Mediators of blood-brain barrier dysfunction and formation of vasogenic brain edema

Differential Vulnerability and Response to Injury among Brain Cell Types Comprising the Neurovascular Unit

The neurovascular unit (NVU) includes multiple different cell types, including neurons, astrocytes, endothelial cells, and pericytes, which respond to insults on very different time or dose scales. We defined differential vulnerability among these cell types, using response to two different insults: oxygen-glucose deprivation (OGD) and thrombin-mediated cytotoxicity. We found that neurons are most vulnerable, followed by endothelial cells and astrocytes. After temporary focal cerebral ischemia in male rats, we found significantly more injured neurons, compared with astrocytes in the ischemic area, consistent with differential vulnerability in vivo. We sought to illustrate different and shared mechanisms across all cell types during response to insult. We found that gene expression profiles in response to OGD differed among the cell types, with a paucity of gene responses shared by all types. All cell types activated genes relating to autophagy, apoptosis, and necroptosis, but the specific genes differed. Astrocytes and endothelial cells also activated pathways connected to DNA repair and antiapoptosis. Taken together, the data support the concept of differential vulnerability in the NVU and suggest that different elements of the unit will evolve from salvageable to irretrievable on different time scales while residing in the same brain region and receiving the same (ischemic) blood flow. Future work will focus on the mechanisms of these differences. These data suggest future stroke therapy development should target different elements of the NVU differently.

Nanodelivery of histamine H3 receptor inverse agonist BF-2649 with H3 receptor antagonist and H4 receptor agonist clobenpropit induced neuroprotection is potentiated by antioxidant compound H-290/51 in spinal cord injury

Military personnel are often victims of spinal cord injury resulting in lifetime disability and decrease in quality of life. However, no suitable therapeutic measures are still available to restore functional disability or arresting the pathophysiological progression of disease in victims for leading a better quality of life. Thus, further research in spinal cord injury using novel strategies or combination of available neuroprotective drugs is urgently needed for superior neuroprotection. In this regard, our laboratory is engaged in developing TiO2 nanowired delivery of drugs, antibodies and enzymes in combination to attenuate spinal cord injury induced pathophysiology and functional disability in experimental rodent model. Previous observations show that histamine antagonists or antioxidant compounds when given alone in spinal cord injury are able to induce neuroprotection for short periods after trauma. In this investigation we used a combination of histaminergic drugs with antioxidant compound H-290/51 using their nanowired delivery for neuroprotection in spinal cord injury of longer duration. Our observations show that a combination of H3 receptor inverse agonist BF-2549 with H3 receptor antagonist and H4 receptor agonist clobenpropit induced neuroprotection is potentiated by antioxidant compound H-290/51 in spinal cord injury. These observations suggests that histamine receptors are involved in the pathophysiology of spinal cord injury and induce superior neuroprotection in combination with an inhibitor of lipid peroxidation H-290/51, not reported earlier. The possible mechanisms and significance of our findings in relation to future clinical approaches in spinal cord injury is discussed.

Sleep deprivation enhances amyloid beta peptide, p-tau and serotonin in the brain: Neuroprotective effects of nanowired delivery of cerebrolysin with monoclonal antibodies to amyloid beta peptide, p-tau and serotonin

Sleep deprivation is quite frequent in military during combat, intelligence gathering or peacekeeping operations. Even one night of sleep deprivation leads to accumulation of amyloid beta peptide burden that would lead to precipitation of Alzheimer's disease over the years. Thus, efforts are needed to slow down or neutralize accumulation of amyloid beta peptide (AβP) and associated Alzheimer's disease brain pathology including phosphorylated tau (p-tau) within the brain fluid environment. Sleep deprivation also alters serotonin (5-hydroxytryptamine) metabolism in the brain microenvironment and impair upregulation of several neurotrophic factors. Thus, blockade or neutralization of AβP, p-tau and serotonin in sleep deprivation may attenuate brain pathology. In this investigation this hypothesis is examined using nanodelivery of cerebrolysin- a balanced composition of several neurotrophic factors and active peptide fragments together with monoclonal antibodies against AβP, p-tau and serotonin (5-hydroxytryptamine, 5-HT). Our observations suggest that sleep deprivation induced pathophysiology is significantly reduced following nanodelivery of cerebrolysin together with monoclonal antibodies to AβP, p-tau and 5-HT, not reported earlier.

Nanodelivery of Histamine H3/H4 Receptor Modulators BF-2649 and Clobenpropit with Antibodies to Amyloid Beta Peptide in Combination with Alpha Synuclein Reduces Brain Pathology in Parkinson's Disease

Parkinson's disease (PD) in military personnel engaged in combat operations is likely to develop in their later lives. In order to enhance the quality of lives of PD patients, exploration of novel therapy based on new research strategies is highly warranted. The hallmarks of PD include increased alpha synuclein (ASNC) and phosphorylated tau (p-tau) in the cerebrospinal fluid (CSF) leading to brain pathology. In addition, there are evidences showing increased histaminergic nerve fibers in substantia niagra pars compacta (SNpc), striatum (STr), and caudate putamen (CP) associated with upregulation of histamine H3 receptors and downregulation of H4 receptors in human brain. Previous studies from our group showed that modulation of potent histaminergic H3 receptor inverse agonist BF-2549 or clobenpropit (CLBPT) partial histamine H4 agonist with H3 receptor antagonist induces neuroprotection in PD brain pathology. Recent studies show that PD also enhances amyloid beta peptide (AβP) depositions in brain. Keeping these views in consideration in this review, nanowired delivery of monoclonal antibodies to AβP together with ASNC and H3/H4 modulator drugs on PD brain pathology is discussed based on our own observations. Our investigation shows that TiO₂ nanowired BF-2649 (1 mg/kg, i.p.) or CLBPT (1 mg/kg, i.p.) once daily for 1 week together with nanowired delivery of monoclonal antibodies (mAb) to AβP and ASNC induced superior neuroprotection in PD-induced brain pathology. These observations are the first to show the modulation of histaminergic receptors together with antibodies to AβP and ASNC induces superior neuroprotection in PD. These observations open new avenues for the development of novel drug therapies for clinical strategies in PD.

