Measurement of OH radicals distribution in a microwave plasma sheet using LIF method.

Microwave plasma sources (MPSs) operating at atmospheric pressure provide plasmas in the form of a flame or cylindrical column. In contrast, this article presents an innovative MPS (patented by us) for generating a new type of plasma, i.e. in the form of a plasma sheet, which is generated in a flat cuboidal quartz box. It is based on a WR 340 waveguide, powered by microwaves of 2.45 GHz and operated in argon at atmospheric pressure. The plasma sheet contains a multitude of filaments typical of microwave argon plasmas. In the presented experiment, the spatial distribution of the OH radicals in the microwave plasma sheet was measured by means of the LIF method. Studies have shown that the relative concentration of OH radicals increases with the increase in microwave power and decreases with the increasing argon flow rate.

Direct comparison of autologous and allogeneic transplantation of iPSC-derived neural cells in the brain of a non-human primate.

Induced pluripotent stem cells (iPSCs) provide the potential for autologous transplantation using cells derived from a patient's own cells. However, the immunogenicity of iPSCs or their derivatives has been a matter of controversy, and up to now there has been no direct comparison of autologous and allogeneic transplantation in the brains of humans or nonhuman primates. Here, using nonhuman primates, we found that the autologous transplantation of iPSC-derived neurons elicited only a minimal immune response in the brain. In contrast, the allografts caused an acquired immune response with the activation of microglia (IBA-1(+)/MHC class II(+)) and the infiltration of leukocytes (CD45(+)/CD3(+)). Consequently, a higher number of dopaminergic neurons survived in the autografts. Our results suggest that the autologous transplantation of iPSC-derived neural cells is advantageous for minimizing the immune response in the brain compared with allogeneic grafts.

The selective metabotropic glutamate 2/3 receptor agonist MGS0028 reverses psychomotor abnormalities and recognition memory deficits in mice lacking the pituitary adenylate cyclase-activating polypeptide.

Previous studies suggest that metabotropic glutamate 2/3 receptors are involved in psychiatric disorders. In this study, we examined the effects of the selective metabotropic glutamate 2/3 (mGlu2/3) receptor agonist MGS0028 on behavioral abnormalities in mice lacking the pituitary adenylate cyclase-activating polypeptide (PACAP), an experimental model of psychiatric disorders such as schizophrenia and attention-deficit/hyperactivity disorder. We found that PACAP-deficient mice showed impairments in the novel object recognition test and these impairments were improved by MGS0028 (0.1 mg/kg). Similarly, MGS0028 improved hyperactivity and jumping behaviors, but did not reverse increased immobility times in the forced swim test in PACAP-deficient mice. These results suggest that MGS0028 may be a potential, novel treatment for psychiatric disorders.

Metabotropic glutamate 2/3 receptor antagonists improve behavioral and prefrontal dopaminergic alterations in the chronic corticosterone-induced depression model in mice.

Metabotropic glutamate 2/3 (mGlu2/3) receptor antagonists have an antidepressant-like effect, but the exact mechanism still remains unclear. This study examined the effects of mGlu2/3 receptor antagonists in chronic corticosterone-treated mice which could be used as an animal model of depression. In the forced swim test, the mGlu2/3 receptor antagonists MGS0039 (1.0 mg/kg, i.p.) and LY341495 (0.3 mg/kg, i.p) significantly reduced the increased immobility time of mice pretreated with corticosterone (20 mg/kg, s.c.) for 21 days, while desipramine (30 mg/kg, i.p.) and fluoxetine (30 mg/kg, i.p.) did not. The antidepressant-like effect of LY341495 was not blocked by the α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor antagonist NBQX (10 mg/kg, i.p.). Systemic administration of LY341495 did not affect basal release of glutamate, dopamine or serotonin in the prefrontal cortex of the control or chronic corticosterone-treated mice. Chronic corticosterone markedly enhanced high K(+)-induced release of dopamine, but not serotonin or glutamate, in the prefrontal cortex. This neurochemical change was blocked by systemic administration of MGS0039 and LY341495, but not desipramine or fluoxetine. These results suggest that chronic corticosterone-treated mice could be used as an animal model of treatment-resistant depression. This study also suggests that the prefrontal dopaminergic system is involved in the antidepressant-like effect of mGlu2/3 receptor antagonists in the chronic corticosterone-induced depression model.

