Regional differences in the neuroprotective effect of minocycline in a mouse model of global forebrain ischemia

The association of matrix metalloproteinase 9 (MMP9) with hippocampal volume in schizophrenia: a preliminary MRI study

Matrix metalloproteinases 9 (MMP9) are enzymes involved in regulating neuroplasticity in the hippocampus. This, combined with evidence for disrupted hippocampal structure and function in schizophrenia, has prompted our current investigation into the relationship between MMP9 and hippocampal volumes in schizophrenia. 34 healthy individuals (mean age = 32.50, male = 21, female = 13) and 30 subjects with schizophrenia (mean age = 33.07, male = 19, female = 11) underwent a blood draw and T1-weighted magnetic resonance imaging. The hippocampus was automatically segmented utilizing FreeSurfer. MMP9 plasma levels were measured with ELISA. ANCOVAs were conducted to compare MMP9 plasma levels (corrected for age and sex) and hippocampal volumes between groups (corrected for age, sex, total intracranial volume). Spearman correlations were utilized to investigate the relationship between symptoms, medication, duration of illness, number of episodes, and MMP9 plasma levels in patients. Last, we explored the correlation between MMP9 levels and hippocampal volumes in patients and healthy individuals separately. Patients displayed higher MMP9 plasma levels than healthy individuals (F(1, 60) = 21.19, p < 0.0001). MMP9 levels correlated with negative symptoms in patients (R = 0.39, p = 0.035), but not with medication, duration of illness, or the number of episodes. Further, patients had smaller left (F(1,59) = 9.12, p = 0.0040) and right (F(1,59) = 6.49, p = 0.013) hippocampal volumes. Finally, left (R = -0.39, p = 0.034) and right (R = -0.37, p = 0.046) hippocampal volumes correlated negatively with MMP9 plasma levels in patients. We observe higher MMP9 plasma levels in SCZ, associated with lower hippocampal volumes, suggesting involvement of MMP9 in the pathology of SCZ. Future studies are needed to investigate how MMP9 influences the pathology of SCZ over the lifespan, whether the observed associations are specific for schizophrenia, and if a therapeutic modulation of MMP9 promotes neuroprotective effects in SCZ.

Minocycline fails to improve neurologic and histologic outcome after ventricular fibrillation cardiac arrest in rats

BACKGROUND

Prolonged cardiac arrest (CA) produces extensive neuronal death and microglial proliferation and activation resulting in neuro-cognitive disabilities. Among other potential mechanisms, microglia have been implicated as triggers of neuronal death after hypoxic-ischemic insults. Minocycline is neuroprotective in some brain ischemia models, either by blunting the microglial response or by a direct effect on neurons.

AIM

To improve survival, attenuate neurologic deficits, neuroinflammation, and histological damage after ventricular fibrillation (VF) CA in rats.

METHODS

Adult male isoflurane-anesthetized rats were subjected to 6 min VF CA followed by 2 min resuscitation including chest compression, epinephrine, bicarbonate, and defibrillation. After return of spontaneous circulation (ROSC), rats were randomized to two groups: (1) Minocycline 90 mg/kg intraperitoneally (i.p.) at 15 min ROSC, followed by 22.5 mg/kg i.p. every 12 h for 72 h; and (2) Controls, receiving the same volume of vehicle (phosphate-buffered saline). The rats were kept normothermic during the postoperative course. Neurologic injury was assessed daily using Overall Performance Category (OPC; 1 = normal, 5 = dead) and Neurologic Deficit Score (NDS; 0% = normal, 100% = dead). Rats were sacrificed at 72 h. Neuronal degeneration (Fluoro-Jade C staining) and microglia proliferation (anti-Iba-1 staining) were quantified in four selectively vulnerable brain regions (hippocampus, striatum, cerebellum, cortex) by three independent reviewers masked to the group assignment.