Drug Delivery Systems as a Strategy to Improve the Efficacy of FDA-Approved Alzheimer's Drugs

Alzheimer's disease (AD) is the most common form of dementia, with a high impact worldwide, accounting for more than 46 million cases. The continuous increase of AD demands the fast development of preventive and curative therapeutic strategies that are truly effective. The drugs approved for AD treatment are classified into acetylcholinesterase inhibitors and N-methyl-D-aspartate receptor antagonists. The therapeutic effectiveness of those drugs is hindered by their restricted access to the brain due to the blood-brain barrier, low bioavailability, and poor pharmacokinetic properties. In addition, the drugs are reported to have undesirable side effects. Several drug delivery systems (DDSs) have been widely exploited to address these issues. DDSs serve as drug carriers, combining the ability to deliver drugs locally and in a targeted manner with the ability to release them in a controlled and sustained manner. As a result, the pharmacological therapeutic effectiveness is raised, while the unwanted side effects induced by the unspecific distribution decrease. This article reviews the recently developed DDSs to increase the efficacy of Food and Drug Administration-approved AD drugs.

Blood-Brain Barrier Alterations and Edema Formation in Different Brain Mass Lesions

Differential diagnosis of brain lesion pathologies is complex, but it is nevertheless crucial for appropriate clinical management. Advanced imaging methods, including diffusion-weighted imaging and apparent diffusion coefficient, can help discriminate between brain mass lesions such as glioblastoma, brain metastasis, brain abscesses as well as brain lymphomas. These pathologies are characterized by blood-brain barrier alterations and have been extensively studied. However, the changes in the blood-brain barrier that are observed around brain pathologies and that contribute to the development of vasogenic brain edema are not well described. Some infiltrative brain pathologies such as glioblastoma are characterized by glioma cell infiltration in the brain tissue around the tumor mass and thus affect the nature of the vasogenic edema. Interestingly, a common feature of primary and secondary brain tumors or tumor-like brain lesions characterized by vasogenic brain edema is the formation of various molecules that lead to alterations of tight junctions and result in blood-brain barrier damage. The resulting vasogenic edema, especially blood-brain barrier disruption, can be visualized using advanced magnetic resonance imaging techniques, such as diffusion-weighted imaging and apparent diffusion coefficient. This review presents a comprehensive overview of blood-brain barrier changes contributing to the development of vasogenic brain edema around glioblastoma, brain metastases, lymphomas, and abscesses.

Transcellular routes of blood-brain barrier disruption

Disruption of the blood-brain barrier (BBB) can occur through different mechanisms and pathways. As these pathways result in increased permeability to different classes of substances, it is likely that the neurological insults that occur will also differ for these pathways. The major categories of BBB disruption are paracellular (between cells) and transcellular (across cells) with a subcategory of transcellular leakage involving vesicles (transcytotic). Older literature, as well as more recent studies, highlights the importance of the transcellular pathways in BBB disruption. Of the various transcytotic mechanisms that are thought to be active at the BBB, some are linked to receptor-mediated transcytosis, whereas others are likely involved in BBB disruption. For most capillary beds, transcytotic mechanisms are less clearly linked to permeability than are membrane spanning canaliculi and fenestrations. Disruption pathways share cellular mechanisms to some degree as exemplified by transcytotic caveolar and transcellular canaliculi formations. The discovery of some of the cellular components involved in transcellular mechanisms of BBB disruption and the ability to measure them are adding greatly to our classic knowledge, which is largely based on ultrastructural studies. Future work will likely address the conditions and diseases under which the various pathways of disruption are active, the different impacts that they have, and the cellular biology that underlies the different pathways to disruption.

Histamine H3 and H4 receptors modulate Parkinson's disease induced brain pathology. Neuroprotective effects of nanowired BF-2649 and clobenpropit with anti-histamine-antibody therapy

Military personnel deployed in combat operations are highly prone to develop Parkinson's disease (PD) in later lives. PD largely involves dopaminergic pathways with hallmarks of increased alpha synuclein (ASNC), and phosphorylated tau (p-tau) in the cerebrospinal fluid (CSF) precipitating brain pathology. However, increased histaminergic nerve fibers in substantia nigra pars Compacta (SNpc), striatum (STr) and caudate putamen (CP) associated with upregulation of Histamine H3 receptors and downregulation of H4 receptors in human cases of PD is observed in postmortem cases. These findings indicate that modulation of histamine H3 and H4 receptors and/or histaminergic transmission may induce neuroprotection in PD induced brain pathology. In this review effects of a potent histaminergic H3 receptor inverse agonist BF-2549 or clobenpropit (CLBPT) partial histamine H4 agonist with H3 receptor antagonist, in association with monoclonal anti-histamine antibodies (AHmAb) in PD brain pathology is discussed based on our own observations. Our investigation shows that chronic administration of conventional or TiO₂ nanowired BF 2649 (1mg/kg, i.p.) or CLBPT (1mg/kg, i.p.) once daily for 1 week together with nanowired delivery of HAmAb (25μL) significantly thwarted ASNC and p-tau levels in the SNpC and STr and reduced PD induced brain pathology. These observations are the first to show the involvement of histamine receptors in PD and opens new avenues for the development of novel drug strategies in clinical strategies for PD, not reported earlier.

Blood-brain barrier models: Rationale for selection

Brain delivery is a broad research area, the outcomes of which are far hindered by the limited permeability of the blood-brain barrier (BBB). Over the last century, research has been revealing the BBB complexity and the crosstalk between its cellular and molecular components. Pathologically, BBB alterations may precede as well as be concomitant or lead to brain diseases. To simulate the BBB and investigate options for drug delivery, several in vitro, in vivo, ex vivo, in situ and in silico models are used. Hundreds of drug delivery vehicles successfully pass preclinical trials but fail in clinical settings. Inadequate selection of BBB models is believed to remarkably impact the data reliability leading to unsatisfactory results in clinical trials. In this review, we suggest a rationale for BBB model selection with respect to the addressed research question and downstream applications. The essential considerations of an optimal BBB model are discussed.

Physiology of the cerebrovascular adaptation to pregnancy

The adaptation of the cerebral circulation to pregnancy is unique compared with other organs and circulatory systems, because the brain requires relatively constant blood flow and water and solute composition to maintain homeostasis. Thus, a major adaptation of the maternal cerebrovasculature to pregnancy is to maintain normalcy in the face of expanded plasma volume, increased cardiac output, and high levels of permeability factors. In this chapter, the effect of pregnancy on critical functions of the cerebral circulation is discussed, including changes occurring at the endothelium and blood-brain barrier (BBB), which protect the maternal brain from changes in BBB permeability. Further, pregnancy-induced changes in the structure and function of cerebral arteries, arterioles, and veins will be discussed as they relate to cerebral vascular resistance, hemodynamics, and cerebral blood flow autoregulation.

