spine injury. The National Health Insurance Research Database of Taiwan was used to identify patients with lumbar spine injury. A total of 2844 patients were grouped into three: no hyperlipidemia, hyperlipidemia using low-dose of statins (≤90 of the defined daily dosage (DDD)), and severe hyperlipidemia using high-dose of statins (>90 DDD). A Cox multiple regression model was used to compare the incidence rates of disability among the three groups. The results showed that patients with hyperlipidemia appeared a higher risk of permanent disability (adjusted HR = 1.38, p = 0.28). In subgroup analysis, patients with severe hyperlipidemia had a higher risk of disability (adjusted HR = 3.1, p < 0.004), whereas hyperlipidemia using low-dose statins had a similar risk of permanently disability (adjusted HR = 0.83, p = 0.661). Hyperlipidemia adversely affected the neurological outcomes of lumbar spinal injury. Statins may have the potential to reverse this higher risk of disability. However, this beneficiary effect of statins only existed in patients using a lower dose (≤90 DDD).

Allicin protects spinal cord neurons from glutamate-induced oxidative stress through regulating the heat shock protein 70/inducible nitric oxide synthase pathway

Allicin, the main biologically active compound derived from garlic, exerts a broad spectrum of pharmacological activities and is considered to have therapeutic potential in many neurological disorders. Using an in vitro spinal cord injury model induced by glutamate treatment, we sought to investigate the neuroprotective effects of allicin in primary cultured spinal cord neurons. We found that allicin treatment significantly attenuated glutamate-induced lactate dehydrogenase (LDH) release, loss of cell viability and apoptotic neuronal death. This protection was associated with reduced oxidative stress, as evidenced by decreased reactive oxygen species (ROS) generation, reduced lipid peroxidation and preservation of antioxidant enzyme activities. The results of western blot analysis showed that allicin decreased the expression of inducible nitric oxide synthase (iNOS), but had no effects on the expression of neuronal NOS (nNOS) following glutamate exposure. Moreover, allicin treatment significantly increased the expression of heat shock protein 70 (HSP70) at both mRNA and protein levels. Knockdown of HSP70 by specific targeted small interfere RNA (siRNA) not only mitigated allicin-induced protective activity, but also partially nullified its effects on the regulation of iNOS. Collectively, these data demonstrate that allicin treatment may be an effective therapeutic strategy for spinal cord injury, and that the potential underlying mechanism involves HSP70/iNOS pathway-mediated inhibition of oxidative stress.

Single-dose rosuvastatin ameliorates lung ischemia-reperfusion injury via upregulation of endothelial nitric oxide synthase and inhibition of macrophage infiltration in rats with pulmonary hypertension

OBJECTIVE

Lung ischemia-reperfusion (IR) injury during cardiopulmonary surgery is associated with postoperative morbidity and mortality, particularly in patients with pulmonary hypertension (PH). Using a rat model for monocrotaline-induced PH, we investigated the protective effect of rosuvastatin against IR injury in lungs affected by PH and attempted to elucidate its mechanism of action.

METHODS

Male Sprague-Dawley monocrotaline-treated rats were divided into 4 groups (n = 8-9): sham, control + IR, statin + IR, and statin + mevalonolactone + IR. Lung ischemia was induced by left pulmonary artery occlusion (1 hour), followed by reperfusion (4 hours). Rosuvastatin (2 mg/kg) was injected 18 hours before reperfusion and mevalonolactone (1 mg/kg) was injected immediately before reperfusion. The arterial oxygen tension/inspired oxygen fraction ratio was used as a measure of lung oxygenation. Left lung tissue was analyzed for the wet-to-dry lung weight ratio and protein expression of endothelial nitric oxide synthase (eNOS) and phospho-eNOS. Macrophage recruitment was assessed by CD68 immunostaining.