RESULTS

In the minocycline group, 8 out of 14 rats survived to 72 h compared to 8 out of 19 rats in the control group (P = 0.46). The degree of neurologic deficit at 72 h [median, (interquartile range)] was not different between survivors in minocycline vs controls: OPC 1.5 (1-2.75) vs 2 (1.25-3), P = 0.442; NDS 12 (2-20) vs 17 (7-51), P = 0.328) or between all studied rats. The number of degenerating neurons (minocycline vs controls, mean ± SEM: Hippocampus 58 ± 8 vs 76 ± 8; striatum 121 ± 43 vs 153 ± 32; cerebellum 20 ± 7 vs 22 ± 8; cortex 0 ± 0 vs 0 ± 0) or proliferating microglia (hippocampus 157 ± 15 vs 193 cortex 0 ± 0 vs 0 ± 0; 16; striatum 150 ± 22 vs 161 ± 23; cerebellum 20 ± 7 vs 22 ± 8; cortex 26 ± 6 vs 31 ± 7) was not different between groups in any region (all P > 0.05). Numerically, there were approximately 20% less degenerating neurons and proliferating microglia in the hippocampus and striatum in the minocycline group, with a consistent pattern of histological damage across the individual regions of interest.

CONCLUSION

Minocycline did not improve survival and failed to confer substantial benefits on neurologic function, neuronal loss or microglial proliferation across multiple brain regions in our model of rat VF CA.

Minocycline treatment prevents depression and anxiety-like behaviors and promotes neuroprotection after experimental ischemic stroke

Depression and anxiety have been reported as the major neuropsychiatric consequences following stroke. Minocycline, a neuroprotective drug has minimized depressive symptoms in patients with major depressive disorders and anxiety-like symptoms. In addition, minocycline demonstrated efficacy and seemed a promising neuroprotective agent in acute stroke patients. The present studied evaluated the effects of minocycline treatment on the depression and anxiety-like behaviors, brain damage and expression of inflammatory and neuroprotective mediators after transient global cerebral ischemia in C57BL/6 mice. Brain ischemia was induced by bilateral occlusion of the common carotids (BCCAo) for 25 min and subsequent reperfusion. Sham and BCCAo animals received minocycline at a dose of 30 mg/kg by intraperitoneal injection during 14 days. The locomotor activity, depression and anxiety-like behaviors were assessed by open field, forced swim and elevated plus maze tests, respectively. Then, the brains were removed and processed to evaluate brain damage by histological and morphometric analysis, hippocampal neurodegeneration using Fluoro-Jade C histochemistry, microglial activity using iba-1 immunohistochemistry, brain levels of TNF, IFN-γ, IL-6, IL-10, IL-12p70 and CCL2 by CBA, CX3CL1 and BDNF by ELISA assays. The animals developed depression and anxiety-like behaviors post-stroke and minocycline treatment prevented those neurobehavioral changes. Moreover, minocycline-treated BCCAo animals showed less intense brain damage in the cerebral cortex, brainstem and cerebellum as well as significantly reduced hippocampal neurodegeneration. BCCAo groups exhibited up-regulation of some cytokines at day 14 after ischemia and brain levels of CX3CL1 and BDNF remained unaltered. Our data indicate that the depression and anxiety-like behavioral improvements promoted by minocycline treatment might be related to its neuroprotective effect after brain ischemia in mice.

Heterogeneity of GRIM-19 Expression in the Adult Mouse Brain

Gene associated with retinoid-interferon-induced mortality-19 (GRIM-19) is a subunit of the mitochondrial respiratory chain complex I that has a significant effect on ATP production. The brain is particularly susceptible to ATP deficiency due to its limited energy storage capability and its high rate of oxygen consumption. Thus, GRIM-19 might be involved in regulating ATP level in the brain or cell death caused by several neurological disorders. To understand the physiological and pathophysiological roles of GRIM-19 in the brain, a thorough investigation of the neuroanatomic distribution of GRIM-19 in the normal brain is necessary. Therefore, the present study examined the distribution patterns of GRIM-19 in the adult C57BL/6 mouse brain using immunohistochemistry and identified cell types expressing GRIM-19 using double immunofluorescence staining. We found that GRIM-19 was ubiquitously but not homogenously expressed throughout the brain. GRIM-19 immunoreactivity was predominantly observed in neurons, but not in astrocytes, microglia, or oligodendrocytes under normal physiological conditions. Following transient global cerebral ischemia, GRIM-19-positive immunoreactivity was, however, observed in neurons as well as glial cells including astrocytes in the hippocampus. Furthermore, GRIM-19 was weakly expressed in the hippocampal subgranular zone, in which neural stem and progenitor cells are abundant, but highly expressed in the immature and mature neuronal cells in the granular cell layer of the normal brain, suggesting an inverse correlation between expression of GRIM-19 and stemness activity. Collectively, our study demonstrating widespread and differential distribution of GRIM-19 in the adult mouse brain contributes to investigating the functional and pathophysiological roles of this protein.