Posterior reversible encephalopathy syndrome: A neuropsychiatric manifestation of systemic lupus erythematosus

Posterior Reversible Encephalopathy Syndrome (PRES) is an acute neurological syndrome clinically characterized by seizures, altered mental status, headache, and visual disturbances. It is caused by a variety of abnormalities in the endothelial function that ultimately result in vasogenic edema in the circulation of the central nervous system. This is reflected by the neuroimaging findings, that most often show reversible parieto-occipital edema. An important proportion of patients with PRES present with Systemic Lupus Erythematosus (SLE), and its complications, as their sole risk factors. This review describes the relationship between these two clinical entities and explains the pathophysiological models that have been proposed to describe the development of PRES. We explain how SLE can cause alterations in every pathway implicated in the development of PRES. Given the relatively high frequency and the distinct clinical course, PRES in the setting of SLE might be best described as a distinct neuropsychiatric syndrome associated with SLE.

Mild traumatic brain injury exacerbates Parkinson's disease induced hemeoxygenase-2 expression and brain pathology: Neuroprotective effects of co-administration of TiO2 nanowired mesenchymal stem cells and cerebrolysin

Mild traumatic brain injury (mTBI) is one of the leading predisposing factors in the development of Parkinson's disease (PD). Mild or moderate TBI induces rapid production of tau protein and alpha synuclein (ASNC) in the cerebrospinal fluid (CSF) and in several brain areas. Enhanced tau-phosphorylation and ASNC alters the molecular machinery of the brain leading to PD pathology. Recent evidences show upregulation of constitutive isoform of hemeoxygenase (HO-2) in PD patients that correlates well with the brain pathology. mTBI alone induces profound upregulation of HO-2 immunoreactivity. Thus, it would be interesting to explore whether mTBI exacerbates PD pathology in relation to tau, ASNC and HO-2 expression. In addition, whether neurotrophic factors and stem cells known to reduce brain pathology in TBI could induce neuroprotection in PD following mTBI. In this review role of mesenchymal stem cells (MSCs) and cerebrolysin (CBL), a well-balanced composition of several neurotrophic factors and active peptide fragments using nanowired delivery in PD following mTBI is discussed based on our own investigation. Our results show that mTBI induces concussion exacerbates PD pathology and nanowired delivery of MSCs and CBL induces superior neuroprotection. This could be due to reduction in tau, ASNC and HO-2 expression in PD following mTBI, not reported earlier. The functional significance of our findings in relation to clinical strategies is discussed.

Diabetes exacerbates brain pathology following a focal blast brain injury: New role of a multimodal drug cerebrolysin and nanomedicine

Blast brain injury (bBI) is a combination of several forces of pressure, rotation, penetration of sharp objects and chemical exposure causing laceration, perforation and tissue losses in the brain. The bBI is quite prevalent in military personnel during combat operations. However, no suitable therapeutic strategies are available so far to minimize bBI pathology. Combat stress induces profound cardiovascular and endocrine dysfunction leading to psychosomatic disorders including diabetes mellitus (DM). This is still unclear whether brain pathology in bBI could exacerbate in DM. In present review influence of DM on pathophysiology of bBI is discussed based on our own investigations. In addition, treatment with cerebrolysin (a multimodal drug comprising neurotrophic factors and active peptide fragments) or H-290/51 (a chain-breaking antioxidant) using nanowired delivery of for superior neuroprotection on brain pathology in bBI in DM is explored. Our observations are the first to show that pathophysiology of bBI is exacerbated in DM and TiO₂-nanowired delivery of cerebrolysin induces profound neuroprotection in bBI in DM, not reported earlier. The clinical significance of our findings with regard to military medicine is discussed.

Concussive head injury exacerbates neuropathology of sleep deprivation: Superior neuroprotection by co-administration of TiO2-nanowired cerebrolysin, alpha-melanocyte-stimulating hormone, and mesenchymal stem cells

Sleep deprivation (SD) is common in military personnel engaged in combat operations leading to brain dysfunction. Military personnel during acute or chronic SD often prone to traumatic brain injury (TBI) indicating the possibility of further exacerbating brain pathology. Several lines of evidence suggest that in both TBI and SD alpha-melanocyte-stimulating hormone (α-MSH) and brain-derived neurotrophic factor (BDNF) levels decreases in plasma and brain. Thus, a possibility exists that exogenous supplement of α-MSH and/or BDNF induces neuroprotection in SD compounded with TBI. In addition, mesenchymal stem cells (MSCs) are very portent in inducing neuroprotection in TBI. We examined the effects of concussive head injury (CHI) in SD on brain pathology. Furthermore, possible neuroprotective effects of α-MSH, MSCs and neurotrophic factors treatment were explored in a rat model of SD and CHI. Rats subjected to 48h SD with CHI exhibited higher leakage of BBB to Evans blue and radioiodine compared to identical SD or CHI alone. Brain pathology was also exacerbated in SD with CHI group as compared to SD or CHI alone together with a significant reduction in α-MSH and BDNF levels in plasma and brain and enhanced level of tumor necrosis factor-alpha (TNF-α). Exogenous administration of α-MSH (250μg/kg) together with MSCs (1×10⁶) and cerebrolysin (a balanced composition of several neurotrophic factors and active peptide fragments) (5mL/kg) significantly induced neuroprotection in SD with CHI. Interestingly, TiO₂ nanowired delivery of α-MSH (100μg), MSCs, and cerebrolysin (2.5mL/kg) induced enhanced neuroprotection with higher levels of α-MSH and BDNF and decreased the TNF-α in SD with CHI. These observations are the first to show that TiO₂ nanowired administration of α-MSH, MSCs and cerebrolysin induces superior neuroprotection following SD in CHI, not reported earlier. The clinical significance of our findings in light of the current literature is discussed.

