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

A novel pharmacological mechanism of anti-cancer drugs that induce pyroptosis

Pyroptosis is an inflammasome-induced lytic form of programmed cell death, and its main effect involves the release of inflammatory mediators when a cell dies, resulting in an inflammatory response in the body. The key to pyroptosis is the cleavage of GSDMD or other gasdermin families. Some drugs can cause cleavage GSDMD or other gasdermin members cause pyroptosis and suppress cancer growth and development. This review explores several drugs that may induce pyroptosis, thereby contributing to tumor treatment. Pyroptosis-inducing drugs, such as arsenic, platinum, and doxorubicin, were used originally in cancer treatment. Other pyroptosis-inducing drugs, such as metformin, dihydroartemisinin, and famotidine, were used to control blood glucose, treat malaria, and regulate blood lipid levels and are effective tumor treatments. By summarizing drug mechanisms, we provide a valuable basis for treating cancers by inducing pyroptosis. In future, the use of these drugs may contribute to new clinical treatments.

Role of integrating cannabinoids and the endocannabinoid system in neonatal hypoxic-ischaemic encephalopathy

Neonatal hypoxic-ischaemic events, which can result in long-term neurological impairments or even cell death, are among the most significant causes of brain injury during neurodevelopment. The complexity of neonatal hypoxic-ischaemic pathophysiology and cellular pathways make it difficult to treat brain damage; hence, the development of new neuroprotective medicines is of great interest. Recently, numerous neuroprotective medicines have been developed to treat brain injuries and improve long-term outcomes based on comprehensive knowledge of the mechanisms that underlie neuronal plasticity following hypoxic-ischaemic brain injury. In this context, understanding of the medicinal potential of cannabinoids and the endocannabinoid system has recently increased. The endocannabinoid system plays a vital neuromodulatory role in numerous brain regions, ensuring appropriate control of neuronal activity. Its natural neuroprotection against adult brain injury or acute brain injury also clearly demonstrate the role of endocannabinoid signalling in modulating neuronal activity in the adult brain. The goal of this review is to examine how cannabinoid-derived compounds can be used to treat neonatal hypoxic-ischaemic brain injury and to assess the critical function of the endocannabinoid system and its potential for use as a new neuroprotective treatment for neonatal hypoxic-ischaemic brain injury.

Peripheral immune cells and perinatal brain injury: a double-edged sword?

Perinatal brain injury is the leading cause of neurological mortality and morbidity in childhood ranging from motor and cognitive impairment to behavioural and neuropsychiatric disorders. Various noxious stimuli, including perinatal inflammation, chronic and acute hypoxia, hyperoxia, stress and drug exposure contribute to the pathogenesis. Among a variety of pathological phenomena, the unique developing immune system plays an important role in the understanding of mechanisms of injury to the immature brain. Neuroinflammation following a perinatal insult largely contributes to evolution of damage to resident brain cells, but may also be beneficial for repair activities. The present review will focus on the role of peripheral immune cells and discuss processes involved in neuroinflammation under two frequent perinatal conditions, systemic infection/inflammation associated with encephalopathy of prematurity (EoP) and hypoxia/ischaemia in the context of neonatal encephalopathy (NE) and stroke at term. Different immune cell subsets in perinatal brain injury including their infiltration routes will be reviewed and critical aspects such as sex differences and maturational stage will be discussed. Interactions with existing regenerative therapies such as stem cells and also potentials to develop novel immunomodulatory targets are considered. IMPACT: Comprehensive summary of current knowledge on the role of different immune cell subsets in perinatal brain injury including discussion of critical aspects to be considered for development of immunomodulatory therapies.

Simvastatin Prevents Neurodegeneration in the MPTP Mouse Model of Parkinson's Disease via Inhibition of A1 Reactive Astrocytes

Emerging evidence indicates that A1 reactive astrocytes play crucial roles in the pathogenesis of Parkinson's disease (PD). Thus, development of agents that could inhibit the formation of A1 reactive astrocytes could be used to treat PD. Simvastatin has been touted as a potential neuroprotective agent for neurologic disorders such as PD, but the specific underlying mechanism remains unclear. The 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD and primary astrocytes/neurons were prepared to investigate the effects of simvastatin on PD and its underlying mechanisms in vitro and in vivo. We show that simvastatin protects against the loss of dopamine neurons and behavioral deficits in the MPTP mouse model of PD. We also found that simvastatin suppressed the expression of A1 astrocytic specific markers in vivo and in vitro. In addition, simvastatin alleviated neuron death induced by A1 astrocytes. Our findings reveal that simvastatin is neuroprotective via the prevention of conversion of astrocytes to an A1 neurotoxic phenotype. In light of simvastatin favorable properties, it should be evaluated in the treatment of PD and related neurologic disorders characterized by A1 reactive astrocytes.