Black Rice (Oryza sativa L., Poaceae) Extract Reduces Hippocampal Neuronal Cell Death Induced by Transient Global Cerebral Ischemia in Mice

Rice is the most commonly consumed grain in the world. Black rice has been suggested to contain various bioactive compounds including anthocyanin antioxidants. There is currently little information about the nutritional benefits of black rice on brain pathology. Here, we investigated the effects of black rice (Oryza sativa L., Poaceae) extract (BRE) on the hippocampal neuronal damage induced by ischemic insult. BRE (300 mg/kg) was orally administered to adult male C57BL/6 mice once a day for 21 days. Bilateral common carotid artery occlusion (BCCAO) was performed for 23 min on the 8th day of BRE or vehicle administration. Histological analyses conducted on the 22nd day of BRE or vehicle administration revealed that administering BRE profoundly attenuated neuronal cell death, inhibited reactive astrogliosis, and prevented loss of glutathione peroxidase expression in the hippocampus when compared to vehicle treatment. In addition, BRE considerably ameliorated BCCAO-induced memory impairment on the Morris water maze test from the 15th day to the 22nd day of BRE or vehicle administration. These results indicate that chronic administration of BRE is potentially beneficial in cerebral ischemia.

Inhibition of PMCA activity by tau as a function of aging and Alzheimer's neuropathology

Ca2+-ATPases are plasma membrane and intracellular membrane transporters that use the energy of ATP hydrolysis to pump cytosolic Ca2+ out of the cell (PMCA) or into internal stores. These pumps are the main high-affinity Ca2+ systems involved in the maintenance of intracellular free Ca2+ at the properly low level in eukaryotic cells. The failure of neurons to keep optimal intracellular Ca2+ concentrations is a common feature of neurodegeneration by aging and aging-linked neuropathologies, such as Alzheimer's disease (AD). This disease is characterized by the accumulation of β-amyloid senile plaques and neurofibrillary tangles of tau, a protein that plays a key role in axonal transport. Here we show a novel inhibition of PMCA activity by tau which is concentration-dependent. The extent of inhibition significantly decreases with aging in mice and control human brain membranes, but inhibition profiles were similar in AD-affected brain membrane preparations, independently of age. No significant changes in PMCA expression and localization with aging or neuropathology were found. These results point out a link between Ca2+-transporters, aging and neurodegeneration mediated by tau protein.

Edaravone enhances brain-derived neurotrophic factor production in the ischemic mouse brain

Edaravone, a clinical drug used to treat strokes, protects against neuronal cell death and memory loss in the ischemic brains of animal models through its antioxidant activity. In the present study, we subcutaneously administrated edaravone to mice (3 mg/kg/day) for three days immediately after bilateral common carotid artery occlusion, and revealed through an immunohistochemical analysis that edaravone (1) accelerated increases in the production of brain-derived neurotrophic factor (BDNF) in the hippocampus; (2) increased the number of doublecortin-positive neuronal precursor cells in the dentate gyrus subgranular zone; and (3) suppressed the ischemia-induced inactivation of calcium-calmodulin-dependent protein kinase II in the hippocampus. We also revealed through a Western blotting analysis that edaravone (4) induced the phosphorylation of cAMP response element-binding (CREB), a transcription factor that regulates BDNF gene expression; and (5) induced the phosphorylation of extracellular signal-regulated kinases 1/2, an upstream signal factor of CREB. These results suggest that the neuroprotective effects of edaravone following brain ischemia were mediated not only by the elimination of oxidative stress, but also by the induction of BDNF production.

Danggui-Jakyak-San ameliorates memory impairment and increase neurogenesis induced by transient forebrain ischemia in mice

Background

Danggui-Jakyak-San (DJS), a traditional herbal prescription, has been used to treat insufficient blood supplies. Recently, regenerative medication for the treatment of cerebral ischemia has drawn the attention of many researchers.