Biological effects of inhaled hydraulic fracturing sand dust VII. Neuroinflammation and altered synaptic protein expression

Hydraulic fracturing (fracking) is a process used to recover oil and gas from shale rock formation during unconventional drilling. Pressurized liquids containing water and sand (proppant) are used to fracture the oil- and natural gas-laden rock. The transportation and handling of proppant at well sites generate dust aerosols; thus, there is concern of worker exposure to such fracking sand dusts (FSD) by inhalation. FSD are generally composed of respirable crystalline silica and other minerals native to the geological source of the proppant material. Field investigations by NIOSH suggest that the levels of respirable crystalline silica at well sites can exceed the permissible exposure limits. Thus, from an occupational safety perspective, it is important to evaluate the potential toxicological effects of FSD, including any neurological risks. Here, we report that acute inhalation exposure of rats to one FSD, i.e., FSD 8, elicited neuroinflammation, altered the expression of blood brain barrier-related markers, and caused glial changes in the olfactory bulb, hippocampus and cerebellum. An intriguing observation was the persistent reduction of synaptophysin 1 and synaptotagmin 1 proteins in the cerebellum, indicative of synaptic disruption and/or injury. While our initial hazard identification studies suggest a likely neural risk, more research is necessary to determine if such molecular aberrations will progressively culminate in neuropathology/neurodegeneration leading to behavioral and/or functional deficits.

The role of neutrophils in mediating stroke injury in the diabetic db/db mouse brain following hypoxia-ischemia

Diabetic mice exhibit increased mortality and morbidity following stroke. Recent studies from our laboratory have indicated that increased morbidity in diabetic db/db mice relative to their non-diabetic db/+ littermates is associated with increased levels of MMP-9 protease activity, increased blood-brain barrier (BBB) permeability, and greater neutrophil infiltration following hypoxic/ischemic (H/I) insult. Neutrophils are a major source of proteases and reactive oxygen species and studies have reported neutrophil depletion/inhibition is protective in certain models of experimental stroke. The objective of the current study is to determine the role of neutrophils in the increased morbidity seen in db/db mice following acute ischemic stroke. In this study, we found a significant increase in circulating neutrophils in the db/db mice at 4 h post H/I, which bound to endothelial cells in the ipsilateral hemisphere and infiltrated into brain tissue by 24 h of recovery. Depletion of circulating neutrophils resulted in reduced neutrophil concentrations in blood and in the ipsilateral hemispheres of the brain of both db/+ and db/db mice and decreased the levels of MMP-9 within the infarcted area. This resulted in smaller infarct size in the db/db mice compared to non-treated controls but did not affect stroke outcome in db/+ mice. While there was a significant correlation between neutrophil number and the levels of MMP-9 in the ipsilateral hemisphere of control and diabetic mice, surprisingly, neutrophil depletion had no effect on BBB permeability in either group. Thus, the current study suggests that neutrophil depletion reduces MMP-9 protease levels and improves stroke outcome in db/db mice but not in their db/+ counterparts.

Polymeric Nanoparticles for the Treatment of Malignant Gliomas

Malignant gliomas are one of the deadliest forms of brain cancer and despite advancements in treatment, patient prognosis remains poor, with an average survival of 15 months. Treatment using conventional chemotherapy does not deliver the required drug dose to the tumour site, owing to insufficient blood brain barrier (BBB) penetration, especially by hydrophilic drugs. Additionally, low molecular weight drugs cannot achieve specific accumulation in cancerous tissues and are characterized by a short circulation half-life. Nanoparticles can be designed to cross the BBB and deliver their drugs within the brain, thus improving their effectiveness for treatment when compared to administration of the free drug. The efficacy of nanoparticles can be enhanced by surface PEGylation to allow more specificity towards tumour receptors. This review will provide an overview of the different therapeutic strategies for the treatment of malignant gliomas, risk factors entailing them as well as the latest developments for brain drug delivery. It will also address the potential of polymeric nanoparticles in the treatment of malignant gliomas, including the importance of their coating and functionalization on their ability to cross the BBB and the chemistry underlying that.

Loading Amlodipine on Diamond Nanoparticles: A Novel Drug Delivery System

Background

Diamond nanoparticles (Nanodiamond) are biocompatible drug delivery platforms with outstanding surface properties. Their passage into the brain has been confirmed previously. Thus, nanodiamond could provide a drug delivery system to shuttle several drugs through the blood-brain barrier (BBB) which represents a real challenge for the effective delivery of several drugs into the brain. Amlodipine is a calcium channel blocker that cannot pass through BBB and may elicit neuroprotective effects to reverse calcium-induced excitotoxicity and mitochondrial dysfunction that underlie several neurologic disorders including Alzheimer’s disease and stroke.

Aim

The study aimed to investigate the loading of amlodipine on nanodiamond particles.

Methods

Nanodiamond particles were oxidized in a strong oxidizing acidic mixture of sulfuric and nitric acids. Adsorption of amlodipine on nanodiamond particles was achieved in alkaline pH using various concentrations of sodium hydroxide. The loaded amlodipine was determined by high-performance liquid chromatography and confirmed by Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy.

Results

The highest percentage (41%) of loaded amlodipine onto nanodiamond particles was achieved in alkaline medium using 2 mM NaOH at a corresponding pH of 8.5. Also, characteristic FTIR bands of amlodipine and nanodiamond were shown obviously in the nanodiamond–amlodipine conjugates. Moreover, the successful loading of amlodipine on diamond nanoparticles was confirmed by transmission electron microscopy.

Conclusion

The present study demonstrates the successful loading of amlodipine onto nanodiamond particles. These findings offer a potential for applying diamond nanoparticles as a drug delivery system to shuttle amlodipine into the brain and open the door to deliver other similar drugs into the brain.

Anesthetics influence concussive head injury induced blood-brain barrier breakdown, brain edema formation, cerebral blood flow, serotonin levels, brain pathology and functional outcome

Several lines of evidences show that anesthetics influence neurotoxicity and neuroprotection. The possibility that different anesthetic agents potentially influence the pathophysiological and functional outcome following neurotrauma was examined in a rat model of concussive head injury (CHI). The CHI was produced by an impact of 0.224N on the right parietal bone by dropping a weight of 114.6g from a 20cm height under different anesthetic agents, e.g., inhaled ether anesthesia or intraperitoneally administered ketamine, pentobarbital, equithesin or urethane anesthesia. Five hour CHI resulted in profound volume swelling and brain edema formation in both hemispheres showing disruption of the blood-brain barrier (BBB) to Evans blue and radioiodine. A marked decrease in the cortical CBF and a profound increase in plasma or brain serotonin levels were seen at this time. Neuronal damages were present in several parts of the brain. These pathological changes were most marked in CHI under ether anesthesia followed by ketamine (35mg/kg, i.p.), pentobarbital (50mg/kg, i.p.), equithesin (3mL/kg, i.p.) and urethane (1g/kg, i.p.). The functional outcome on Rota Rod performances or grid walking tests was also most adversely affected after CHI under ether anesthesia followed by pentobarbital, equithesin and ketamine. Interestingly, the plasma and brain serotonin levels strongly correlated with the development of brain edema in head injured animals in relation to different anesthetic agents used. These observations suggest that anesthetic agents are detrimental to functional and pathological outcomes in CHI probably through influencing the circulating plasma and brain serotonin levels, not reported earlier. Whether anesthetics could also affect the efficacy of different neuroprotective agents in CNS injuries is a new subject that is currently being examined in our laboratory.