Increase of 20-HETE synthase after brain ischemia in rats revealed by PET study with 11C-labeled 20-HETE synthase-specific inhibitor.

20-Hydroxyeicosatetraenoic acid (20-HETE), an arachidonic acid metabolite known to be produced after cerebral ischemia, has been implicated in ischemic and reperfusion injury by mediating vasoconstriction. To develop a positron emission tomography (PET) probe for 20-HETE synthase imaging, which might be useful for monitoring vasoconstrictive processes in patients with brain ischemia, we synthesized a (11)C-labeled specific 20-HETE synthase inhibitor, N'(4-dimethylaminohexyloxy)phenyl imidazole ([(11)C]TROA). Autoradiographic study showed that [(11)C]TROA has high-specific binding in the kidney and liver consistent with the previously reported distribution of 20-HETE synthase. Using transient middle cerebral artery occlusion in rats, PET study showed significant increases in the binding of [(11)C]TROA in the ipsilateral hemisphere of rat brains after 7 and 10 days, which was blocked by co-injection of excess amounts of TROA (10 mg/kg). The increased [(11)C]TROA binding on the ipsilateral side returned to basal levels within 14 days. In addition, quantitative real-time PCR revealed that increased expression of 20-HETE synthase was only shown on the ipsilateral side on day 7. These results indicate that [(11)C]TROA might be a useful PET probe for imaging of 20-HETE synthase in patients with cerebral ischemia.

Disruption of programmed masticatory movements in unilateral MPTP-treated monkeys as a model of jaw movement abnormality in Parkinson's disease.

While motor disturbance in Parkinson's disease can affect innate, programmed processes, such as masticatory mandibular movements, the pathophysiology of such abnormalities remains unclear. This study applies digital analysis by high-speed video signal processing that tracks three dots placed around the mouth for recording masticatory movements in unilateral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys. The system analyzes displacement, velocity and cycle duration of the topography of mandibular movement during mastication of sweet potato slices. In monkeys receiving MPTP into the right carotid artery (n = 3), positron emission tomography indicated significant reduction in the binding of (E)-N-(3-iodoprop-2-enyl)-2ß-carbo[(11)C]methoxy-3ß-(4-methylphenyl)nortropane ([(11)C]PE2I) to the dopamine transporter in the right caudate, putamen, nucleus accumbens and substantia nigra relative to the contralateral hemisphere. These monkeys showed hypokinesia of the left forelimbs and hindlimbs. During mastication, MPTP-treated monkeys chewed preferentially on the left side, while untreated monkeys (n = 3) showed no preference for chewing side. The amplitude of vertical opening and closing movements was reduced in MPTP-treated monkeys, with a slight but significant increase in the lateral component of mandibular movements. The velocity of all phases of horizontal mandibular movements was reduced. In consequence, duration of the occlusal phase was increased, while duration of the closing phase was decreased in MPTP-treated monkeys. These findings indicate that during masticatory movements MPTP-treated monkeys chew preferentially on the side contralateral to loss of dopamine neurons, with reduced amplitude and velocity of mandibular movements. High-speed digital movement analysis is able to define and quantify abnormalities of orofacial movement topography as a sign of parkinsonism.

Prolonged maturation culture favors a reduction in the tumorigenicity and the dopaminergic function of human ESC-derived neural cells in a primate model of Parkinson's disease.

For the safe clinical application of embryonic stem cells (ESCs) for neurological diseases, it is critical to evaluate the tumorigenicity and function of human ESC (hESC)-derived neural cells in primates. We have herein, for the first time, compared the growth and function of hESC-derived cells with different stages of neural differentiation implanted in the brains of primate models of Parkinson's disease. We herein show that residual undifferentiated cells expressing ESC markers present in the cell preparation can induce tumor formation in the monkey brain. In contrast, a cell preparation matured by 42-day culture with brain-derived neurotrophic factor/glial cell line-derived neurotrophic factor (BDNF/GDNF) treatment did not form tumors and survived as primarily dopaminergic (DA) neurons. In addition, the monkeys with such grafts showed behavioral improvement for at least 12 months. These results support the idea that hESCs, if appropriately matured, can serve as a source for DA neurons without forming any tumors in a primate brain.