Methods

In this study, we examined whether DJS exerts a neuronal regenerative effect in the hippocampus of a transient forebrain ischemia mice model. Transient forebrain ischemia was induced by bilateral common carotid artery occlusion (BCCAO). Animals were divided into three groups (sham, BCCAO + vehicle, and BCCAO + DJS). To test the effect of DJS on learning and memory, Morris water maze or passive avoidance test was conducted. To test neuroprotective and neurogenic effect, immunohistochemistry and Western blot analysis were used. Statistical significance was analyzed with Student t-test, one-way or two-way analysis of variance.

Results

We found that the administration of DJS ameliorated ischemia-induced spatial memory impairment in the Morris water maze task. Moreover, Akt/glycogen synthase kinase-3β (GSK3β)/β-catenin signaling was increased by DJS, which would be one possible mechanism of DJS for neurogenesis in the hippocampal dentate gyrus region.

Conclusions

These results suggest that DJS is a possible candidate for the treatment of ischemia-induced neuronal degeneration.

Anti-inflammatory and neuroprotective effects of auraptene, a citrus coumarin, following cerebral global ischemia in mice

Cerebral ischemia causes delayed neuronal cell death in the hippocampus resulting in sequential cognitive impairments. Hyper-activated inflammation following ischemia is one of the etiologies for delayed neuronal cell death. In the present study, using a transient global ischemia mouse model, we showed that auraptene (AUR), a citrus coumarin, effectively inhibited microglia activation, cyclooxygenase-2 expression by astrocytes, and neuronal cell death in the hippocampus following ischemic insults. These results suggest that AUR acts as a neuroprotective agent in the ischemic brain, which may be mediated by suppression of the inflammatory response.

Effect of hydrogen gas on the survival rate of mice following global cerebral ischemia

Global cerebral ischemia and reperfusion (I/R) often result in high mortality. Free radicals have been reported to play an important role in global cerebral I/R, and therefore, reduction of these might improve the outcome. Here, we investigated the effect of hydrogen gas (H2) (a strong free radical scavenger) on the survival rate of mice following global cerebral I/R. We further examined the histopathological outcome and also the brain water content (as a possible determinant of mortality). Male C57BL/6J mice were subjected to global cerebral I/R by means of 45-min bilateral common carotid artery occlusion (BCCAO). A total of 160 mice were divided into three groups: sham surgery (sham group), BCCAO without H2 (BCCAO group), and BCCAO treated with 1.3% H2 (BCCAO + H2 group). We observed that H2 treatment significantly (P = 0.0232) improved the 7-day survival rate of mice, from 8.3% (BCCAO group, n = 12) to 50% (BCCAO + H2 group, n = 10). Histopathological analysis revealed that H2 treatment significantly attenuated neuronal injury and autophagy in the hippocampal cornu ammonis 1 sector and also brain edema, after 24 h of reperfusion. The beneficial effects of H2 treatment on brain injury were associated with significantly lower levels of oxidative stress markers (8-hydroxy-2'-deoxyguanosine and malondialdehyde) in the brain tissue. Thus, we believe that H2 may be an effective treatment for global cerebral I/R.

6-Shogaol, a ginger product, modulates neuroinflammation: a new approach to neuroprotection

Inflammatory processes in the central nervous system play an important role in a number of neurodegenerative diseases mediated by microglial activation, which results in neuronal cell death. Microglia act in immune surveillance and host defense while resting. When activated, they can be deleterious to neurons, even resulting in neurodegeneration. Therefore, the inhibition of microglial activation is considered a useful strategy in searching for neuroprotective agents. In this study, we investigated the effects of 6-shogaol, a pungent agent from Zingiber officinale Roscoe, on microglia activation in BV-2 and primary microglial cell cultures. 6-Shogaol significantly inhibited the release of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS) induced by lipopolysaccharide (LPS). The effect was better than that of 6-gingerol, wogonin, or N-monomethyl-l-arginine, agents previously reported to inhibit nitric oxide. 6-Shogaol exerted its anti-inflammatory effects by inhibiting the production of prostaglandin E(2) (PGE(2)) and proinflammatory cytokines, such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), and by downregulating cyclooxygenase-2 (COX-2), p38 mitogen-activated protein kinase (MAPK), and nuclear factor kappa B (NF-κB) expression. In addition, 6-shogaol suppressed the microglial activation induced by LPS both in primary cortical neuron-glia culture and in an in vivo neuroinflammatory model. Moreover, 6-shogaol showed significant neuroprotective effects in vivo in transient global ischemia via the inhibition of microglia. These results suggest that 6-shogaol is an effective therapeutic agent for treating neurodegenerative diseases.