RESULTS

Our results showed that rosuvastatin decreased IR lung injury (control + IR vs statin + IR) in terms of the arterial oxygen tension/inspired oxygen fraction ratio (272 ± 43 vs 442 ± 13), wet-to-dry ratio (5.7 ± 0.7 vs 4.8 ± 0.6), and macrophage infiltration (8.0 ± 0.6/field vs 4.0 ± 0.5/field) (P < .05 for all). eNOS and phospho-eNOS were downregulated by IR, which was blocked by rosuvastatin. Effects of rosuvastatin were blunted by mevalonolactone.

CONCLUSIONS

Single-dose rosuvastatin decreased IR injury in lungs affected by PH via 2 anti-inflammatory mechanisms: preserving eNOS function and inhibiting macrophage infiltration.

Neuroprotective effects of rosuvastatin against traumatic spinal cord injury in rats

Rosuvastatin, which is a potent statin, has never been studied in traumatic spinal cord injury. The aim of this study was to investigate whether rosuvastatin treatment could protect the spinal cord after experimental spinal cord injury. Rats were randomized into the following five groups of eight animals each: control, sham, trauma, rosuvastatin, and methylprednisolone. In the control group, no surgical intervention was performed. In the sham group, only laminectomy was performed. In all the other groups, the spinal cord trauma model was created by the occlusion of the spinal cord with an aneurysm clip. In the spinal cord tissue, caspase-3 activity, tumor necrosis factor-alpha levels, myeloperoxidase activity, malondialdehyde levels, nitric oxide levels, and superoxide dismutase levels were analyzed. Histopathological and ultrastructural evaluations were also performed. Neurological evaluation was performed using the Basso, Beattie, and Bresnahan locomotor scale and the inclined-plane test.After traumatic spinal cord injury, increases in caspase-3 activity, tumor necrosis factor-alpha levels, myeloperoxidase activity, malondialdehyde levels, and nitric oxide levels were detected. In contrast, the superoxide dismutase levels were decreased. After the administration of rosuvastatin, decreases were observed in the tissue caspase-3 activity, tumor necrosis factor-alpha levels, myeloperoxidase activity, malondialdehyde levels, and nitric oxide levels. In contrast, tissue superoxide dismutase levels were increased. Furthermore, rosuvastatin treatment showed improved results concerning the histopathological scores, the ultrastructural score and the functional tests. Biochemical, histopathological, ultrastructural analysis and functional tests revealed that rosuvastatin exhibits meaningful neuroprotective effects against spinal cord injury.

Preconditioning provides neuroprotection in models of CNS disease: paradigms and clinical significance

Preconditioning is a phenomenon in which brief episodes of a sublethal insult induce robust protection against subsequent lethal injuries. Preconditioning has been observed in multiple organisms and can occur in the brain as well as other tissues. Extensive animal studies suggest that the brain can be preconditioned to resist acute injuries, such as ischemic stroke, neonatal hypoxia/ischemia, surgical brain injury, trauma, and agents that are used in models of neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. Effective preconditioning stimuli are numerous and diverse, ranging from transient ischemia, hypoxia, hyperbaric oxygen, hypothermia and hyperthermia, to exposure to neurotoxins and pharmacological agents. The phenomenon of "cross-tolerance," in which a sublethal stress protects against a different type of injury, suggests that different preconditioning stimuli may confer protection against a wide range of injuries. Research conducted over the past few decades indicates that brain preconditioning is complex, involving multiple effectors such as metabolic inhibition, activation of extra- and intracellular defense mechanisms, a shift in the neuronal excitatory/inhibitory balance, and reduction in inflammatory sequelae. An improved understanding of brain preconditioning should help us identify innovative therapeutic strategies that prevent or at least reduce neuronal damage in susceptible patients. In this review, we focus on the experimental evidence of preconditioning in the brain and systematically survey the models used to develop paradigms for neuroprotection, and then discuss the clinical potential of brain preconditioning.

Osthole attenuates spinal cord ischemia-reperfusion injury through mitochondrial biogenesis-independent inhibition of mitochondrial dysfunction in rats

BACKGROUND

Osthole, the main bioactive compounds isolated from the traditional Chinese medical herb broad Cnidium monnieri (L.) cusson, has been shown to exert spectrum of pharmacologic activities. The aim of this study was to investigate the potential neuroprotective effects of osthole against spinal cord ischemia-reperfusion injury in rats.