The selective metabotropic glutamate 2/3 receptor agonist MGS0028 reverses isolation rearing-induced abnormal behaviors in mice.

Isolation-induced abnormal behaviors are useful animal models for assessing potential anti-psychotic drugs. This study examined the effect of MGS0028, a selective metabotropic glutamate 2/3 receptor agonist, on abnormal behaviors such as hyperactivity, aggression, and deficits of prepulse inhibition in isolation-reared mice. MGS0028 attenuated hyperactivity and aggressive behaviors in isolation-reared mice. The agonist also reversed isolation rearing-induced deficits of prepulse inhibition. On the other hand, MGS0028 did not affect locomotor activity and prepulse inhibition in group-reared mice. These results suggest that the metabotropic glutamate 2/3 receptor agonist, MGS0028, is a potential compound for the treatment of psychiatric disorders.

SEA0400, a specific Na+/Ca2+ exchange inhibitor, prevents dopaminergic neurotoxicity in an MPTP mouse model of Parkinson's disease.

We have recently shown that the Na(+)/Ca(2+) exchanger (NCX) is involved in nitric oxide (NO)-induced cytotoxicity in cultured astrocytes and neurons. However, there is no in vivo evidence suggesting the role of NCX in neurodegenerative disorders associated with NO. NO is implicated in the pathogenesis of neurodegenerative disorders such as Parkinson's disease. This study examined the effect of SEA0400, the specific NCX inhibitor, on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopaminergic neurotoxicity, a model of Parkinson's disease, in C57BL/6J mice. MPTP treatment (10 mg/kg, four times at 2-h intervals) decreased dopamine levels in the midbrain and impaired motor coordination, and these effects were counteracted by S-methylthiocitrulline, a selective neuronal NO synthase inhibitor. SEA0400 protected against the dopaminergic neurotoxicity (determined by dopamine levels in the midbrain and striatum, tyrosine hydroxylase immunoreactivity in the substantia nigra and striatum, striatal dopamine release, and motor deficits) in MPTP-treated mice. SEA0400 had no radical-scavenging activity. SEA0400 did not affect MPTP metabolism and MPTP-induced NO production and microglial activation, while it attenuated MPTP-induced increases in extracellular signal-regulated kinase (ERK) phosphorylation and lipid peroxidation product, thiobarbituric acid reactive substance. These findings suggest that SEA0400 protects against MPTP-induced neurotoxicity probably by blocking ERK phosphorylation and lipid peroxidation which are downstream of NCX-mediated Ca(2+) influx.

The specific Na(+)/Ca(2+) exchange inhibitor SEA0400 prevents nitric oxide-induced cytotoxicity in SH-SY5Y cells.

The Na(+)/Ca(2+) exchanger (NCX) plays a role in the regulation of intracellular Ca(2+) levels, and nitric oxide (NO) is involved in many pathological conditions including neurodegenerative disorders. We have previously found that sodium nitroprusside (SNP), an NO donor, causes apoptotic-like cell death in cultured glial cells via NCX-mediated pathways and the mechanism for NO-induced cytotoxicity is cell type-dependent. The present study examined using the specific NCX inhibitor 2-[4-[(2,5-difluorophenyl)methoxy]phenoxy]-5-ethoxyaniline (SEA0400) whether NCX is involved in NO-induced injury in cultured neuronal cells. The treatment of neuroblastoma SH-SY5Y cells with SNP resulted in apoptosis and the cytotoxicity was blocked by the mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase inhibitor U0126 and the p38 MAP kinase (MAPK) inhibitor SB203580, but not by the c-Jun N-terminal kinase (JNK) inhibitor SP60012. SNP increased Ca(2+) influx and intracellular Ca(2+) levels. In addition, SNP increased ERK and p38 MAPK phosphorylation, and production of reactive oxygen species (ROS) in an extracellular Ca(2+)-dependent manner. These effects of SNP were prevented by SEA0400. SNP-induced cytotoxicity was not affected by inhibitors of the Ca(2+), Na(+) and store-operated/capacitative channels. Moreover, SNP-induced increase in intracellular Ca(2+) levels, ROS production and decrease in cell viability were blocked by a cGMP-dependent protein kinase (PKG) inhibitor. These results suggest that Ca(2+) influx via the reverse of NCX is involved in the cascade of NO-induced neuronal apoptosis and NO activates the NCX through guanylate cyclase/PKG pathway.