Recent Topics on The Mechanisms of Immunosuppressive Therapy-Related Neurotoxicities

Although transplantation procedures have been developed for patients with end-stage hepatic insufficiency or other diseases, allograft rejection still threatens patient health and lifespan. Over the last few decades, the emergence of immunosuppressive agents such as calcineurin inhibitors (CNIs) and mammalian target of rapamycin (mTOR) inhibitors have strikingly increased graft survival. Unfortunately, immunosuppressive agent-related neurotoxicity commonly occurs in clinical practice, with the majority of neurotoxicity cases caused by CNIs. The possible mechanisms through which CNIs cause neurotoxicity include increasing the permeability or injury of the blood–brain barrier, alterations of mitochondrial function, and alterations in the electrophysiological state. Other immunosuppressants can also induce neuropsychiatric complications. For example, mTOR inhibitors induce seizures, mycophenolate mofetil induces depression and headaches, methotrexate affects the central nervous system, the mouse monoclonal immunoglobulin G2 antibody (used against the cluster of differentiation 3) also induces headaches, and patients using corticosteroids usually experience cognitive alteration. Therapeutic drug monitoring, individual therapy based on pharmacogenetics, and early recognition of symptoms help reduce neurotoxic events considerably. Once neurotoxicity occurs, a reduction in the drug dosage, switching to other immunosuppressants, combination therapy with drugs used to treat the neuropsychiatric manifestation, or blood purification therapy have proven to be effective against neurotoxicity. In this review, we summarize recent topics on the mechanisms of immunosuppressive drug-related neurotoxicity. In addition, information about the neuroprotective effects of several immunosuppressants is also discussed.

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.

Simvastatin blocks soluble SSAO/VAP-1 release in experimental models of cerebral ischemia: Possible benefits for stroke-induced inflammation control

Beyond cholesterol reduction, statins mediate their beneficial effects on stroke patients through pleiotropic actions. They have shown anti-inflammatory properties by a number of different mechanisms, including the inhibition of NF-κB transcriptional activity and the consequent increase and release of adhesion molecules. We have studied simvastatin's effects on the vascular enzyme semicarbazide-sensitive amine oxidase/vascular adhesion protein 1 (SSAO/VAP-1), which is involved in stroke-mediated brain injury. SSAO/VAP-1 has leukocyte-binding capacity and mediates the expression of other adhesion proteins through signaling molecules generated by its catalytic activity. Our results indicate that soluble SSAO/VAP-1 is released into the bloodstream after an ischemic stimulus, in parallel with an increase in E-selectin and VCAM-1 and correlating with infarct volume. Simvastatin blocks soluble SSAO/VAP-1 release and prevents E-selectin and VCAM-1 overexpression as well. Simvastatin also effectively blocks SSAO/VAP-1-mediated leukocyte adhesion, although it is not an enzymatic inhibitor of SSAO in vitro. In addition, simvastatin-induced changes in adhesion molecules are greater in human brain endothelial cell cultures expressing SSAO/VAP-1, compared to those not expressing it, indicating some synergic effect with SSAO/VAP-1. We think that part of the beneficial effect of simvastatin in stroke is mediated by the attenuation of the SSAO/VAP-1-dependent inflammatory response.

Characterization of simvastatin acid uptake by organic anion transporting polypeptide 3A1 (OATP3A1) and influence of drug-drug interaction

Human organic anion transporting polypeptide 3A1 (OATP3A1) is predominately expressed in the heart. The ability of OATP3A1 to transport statins into cardiomyocytes is unknown, although other OATPs are known to mediate the uptake of statin drugs in liver. The pleiotropic effects and uptake of simvastatin acid were analyzed in primary human cardiomyocytes and HEK293 cells transfected with the OATP3A1 gene. Treatment with simvastatin acid reduced indoxyl sulfate-mediated reactive oxygen species and modulated OATP3A1 expression in cardiomyocytes and HEK293 cells transfected with the OATP3A1 gene. We observed a pH-dependent effect on OATP3A1 uptake, with more efficient simvastatin acid uptake at pH5.5 in HEK293 cells transfected with the OATP3A1 gene. The Michaelis-Menten constant (K_m) for simvastatin acid uptake by OATP3A1 was 0.017±0.002μM and the V_max was 0.995±0.027fmol/min/10⁵ cells. Uptake of simvastatin acid was significantly increased by known (benzylpenicillin and estrone-3-sulfate) and potential (indoxyl sulfate and cyclosporine) substrates of OATP3A1. In conclusion, the presence of OATP3A1 in cardiomyocytes suggests that this transporter may modulate the exposure of cardiac tissue to simvastatin acid due to its enrichment in cardiomyocytes. Increases in uptake of simvastatin acid by OATP3A1 when combined with OATP substrates suggest the potential for drug-drug interactions that could influence clinical outcomes.

