A comparative neuroethological study of limbic seizures induced by Parawixia bistriata venom and kainic acid injections in rats

A number of neurotoxins derived from arthropod venoms are known to show highly selective effects on nervous tissue. These neurotoxins have been proved to be extremely useful tools to investigate either convulsive or anticonvulsive mechanisms in the nervous system. In the present work, intracerebroventricular injection of the crude venom from the spider Parawixia bistriata (Araneae, Araneidae) in rats induced convulsive limbic seizures (head and forelimb myoclonus, as well as rearing and falling). Neuroethological analysis showed that the limbic seizures induced by the venom were different from those induced by kainic acid. Intravenous injection of the same venom did not induce seizures, but the neuroethological analysis showed an intensification of grooming behavior similar to a displaced activity. In conclusion, our experiments point that crude venom of P. bistriata may contain convulsant neurotoxins probably acting in limbic system structures. The mechanism of action of these neurotoxins may be different from simple activation of glutamatergic kainate receptors, as evidenced by a comparative neuroethological analysis of seizures induced by either venom or kainic acid.     

Inhibition of nitric oxide synthase dramatically potentiates seizures induced by kainic acid and pilocarpine in rats

We investigated whether the severity of convulsions evoked by kainic acid and pilocarpine is modified in nitric oxide synthase inhibitor-treated rats. We found that chronic treatment (4 days) withN_w-nitro-l-arginine greatly potentiates seizures induced by both convulsants suggesting a potential role for nitric oxide in mechanisms regulating seizure induction and propagation.     

Brain oxygen tension monitoring following penetrating ballistic-like brain injury in rats

While brain oxygen tension (PbtO₂) monitoring is an important parameter for evaluating injury severity and therapeutic efficiency in severe traumatic brain injury (TBI) patients, many factors affect the monitoring. The goal of this study was to identify the effects of FiO₂ (fraction of inspired oxygen) on PbtO₂ in uninjured anesthetized rats and measure the changes in PbtO₂ following penetrating ballistic-like brain injury (PBBI). Continuous PbtO₂ monitoring in uninjured anesthetized rats showed that PbtO₂ response was positively correlated with FiO₂ (0.21-0.35) but PbtO₂ remained stable when FiO₂ was maintained at ∼0.26. Importantly, although increasing FiO₂ from 0.21 to 0.35 improved P_aO₂, it concomitantly reduced pH levels and elevated P_aCO₂ values out of the normal range. However, when the FiO₂ was maintained between 0.26 and 0.30, the pH and P_aO₂ levels remained within the normal or clinically acceptable range. In PBBI rats, PbtO₂ was significantly reduced by ∼40% (16.9 ± 1.2 mmHg) in the peri-lesional region immediately following unilateral, frontal 10% PBBI compared to sham rats (28.6 ± 1.7 mmHg; mean ± SEM, p < 0.05) and the PBBI-induced reductions in PbtO₂ were sustained for at least 150 min post-PBBI. Collectively, these results demonstrate that FiO₂ affects PbtO₂ and that PBBI produces acute and sustained hypoxia in the peri-lesional region of the brain injury. This study provides important information for the management of PbtO₂ monitoring in this brain injury model and may offer insight for therapeutic strategies targeted to improve the hypoxia/ischemia state in the penetrating-type brain injury.     

Catalase prevents elevation of [Ca(2+)](i) induced by alcohol in cultured canine cerebral vascular smooth muscle cells: Possible relationship to alcohol-induced stroke and brain pathology