MATERIALS AND METHODS

Osthole was administrated at the concentration of 0.1, 1, 10, 50, or 200 mg/kg (intraperitoneally) 1 h before spinal cord ischemia. The effects on spinal cord injury were measured by spinal cord water content, infarct volume, hematoxylin and eosin staining, and neurologic assessment. Mitochondria were purified from injured spinal cord tissue to determine mitochondrial function.

RESULTS

We found that treatment with osthole (10 and 50 mg/kg) significantly decreased spinal cord water content and infarct volume, preserved normal motor neurons, and improved neurologic functions. These protective effects can be also observed even if the treatment was delayed to 4 h after reperfusion. Osthole treatment preserved mitochondrial membrane potential level, reduced reactive oxygen species production, increased adenosine triphosphate generation, and inhibited cytochrome c release in mitochondrial samples. Moreover, osthole increased mitochondria respiratory chain complex activities in spinal cord tissue, with no effect on mitochondrial DNA content and the expression of mitochondrial-specific transcription factors.

CONCLUSIONS

All these findings demonstrate the neuroprotective effect of osthole in spinal cord ischemia-reperfusion injury model and suggest that oshtole-induced neuroprotection was mediated by mitochondrial biogenesis-independent inhibition of mitochondrial dysfunction.

Altered microRNA expression in the ischemic-reperfusion spinal cord with atorvastatin therapy

We explored the neuroprotection by atorvastatin in the ischemia/reperfusion model of rat and its microRNA-related mechanisms. At first, we uncovered a previously unknown alteration in temporal expression of a large set of microRNAs following spinal cord ischemia-reperfusion injury (IRI). The target genes for the differentially expressed microRNAs include genes encoding components that are involved in the inflammation, apoptosis, and neural damage that are known to play important roles in IRI. Atorvastatin pretreatment restored part of the up or down regulations. These findings suggest that altered expression of microRNAs may contribute to the mechanism of neuroprotection of statins in spinal cord IRI.

Simvastatin ameliorates cauda equina compression injury in a rat model of lumbar spinal stenosis

Lumbar spinal stenosis (LSS) is the leading cause of morbidity and mortality worldwide. LSS pathology is associated with secondary injury caused by inflammation, oxidative damage and cell death. Apart from laminectomy, pharmacological therapy targeting secondary injury is limited. Statins are FDA-approved cholesterol-lowering drug. They also show pleiotropic anti-inflammatory, antioxidant and neuroprotective effects. To investigate the therapeutic efficacy of simvastatin in restoring normal locomotor function after cauda equina compression (CEC) in a rat model of LSS, CEC injury was induced in rats by implanting silicone gels into the epidural spaces of L4 and L6. Experimental group was treated with simvastatin (5 mg/kg body weight), while the injured (vehicle) and sham operated (sham) groups received vehicle solution. Locomotor function in terms of latency on rotarod was measured for 49 days and the threshold of pain was determined for 14 days. Rats were sacrificed on day 3 and 14 and the spinal cord and cauda equina fibers were extracted and studied by histology, immunofluorescence, electron microscopy (EM) and TUNEL assay. Simvastatin aided locomotor functional recovery and enhanced the threshold of pain after the CEC. Cellular Infiltration and demyelination decreased in the spinal cord from the simvastatin group. EM revealed enhanced myelination of cauda equina in the simvastatin group. TUNEL assay showed significantly decreased number of apoptotic neurons in spinal cord from the simvastatin group compared to the vehicle group. Simvastatin hastens the locomotor functional recovery and reduces pain after CEC. These outcomes are mediated through the neuroprotective and anti-inflammatory properties of simvastatin. The data indicate that simvastatin may be a promising drug candidate for LSS treatment in humans.