Activation of metabotropic glutamate 2/3 receptors attenuates methamphetamine-induced hyperlocomotion and increase in prefrontal serotonergic neurotransmission.

RATIONALE: Metabotropic glutamate (mGlu) 2/3 receptor agonists inhibit amphetamine- and phencyclidine-induced hyperlocomotion. The mechanism for the antipsychotic effect of mGlu2/3 receptor agonists was studied in a hypoglutamatergic model, but not a hyperdopaminergic model. OBJECTIVES: To study the mechanism for the antipsychotic effect of the agonist in the hyperdopaminergic model, this study examined the effects of the selective mGlu2/3 receptor agonist MGS0028 on methamphetamine-induced hyperlocomotion and the increases in extracellular levels of serotonin, dopamine, noradrenaline, and glutamate in the prefrontal cortex and nucleus accumbens of mice. RESULTS: Systemic administration of MGS0028 attenuated methamphetamine-induced hyperlocomotion in a dose-dependent manner. Microdialysis studies showed that MGS0028 significantly inhibited methamphetamine-induced increases in the extracellular serotonin, but not dopamine and noradrenaline, levels in the prefrontal cortex, and it did not affect methamphetamine-induced increases in the extracellular amine levels in the nucleus accumbens. Methamphetamine did not affect the glutamate release in the prefrontal cortex and nucleus accumbens. Local application of MGS0028 into the prefrontal cortex also attenuated methamphetamine-induced hyperlocomotion and increases in the extracellular serotonin levels in the prefrontal cortex. Moreover, MGS0028 did not affect methamphetamine-induced hyperlocomotion in the mice pretreated with p-chlorophenylalanine, a serotonin synthesis inhibitor. CONCLUSIONS: Activation of prefrontal mGlu2/3 receptors inhibits the psychomotor stimulant effect of methamphetamine in mice, and the prefrontal serotonergic system may be involved in this effect. The finding provides evidence that prefrontal mGlu2/3 receptors are functionally coupled with the serotonergic system.

Increased binding of cortical and hippocampal group II metabotropic glutamate receptors in isolation-reared mice.

Post-weaning social isolation in rodents induces behavioral alterations, including hyperlocomotion, depression- and anxiety-like behaviors, aggression, and learning and memory deficits. These behavioral abnormalities may be related to the core symptoms in patients with neuropsychiatric disorders, such as schizophrenia and depression. In view of the recent studies that the group II metabotropic glutamate receptor (mGluR2/3) is involved in neuropsychiatric disorders, the present study examined the effect of isolation rearing on the binding of the mGluR2/3 antagonist [(3)H]LY341495 to mGluR2/3 in the mouse brain by in vitro autoradiography. The [(3)H]LY341495 binding in the prefrontal cortex, cerebral cortical layers I-III and hippocampus was significantly increased by rearing in social isolation while the binding in other brain regions was not altered. A saturation binding study of hippocampal membranes from isolation-reared mice revealed that the B(max) value increased significantly without any changes in the K(d) value. Moreover, the mGluR2/3 antagonist MGS0039 (1.0mg/kg, intraperitoneally) decreased the immobility time of isolation-reared mice in the forced swim test. These results suggest that isolation rearing causes an increase in mGluR2/3 densities in the prefrontal cortex and hippocampus and that the increased receptor function may contribute to pathogenic mechanisms for depression-like behavior of the isolation-reared mice.

Survival of human induced pluripotent stem cell-derived midbrain dopaminergic neurons in the brain of a primate model of Parkinson's disease.