Synaptic plasticity in area CA1 of rat hippocampal slices following intraventricular application of albumin

Epileptogenesis following insults to the brain may be triggered by a dysfunctional blood-brain barrier (BBB) associated with albumin extravasation and activation of astrocytes. Using ex vivo recordings from the BBB-disrupted hippocampus after neocortical photothrombotic stroke, we previously demonstrated abnormal activity-dependent accumulation of extracellular potassium with facilitated generation of seizure like events and spreading depolarizations. Similar changes could be observed after intracerebroventricular (icv) application of albumin. We hypothesized that alterations in extracellular potassium and glutamate homeostasis might lead to alterations in synaptic interactions. We therefore assessed the effects of icv albumin on homo- and heterosynaptic plasticity in hippocampal CA1, 24h after a single injection or 7days after continuous infusion of icv albumin. We demonstrate alterations in both homo- and heterosynaptic plasticity compared to control conditions in ex vivo slice studies. Albumin-treated tissue reveals (1) reduced long-term depression following low-frequency stimulation; (2) increased long-term potentiation of population spikes in response to 20Hz stimulation; (3) potentiated responses to Schaffer collateral stimulation following high-frequency stimulation of the direct cortical input and low-frequency stimulation of alveus and finally, (4) TGFβ receptor II (TGFβR-II) involvement in albumin-induced homosynaptic plasticity changes. We conclude that albumin-induced network hyperexcitability is associated with abnormal homo- and heterosynaptic plasticity that could partly be reversed by interference with TGFβR-II-mediated signaling and therefore it might be an important factor in the process of epileptogenesis.

From blood-brain barrier to blood-brain interface: new opportunities for CNS drug delivery

One of the biggest challenges in the development of therapeutics for central nervous system (CNS) disorders is achieving sufficient blood-brain barrier (BBB) penetration. Research in the past few decades has revealed that the BBB is not only a substantial barrier for drug delivery to the CNS but also a complex, dynamic interface that adapts to the needs of the CNS, responds to physiological changes, and is affected by and can even promote disease. This complexity confounds simple strategies for drug delivery to the CNS, but provides a wealth of opportunities and approaches for drug development. Here, I review some of the most important areas that have recently redefined the BBB and discuss how they can be applied to the development of CNS therapeutics.

The cerebral circulation during pregnancy: adapting to preserve normalcy

The adaptation of the brain and cerebral circulation to pregnancy are unique compared with other organs and circulatory systems, ultimately functioning to maintain brain homeostasis. In this review, the effect of pregnancy on critical functions of the cerebral circulation is discussed, including changes occurring at the endothelium and blood-brain barrier, and changes in the structure and function of cerebral arteries and arterioles, hemodynamics, and cerebral blood flow autoregulation.

Nanoparticles for brain drug delivery

The central nervous system, one of the most delicate microenvironments of the body, is protected by the blood-brain barrier (BBB) regulating its homeostasis. BBB is a highly complex structure that tightly regulates the movement of ions of a limited number of small molecules and of an even more restricted number of macromolecules from the blood to the brain, protecting it from injuries and diseases. However, the BBB also significantly precludes the delivery of drugs to the brain, thus, preventing the therapy of a number of neurological disorders. As a consequence, several strategies are currently being sought after to enhance the delivery of drugs across the BBB. Within this review, the recently born strategy of brain drug delivery based on the use of nanoparticles, multifunctional drug delivery systems with size in the order of one-billionth of meters, is described. The review also includes a brief description of the structural and physiological features of the barrier and of the most utilized nanoparticles for medical use. Finally, the potential neurotoxicity of nanoparticles is discussed, and future technological approaches are described. The strong efforts to allow the translation from preclinical to concrete clinical applications are worth the economic investments.

Drug delivery to the brain in Alzheimer's disease: consideration of the blood-brain barrier

The successful treatment of Alzheimer's disease (AD) will require drugs that can negotiate the blood-brain barrier (BBB). However, the BBB is not simply a physical barrier, but a complex interface that is in intimate communication with the rest of the central nervous system (CNS) and influenced by peripheral tissues. This review examines three aspects of the BBB in AD. First, it considers how the BBB may be contributing to the onset and progression of AD. In this regard, the BBB itself is a therapeutic target in the treatment of AD. Second, it examines how the BBB restricts drugs that might otherwise be useful in the treatment of AD and examines strategies being developed to deliver drugs to the CNS for the treatment of AD. Third, it considers how drug penetration across the AD BBB may differ from the BBB of normal aging. In this case, those differences can complicate the treatment of CNS diseases such as depression, delirium, psychoses, and pain control in the AD population.

Methylmethacrylate-sulfopropylmethacrylate nanoparticles with surface RMP-7 for targeting delivery of antiretroviral drugs across the blood-brain barrier

This study investigates the capability of methylmethacrylate-sulfopropylmethacrylate (MMA-SPM) nanoparticles (NPs) with grafted RMP-7 (RMP-7/MMA-SPM NPs) to deliver stavudine (D4T), delavirdine (DLV), and saquinavir (SQV) across the blood-brain barrier (BBB). The permeability coefficients of the three drugs across the BBB were evaluated by a co-culture model containing human brain-microvascular endothelial cells and human astrocytes. An increase in the concentration of ammonium persulfate (APS), the polymerization initiator, enhanced the particle size of drug-loaded RMP-7/MMA-SPM NPs. When the concentration of APS was 0.6%, the average particle diameter was smaller than 50 nm. These spherical drug carriers were uniform in size and displayed a dominant topography of discrete hillocks and deep pits in deposited film. Smaller RMP-7/MMA-SPM NPs yielded a larger drug loading efficiency. The order of drug in the loading efficiency and in the particle uptake was, respectively, D4T>DLV>SQV and D4T>SQV>DLV. Endocytosis of RMP-7/MMA-SPM NPs and tight junction mediation can improve the permeability of D4T, DLV, and SQV across the BBB.