Clinical application of preconditioning and postconditioning to achieve neuroprotection

Ischemic conditioning is a form of endogenous protection induced by transient, subcritical ischemia in a tissue. Organs with high sensitivity to ischemia, such as the heart, the brain, and spinal cord, represent the most critical and potentially promising targets for potential therapeutic applications of ischemic conditioning. Numerous preclinical investigations have systematically studied the molecular pathways and potential benefits of both pre- and postconditioning with promising results. The purpose of this review is to summarize the present knowledge on cerebral pre- and postconditioning, with an emphasis in the clinical application of these forms of neuroprotection. A systematic MEDLINE search for the terms preconditioning and postconditioning was performed. Publications related to the nervous system and to human applications were selected and analyzed. Pre- and postconditioning appear to provide similar levels of neuroprotection. The preconditioning window of benefit can be subdivided into early and late effects, depending on whether the effect appears immediately after the sublethal stress or with a delay of days. In general, early effects have been associated posttranslational modification of critical proteins (membrane receptors, mitochondrial respiratory chain) while late effects are the result of gene up- or downregulation. Transient ischemic attacks appear to represent a form of clinically relevant preconditioning by inducing ischemic tolerance in the brain and reducing the severity of subsequent strokes. Remote forms of ischemic pre- and postconditioning have been more commonly used in clinical studies, as the remote application reduces the risk of injuring the target tissue for which protection is pursued. Limb transient ischemia is the preferred method of induction of remote conditioning with evidence supporting its safety. Clinical studies in a variety of populations at risk of central nervous damage including carotid disease, cervical myelopathy, and subarachnoid hemorrhage have shown improvement in surrogate markers of injury. Promising preclinical and early clinical studies noting improvement in surrogate markers of central nervous injury after the use of remote pre- and postconditioning treatments demand follow-up systematic investigations to address effectiveness. Challenges in the application of these techniques to pressing clinical cerebrovascular disease ought to be overcome through careful, well-designed, translational investigations.

Expression of inducible nitric oxide synthase in muscle flaps treated with ischemic postconditioning

BACKGROUND/OBJECTIVE

Preconditioning has been considered promising for the treatment of ischemic flaps. In this study, the therapeutic effect of postconditioning was compared with that of preconditioning during ischemia/reperfusion (I/R) injury, and a role of inducible nitric oxide synthase (iNOS) in postconditioning treatment was also explored.

METHODS

Sixty rats were randomly divided into four groups with 15 rats in each group. Ischemic injury was induced in a rat's gracilis muscle flap model. Preconditioning and postconditioning were performed respectively on the flaps in the pre-con group and the post-con group. No treatment was given to the flaps in the control group, and flaps without I/R injury were used as a sham control. Muscle viability ratio, histology, and gene expression of iNOS were examined at different time intervals (3, 12, and 18 h).

RESULTS

A significantly higher survival ratio was observed in both the pre-con group (78.98 ± 3.39, 62.74 ± 3.7, and 54.42 ± 4.45 %) and the post-con group (77.42 ± 4.14, 59.74 ± 6.67, and 49.52 ± 4.13 %) than the control group (45.22 ± 3.69, 42.44 ± 3.76, and 33.2 ± 3.29 %) at 3, 12, and 18 h postoperatively (P < 0.05). There was no statistical difference between the pre-con group and the post-con group (P > 0.05). Histological examination showed delayed and attenuated tissue damage in both the pre-con group and the post-con group when compared to that of the control group. A higher expression of iNOS was observed in both the pre-con group and the post-con group than the control group and the sham group (P < 0.05).

CONCLUSIONS

Significant improvement of flap survival could be achieved by both preconditioning and postconditioning treatments; however, better protection could be provided by preconditioning. The higher expression of iNOS may play an important role in the therapeutic effect of postconditioning during I/R injury.