Several studies have suggested that alcohol-induced brain injury is associated with generation of reactive oxygen species (ROS). The recent findings, that antioxidants (Vitamin E and pyrrolidine dithiocarbamate (PDTC)) prevent intracellular Ca(2+) ([Ca(2+)](i)) overload in cerebral vascular smooth muscle cells, induced by alcohol, demonstrate indirectly that ROS formation is related to cerebral vascular injury. The present experiments were designed to test the hypothesis that catalase, an hydrogen peroxide (H(2)O(2)) scavenging enzyme, can prevent or ameliorate alcohol-induced elevation of [Ca(2+)](i). Preincubation of cultured canine cerebral vascular smooth muscle cells with catalase (20-1000 units/ml) didn't produce any apparent changes from controls in resting levels of [Ca(2+)](i) after 1-3 days. Exposure of the cerebral vascular cells to culture media containing 10-100mM ethanol resulted in significant rises in [Ca(2+)](i) (p<0.01). Although exposure of these cells to a low concentration of catalase (20 units/ml) failed to prevent the increased level of [Ca(2+)](i) induced by ethanol, concomitant addition of higher concentrations of catalase (100-1000 units/ml) and ethanol (10-100mM) inhibited or ameliorated the rises of [Ca(2+)](i) induced by ethanol either at 24h or at 3 days, in a concentration-dependent manner. Catalase, in the range of 100-200 units/ml, inhibited approximately 50% of the [Ca(2+)](i) increases caused by ethanol in the first 24h. Catalase at a concentration of 1000 units/ml inhibited completely excessive [Ca(2+)](i) accumulation. The present results when viewed in light of other recently published data suggest that H(2)O(2) generation may be one of the earliest events triggered by alcohol in alcohol-induced brain-vascular damage, neurobehavioral actions and stroke.     

Modelling the roles of MAO and SSAO in glucose transport

Summary Amine oxidase substrates such as benzylamine and methylamine have been shown to stimulate glucose uptake by increasing the recruitment of the glucose transporter GLUT4 from vesicles within the cell to the cell surface. Inhibition of this effect by the presence of semicarbazide and catalase led to the suggestion that the process is mediated by the H₂O₂ produced in the oxidation of these amines. Tyramine, which is a substrate for both MAO and SSAO, can also stimulate this process and in that case both MAO and SSAO inhibitors attenuate the effect. Benzylamine does not occur physiologically and tyramine is normally present in only very low amounts. We have suggested that adrenaline, which also stimulates glucose metabolism through adrenoceptors, may act as the physiological substrate for GLUT4 recruitment. It is a substrate for MAO but not SSAO. However, oxidation of adrenaline by MAO releases both H₂O₂ and methylamine for further oxidation by SSAO. In order to gain a fuller understanding of this process we have performed simulation studies that may be used to assess the contributions of the amine oxidases to the process under a variety of conditions. The results are consistent with the experimentally observed behaviour. This approach not only helps to establish the feasibility of this process but also allows behaviour prediction and the identification of further experimental approaches.     

NADPH-oxidase activity is elevated in penumbral and non-ischemic cerebral arteries following stroke

Reactive oxygen species play a role in neuronal damage following cerebral ischemia-reperfusion. We tested whether activity of the superoxide-generating enzyme, NADPH-oxidase, is enhanced in cerebral arteries within, adjacent and distant from the ischemic core. The right middle cerebral artery (MCA) of conscious rats was temporarily occluded by perivascular injection of endothelin-1 to induce stroke (ET-1; n=19). Control rats were injected with saline (n=9). At 24 h or 72 h post-administration of ET-1, the MCA and its branches within the ipsilateral penumbra and infarcted core, corresponding arteries in the contralateral hemisphere, and basilar artery were excised. Anatomically similar arteries were excised from saline-injected rats. At 24 h after stroke, NADPH-stimulated superoxide production by arteries from the infarcted core did not differ from levels generated by arteries from control rats, whereas levels were significantly lower 72 h after stroke. However, at both time points after stroke, superoxide production by arteries from the ischemic penumbra was 8-fold greater than levels generated by arteries from control rats. Surprisingly, even in the non-ischemic arteries from the contralateral hemisphere and in the basilar artery, superoxide production was increased approximately 4- to 6-fold at 24 h, but had returned to normal 72 h after stroke. The NADPH-oxidase inhibitor, diphenyleneiodonium, virtually abolished superoxide production by all arteries. Thus, the activity of NADPH-oxidase is enhanced in cerebral arteries from the ischemic penumbra at 24 h and 72 h following cerebral ischemia. Additionally, NADPH-oxidase activity is temporarily enhanced after cerebral ischemia within arteries from non-ischemic parts of the brain.     