The Neuroprotective Potential of Cyanidin-3-glucoside Fraction Extracted from Mulberry Following Oxygen-glucose Deprivation

In this study, cyanidin-3-glucoside (C3G) fraction extracted from the mulberry fruit (Morus alba L.) was investigated for its neuroprotective effects against oxygen-glucose deprivation (OGD) and glutamate-induced cell death in rat primary cortical neurons. Cell membrane damage and mitochondrial function were assessed by LDH release and MTT reduction assays, respectively. A time-course study of OGD-induced cell death of primary cortical neurons at 7 days in vitro (DIV) indicated that neuronal death was OGD duration-dependent. It was also demonstrated that OGD for 3.5 h resulted in approximately 50% cell death, as determined by the LDH release assay. Treatments with mulberry C3G fraction prevented membrane damage and preserved the mitochondrial function of the primary cortical neurons exposed to OGD for 3.5 h in a concentration-dependent manner. Glutamate-induced cell death was more pronounced in DIV-9 and DIV-11 cells than that in DIV-7 neurons, and an application of 50µM glutamate was shown to induce approximately 40% cell death in DIV-9 neurons. Interestingly, treatment with mulberry C3G fraction did not provide a protective effect against glutamate-induced cell death in primary cortical neurons. On the other hand, treatment with mulberry C3G fraction maintained the mitochondrial membrane potential (MMP) in primary cortical neurons exposed to OGD as assessed by the intensity of rhodamine-123 fluorescence. These results therefore suggest that the neuroprotective effects of mulberry C3G fraction are mediated by the maintenance of the MMP and mitochondrial function but not by attenuating glutamate-induced excitotoxicity in rat primary cortical neurons.

Consistent injury to medium spiny neurons and white matter in the mouse striatum after prolonged transient global cerebral ischemia

A reproducible transient global cerebral ischemia (tGCI) mouse model has not been fully established. Although striatal neurons and white matter are recognized to be vulnerable to ischemia, their injury after tGCI in mice has not been elucidated. The purpose of this study was to evaluate injuries to striatal neurons and white matter after tGCI in C57BL/6 mice, and to develop a reproducible tGCI model. Male C57BL/6 mice were subjected to tGCI by bilateral common carotid artery occlusion (BCCAO). Mice whose cortical cerebral blood flow after BCCAO decreased to less than 13% of the pre-ischemic value were used. Histological analysis showed that at 3 days after 22 min of BCCAO, striatal neurons were injured more consistently than those in other brain regions. Quantitative analysis of cytochrome c release into the cytosol and DNA fragmentation in the striatum showed consistent injury to the striatum. Immunohistochemistry and Western blot analysis revealed that DARPP-32-positive medium spiny neurons, the majority of striatal neurons, were the most vulnerable among the striatal neuronal subpopulations. The striatum (especially medium spiny neurons) was susceptible to oxidative stress after tGCI, which is probably one of the mechanisms of vulnerability. SMI-32 immunostaining showed that white matter in the striatum was also consistently injured 3 days after 22 min of BCCAO. We thus suggest that this is a tGCI model using C57BL/6 mice that consistently produces neuronal and white matter injury in the striatum by a simple technique. This model can be highly applicable for elucidating molecular mechanisms in the brain after global ischemia.

Poly(ADP-ribose) metabolism in brain and its role in ischemia pathology

The biological roles of poly(ADP-ribose) polymers (PAR) and poly(ADP-ribosyl)ation of proteins in the central nervous system are diverse. The homeostasis of PAR orchestrated by poly(ADP-ribose) polymerase-1 (PARP-1) and poly(ADP-ribose) glycohydrolase (PARG) is crucial for cell physiology and pathology. Both enzymes are ubiquitously distributed in neurons and glia; however, they are segregated at the subcellular level. PARP-1 serves as a "nick sensor" for single- or double-stranded breaks in DNA and is involved in long and short patch base-excision repair, while PARG breaks down PAR. The stimulation of PARP-1 and PAR formation can activate proinflammatory transcription factors, including nuclear factor kappa B. However, hyperactivation of PARP-1 can result in depletion of NAD/ATP, and in PAR-dependent mitochondrial pore formation leading to release of apoptosis inducing factor and cell death. The role of PAR as a death signaling molecule in brain ischemia-reperfusion and inflammation as well as the effect of gender and aging is presented in this review. Modulating the PAR level through pharmacological or genetic intervention on PARP-1/PARG activity and gene expression should be a valuable way for neuroprotective strategy.