Nutrients, Microglia Aging, and Brain Aging

As the life expectancy continues to increase, the cognitive decline associated with Alzheimer's disease (AD) becomes a big major issue in the world. After cellular activation upon systemic inflammation, microglia, the resident immune cells in the brain, start to release proinflammatory mediators to trigger neuroinflammation. We have found that chronic systemic inflammatory challenges induce differential age-dependent microglial responses, which are in line with the impairment of learning and memory, even in middle-aged animals. We thus raise the concept of “microglia aging.” This concept is based on the fact that microglia are the key contributor to the acceleration of cognitive decline, which is the major sign of brain aging. On the other hand, inflammation induces oxidative stress and DNA damage, which leads to the overproduction of reactive oxygen species by the numerous types of cells, including macrophages and microglia. Oxidative stress-damaged cells successively produce larger amounts of inflammatory mediators to promote microglia aging. Nutrients are necessary for maintaining general health, including the health of brain. The intake of antioxidant nutrients reduces both systemic inflammation and neuroinflammation and thus reduces cognitive decline during aging. We herein review our microglia aging concept and discuss systemic inflammation and microglia aging. We propose that a nutritional approach to controlling microglia aging will open a new window for healthy brain aging.

Combustion smoke-induced inflammation in the olfactory bulb of adult rats

BACKGROUND

The damaging effect of combustion smoke inhalation on the lung is widely reported but information on its effects on the olfactory bulb is lacking. This study sought to determine the effects of smoke inhalation on the olfactory bulb, whose afferent input neurons in the nasal mucosa are directly exposed to external stimuli, such as smoke.

METHODS

Adult male Sprague-Dawley rats were subjected to combustion smoke inhalation and sacrificed at different time points. Changes in olfactory bulb proteins including vascular endothelial growth factor (VEGF), inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), Na+-K+-Cl- cotransporter 1 (NKCC1), glial fibrillary acidic protein (GFAP), and aquaporin-4 (AQP4) were evaluated by Western blot analysis. In addition, ELISA was conducted for cytokine and chemokine levels, and double immunofluorescence labeling was carried out for GFAP/VEGF, GFAP/AQP4, NeuN/nNOS, GFAP/NKCC1, NeuN/NKCC1, GFAP/Rhodamine isothiocyanate (RITC), and transferase dUTP nick end labeling (TUNEL). Aminoguanidine was administered to determine the effects of iNOS inhibition on the targets probed after smoke inhalation.

RESULTS

The results showed a significant increase in VEGF, iNOS, eNOS, nNOS, NKCC1, and GFAP expression in the bulb tissues, with corresponding increases in inflammatory cytokines and chemokines after smoke inhalation. Concurrent to this was a drastic increase in AQP4 expression and RITC permeability. Aminoguanidine administration decreased the expression of iNOS and RITC extravasation after smoke inhalation. This was coupled with a significant reduction in incidence of TUNEL + cells that was not altered with administration of L-NG-nitroarginine methyl ester (L-NAME).

CONCLUSIONS

These findings suggest that the upregulation of iNOS in response to smoke inhalation plays a major role in the olfactory bulb inflammatory pathophysiology, along with a concomitant increase in pro-inflammatory molecules, vascular permeability, and edema. Overall, these findings indicate that the olfactory bulb is vulnerable to smoke inhalation.

Combustion smoke-induced inflammation in the cerebellum and hippocampus of adult rats

AIMS

The effect of combustion smoke inhalation on the respiratory system is widely reported but its effects on the central nervous system remain unclear. Here, we aimed to determine the effects of smoke inhalation on the cerebellum and hippocampus which are areas vulnerable to hypoxia injury.

METHODS

Adult male Sprague-Dawley rats were subjected to combustion smoke inhalation and sacrificed at 0.5, 3, 24 and 72 h after exposure. The cerebellum and hippocampus were subjected to Western analysis for VEGF, iNOS, eNOS, nNOS and AQP4 expression; ELISA analysis for cytokine and chemokine levels; and immunohistochemistry for GFAP/AQP4, RECA-1/RITC and TUNEL. Aminoguanidine (AG) was administered to determine the effects of iNOS after smoke inhalation.

RESULTS

Both the cerebellum and hippocampus showed a significant increase in VEGF, iNOS, eNOS, nNOS and AQP4 expression with corresponding increases in inflammatory cytokines and chemokines and increased AQP4 expression and RITC permeability after smoke exposure. AG was able to decrease the expression of iNOS, followed by VEGF, eNOS, nNOS, RITC and AQP4 after smoke exposure. There was also a significant increase in TUNEL+ cells in the cerebellum and hippocampus which were not significantly reduced by AG. Beam walk test revealed immediate deficits after smoke inhalation which was attenuated with AG.

CONCLUSION

The findings suggest that iNOS plays a major role in the central nervous system inflammatory pathophysiology after smoke inhalation exposure with concomitant increase in proinflammatory molecules, vascular permeability and oedema, for which the cerebellum appears to be more vulnerable to smoke exposure than the hippocampus.