Reduction of lipid and protein damage in patients with disorders of propionate metabolism under treatment: a possible protective role of l-carnitine supplementation

Disorders of propionate metabolism are autosomal recessive diseases clinically characterized by acute metabolic crises in the neonatal period and long-term neurological deficits whose pathophysiology is not completely established. There are increasing evidences demonstrating antioxidant properties for l-carnitine, which is used in the treatment of propionic and methylmalonic acidemias to increase the excretion of organic acids accumulated in tissues and biological fluids of the affected patients. In this work we aimed to evaluate lipid (malondialdehyde content) and protein (carbonyl formation and sulfhydryl oxidation) oxidative damage in plasma from patients with propionic and methylmalonic acidemias at the moment of diagnosis and during treatment with l-carnitine. We also correlated the parameters of oxidative damage with plasma total, free and esterified l-carnitine levels. We found a significant increase of malondialdehyde and carbonyl groups, as well as a reduction of sulfhydryl groups in plasma of these patients at diagnosis compared to controls. Furthermore, patients under treatment presented a marked reduction of the content of protein carbonyl groups, similar to controls, and malondialdehyde content in relation to patients at diagnosis. In addition, plasma total and free l-carnitine concentrations were negatively correlated with malondialdehyde levels. Taken together, the present data indicate that treatment significantly reduces oxidative damage in patients affected by disorders of propionate metabolism and that l-carnitine supplementation may be involved in this protection.     

Enhancement of γ-aminobutyric acid (GABA) receptor binding by lipophilic antioxidants

Treatment of synaptic membrane preparations from rat brain with various lipophilic antioxidants invariably resulted in a significant enhancement of the binding of [³H]muscimol and [³H]γ-aminobutyric acid with a concomitant facilitation of superoxide anion formation, whereas treatment with hydrophilic antioxidants exhibited no significant alterations in the binding and the formation of superoxide anion. These results suggests that the superoxide anion may play a modulatory role in the binding of γ-aminobutyric acid to its relevant synaptic receptor.     

Propofol and erythropoietin antioxidant properties in rat brain injured tissue

So far, several treatment modalities have been attempted to brain protection in cases such as brain trauma, stroke or brain hemorrhage. However, a treatment method that the effect begins immediately and definitely helpful has not been discovered yet. In this study, we aimed to compare the effects of propofol and erythropoietin (Epo) on brain injury caused by oxidative stress and antioxidant properties of these agents after closed head injury (CHI) in rats. For this study, female Wistar Albino rats were divided into five groups: non-traumatic control group, trauma performed group CHI, trauma with propofol (100 mg/kg) intraperitoneally (i.p.), trauma with Epo (5000 U/kg) i.p. and trauma with propofol and Epo performed study groups. Twenty-four hours after CHI, rats were sacrificed and the brains were removed. Superoxide dismutase (SOD), catalase (CAT), xanthine oxidase (XO), nitric oxide (NO), and malondialdehyde (MDA) levels were measured in brain tissue. MDA and NO levels were decreased significantly in Groups Epo, Propofol and Epo+Propofol than Group CHI (p<0.01). XO activity was significantly lower in Group Epo than Group CHI (p<0.05). Epo and propofol decreased oxidative stress by decreasing MDA and NO level in brain tissue after CHI. However, combination of Epo and propofol has no significant beneficial advantage than Epo or propofol alone.     

Omega-3 fatty acid deficiency during perinatal development increases serotonin turnover in the prefrontal cortex and decreases midbrain tryptophan hydroxylase-2 expression in adult female rats: dissociation from estrogenic effects