Before induced pluripotent stem cells (iPSCs) can be used to treat neurologic diseases, human iPSC-derived neural cells must be analyzed in the primate brain. In fact, although mouse and human iPSCs have been used to generate dopaminergic (DA) neurons that are beneficial in rat models of Parkinson's disease (PD), human iPSC-derived neural progenitor cells (NPCs) have not been examined in primate brains. Here, we generated NPCs at different stages of predifferentiation using a feeder-free culture method, and grafted them into the brains of a monkey PD model and NOD-SCID mice. Magnetic resonance imaging (MRI), positron emission tomography (PET), immunocytochemistry, and behavioral analyses revealed that NPCs pretreated with Sonic hedgehog and fibroblast growth factor-8 followed by glial cell-derived neurotrophic factor, brain-derived neurotrophic factor, ascorbic acid, and dibutyryl cyclic AMP resulted in smaller grafts than those without these treatments, and survived as DA neurons in a monkey brain as long as six months. Thus, for the first time, we describe a feeder-free neural differentiation method from human iPSCs and an evaluation system that can be used to assess monkey PD models.

Use of [18F]FDOPA-PET for in vivo evaluation of dopaminergic dysfunction in unilaterally 6-OHDA-lesioned rats.

BACKGROUND: We evaluated the utility of L-3,4-dihydroxy-6-[18F]fluoro-phenylalanine ([18F]FDOPA) positron emission tomography (PET) as a method for assessing the severity of dopaminergic dysfunction in unilaterally 6-hydroxydopamine (6-OHDA)-lesioned rats by comparing it with quantitative biochemical, immunohistochemical, and behavioral measurements. METHODS: Different doses of 6-OHDA (0, 7, 14, and 28 µg) were unilaterally injected into the right striatum of male Sprague-Dawley rats. Dopaminergic functional activity in the striatum was assessed by [18F]FDOPA-PET, measurement of striatal dopamine (DA) and DA metabolite levels, tyrosine hydroxylase (TH) immunostaining, and methamphetamine-induced rotational testing. RESULTS: Accumulation of [18F]FDOPA in the bilateral striatum was observed in rats pretreated with both aromatic L-amino acid decarboxylase and catechol-O-methyltransferase (COMT) inhibitors. Unilateral intrastriatal injection of 6-OHDA produced a significant site-specific reduction in [18F]FDOPA accumulation. The topological distribution pattern of [18F]FDOPA accumulation in the ipsilateral striatum agreed well with the pattern in TH-stained corresponding sections. A significant positive relationship was found between Patlak plot Ki values and striatal levels of DA and its metabolites (r = 0.958). A significant negative correlation was found between both Ki values (r = -0.639) and levels of DA and its metabolites (r = -0.719) and the number of methamphetamine-induced rotations. CONCLUSIONS: Ki values determined using [18F]FDOPA-PET correlated significantly with the severity of dopaminergic dysfunction. [18F]FDOPA-PET makes it possible to perform longitudinal evaluation of dopaminergic function in 6-OHDA-lesioned rats, which is useful in the development of new drugs and therapies for Parkinson's disease (PD).

The Na+/Ca2+ exchanger-mediated Ca2+ influx triggers nitric oxide-induced cytotoxicity in cultured astrocytes.

Nitric oxide (NO) is involved in many pathological conditions including neurodegenerative disorders. We have previously found that sodium nitroprusside (SNP), an NO donor, stimulates mitogen-activated protein kinases (MAPKs) such as extracellular signal-regulating kinase (ERK), c-jun N-terminal protein kinase (JNK) and p38 MAPK, leading to caspase-independent apoptosis in cultured astrocytes. In view of the previous observation that NO stimulates the activity of the Na(+)/Ca(2+) exchanger (NCX), this study examines the involvement of NCX in cytotoxicity. The specific NCX inhibitor SEA0400 blocked SNP-induced phosphorylation of ERK, JNK and p38 MAPK, and decrease in cell viability. SNP-induced phosphorylation of ERK, JNK and p38 MAPK was blocked by removal of external Ca(2+), and SNP treatment caused an increase in (45)Ca(2+) influx. This increase in (45)Ca(2+) influx was blocked by SEA0400, but not the Ca(2+) channel blocker nifedipine. In addition, SNP-induced (45)Ca(2+) influx and cytotoxicity were reduced in NCX1-deficient cells which were transfected with NCX1 siRNA. Inhibitors of intracellular Ca(2+)-dependent proteins such as calpain and calmodulin blocked SNP-induced ERK phosphorylation and decrease in cell viability. Furthermore, the guanylate cyclase inhibitor LY83583 and the cGMP-dependent protein kinase inhibitor KT5823 blocked SNP-induced cytotoxicity. These findings suggest that NCX-mediated Ca(2+) influx triggers SNP-induced apoptosis in astrocytes, which may be mediated by a cGMP-dependent pathway.