Brazilian green propolis suppresses the hypoxia-induced neuroinflammatory responses by inhibiting NF-κB activation in microglia

Hypoxia has been recently proposed as a neuroinflammatogen, which drives microglia to produce proinflammatory cytokines, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-6. Considering the fact that propolis has hepatoprotective, antitumor, antioxidative, and anti-inflammatory effects, propolis may have protective effects against the hypoxia-induced neuroinflammatory responses. In this study, propolis (50 μg/mL) was found to significantly inhibit the hypoxia-induced cytotoxicity and the release of proinflammatory cytokines, including IL-1β, TNF-α, and IL-6, by MG6 microglia following hypoxic exposure (1% O2, 24 h). Furthermore, propolis significantly inhibited the hypoxia-induced generation of reactive oxygen species (ROS) from mitochondria and the activation of nuclear factor-κB (NF-κB) in microglia. Moreover, systemic treatment with propolis (8.33 mg/kg, 2 times/day, i.p.) for 7 days significantly suppressed the microglial expression of IL-1β, TNF-α, IL-6, and 8-oxo-deoxyguanosine, a biomarker for oxidative damaged DNA, in the somatosensory cortex of mice subjected to hypoxia exposure (10% O2, 4 h). These observations indicate that propolis suppresses the hypoxia-induced neuroinflammatory responses through inhibition of the NF-κB activation in microglia. Furthermore, increased generation of ROS from the mitochondria is responsible for the NF-κB activation. Therefore, propolis may be beneficial in preventing hypoxia-induced neuroinflammation.

Microglia-derived proinflammatory cytokines tumor necrosis factor-alpha and interleukin-1beta induce Purkinje neuronal apoptosis via their receptors in hypoxic neonatal rat brain

The developing cerebellum is extremely vulnerable to hypoxia which can damage the Purkinje neurons. We hypothesized that this might be mediated by tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) derived from activated microglia as in other brain areas. One-day-old rats were subjected to hypoxia following, which the expression changes of various proteins in the cerebellum including hypoxia inducible factor-1α, TNF-α, IL-1β, TNF-R1 and IL-1R1 were analyzed. Following hypoxic exposure, TNF-α and IL-1β immunoexpression in microglia was enhanced coupled by that of TNF-R1 and IL-1R1 in the Purkinje neurons. Along with this, hypoxic microglia in vitro showed enhanced release of TNF-α and IL-1β whose receptor expression was concomitantly increased in the Purkinje neurons. In addition, nitric oxide (NO) level was significantly increased in the cerebellum and cultured microglia subjected to hypoxic exposure. Moreover, cultured Purkinje neurons treated with conditioned medium derived from hypoxic microglia underwent apoptosis but the incidence was significantly reduced when the cells were treated with the same medium that was neutralized with TNF-α/IL-1β antibody. We conclude that hypoxic microglia in the neonatal cerebellum produce increased amounts of NO, TNF-α and IL-1β which when acting via their respective receptors could induce Purkinje neuron death.

Programmed Necrosis: A Prominent Mechanism of Cell Death following Neonatal Brain Injury

Despite the introduction of therapeutic hypothermia, neonatal hypoxic ischemic (HI) brain injury remains a common cause of developmental disability. Development of rational adjuvant therapies to hypothermia requires understanding of the pathways of cell death and survival modulated by HI. The conceptualization of the apoptosis-necrosis “continuum” in neonatal brain injury predicts mechanistic interactions between cell death and hydrid forms of cell death such as programmed or regulated necrosis. Many of the components of the signaling pathway regulating programmed necrosis have been studied previously in models of neonatal HI. In some of these investigations, they participate as part of the apoptotic pathways demonstrating clear overlap of programmed death pathways. Receptor interacting protein (RIP)-1 is at the crossroads between types of cellular death and survival and RIP-1 kinase activity triggers formation of the necrosome (in complex with RIP-3) leading to programmed necrosis. Neuroprotection afforded by the blockade of RIP-1 kinase following neonatal HI suggests a role for programmed necrosis in the HI injury to the developing brain. Here, we briefly review the state of the knowledge about the mechanisms behind programmed necrosis in neonatal brain injury recognizing that a significant proportion of these data derive from experiments in cultured cell and some from in vivo adult animal models. There are still more questions than answers, yet the fascinating new perspectives provided by the understanding of programmed necrosis in the developing brain may lay the foundation for new therapies for neonatal HI.

Apoptotic cell death correlates with ROS overproduction and early cytokine expression after hypoxia-ischemia in fetal lambs

Despite advances in neonatology, the hypoxic-ischemic injury in the perinatal period remains the single most important cause of brain injury in the newborn, leading to death or lifelong sequelae. Using a sheep model of intrauterine asphyxia, we evaluated the correlation between reactive oxygen species (ROS) overproduction, cytokine expression, and apoptotic cell death. Fetal lambs were assigned to sham group, nonasphyctic animals; and hypoxia-ischemia (HI) group, lambs subjected to 60 minutes of HI) by partial cord occlusion and sacrificed 3 hours later. Different brain regions were separated to quantify the number of apoptotic cells and the same territories were dissociated for flow cytometry studies. Our results suggest that the overproduction of ROS and the early increase in cytokine production after HI in fetal lambs correlate in a significant manner with the apoptotic index, as well as with each brain region evaluated.