A dysregulation in central serotonin neurotransmission and omega-3 fatty acid deficiency have been implicated in the pathophysiology of major depression. To determine the effects of omega-3 fatty acid deficiency on indices of serotonin neurotransmission in the adult rat brain, female rats were fed diets with or without the omega-3 fatty acid precursor α-linolenic acid (ALA) during perinatal (E0-P90), post-weaning (P21-P90), and post-pubescent (P60-130) development. Ovariectomized (OVX) rats and OVX rats with cyclic estrogen treatment were also examined. Serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) content, and fatty acid composition were determined in the prefrontal cortex (PFC), and tryptophan hydroxylase-2 (TPH-2), serotonin transporter, and 5-HT_1A autoreceptor mRNA expression were determined in the midbrain. ALA deficiency during perinatal (−62%, p = 0.0001), post-weaning (−34%, p = 0.0001), and post-pubertal (−10%, p = 0.0001) development resulted in a graded reduction in adult PFC docosahexaenoic acid (DHA, 22:6n−3) composition. Relative to controls, perinatal DHA-deficient rats exhibited significantly lower PFC 5-HT content (−65%, p = 0.001), significant greater 5-HIAA content (+15%, p = 0.046), and a significant greater 5-HIAA/5-HT ratio (+73%, p = 0.001). Conversely, post-weaning DHA-deficient rats exhibited significantly greater PFC 5-HT content (+12%, p = 0.03), no change in 5-HIAA content, and a significantly smaller 5-HIAA/5-HT ratio (−9%, p = 0.01). Post-pubertal DHA-deficient and OXV rats did not exhibit significant alterations in PFC 5-HT or 5-HIAA content. Only perinatal DHA-deficient rats exhibited a significant reduction in midbrain TPH-2 mRNA expression (−29%, p = 0.03). These preclinical data support a causal link between perinatal omega-3 fatty acid deficiency and reduced central serotonin synthesis in adult female rats that is independent of ovarian hormones including estrogen.     

Retardation in somatosensory cortex development induced by postnatal BrdU treatment in mice

Cerebral dysgeneses are in the background of several neurological and mental disturbances. The aim of the present study was to investigate structural and activity changes following disturbed postnatal neuronal development in mice. Newborn C57Bl6 mice were exposed to 5-bromo-2′-deoxyuridine (BrdU: daily 50 μg/g body weight) during a period between postnatal days P0–P5 or P0–P11, respectively, and neuronal malformation and malfunctioning of somatosensory (barrel field) cortex was analyzed in adolescent animals. Alterations in histological architecture of interneuronal and glial elements were studied and correlated with electrophysiological modifications. Between P30 and P35 days litters underwent ex vivo electrophysiological experiments to examine the changes in basic excitability and in synaptic efficacy. Parallel immunohistochemistry was performed to detect BrdU, GABA and GFAP.     

The Feverfew plant-derived compound, parthenolide enhances platelet production and attenuates platelet activation through NF-κB inhibition

Introduction

Few treatments are available that can safely and effectively stimulate new platelet production for thrombocytopenic patients. Additionally, recipients of transfused platelets may experience an inflammatory response due to stored platelets becoming unnecessarily activated, thus creating the need for suitable agents that will dampen undesirable platelet activation. We investigated the effect of the feverfew plant-derived compound, parthenolide on platelet production and platelet activation because of its well-studied ability to induce apoptosis or differentiation in some types of cancer.

Methods

Parthenolide was used to treat human megakaryoblastic cell lines, primary human and mouse megakaryocytes. Resulting platelet production and function was measured via flow cytometry. The two most common parthenolide signaling mechanisms, oxidative stress and nuclear factor-κB inhibition, were assessed within the megakaryocytes using reactive oxygen species, glutathione and luciferase reporter assays. The influence of parthenolide on ex vivo platelet activation was tested with parthenolide pretreatment followed by collagen or thrombin activation. The resulting P-selectin surface expression and released soluble CD40 ligand was measured.

Results

Parthenolide stimulates functional platelet production from human megakaryocyte cell lines, and from primary mouse and human megakaryocytes in vitro. Parthenolide enhances platelet production via inhibition of nuclear factor-κB signaling in megakaryocytes and is independent of the parthenolide-induced oxidative stress response. Additionally, parthenolide treatment of human peripheral blood platelets attenuated activation of stimulated platelets.

Conclusion

Overall, these data reveal that parthenolide has strong potential as a candidate to enhance platelet production and to dampen undesirable platelet activation.     