Seizures in Women with Preeclampsia: Mechanisms and Management

Eclampsia is defined in the obstetrical literature as the occurrence of unexplained seizure during pregnancy in a woman with preeclampsia. In the Western world, the incidence of eclampsia is ~1 per 2000 to 1 per 3000 pregnancies, but the incidence is 10-fold higher in tertiary referral centers and undeveloped countries where there is poor prenatal care, and in multi-fetal gestations. Nearly 1 in 50 women with eclampsia die as do 1 in 14 of their offspring, and mortality rates are considerably higher in undeveloped countries. Eclampsia is also associated with significant life-threatening complications, including neurological events. Seizure acutely can cause stroke, haemorrhage, oedema and brain herniation and thus lead to epilepsy and cognitive impairment later in life.

Pigment epithelium-derived factor inhibits vascular endothelial growth factor-and interleukin-1beta-induced vascular permeability and angiogenesis in retinal endothelial cells

Increased vascular permeability associated with retinal vascular leakage is known to occur in patients with diabetes, and contributes to endothelial barrier dysfunction. The purpose of this study was to examine the effect of pigment epithelium-derived factor (PEDF) on signaling cascade in porcine retinal endothelial cells (PREC) related to permeability and angiogenesis induced by vascular endothelial growth factor (VEGF)-and interleukin-1beta (IL-1beta). PREC were exposed to VEGF, IL-1beta and PEDF at different concentrations, and in vitro permeability was assessed by solute flux assay using 70-kDa RITC-dextran. Angiogenic assays such as proliferation, migration and tube formation were determined by MTT, wound-scratch method and on-gel assay system respectively. To explore the signaling pathways behind VEGF-and IL-1beta-induced PREC permeability, an inhibitor assay was carried out using PP2, a Src kinase inhibitor. Further, Src activity was assessed by transient transfection assay using constitutively active (CA) and dominant negative (DN) Src mutants. We report that VEGF-and IL-1beta-stimulates permeability, in a dose and time-dependent manner and PEDF inhibits the VEGF-and IL-1beta-induced PREC permeability. In addition, PEDF inhibits the VEGF-and IL-1beta-induced endothelial cell proliferation, migration and tube formation. In addition, overexpression of DN Src blocked both VEGF-and IL-1beta-stimulation of permeability, proliferation and migration, while overexpression of CA Src overpowers the inhibitory action of PEDF on permeability, proliferation and migration. These results demonstrate that PEDF may inhibit the VEGF-and IL-1beta-induced permeability and angiogenesis via Src-dependent pathway.

Pathology and new players in the pathogenesis of brain edema

Brain edema continues to be a major cause of mortality after diverse types of brain pathologies such as major cerebral infarcts, hemorrhages, trauma, infections and tumors. The classification of edema into vasogenic, cytotoxic, hydrocephalic and osmotic has stood the test of time although it is recognized that in most clinical situations there is a combination of different types of edema during the course of the disease. Basic information about the types of edema is provided for better understanding of the expression pattern of some of the newer molecules implicated in the pathogenesis of brain edema. These molecules include the aquaporins, matrix metalloproteinases and growth factors such as vascular endothelial growth factors A and B and the angiopoietins. The potential of these agents in the treatment of edema is discussed. Since many molecules are involved in the pathogenesis of brain edema, effective treatment cannot be achieved by a single agent but will require the administration of a "magic bullet" containing a variety of agents released at different times during the course of edema in order to be successful.

The Cerebral Endothelium During Pregnancy: A Potential Role in the Development of Eclampsia

The authors investigated the influence of pregnancy on cerebral endothelial cell permeability in response to an acute elevation in intravascular pressure that caused forced dilatation of myogenic tone. Third-order branches of the posterior cerebral artery (PCA) were dissected from nonpregnant (NP) and late-pregnant (LP, days 19 to 20) Sprague-Dawley rats and mounted on glass cannulas in an arteriograph chamber that allowed control over intravascular pressure and measurement of both diameter and permeability to fluorescent dextran (3000 Da). Permeability was determined at 75 mm Hg and after a step increase in pressure to 200 mm Hg. The extent of pinocytosis and transcellular transport in response to pressure was evaluated separately in the same groups of animals at 75 and 200 mm Hg using transmission electron microscopy. All arteries developed myogenic tone at 75 mm Hg that was lost when pressure was increased to 200 mm Hg to cause forced dilatation. The increased pressure caused a significant increase in permeability to dextran and enhanced pinocytosis in arteries from LP animals, but not in NP animals whose permeability remained constant at both pressures. These results suggest a pregnancy-specific effect on the cerebral endothelium that may promote enhanced vascular permeability during acute hypertension and may contribute to the edema formation and neurologic complications of eclampsia.

Recent advances in understanding the molecular basis of group B Streptococcus virulence

Group B Streptococcus commonly colonises healthy adults without symptoms, yet under certain circumstances displays the ability to invade host tissues, evade immune detection and cause serious invasive disease. Consequently, Group B Streptococcus remains a leading cause of neonatal pneumonia, sepsis and meningitis. Here we review recent information on the bacterial factors and mechanisms that direct host-pathogen interactions involved in the pathogenesis of Group B Streptococcus infection. New research on host signalling and inflammatory responses to Group B Streptococcus infection is summarised. An understanding of the complex interplay between Group B Streptococcus and host provides valuable insight into pathogen evolution and highlights molecular targets for therapeutic intervention.

Noninvasive molecular neuroimaging using reporter genes: part II, experimental, current, and future applications

SUMMARY

In this second article, we review the various strategies and applications that make use of reporter genes for molecular imaging of the brain in living subjects. These approaches are emerging as valuable tools for monitoring gene expression in diverse applications in laboratory animals, including the study of gene-targeted and trafficking cells, gene therapies, transgenic animals, and more complex molecular interactions within the central nervous system. Further development of more sensitive and selective reporters, combined with improvements in detection technology, will consolidate the position of in vivo reporter gene imaging as a versatile technique for greater understanding of intracellular biologic processes and underlying molecular neuropathology and will potentially establish a future role in the clinical management of patients with neurologic diseases.