A neuroprotective agent, T-817MA (1-{3-[2-(1-benzothiophen-5-yl)ethoxy]propyl} azetidin-3-ol maleate), prevents 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity in mice.

T-817MA (1-{3-[2-(1-benzothiophen-5-yl)ethoxy]propyl} azetidin-3-ol maleate) is a candidate therapeutic agent for Alzheimer's disease that inhibits oxidative stress and nitric oxide-induced neurotoxicity and acts as a neurotrophic factor. The present study examines the effect of T-817MA on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopaminergic neurotoxicity in C57BL/6J mice. MPTP treatment (10mg/kg, s.c.x4 at 2-h intervals) impaired rotarod performance, and T-817MA improved this deficit. MPTP treatment also decreased dopamine levels and tyrosine hydroxylase immunostaining in the substantia nigra (SNc) and striatum. Pretreatment with T-817MA (10 and 30mg/kg as T-817, p.o.) attenuated these decreases in dopamine levels and tyrosine hydroxylase immunoreactivity, but did not affect brain levels of 1-methyl-4-phenylpyridinium ion, an active metabolite of MPTP. The protective effect was almost complete in the SNc, but only partial in the striatum. MPTP increased levels of the lipid peroxidation product, thiobarbituric acid reactive substance, only in the midbrain, which could be blocked by T-817MA. MPTP caused microglial activation both in the SNc and striatum, but T-817MA did not affect the activation of microglia. These results suggest that T-817MA protects against MPTP-induced neurotoxicity by blocking lipid peroxidation in the SNc, and imply that this compound may be useful for treating neurodegenerative disorders related to oxidative stress, such as Parkinson's disease.

The radical scavenger edaravone counteracts diabetes in multiple low-dose streptozotocin-treated mice.

Edaravone is a potent scavenger of hydroxyl radicals and attenuates oxidative damage-related neurodegenerative diseases. Previous studies suggest that oxidative stress plays a key role in the pathogenesis of diabetes. The present study examined the effect of edaravone on diabetes in multiple low-dose streptozotocin-treated mice. Mice treated with low-doses of streptozotocin for five consecutive days showed progressive hyperglycemia and an increased incidence of diabetes. Daily treatment with edaravone during the streptozotocin injections counteracted the multiple low-dose streptozotocin-induced hyperglycemia in a dose-dependent manner. Edaravone protected against the multiple low-dose streptozotocin-induced reduction in pancreatic insulin. The suppressive effects of edaravone were also observed when it was administered after the last injection of streptozotocin. Histochemical examination showed that multiple low-dose streptozotocin treatment caused mononuclear cell infiltration in pancreatic islets, followed by hyperglycemia, and that edaravone significantly inhibited the multiple low-dose streptozotocin-induced insulitis. Multiple low-dose streptozotocin treatment also increased the lipid peroxidation product thiobarbituric acid reactive substance in pancreatic tissues of mice, and this effect was completely inhibited by edaravone. These findings suggest that edaravone, even after streptozotocin treatment, counteracts the development of multiple low-dose streptozotocin-induced diabetes by scavenging free radicals, which are possible mediators of the immune destruction of islet beta cells.

Galantamine and donepezil differently affect isolation rearing-induced deficits of prepulse inhibition in mice.