Diphenyl diselenide ameliorates behavioral and oxidative parameters in an animal model of mania induced by ouabain

Bipolar disorder (BD) is a common and severe mood disorder associated with higher rates of suicide and disability. Ouabain, a Na(+)/K(+)-ATPase inhibitor, induces behavioral changes in rats and has been used as a model of mania. The aim of this study was to investigate if diphenyl diselenide [(PhSe)(2)], an organoselenium compound with pharmacological properties, is effective against ouabain-induced hyperactivity and alterations in cerebral oxidative status of rats. Male Wistar rats were treated with a single dose of (PhSe)(2) (50 mg/kg, p.o.) 30 min before i.c.v. injection of ouabain (5 μl, 10(-5) M) or with the mood stabilizer, lithium chloride (LiCl) (45 mg/kg, p.o.), twice a day, for 7 days before the administration of ouabain. Open-field locomotion was quantified after ouabain administration. Thiobarbituric acid reactive substances (TBARS), oxidatively modified proteins, tyrosine nitration, ascorbic acid and non-protein thiols (NPSH) levels and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activities were determined in the whole brain. Ouabain increased locomotor activity in the open-field test and pretreatment with (PhSe)(2) or LiCl blocked this effect. In addition, ouabain increased lipid peroxidation and oxidatively modified proteins, demonstrated by a significant increase in TBARS levels and carbonyl content, which were attenuated by pretreatment with (PhSe)(2) or LiCl. The activities of SOD and CAT were increased by ouabain. LiCl was effective on preventing the increases of both enzyme activities, but (PhSe)(2) attenuated the ouabain effect in SOD activity. GPx and GR activities, ascorbic acid, NPSH and tyrosine nitration levels were not altered in all experimental groups. Similarly to LiCl, (PhSe)(2) produced an antimanic-like action, since it was effective against the locomotor hyperactivity elicited by ouabain. The results also indicated that (PhSe)(2) was effective against oxidative stress caused by ouabain in rats.     

D-arginine action against neurotoxicity induced by glucocorticoids in the brain

Glucocorticoids (GC) are necessary for normal life but elevated levels of GC have been implicated in the development of several neurological diseases and psychiatric disorders. Nowadays, it is well known that high levels of GC in the central nervous system (CNS) generate an increase in the production of reactive oxygen species (ROS), derived mainly from the nitric oxide (NO) pathway. Accordingly, there is an increase of l-arginine (l-Arg.) availability. This report reviews the evidence that d-arginine (d-Arg.) induces normalization of l-Arg. resulting in protection against GC neurotoxic actions in the hippocampus. It is important to highlight that this D-amino acid does not interfere with the expected peripheral effects of GC such as suppression of the hypothalamic-pituitary-adrenal axis (HPA axis) and the immune response, commonly used in clinical practice.     

Post-ischemic administration of nimodipine following focal cerebral ischemic-reperfusion injury in rats alleviated excitotoxicity, neurobehavioural alterations and partially the bioenergetics

The present study focuses on the temporal calcium significance in middle cerebral artery occluded (2 h ischemia)-reperfused (70 h reperfusion) rats treated with nimodipine (NM) through concurrent measurements of excitotoxicity, bioenergetics and neurobehavioural paradigms. Further, the suitable therapeutic time window of calcium channel antagonism in stroke was also ascertained. NM (5 mg/kg, i.p.) was administered at pre (30 min before the induction of ischemia), during (1 h following occlusion of MCA) and post-ischemic (3 h after begin of reperfusion) states. The magnitude of neuroprotection in terms of excitotoxicity (glutamate, glutamine synthetase, Na⁺K⁺ATPase), bioenergetics (ATP, NAD⁺) and neurobehavioural paradigms (neurological score and open field exploratory behaviour) were measured and compared to ensure the therapeutic time-window of NM in stroke. Middle cerebral artery occlusion-reperfusion (MCAO/R) was found to elevate glutamate, glutamine synthetase levels and deplete Na⁺K⁺ATPase activity in the vehicle treated group (IR group). Significant decrease in bioenergetics such as ATP and NAD⁺ levels was also observed. Further, IR group demonstrated grievous oxidative stress (increase in lipid peroxidation, protein carbonyl content, nitrite/nitrate levels and decrease in superoxide dismutase and glutathione levels) along with anxiogenic behaviour, neurological deficits and neuronal damage and decreased nuclear to cytoplasm ratio in CA1 hippocampal region. Post-ischemic NM administration reversed the excitotoxicity, neurobehavioural and histopathological alterations significantly, but it restored bioenergetics level in MCAO/R rats only partially.These findings were further confirmed with the combination treatment (CT) of post-ischemic NM and pre-ischemic memantine (MN) administration, since MN showed protective effect in the pre-ischemic administration (Babu and Ramanathan, 2009). The failure of NM to forefend the neurodegeneration on pre- and during-ischemic administration suggests that the initial phase damages in ischemic-reperfusion (IR) might be mediated through other mechanism(s) such as glutamergic overstimulation or reverse operation of glutamate transporters. From the present study, it is concluded that calcium plays a crucial role in post-ischemic status and the suitable therapeutic time window of calcium antagonism is the post-ischemic state.     