Post-ischaemic treatment with the cyclooxygenase-2 inhibitor nimesulide reduces blood-brain barrier disruption and leukocyte infiltration following transient focal cerebral ischaemia in rats

Several studies suggest that cyclooxygenase (COX)-2 plays a pivotal role in the progression of ischaemic brain damage. In the present study, we investigated the effects of selective inhibition of COX-2 with nimesulide (12 mg/kg) and selective inhibition of COX-1 with valeryl salicylate (VAS, 12-120 mg/kg) on prostaglandin E(2) (PGE(2)) levels, myeloperoxidase (MPO) activity, Evans blue (EB) extravasation and infarct volume in a standardized model of transient focal cerebral ischaemia in the rat. Post-ischaemic treatment with nimesulide markedly reduced the increase in PGE(2) levels in the ischaemic cerebral cortex 24 h after stroke and diminished infarct size by 48% with respect to vehicle-treated animals after 3 days of reperfusion. Furthermore, nimesulide significantly attenuated the blood-brain barrier (BBB) damage and leukocyte infiltration (as measured by EB leakage and MPO activity, respectively) seen at 48 h after the initial ischaemic episode. These studies provide the first experimental evidence that COX-2 inhibition with nimesulide is able to limit BBB disruption and leukocyte infiltration following transient focal cerebral ischaemia. Neuroprotection afforded by nimesulide is observed even when the treatment is delayed until 6 h after the onset of ischaemia, confirming a wide therapeutic window of COX-2 inhibitors in experimental stroke. On the contrary, selective inhibition of COX-1 with VAS had no significant effect on the evaluated parameters. These data suggest that COX-2 activity, but not COX-1 activity, contributes to the progression of focal ischaemic brain injury, and that the beneficial effects observed with non-selective COX inhibitors are probably associated to COX-2 rather than to COX-1 inhibition.

Effect of Edaravone, a Free Radical Scavenger, on Ischemic Cerebral Edema Assessed by Magnetic Resonance Imaging

The anti-edema effect of edaravone, a free radical scavenger, was evaluated by magnetic resonance imaging in six patients with extensive hemispheric ischemic stroke. T(2) relaxation time in the infarct core, the boundary zone of the infarct, and the noninfarcted hemisphere were calculated, and T(2) mapping was performed before and after edaravone administration. Edaravone administration significantly decreased the mean T(2) relaxation time in the boundary zone of the infarct from 121.5 +/- 9.2 (mean +/- standard deviation) to 114.5 +/- 9.9 msec (p = 0.008), but not in the core from 142.3 +/- 13.4 to 142.2 +/- 18.5 msec (p = 0.97) or the noninfarcted hemisphere from 93.0 +/- 3.7 to 93.1 +/- 3.8 msec (p = 0.91). The T(2) subtraction map clearly demonstrated shortened T(2) relaxation time in the boundary zone of the infarct. The present results indicate that edaravone can salvage the boundary zone of the infarct and is a useful cytoprotective anti-edema agent.

A Potent Serotonin-Modulating Compound AP-267 Attenuates Morphine Withdrawal-Induced Blood-Brain Barrier Dysfunction in Rats

The possibility that a serotonin 5-HT2c receptor-modulating compound, AP-267, will influence spontaneous morphine withdrawal symptoms and the alterations in the brain fluid microenvironment was examined in a rat model. Daily administration of morphine (10 mg/kg, i.p.) for 10 days resulted in dependence of rats as seen by loss of analgesic response. On the 11th day, no morphine administration was given. This resulted in profound withdrawal symptoms 24 h after morphine withdrawal. The magnitude and severity of these symptoms were increased further 48 h after withdrawal. Measurement of the blood-brain barrier (BBB) permeability, a measure of perturbed brain fluid microenvironment showed leakage of Evans blue and radioiodine tracers in several parts of the brain in rats showing withdrawal symptoms. Whereas, rats treated with AP-267 either on the 1st day or 2nd day morphine withdrawal showed much less symptoms and leakage of the BBB. Taken together, these observations suggest that (a) stress associated with the withdrawal symptoms are sufficient enough to induce breakdown of the BBB function, and (b) modulation of serotonin 5-HT2c receptors may have some protective influence on the stress symptoms and the BBB disruption.

Histamine receptors influence blood-spinal cord barrier permeability, edema formation, and spinal cord blood flow following trauma to the rat spinal cord

The role of histamine in edema formation, blood-spinal cord barrier (BSCB) permeability, and spinal cord blood flow (SCBF) following spinal cord injury (SCI) was examined using modulation of histamine H1, H2, and H3 receptors in the rat. Focal trauma to the spinal cord at the T10-11 level significantly increased spinal cord edema formation, BSCB permeability to protein tracers and SCBF reduction in the T9 and T12 segments. Pretreatment with histamine H1 receptor antagonist mepyramine (1 mg, 5 mg, and 10 mg/kg, i.p.) did not attenuate spinal pathophysiology following SCI. Blockade of histamine H2 receptors with cimetidine or ranitidine (1 mg, 5 mg, or 10 mg/kg 30 minutes before injury) significantly reduced early pathophysiological events in a dose dependent manner. The effects of ranitidine were far superior to cimetidine in identical doses. Pretreatment with a histamine H3 receptor agonist alpha-methylhistamine (1 mg and 2 mg/kg/i.p.), that inhibits histamine synthesis and release in the CNS, thwarted edema formation, BSCB breakdown, and SCBF disturbances after SCI. The lowest dose of histamine H3 agonist was most effective. Blockade of histamine H3 receptors with thioperamide (1 mg, 5 mg/kg, i.p.) exacerbated spinal cord pathology. These observations suggest that stimulation of histamine H3 receptors and blockade of histamine H2 receptors is neuroprotective in SCI.

Study of correlation between expression of bradykinin B2 receptor and pathological grade in human gliomas

In clinical practice there is a difference in response of the blood-tumour barrier (BTB) permeability induced by bradykinin in brain tumours with the same pathology. The variability in response of tumours to bradykinin is likely to be related to the expression level of bradykinin B(2) receptor. This study used fresh human glioma samples to determine the expression level of bradykinin B(2) receptor on gliomas with different pathological grades. The grade of tumour was classified using the WHO classification. To determine the bradykinin B(2) receptor expression level in gliomas, Immunohistochemistry and Western blot methods were used. In 24 cases of gliomas there were eight cases of WHO I glioma, eight cases of WHO II glioma and eight cases of WHO III glioma. Both Western blot and immunohistochemistry showed bradykinin B(2) receptors localized on tumour cells, whilst brain cells at the edge of the glioma hardly expressed B(2) receptor. There were significant differences of bradykinin B(2) receptor expression level among different pathological grades of glioma. The expression of B(2) receptor in the three grades of glioma was in the order of WHO I < WHO II < WHO III. Determination of bradykinin B(2) receptor expression level in human glioma may be useful in screening glioma patients to predict whether they will be suitable for opening of the blood - tumour barrier with bradykinin or its analogue.