Neuroprotective effects of allicin on spinal cord ischemia-reperfusion injury via improvement of mitochondrial function in rabbits

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 beneficial effects of allicin against spinal cord ischemia-reperfusion (I/R) injury and its associated mechanisms. Male New Zealand white rabbits were pretreated with allicin (1, 10 and 50 mg/kg) for two weeks, and exposed to infrarenal aortic occlusion-induced spinal cord I/R injury. We found that allicin significantly reduced the volume of the spinal cord infarctions, improved the histopathologic features and increased the number of motor neurons in a dose-dependent manner. This protection was associated with an improvement in neurological function, which was measured by the hind-limb motor function scores. Furthermore, allicin also significantly suppressed the accumulations of protein and lipid peroxidation products, and increased the activities of endogenous antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione S-transferase (GST). In addition, allicin treatment preserved the function of mitochondria respiratory chain complexes and inhibited the production of ROS and the release of mitochondrial cytochrome c in the spinal cord of this model. Collectively, these findings demonstrated that allicin exerts neuroprotection against spinal cord I/R injury in rabbits, which may be associated with the improvement of mitochondrial function.

Current therapeutic strategies to mitigate the eNOS dysfunction in ischaemic stroke

Impairment of endothelial nitric oxide synthase (eNOS) activity is implicated in the pathogenesis of endothelial dysfunction in many diseases including ischaemic stroke. The modulation of eNOS during and/or following ischaemic injury often represents a futile compensatory mechanism due to a significant decrease in nitric oxide (NO) bioavailability coupled with dramatic increases in the levels of reactive oxygen species that further neutralise NO. However, applications of a number of therapeutic agents alone or in combination have been shown to augment eNOS activity under a variety of pathological conditions by potentiating the expression and/or activity of Akt/eNOS/NO pathway components. The list of these therapeutic agents include NO donors, statins, angiotensin-converting enzyme inhibitors, calcium channel blockers, phosphodiesterase-3 inhibitors, aspirin, dipyridamole and ellagic acid. While most of these compounds exhibit anti-platelet properties and are able to up-regulate eNOS expression in endothelial cells and platelets, others suppress eNOS uncoupling and tetrahydrobiopterin (an eNOS stabiliser) oxidation. As the number of therapeutic molecules that modulate the expression and activity of eNOS increases, further detailed research is required to reveal their mode of action in preventing and/or reversing the endothelial dysfunction.

Rosuvastatin, a new generation 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitor, reduces ischemia/reperfusion-induced spinal cord tissue injury in rats

BACKGROUND

Severe neurological injury still represents one of the most devastating complications occurring after surgical repair of thoracoabdominal aneurysms. We aimed to investigate the role of rosuvastatin (RSV) against ischemia/reperfusion injury in an experimental model of spinal cord ischemia in rats.

METHODS

Experimental groups included control group (n = 8), ischemia/reperfusion group (n = 8) undergoing aortic occlusion without pharmacologic treatment, and RSV-treated group (n = 8) receiving 10 mg/kg/day of RSV orally for 3 days before spinal cord ischemia. Spinal cord ischemia was induced by occlusion of the abdominal aorta between the left renal artery and aortic bifurcation for 45 minutes, followed by reperfusion. Neurological status was assessed before spinal ischemia and at 48 hours postoperatively. Spinal cords were harvested for histopathologic examination with hematoxylin-eosin staining and biochemical analysis for tissue malondialdehyde, superoxide dismutase, and glutathione peroxidase levels.

RESULTS

Decreased spinal cord tissue malondialdehyde levels (p = .01) and increased tissue superoxide dismutase (p = .01) and glutathione peroxidase (p = .09) levels were observed in the RSV-treated group, as compared with the ischemia group. Histopathologic analyses demonstrated typical changes of ischemic necrosis in the ischemia group; however, RSV attenuated tissue necrosis. Total injury score in the RSV-treated group was significantly decreased, as compared with the ischemia group (p < .05). The Tarlov scores at 48 hours postoperatively were higher in the RSV group as compared with the ischemia group.

CONCLUSION

RSV administration before spinal cord ischemia reduces spinal cord tissue injury by increasing antioxidant enzyme levels and may reduce the incidence of associated neurological dysfunction.