Total oligomeric flavonoids of Cyperus rotundus ameliorates neurological deficits, excitotoxicity and behavioral alterations induced by cerebral ischemic-reperfusion injury in rats

Interactions between neurons and astrocytes play a critical role in the central nervous system homeostasis. Cyperus rotundus (family: Cyperaceae), a traditional Indian medicinal herb, used as nervine tonic and nootropic in the Ayurvedic system of medicine. The present study was undertaken to investigate the neuroprotective effect of total oligomeric flavonoids (TOFs), prepared from C. rotundus, in rat model of cerebral ischemia and reperfusion. Male Sprague Dawley rats (290-340 g) were subjected to middle cerebral artery occlusion (MCAO) for 2 h and reperfusion for 70 h. Experimental animals were divided into four groups: Group I - sham operated (n = 7); Group II - vehicle treated ischemic-reperfusion (IR) (n = 9), and Group III and IV - TOFs treated (100 and 200 mg/kg body weight, p.o., respectively; n = 7 in each group). Vehicle or TOFs were pretreated for four days before the induction of ischemia and continued for next three days after the ischemia i.e. treatment was scheduled totally for a period of 7 days. MCAO surgery was performed on day 4, 1 h after TOFs administration. Neuroprotective effect of TOFs was substantiated in terms of neurological deficits, excitotoxicity (glutamate, glutamine synthetase and Na⁺K⁺ATPase levels), oxidative stress (malondialdehyde, super oxide dismutase, and glutathione) and neurobehavioral functions in the experimental animals. TOFs decreased glutamate, glutamine synthetase (GS) and increased Na⁺K⁺ATPase activity in a dose dependent manner when compared to the IR rats. Treatment with TOFs significantly reduced the neurological deficits and reversed the anxiogenic behavior in rats. Further, it also significantly decreased MDA and increased superoxide dismutase (SOD) and glutathione content in brains of experimental rats. Histopathological examination using cresyl violet staining revealed the attenuation of neuronal loss by TOFs in stroke rats. The present study demonstrates the unswerving involvement of TOFs on ischemia-reperfusion triggered biochemical alterations in MCAO/R rats. Hence, TOFs might be an attractive candidate for further studies in the development of new drugs for cerebral stroke treatment.     

Association between the MnSOD Ala-9Val polymorphism and development of schizophrenia and abnormal involuntary movements in the Xhosa population

Reactive oxygen species (ROS)-mediated damage has been hypothesized to play a role in the development and poor outcome of schizophrenia, as well as the development of neuroleptic-induced abnormal involuntary movements. Recently, the functional polymorphism (Ala-9Val) in the manganese superoxide dismutase (MnSOD) gene (part of the antioxidant defense mechanism) was found to be associated with schizophrenia in a Turkish population. This study was aimed at replicating this finding in a Xhosa population. In addition, the role of Ala-9Val in abnormal involuntary movement and tardive dyskinesia development in the Xhosa population was also investigated. The schizophrenic patient group (n=286) and a healthy control group (n=243) were genotyped for the Ala-9Val polymorphism using heteroduplex-single stranded conformational polymorphism (HEX-SSCP) analysis. No significant difference in genotype or allele frequency could be observed between the schizophrenia and control group (P=0.294 and P=0.528 respectively). In addition no association could be found between the polymorphism and symptom severity (SANS and SAPS). The Xhosa schizophrenia patient group with abnormal involuntary movements (n=54) and a subgroup with tardive dyskinesia (n=30) was found to significantly differ in Ala-9Val genotype frequency (P=0.008 and P=0.011 respectively) compared to the Xhosa schizophrenia patient group without abnormal involuntary movements (n=204). However, no significant difference was found for the allele frequencies (P=0.955 and P=0.161). Further, using ANCOVA no association was found between AIMS score and genotype in the group with abnormal involuntary movements (P=0.1234). However, in the patient group with tardive dyskinesia an association was observed between genotype and AIMS score (P=0.0365). These results do not support a major role of the MnSOD Ala-9Val polymorphism in the development of schizophrenia or symptom severity in the Xhosa population. Yet it seems to be involved in the development of abnormal involuntary movements and tardive dyskinesia and may even modulate the severity of tardive dyskinesia.     