Cerebral mast cells regulate early ischemic brain swelling and neutrophil accumulation

We previously observed degranulated mast cells (MC) in association with perivascular brain edema formation during focal cerebral ischemia. Brain MC are typically located perivascularly and contain potent fast-acting vasoactive and proteolytic substances. We examined in a rat model of transient middle cerebral artery occlusion (MCAO) whether, in the early phase of ischemia, MC regulate microcirculation, the blood-brain barrier (BBB) permeability, and edema formation. First, animals received MC inhibitor (cromoglycate), MC-degranulating drug (compound 48/80), or saline. Thereafter, we performed transient MCAO in gene-manipulated MC-deficient rats and their wild-type (WT) littermates, calculating brain swelling, visualizing BBB leakage by intravenously administered Evans blue albumin, and determining neutrophil infiltration with light microscopy. Cerebral blood flow, monitored by laser-Doppler flowmetry in separate experiments, was similar among pharmacological treatments. Ischemic swelling resulted in increased hemispheric volume of 13.4%+/-1.0% in controls, 8.1%+/-0.4% (39% reduction) after cromoglycate, and 25.2%+/-2.0% (89% increase) after compound 48/80 (P<0.05). Early ischemic BBB leakage was reduced by 51% after cromoglycate, and 50% enhanced by compound 48/80 (P<0.05). The cromoglycate group showed 37% less postischemic neutrophil infiltration than did controls (P<0.05). Furthermore, MC-deficient rats responded to focal ischemia with 58% less brain swelling (6.7%+/-1.2%) than did their WT littermates (15.8%+/-1.4%, P<0.05). Blood-brain barrier damage was 47% lower in MC-deficient rats than in the WT (P<0.05). Neutrophil infiltration after MCAO was decreased 47% in MC-deficient rats in comparison to WT (P<0.05). Pharmacological MC inhibition thus appears to deserve further investigation regarding reduction of brain swelling and inflammation early after stroke.

A single dose, three-arm, placebo-controlled, phase I study of the bradykinin B2 receptor antagonist Anatibant (LF16-0687Ms) in patients with severe traumatic brain injury

Traumatic brain injury (TBI) mortality and morbidity remains a public health challenge. Because experimental studies support an important role of bradykinin (BK) in the neurological deterioration that follows TBI, a double-blind, randomized, placebo-controlled study of Anatibant (LF16- 0687Ms), a selective and potent antagonist of the BK B(2) receptor, was conducted in severe (Glasgow Coma Scale [GCS] < 8) TBI patients (n = 25) at six sites in the United States. At 8-12 h after injury (9.9 +/- 2.8 h), patients received a single subcutaneous injection of Anatibant (3.75 mg or 22.5 mg, n = 10 each) or placebo (n = 5). The primary objective was to investigate the pharmacokinetics of Anatibant; general safety, local tolerability, levels of the bradykinin metabolite BK1-5 in plasma and cerebrospinal fluid (CSF), intracranial pressure (ICP), and cerebral perfusion pressure were also assessed. We observed a dose-proportionality of the pharmacokinetics, Cmax, and AUC of Anatibant. V(d)/F, Cl/F, and t(1/2) were independent on the dose and protein binding was >97.7%. Anatibant, administered as single subcutaneous injections of 3.75 g and 22.5 mg, was well tolerated in severe TBI patients with no unexpected clinical adverse events or biological abnormalities observed. Interestingly, plasma and CSF levels of BK1-5 were significantly and markedly increased after trauma (e.g., 34,700 +/- 35,300 fmol/mL in plasma vs. 34.9 +/- 5.6 fmol/mL previously reported for normal volunteers), supporting the use of Anatibant as a treatment of secondary brain damage. To address this issue, a dose-response trial that would investigate the effects of Anatibant on the incidence of raised ICP and on functional outcome in severe TBI patients is needed.

Homocysteine causes cerebrovascular leakage in mice

Elevated plasma homocysteine (Hcy) is associated with cerebrovascular disease and activates matrix metalloproteinases (MMPs), which lead to vascular remodeling that could disrupt the blood-brain barrier. To determine whether Hcy administration can increase brain microvascular leakage secondary to activation of MMPs, we examined pial venules by intravital video microscopy through a craniotomy in anesthetized mice. Bovine serum albumin labeled with fluorescein isothiocyanate (BSA-FITC) was injected into a carotid artery to measure extravenular leakage. Hcy (30 microM/total blood volume) was injected 10 min after FITC-BSA injection. Four groups of mice were examined: 1) wild type (WT) given vehicle; 2) WT given Hcy (WT + Hcy); 3) MMP-9 gene knockout given Hcy (MMP-9-/- + Hcy); and 4) MMP-9-/- with topical application of histamine (10(-4) M) (MMP-9-/- + histamine). In the WT + Hcy mice, leakage of FITC-BSA from pial venules was significantly (P < 0.05) greater than in the other groups. There was no significant leakage of pial microvessels in MMP-9-/- + Hcy mice. Increased cerebrovascular leakage in the MMP-9-/- + histamine group showed that microvascular permeability could still increase by a mechanism independent of MMP-9. Treatment of cultured mouse microvascular endothelial cells with 30 microM Hcy resulted in significantly greater F-actin formation than in control cells without Hcy. Treatment with a broad-range MMP inhibitor (GM-6001; 1 microM) ameliorated Hcy-induced F-actin formation. These data suggest that Hcy increases microvascular permeability, in part, through MMP-9 activation.

Post-seizures amygdaloallocortical microvascular lesion leading to atrophy and memory impairment

Although the incidence of seizures after a cerebrovascular event including intracerebral hemorrhage has been widely recognized, the present studies have demonstrated that generalized convulsive seizures can cause multifocal amygdaloallocortical hemorrhage and tissue necrosis, the origin of which remains to be established. The seizure-elicited amygdaloallocortical injured area, which we refer to as a focal injury-prone area (FIPA), was caused by cholinergic stimulation of the ventroposterolateral and thalamic reticular nuclei. The amygdaloallocortical injury was preceded by focal absence of neuronal COX-2 and presence of microvascular immunoreactivity to the pro-inflammatory cytokines, IL-1beta and TNF-alpha. The microvascular inflammation was followed by edema and multifocal amygdaloallocortical microhemorrhages, leading to atrophy and cognitive impairment. On the basis of the present results, we conclude that generalized convulsive seizures may be at the origin of amygdaloallocortical microvascular injury suggesting that, in addition to anticonvulsant treatment, an appropriate clinical evaluation and therapy for seizures-associated cerebrovascular accidents should be considered.