Lifelong protection from global cerebral ischemia and reperfusion in long-lived Mclk1(+/)(-) mutants

To achieve a long life span, animals must be resistant to various injuries as well as avoid or delay lethality from age-dependent diseases. Reduced expression of the mitochondrial enzyme CLK-1/MCLK1 (a.k.a. Coq7), a mitochondrial hydroxylase that is necessary for the biosynthesis of ubiquinone (UQ), extends lifespan in Caenorhabditiselegans and in mice. Here, we show that long-lived Mclk1(+/)(-) mutants have enhanced resistance to neurological damage following global cerebral ischemia-reperfusion (I/R) injury induced by transient bilateral common carotid artery occlusion (BCCAO). Both young ( approximately 100days old) and relatively aged ( approximately 450days old) mutants display increased resistance as indicated by a significant decrease in the amount of degenerating cells observed in forebrain cortex and in hippocampal areas after ischemia and reperfusion. Furthermore, less oxidative damage resulting from the procedure was measured in the brain of young Mclk1(+/)(-) animals. The finding that both young and old mutants are protected indicates that this is a basic phenotype of these mutants and not a secondary consequence of their slow rate of aging. Thus, the partial resistance to I/R injury suggests that Mclk1(+/)(-) mutants have an enhanced recovery potential following age-dependant vascular accidents, which correlates well with their longer survival. By relating this neuroprotective effect to previously reported characteristics of the Mclk1(+/)(-) phenotype, including altered mitochondrial metabolism and increased HIF-1alpha expression, this study establishes these mutants as useful models to analyze the mechanisms underlying tolerance to ischemia, particularly those associated with ischemic preconditioning, as well as to clarify the relation between aging and age-dependent diseases.

Minocycline attenuates microglial activation but fails to mitigate degeneration in inferior olive and pontine nuclei after focal cerebellar lesion

Degenerative changes in areas remote from the primary lesion site have been linked to the clinical outcome of focal brain damage, and inflammatory mechanisms have been considered to play a key role in the pathogenesis of these remote cell death phenomena. Minocycline is a tetracycline derivative, therapeutically effective in various experimental models of central nervous system (CNS) injuries that include inflammatory and apoptotic mechanisms, although recent findings have yielded mixed results. In this study, we investigated the effectiveness of minocycline treatment in reducing remote cell death. Glial activation and neuronal loss in precerebellar stations following cerebellar lesion were investigated using immunohistochemistry and Western blot techniques. Our results show that minocycline was effective in reducing microglial activations in axotomized precerebellar nuclei, but failed to mitigate either astrocytic response or neuronal loss. This finding supports the role of minocycline in modulating inflammatory response after CNS lesion and suggests its ineffectiveness in influencing degenerative phenomena in areas remote from the primary lesion site.

Remote cell death in the cerebellar system

Functional impairment after focal CNS lesion is highly dependent on damage that occurs in regions that are remote but functionally connected to the primary lesion site. This pattern is particularly evident in the cerebellar system, in which functional interactions between the cerebellar cortex, deep cerebellar nuclei, and precerebellar stations are of paramount importance. Diffuse degeneration after development of a focal CNS lesion has been associated with poor outcomes in several pathologies, such as stroke, multiple sclerosis, and brain trauma. A greater understanding of the mechanisms that underlie the spread of death signals from focal lesions, however, can aid in identifying a neuroprotective approach for CNS pathologies. To this end, studies on degenerative mechanisms in the inferior olive and pontine nuclei after focal cerebellar damage have been a valuable asset in which pharmacological approaches have been tested. In this review, we focus on mechanisms of remote cell death in cerebellar circuits, analyzing the neuroprotective effects of inflammation-modulating drugs in particular.