Roles of activated microglia in hypoxia induced neuroinflammation in the developing brain and the retina

Amoeboid microglial cells (AMCs) in the developing brain display surface receptors and antigens shared by the monocyte-derived tissue macrophages. Activation of AMCs in the perinatal brain has been associated with periventricular white matter damage in hypoxic-ischemic conditions. The periventricular white matter, where the AMCs preponderate, is selectively vulnerable to hypoxia as manifested by death of premyelinating oligodendrocytes and degeneration of axons leading to neonatal mortality and long-term neurodevelopmental deficits. AMCs respond vigorously to hypoxia by producing excess amounts of inflammatory cytokines e.g. the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) along with glutamate, nitric oxide (NO) and reactive oxygen species which collectively cause oligodendrocyte death, axonal degeneration as well as disruption of the immature blood brain barrier. A similar phenomenon is observed in the hypoxic developing cerebellum in which activated AMCs induced Purkinje neuronal death through production of TNF-α and IL-1β via their respective receptors. Hypoxia is also implicated in retinopathy of prematurity in which activation of AMCs has been shown to cause retinal ganglion cell death through production of TNF-α and IL-1β and NO. Because AMCs play a pivotal role in hypoxic injuries in the developing brain affecting both neurons and oligodendrocytes, a fuller understanding of the underlying molecular mechanisms of microglial activation under such conditions would be desirable for designing of a novel therapeutic strategy for management of hypoxic damage.

Cannabinoid as a neuroprotective strategy in perinatal hypoxic-ischemic injury

Perinatal hypoxia-ischemia remains the single most important cause of brain injury in the newborn, leading to death or lifelong sequelae. Because of the fact that there is still no specific treatment for perinatal brain lesions due to the complexity of neonatal hypoxic-ischemic pathophysiology, the search of new neuroprotective therapies is of great interest. In this regard, therapeutic possibilities of the endocannabinoid system have grown lately. The endocannabinoid system modulates a wide range of physiological processes in mammals and has demonstrated neuroprotective effects in different paradigms of acute brain injury, acting as a natural neuroprotectant. Concerning perinatal asphyxia, the neuroprotective role of this endogenous system is emerging these years. The present review mainly focused on the current knowledge of the cannabinoids as a new neuroprotective strategy against perinatal hypoxic-ischemic brain injury.

Neuroprotective potentials of candesartan, atorvastatin and their combination against stroke induced motor dysfunction

Cerebral ischaemia is a leading cause of death and disability. The objective of the present investigation was to explore the neuroprotective potentials of candesartan and atorvastatin alone and their combination against the cerebral ischaemia induced behavioral, biochemical, and mitochondrial dysfunction. Male Wistar rats (200-220 g) were subjected to bilateral common carotid artery occlusion for 30 min followed by 24 h reperfusion. Candesartan (0.1 and 0.3 mg/kg) and atorvastatin (10 and 20 mg/kg) were pretreated for 7 days before animals were subjected to ischaemia reperfusion injury. Various behavioral tests (locomotor activity and rotarod performance), biochemical parameters (Malondialdehyde levels, nitrite concentration, superoxide dismutase and catalase activity, redox ratio, and GST) and mitochondrial enzyme (Complex I, II, III, and IV) dysfunctions were measured in cerebral cortex, striatum and hippocampus of the ischaemic brain. Seven days candesartan (0.1 and 0.3 mg/kg) or atorvastatin (10 and 20 mg/kg) pretreatment significantly attenuated neurobehavioral alterations, oxidative damage and restored mitochondrial enzyme dysfunction as compared to control (I/R) group. Further, combined treatment of candesartan (0.1 mg/kg) and atorvastatin (10 mg/kg) significantly potentiated their protective effect which was significant as compared to their effect alone. Present study suggests the protective effect of candesartan and atorvastatin and their combination against ischaemia reperfusion induced behavioral and biochemical alterations in rats.

Neuroprotective, immunosuppressant and antineoplastic properties of mTOR inhibitors: current and emerging therapeutic options

The acronym mTOR defines a family of serine-threonine protein kinase called mammalian target of rapamycin. The major role of these kinases in the cell is to merge extracellular instructions with information about cellular metabolic resources and to control the rate of anabolic and catabolic processes accordingly. In mammalian cells mTOR is present in two distinct heteromeric protein complexes commonly referred to as mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), involved in the control of a wide variety of cellular processes. It has been recently reported that compounds acting modulating mTOR activity, beside mediating the well recognized processes exploited in the anticancer and immunosuppressant effects, are provided with neuroprotective properties. In fact, mTOR is involved in the mechanism of PI3K/Akt-induced upregulation of glutamate transporter 1, GLT1, that is linked to several neuronal disorders such as stroke, Alzheimer's disease, and amyotrophic lateral sclerosis. Furthermore, in adult brain mTOR is crucial for numerous physiological processes such as synaptic plasticity, learning, memory, and brain control of food uptake. Moreover, the activation of mTOR pathway is involved in neuronal development, dendrite development and spine morphogenesis.