RATIONALE: Previous studies have shown that alterations in acetylcholine (ACh) receptor subtypes might contribute to cognitive impairment observed in schizophrenia and that choline acetyltransferase activity in the parietal cortex is negatively correlated with the severity of such cognitive impairment. However, clinical data suggest that the acetylcholinesterase (AChE) inhibitors galantamine and donepezil have different effects on negative and cognitive symptoms in schizophrenia. Prepulse inhibition (PPI) deficits--sensory information-processing deficits observed in schizophrenia--may be useful models for studying the efficacy of AChE inhibitors as cognitive enhancers. OBJECTIVES: The present study examined the effects of galantamine and donepezil on PPI deficits induced by an environmental factor and drugs. MATERIALS AND METHODS: In the isolation-rearing model, 3-week-old male ddY mice were housed either in groups of five or six per cage or isolated in cages of the same size for more than 6 weeks. In the drug-induced model, apomorphine 1 mg/kg and MK-801 0.2 mg/kg were administered to 9- to 10-week-old male ddY mice. RESULTS: In isolation-reared mice, galantamine attenuated PPI deficits, while donepezil did not. Galantamine and donepezil both attenuated PPI deficits induced by apomorphine, but not by MK-801. The galantamine-induced improvements in PPI deficits were not prevented by the nicotinic ACh receptor antagonists mecamylamine and methyllycaconitine. CONCLUSIONS: These observations suggest that galantamine and donepezil have different effects on the environmentally induced PPI deficits and that these observations may be relevant to the different effects of these drugs observed clinically in schizophrenia.

Nitric oxide-induced apoptosis in cultured rat astrocytes: protection by edaravone, a radical scavenger.

Nitric oxide induces apoptosis-like cell death in cultured astrocytes, but the exact mechanism is not known. This study further characterized the mechanism of nitric oxide-induced cytotoxicity, and examined the effect of edaravone, a radical scavenger, on cytotoxicity. Treatment of cultured rat astrocytes with sodium nitroprusside (SNP), a nitric oxide donor, for 72 h, decreased cell viability by causing apoptosis-like cell death. The injury was accompanied by increases in the production of reactive oxygen species and in the level of nuclear apoptosis-inducing factor, but not in caspase activity. SNP-induced cytotoxicity was blocked by the c-jun N-terminal protein kinase (JNK) inhibitor SP600125 (20 microM), the p38 mitogen-activated protein (MAP) kinase inhibitor SB203580 (20 microM), and the extracellular signal-regulating kinase (ERK) inhibitor U0126 (10 microM), and the nitric oxide donor stimulated the phosphorylation of p38 MAP kinase, JNK, and ERK. Edaravone (10 microM) protected astrocytes against SNP-induced cell injury and it inhibited SNP-induced phosphorylation of p38 MAP kinase, JNK, and ERK, and the production of reactive oxygen species. Edaravone also attenuated SNP-induced increase in nuclear apoptosis-inducing factor levels. These results suggest that MAP kinase pathways play a key role in nitric oxide-induced apoptosis and that edaravone protects against nitric oxide-induced cytotoxicity by inhibiting nitric oxide-induced MAP kinase activation in astrocytes.

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a radical scavenger, prevents 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity in the substantia nigra but not the striatum.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes nigrostriatal dopaminergic neurotoxicity and behavioral impairment in rodents, and previous studies suggest that nitric oxide and reactive oxygen species are involved in MPTP-induced neurotoxicity. The present study examines the effect of edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a radical scavenger, on MPTP-induced neurotoxicity in the striatum and substantia nigra pars compacta (SNc) of C57BL/6J mice. MPTP treatment (10 mg/kg s.c. x 4 with 2-h intervals) decreased dopamine levels and tyrosine hydroxylase immunostaining in the striatum and SNc. Pretreatment with edaravone (1 and 3 mg/kg i.p.) significantly reduced the neurotoxicity in the SNc but not striatum. An immunohistochemical study showed that MPTP caused microglial activation both in the striatum and SNc, whereas it increased 3-nitrotyrosine immunoreactivity, an in vivo biomarker of peroxynitrite production, in the SNc but not the striatum. Furthermore, MPTP increased lipid peroxidation product thiobarbituric acid reactive substance in the midbrain, but not the striatum. Edaravone inhibited activation of the microglia and the increased 3-nitrotyrosine immunoreactivity in the SNc but not the striatum, and it also inhibited thiobarbituric acid reactive substance levels in the midbrain. Behavioral analyses showed that edaravone improved MPTP-induced impairment of locomotion and Rotorod performance. These results suggest that edaravone protects against MPTP-induced neurotoxicity in the SNc by blocking the production of reactive oxygen species or peroxynitrite and imply that dopaminergic degeneration in the SNc may play an important role in MPTP-induced motor dysfunction of mice.