Curcumin enhances neuronal survival in N-methyl-d-aspartic acid toxicity by inducing RANTES expression in astrocytes via PI-3K and MAPK signaling pathways

Object

Neuroinflammation, which is characterized by the overproduction of cytokines and chemokines, plays an important role in neurodegenerative diseases, especially in Alzheimer's disease (AD). In the brain, chemokines are predominantly released by astrocytes and microglias. Expression of RANTES, as well as other cytokines, is involved in the inflammatory cascade that contributes to neurodegeneration in AD. Expression of RANTES may also have a neuroprotective effect. We sought to investigate whether curcumin exhibited neuroprotective and antioxidant activity via enhanced RANTES expression by astrocytes in cortical neuron cultures. We evaluated the neuroprotective and anti-neurodegenerative effects of curcumin in NMDA toxicity and in long-term cultures.

Methods

Pregnant female Sprague-Dawley (SD) rats were used for primary culture of cortical neurons, and neonatal 0- to 2-day-old SD rats were used for primary culture of astrocytes. Cultured astrocytes were conditioned with curcumin to prepare astrocyte-conditioned medium (ACM). Real-time polymerase chain reaction was performed to assess RANTES and iNOS mRNA expression in astrocytes following curcumin treatment. ELISA was used to detect astrocyte-secreted RANTES protein in ACM with curcumin treatment. JAK/STAT, PI-3K, PKC and MAPK inhibitors were used to ascertain whether the effects of curcumin involved these signaling pathways. To evaluate the effects of curcumin-enhanced astrocytes on neuronal survival, cultured cortical neurons treated or untreated with NMDA were incubated in ACM with or without curcumin treatment. Long-term culture (15 days in vitro, DIV) was performed to investigate the effects of curcumin-treated astrocytes on the survival of cultured cortical neurons. Neuronal survival rate was assessed by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction activity assay (for cell viability), and the lactate dehydrogenase (LDH) release assay (for cell death).

Results

We demonstrated that curcumin enhanced RANTES expression in primary cultured astrocytes, and that this effect was related to activation of PI-3K and MAPK signaling pathways. We found that curcumin inhibited iNOS expression in primary cultured astrocytes in non-stressed condition. We also found that neurons exposed to NMDA and cultured with curcumin treated ACM, which characteristically exhibited elevated RANTES expression showed higher level of cell viability and lower level of cell death. Using a small interfering RNA (siRNA) knockdown model, we found evidence that the basal level of RANTES expression in non-stimulated astrocytes provided neuroprotection.

Conclusion

We postulate that the enhanced neuronal survival by curcumin treatment in NMDA toxicity and long-term cultures was in part attributable to elevated astrocyte-derived RANTES expression via activation of PI3K/MAPK signaling pathways.     

The role of glutamate receptors in traumatic brain injury: implications for postsynaptic density in pathophysiology

Traumatic brain injury (TBI) is the major cause of death and disability, and the incidence of TBI continues to increase rapidly. In recent years, increasing attention has been paid to an important structure at the postsynaptic membrane: the postsynaptic density (PSD). Glutamate receptors, as major components of the PSD, are highly responsive to alterations in the glutamate concentration at excitatory synapses and activate intracellular signal transduction via calcium and other second messengers following TBI. PSD scaffold proteins (PSD-95, Homer, and Shank), which anchor glutamate receptors and form a network structure, also have potential effects on these downstream signaling pathways. The changes in the function and structure of these major PSD proteins are also induced by TBI, indicating that there is a more complicated mechanism associated with PSD proteins in the pathophysiological process of TBI.