Synergistic benefits of erythropoietin and simvastatin after traumatic brain injury

Simvastatin and recombinant human erythropoietin (rhEpo) are implicated as potential therapeutic candidates for traumatic brain injury (TBI). Prominent effects of simvastatin include its anti-inflammatory, neurotrophic and neuroregenerative actions studied in various models of neuronal injury. On the other hand, rhEpo has been shown to promote cell survival mechanisms by producing anti-apoptotic and cell proliferative actions. Beneficial effects of rhEpo and statin monotherapies have been well studied. However, there are no reports showing combined use of rhEpo and statins after TBI. This investigation examined if combined efficacy of cell proliferative ability of rhEpo along with the neuroregenerative ability of simvastatin will render maximum recovery in a controlled cortical impact (CCI) mouse model of TBI. Results showed that compared to baseline TBI, rhEpo was more effective than simvastatin in promoting cell proliferation while simvastatin was more effective than rhEpo in restoring axonal damage following TBI. Combined treatment with simvastatin and rhEpo maximally restored axonal integrity while simultaneously inducing greater proliferation of newly formed cells resulting in better functional recovery after TBI than either alone. This is the first study showing the efficacy of erythropoietin-simvastatin combinational therapeutic approach in achieving greater structural and cognitive recovery after TBI.

Simvastatin attenuates hypomyelination induced by hypoxia-ischemia in neonatal rats

OBJECTIVES

Simvastatin, the most widely used cholesterol-lowering drug, has been reported to protect the adult brain from ischemia. Nevertheless, little is known about its action on developing brain after stroke. Although a few reports have found recently that simvastatin displays anti-inflammation and anti-apoptosis properties and improves the cognitive and morphological consequences in the neonatal rats after hypoxia-ischemia (HI) damage, to our best knowledge, there has been no study of the effect of it on myelin formation after neonatal brain damage. Therefore, we investigated whether simvastatin could promote the myelination of oligodendrocytes in the neonatal rats after HI and explored the possible role of microglial responses in this process.

METHODS

Postnatal day 7 Sprague-Dawley rats were subjected to HI. White matter integrity and myelination were evaluated by the densitometry of myelin basic protein (MBP) immunostaining. OX-42 immunoreactivity and nissl staining were used for identifying microglial responses and the structure changes of white matter and adjacent gray matter after HI. Simvastatin was administrated prophylactically to rats.

RESULTS

HI induced serious hypomyelination especially in external and internal capsules 3 and 7 days after HI, accompanying with microglial activation remarkably. Simvastatin treatment greatly increased the densities of MBP immunostaining, inhibited microglial activation and reduced the numbers of pyknotic cells and neuronal loss.

DISCUSSION

The present study shows that simvastatin treatment in neonatal rats attenuates HI-induced developing oligodendrocytes injury and hypomyelination. Its anti-inflammatory properties via suppression of microglial activation are likely to contribute to this action. It provides experimental evidence to support the neuroprotective effects of statins in neonatal ischemic stroke.

Systemic hypotheses for generalized cognitive deficits in schizophrenia: a new take on an old problem

The schizophrenia research community, including government, industry, and academia, has made development of procognitive treatment strategies a priority. Much current research is directed at dividing broad impairments in cognition into more delineated components that might correspond to relatively specific neural systems and serve as targets for intervention. Sometimes overlooked in this ambitious agenda is the substantial neuropsychological literature that signals a more broadly generalized dysfunction in higher order cognitive functions in this illness. In this article, we argue that a generalized cognitive deficit is at the core of the disorder, is not a methodological artifact, and deserves more focused consideration from cognitive specialists in the field. Further, we weigh evidence that this broad deficit may have systemic biological underpinnings. At the level of the central nervous system, examples of findings that might help to account for broad cognitive impairment include gray and white matter irregularities, poor signal integration by neurons and neural networks, and abnormalities in glutamate and gamma-aminobutyric acid neurotransmission. Other, more speculative hypotheses focus on even broader somatic systems, including energy metabolism and inflammatory processes. Treatment implications of systemic conceptualizations of schizophrenia are also considered.

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.

Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases

BACKGROUND

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation.

REVIEW

We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here.

CONCLUSION

Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.

Acute treatment with rosuvastatin protects insulin resistant (C57BL/6J ob/ob) mice against transient cerebral ischemia

The purpose of this study was to investigate the short-term effects of rosuvastatin (RSV), a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on transient, focal cerebral ischemia in C57BL/6J ob/ob mice with insulin resistance (IR). Male ob/ob, lean, or wild-type (WT) mice were treated with RSV (10 mg/kg per day, i.p.) or vehicle for 3 days. Ischemia was induced by 60 mins of middle cerebral artery occlusion (MCAO) and cortical blood flow (CBF) was monitored by laser-Doppler flowmetry. Infarct volumes were measured 24 h after reperfusion. IR mice exhibited a higher infarct volume compared with Lean or WT mice, and RSV reduced infarct volume only in obese mice (40%+/-3% versus 32%+/-3%, P<0.05). Blood cholesterol and insulin levels were elevated in ob/ob mice but were unaffected by RSV. The CBF reductions during MCAO were similar in all groups and were not affected by RSV. Although RSV did not increase cortical endothelial NO synthase (eNOS) levels in the ob/ob mice, it attenuated the increased cortical expression of intracellular adhesion molecule-1 (ICAM-1) after MCAO from ob/ob mice. Thus, RSV protects against stroke in IR mice by a mechanism independent of effects on the lipid profile, CBF, or eNOS but dependent on suppression of post-MCAO ICAM-1 expression.