The plasticity of posterior communicating artery influences on the outcome of white matter injury induced by chronic cerebral hypoperfusion in rats

OBJECTIVE

This study was performed to identify which factors are involved in the development of white matter lesions induced by chronic cerebral hypoperfusion in rats.

METHODS

Male Wistar and Sprague-Dawley (SD) rats (250-270 g) were subjected to the permanent occlusion of bilateral common carotid arteries (BCCAO). The regional cerebral blood flow (rCBF) was measured by laser Doppler flowmetry and the plasticity of the posterior communicating artery (PcomA) was visualized by transcardiac perfusion of latex solution. For the histological examination, Klüver-Barrera staining was used to evaluate white matter damage.

RESULTS

When compared with SD rats, Wistar rats showed lower rCBF after BCCAO, as well as thinner PcomAs. Moreover, 21 days after BCCAO, Wistar rats showed marked vacuolation of white matter in the optic tract, whereas SD rats had an almost intact optic tract.

DISCUSSION

These results suggest that the plasticity of the PcomA and the reduction of rCBF in Wistar rats are important factors in the development of BCCAO-induced white matter lesions.

Herbal formula FBD extracts prevented brain injury and inflammation induced by cerebral ischemia-reperfusion

The aim of this work was to verify neuroprotective and anti-inflammatory properties of FBD, a herbal formula composed of Poria cocos, Atractylodes macrocephala and Angelica sinensis, in ICR mice subjected to repetitive 10 min of common carotid arteries occlusion followed 24 h reperfusion. Intragastrical pretreatment with supercritical carbon dioxide extract (FBD-CO(2), 37.5 mg/kg) twice daily for 3.5 d, significantly reduced Evans Blue influx, neuron specific enolase (NSE) efflux, brain infarction (all p<0.05), also inhibited polymorphonuclear leukocytes (PMNs) infiltration (p<0.001), suppressed secretion of tumor necrosis factor (TNF)-alpha in blood (p<0.05), interleukin (IL)-1beta and IL-8 in brain (both p<0.01), and down-regulated cerebral expression of phosphor-IkappaB-alpha and phosphor-nuclear factor kappa-B (NF-kappaB), whether coupled with aqueous extract (FBD-H(2)O, 150 mg/kg) or not. Moreover, FBD-CO(2) (0.1-10 microg/ml) inhibited 0.1 microM phorbol myristate acetate-evoked oxidative burst in rat PMNs, 20 ng/ml TNF-alpha-triggered PMNs adhesion to ECV304 endothelial cells, and PMNs neurotoxicity to PC12 neuron-like cells as well as NSE release (IC(50) 1.30, 0.98, 0.24 and 0.82 microg/ml, respectively). Our study demonstrated that FBD-CO(2) prevented brain ischemia/reperfusion injury, at least in part, by limiting PMNs infiltration and neurotoxicity mediated by TNF-alpha, IL-1beta and IL-8, via inhibition on NF-kappaB activation.

Reduction of hippocampal cell death and proteolytic responses in tissue plasminogen activator knockout mice after transient global cerebral ischemia

Knockout mice deficient in tissue plasminogen activator (tPA) are protected against hippocampal excitotoxicity. But it is unknown whether similar neuroprotection occurs after transient global cerebral ischemia, which is known to selectively affect the hippocampus. In this study, we tested the hypothesis that hippocampal cell death in tPA knockout mice would be reduced after transient global cerebral ischemia, and this neuroprotection would occur concomitantly with amelioration of both intra- and extracellular proteolytic cascades. Wild-type and tPA knockout mice were subjected to 20 min of transient bilateral occlusions of the common carotid arteries. Three days later, Nissl and terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling staining demonstrated that hippocampal cell death was significantly reduced in tPA knockout brains compared with wild-type brains. Caspase-3 and the two major brain gelatinases (matrix metalloproteinase (MMP)-9 and MMP-2) were assessed as representative measurements of intra- and extracellular proteolysis. Post-ischemic levels of caspase-3, MMP-9 and MMP-2 were similarly reduced in tPA knockouts compared with wild-type hippocampi. Taken together, these data suggest that endogenous tPA contributes to hippocampal injury after cerebral ischemia, and these pathophysiologic pathways may involve links to aberrant activation of caspases and MMPs.