Increase in phosphorylation of Akt and its downstream signaling targets and suppression of apoptosis by simvastatin after traumatic brain injury

OBJECT

In their previous studies, the authors found that simvastatin treatment of traumatic brain injury (TBI) in rats had beneficial effects on spatial learning functions. In the current study they wanted to determine whether simvastatin suppressed neuronal cell apoptosis after TBI, and if so, they wanted to examine the underlying mechanisms of this process.

METHODS

Saline or simvastatin (1 mg/kg) was administered orally to rats starting on Day 1 after TBI and then daily for 14 days. Modified Neurological Severity Scores were used to evaluate the sensory motor functional recovery. Rats were killed at 1, 3, 7, 14, and 35 days after treatment, and brain tissue was harvested for terminal deoxynucleotidyl nick-end labeling (TUNEL) staining, caspase-3 activity assay, and Western blot analysis.

RESULTS

Simvastatin significantly decreased the modified Neurological Severity Scores from Days 7 to 35 after TBI, significantly reduced the number of TUNEL-positive cells at Day 3, suppressed the caspase-3 activity at Days 1 and 3 after TBI, and increased phosphorylation of Akt as well as Forkhead transcription factor 1, inhibitory-kappaB, and endothelial nitric oxide synthase, which are the downstream targets of the prosurvival Akt signaling protein.

CONCLUSIONS

These data suggested that simvastatin reduces the apoptosis in neuronal cells and improves the sensory motor function recovery after TBI. These beneficial effects of simvastatin may be mediated through activation of Akt, Forkhead transcription factor 1 and nuclear factor-kappaB signaling pathways, which suppress the activation of caspase-3 and apoptotic cell death, and thereby, lead to neuronal function recovery after TBI.

Amoeboid microglia in the periventricular white matter induce oligodendrocyte damage through expression of proinflammatory cytokines via MAP kinase signaling pathway in hypoxic neonatal rats

Hypoxic injury in the perinatal period results in periventricular white matter (PWM) lesions with axonal damage and oligodendroglial loss. It also alters macrophage function by perpetuating expression of inflammatory mediators. Relevant to this is the preponderance of amoeboid microglial cells (AMC) characterized as active macrophages in the developing PWM. This study aimed to determine if AMC produce proinflammatory cytokines that may be linked to the oligodendroglial loss observed in hypoxic PWM damage (PWMD). Wistar rats (1 day old) were subjected to hypoxia, following which upregulated expression of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), TNF receptor 1 (TNF-R(1)) and IL-1 receptor 1 (IL-1R(1)) was observed. This was coupled with apoptosis and expression of TNF-R(1) and IL-1R(1) in oligodendrocytes. Primary cultured microglial cells subjected to hypoxia (3% oxygen, 5% CO(2) and 92% nitrogen) showed enhanced expression of TNF-alpha and IL-1beta. Furthermore, mitogen-activated protein (MAP) kinase signaling pathway was involved in the expression of TNF-alpha and IL-1beta in microglia subjected to hypoxia. Our results suggest that following a hypoxic insult, microglial cells in the neonatal rats produce inflammatory cytokines such as TNF-alpha and IL-1beta via MAP kinase signaling pathway. These cytokines are detrimental to oligodendrocytes resulting in PWM lesion.

Extended role of necrotic cell death after hypoxia–ischemia-induced neurodegeneration in the neonatal rat

The relative contribution of apoptosis and necrosis after neonatal hypoxia-ischemia (HI) is still a matter of debate. Here we determined the time course of necrotic cell death after neonatal HI and its relationship to caspase-3 activation and apoptotic cell death. Necrosis was evaluated by intracerebroventricular injection of propidium iodide (PI) before sacrificing the animal and processing brain sections for caspase-3 immunohistochemistry and TUNEL assay. PI-positive cells were found starting from 30 min after HI and increased rapidly in different brain areas. PI co-localized with the neuronal-specific nuclear marker NeuN but not with GFAP indicating that the dye label neurons with damaged plasma membrane but not reactive astrocytes. In the cerebral cortex 24 h after HI, the superficial layers showed cells with strong caspase-3 and TUNEL staining and with nuclei having apoptotic morphology whereas the deep layers of the cortex and the hippocampus showed cells with necrotic features. At later times, cells of the superficial layers were positive to PI, caspase-3, TUNEL and cathepsin-B. These data indicate that necrosis has an extended role in the progression of brain injury after neonatal HI and that a different spectrum of suicidal programs can be activated in the same cell. The extended period of caspase-3 activation in PI-positive necrotic cells supports the possibility that the apoptotic-to-necrotic continuum may ensue as the result of an incomplete execution of the apoptotic program.

Statins: multiple mechanisms of action in the ischemic brain

Although substantial epidemiological studies have failed to find a correlation between cholesterol levels and stroke, clinical trials have shown that HMG-CoA reductase inhibitors (or statins, the most potent hypocholesterolemic drugs available) greatly reduce the incidence of stroke. These clinical observations have opened the way to a number of studies of the non-cholesterol-dependent (or pleiotropic) effects in animal models of stroke, indicating that the neuroprotection is attributable to multiple activities. One of the main protective mechanisms elicited by statin administration is the increase in nitric oxide bioavailability that regulates cerebral perfusion and improves endothelial function, but others include antioxidant properties, the inhibition of inflammatory responses, immunomodulatory actions, the regulation of progenitor cells, and the stabilization of atherosclerotic plaques. Many of these effects are due to the inhibited synthesis of isoprenoid intermediates, which serve as lipid attachments for a variety of intracellular signaling molecules. This article describes the mechanisms involved in the neuroprotective effects of statins.

Bcl-2 upregulation and neuroprotection in guinea pig brain following chronic simvastatin treatment

The present study determined if chronic simvastatin administration in vivo would provide neuroprotection in brain cells isolated from guinea pigs after challenge with the Bcl-2 inhibitor HA 14-1 or the NO donor sodium nitroprusside (SNP). Bcl-2 levels were significantly increased in brains of simvastatin-treated guinea pigs while levels of the pro-apoptotic protein Bax were significantly reduced. The ratio of Bax/Bcl-2, being a critical factor of the apoptotic state of cells, was significantly reduced in simvastatin-treated animals. Cholesterol levels in the brain remained unchanged in the simvastatin group. Brain cells isolated from simvastatin-treated guinea pigs were significantly less vulnerable to mitochondrial dysfunction and caspase-activation. These results provide new insight into potential mechanisms for the protective actions of statins within the CNS where programmed cell death has been implicated.

Simvastatin protects neurons from cytotoxicity by up-regulating Bcl-2 mRNA and protein

Statins are most commonly prescribed to reduce hypercholesterolemia; however, recent studies have shown that statins have additional benefits, including neuroprotection. Until now, the mechanism underlying statin-induced neuroprotection has been poorly understood. Recent in vivo studies from our lab reported the novel finding that simvastatin increased expression levels of a gene encoding for a major cell survival protein, bcl-2 [Johnson-Anuna et al., J. Pharmacol. Exp. Ther.312 (2005) 786]. The purpose of the present experiments was to determine if simvastatin could protect neurons from excitotoxicity by altering Bcl-2 levels. Neurons were pre-treated with simvastatin and challenged with a compound known to reduce Bcl-2 levels and induce cell death. Simvastatin pre-treatment resulted in a significant reduction in cytotoxicity (lactate dehydrogenase release and caspase 3 activation) following challenge compared with unchallenged neurons. In addition, chronic simvastatin treatment significantly increased Bcl-2 mRNA and protein levels while challenge resulted in a significant reduction in Bcl-2 protein abundance. G3139, an antisense oligonucleotide directed against Bcl-2, abolished the protective effects of simvastatin and eliminated simvastatin-induced up-regulation of Bcl-2 protein. These findings suggest that neuroprotection by simvastatin is dependent on the drug's previously unexplored and important effect of up-regulating Bcl-2.

Postnatal nicotine and/or intermittent hypercapnic hypoxia effects on apoptotic markers in the developing piglet brainstem medulla

The most important risk factors currently identified for the sudden infant death syndrome (SIDS) are prone sleeping and cigarette smoke exposure. In this study, we investigated the neuropathological sequelae of these risk factors by exposing piglets to intermittent hypercapnic-hypoxia (IHH) and/or nicotine (nic) in the early postnatal period. Our hypothesis was that either nic or IHH exposure could increase neuronal cell death, and that combined exposure (nic+IHH) would be additive. Four exposure patterns were studied: controls (n=14), IHH (n=10), nic (n=14), and nic+IHH (n=14). All groups had equal gender ratios. Nic exposure via an implanted osmotic minipump commenced within 48 h of birth and continued until age 13-14 days when animals were killed and brains collected. A total of 48 min of hypercapnic-hypoxia was delivered on the day immediately prior to killing in a pattern comprising 6 min of HH (8% O(2), 7% CO(2), balance N(2)) alternating with 6 min of air. Immunohistochemistry was performed to identify neurons positive for active caspase-3 and DNA fragmentation (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, TUNEL) in seven nuclei of the caudal medulla. Staining quantification showed that: 1. IHH induced neuronal death (increased both TUNEL and casapse-3) in more brainstem nuclei than nicotine. 2. Females were more severely affected by IHH than males. 3. Where IHH and nicotine were combined, TUNEL expression was approximately 5% less than IHH alone, but changes in caspase-3 were variable. We conclude that acute exposure to IHH in the postnatal period is more neurotoxic than exposure to nicotine alone. Combined exposure to IHH and nicotine produced variable responses with some results suggesting that nicotine can be neuroprotective. These results indicate that environmental insults attributable to prone sleeping can produce neurotoxic sequelae in SIDS, with some regional specificity in the response. However, no consistent relationship is evident when combining the two insults.