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J Krieglstein

Publications and source records attributed to J Krieglstein.

At least 19 recordsLinked to original sources
PubMed2006

PTEN: a crucial mediator of mitochondria-dependent apoptosis.

The highly frequent mutation of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) in various cancers has attracted much attention to study its role in tumorigenesis. As an important tumor suppressor, the pro-apoptotic function of PTEN has been linked to its capacity antagonizing the PI3K/Akt signaling pathway. However, less data are available concerning its role in neurodegeneration in which apoptotic processes are also involved. In the present study, we attempted to study the role and the underlying mechanism of PTEN in neuronal apoptosis. Using primary rat hippocampal cultures, staurosporine (STS, 100 nM) induced a time-dependent apoptosis, accompanied by a marked production of reactive oxygen species (ROS), release of cytochrome c and activation of caspase 9 and 3. However, the expression of PTEN, and the levels of phospho-PTEN and phospho-Akt were not changed at all time points tested (0.5-24 h) after STS stimulation, suggesting that the protein level as well as the phosphorylation status of PTEN were not related to the procession of apoptosis. Interestingly, immunostaining revealed a punctate intracellular distribution of PTEN from 2 to 8 h after adding STS. Double labeling and Western blotting of mitochondrial fraction demonstrated a mitochondrial location and accumulation of PTEN, respectively, after challenging with STS. Furthermore, we provide evidence for the first time that PTEN was associated with Bax in the absence and the presence of STS. Of note, the STS-induced marked increase in the cellular ROS level, release of cytochrome c and activation of caspase 3 were inhibited in cultured hippocampal cells when PTEN was knocked down by a specific antisense. Moreover, knockdown of PTEN significantly protected hippocampal cells from apoptotic damage. These findings demonstrated that PTEN is a crucial mediator of mitochondria-dependent apoptosis, and thus could become a molecular target for interfering with neurodegenerative diseases.

Animals↗
PubMed2006

Protein phosphatases types 2Calpha and 2Cbeta in apoptosis.

This mini-review highlights the involvement of PP2C (protein phosphatase type 2C) family members alpha and beta in apoptosis. The activity of these isoenzymes can be stimulated by unsaturated fatty acids with special structural features, e.g. oleic acid. Those fatty acids capable of activating PP2Calpha and PP2Cbeta in vitro induce apoptosis in various cell types as shown here for neurons and endothelial cells. Using RNA interference to reduce the amount of PP2Calpha and PP2Cbeta results in cells significantly less susceptible to the apoptotic effect of oleic acid. Increased endothelial cell death is considered to be an initial step of atherogenesis. Thus activation of PP2C by physiological unbound ('free') unsaturated fatty acids (liberated from lipoproteins) could represent a crucial mechanism in the development of atherosclerosis.

Animals↗
PubMed2005

Unsaturated fatty acids isolated from human lipoproteins activate protein phosphatase type 2Cbeta and induce apoptosis in endothelial cells.

Activity of serine/threonine protein phosphatase type 2C is known to be stimulated by certain unsaturated fatty acids and this enzyme dephosphorylates Bad, thus acting on apoptosis. This prompted us to investigate endothelial cell death. Here, we present evidence for the presence of protein phosphatase type 2Cbeta (PP2Cbeta) in human umbilical vein endothelial cells (HUVECs) and report on colocalization of PP2Cbeta and Bad in the cytosol of endothelial cells. Lipophilic compounds that stimulated PP2Cbeta activity in vitro were found to induce cell death of HUVECs. Lipoproteins did neither influence PP2Cbeta activity nor affect cell behaviour. Lipoproteins treated with the lipoprotein lipase, however, stimulated the activity of PP2Cbeta at least 10-fold concomitantly triggering cell death. Analytical methods revealed that both effects - stimulation of PP2Cbeta and apoptosis - were caused by free fatty acids liberated from VLDL, LDL and HDL with oleic acid and linoleic acid as major constituents. The results provide novel insights in endothelial apoptosis and suggest that PP2Cbeta participates in the development and progress of atherosclerosis.

Apoptosis↗
PubMed2004

Neuroprotection by transforming growth factor-beta1 involves activation of nuclear factor-kappaB through phosphatidylinositol-3-OH kinase/Akt and mitogen-activated protein kinase-extracellular-signal regulated kinase1,2 signaling pathways.

Prevention of neuronal apoptosis has been introduced as a new therapeutic strategy for neurodegenerative disorders. We have previously reported anti-apoptotic effects of transforming growth factor-beta1 (TGF-beta1), a multifunctional cytokine, in models of cerebral ischemia and in cultured neurons and recently focused on the mechanisms underlying the anti-apoptotic effect of TGF-beta1. The anti-apoptotic transcriptional factor nuclear factor kappa B (NF-kappaB) shows high impact in the cell survival function of multiple cytokines and growth factors. The present study explored whether NF-kappabeta is a target of TGF-beta1 and which signaling pathways involved in the activation of NF-kappabeta are triggered by TGF-beta1. We demonstrated that TGF-beta1 increased the transcriptional activity of NF-kappabeta in cultured hippocampal neurons in a time- and concentration-dependent manner. Furthermore, TGF-beta1 induced translocation of p65/NF-kappabeta to the nucleus and enhanced NF-kappabeta transcriptional activity in the presence of apoptotic stimuli. TGF-beta1-mediated NF-kappabeta activation was blocked by wortmannin and U0126, indicating the involvement of both phosphatidylinositol-3-OH kinase (PI3k)/Akt and mitogen-activated protein kinase (MAPK)/extracellular-signal regulated kinase (Erk)1,2 pathways in the action of TGF-beta1. TGF-beta1 produced a concomitant increase in the phosphorylations of Ikappabeta kinase (IKKalpha/beta) and Ikappabetaalpha with a subsequent degradation of Ikappabetaalpha. Interestingly, the increased phosphorylation of IKKalpha/beta and Ikappabetaalpha was abrogated by wortmannin, but not by U0126, suggesting that PI3k/Akt and MAPK/Erk1,2 pathways triggered by TGF-beta1 regulated the activation of NF-kappabeta through different mechanisms. Of note, wortmannin and U0126, as well as kappabeta-decoy DNA, abolished the anti-apoptotic effect of TGF-beta1, corroborating the notion that both PI3k/Akt and MAPK/Erk1,2 pathways, and NF-kappabeta activity are necessary for the anti-apoptotic activity of TGF-beta1.

Animals↗
PubMed2003

Neuroprotective effects of Ginkgo biloba extract.

Ginkgo biloba extract has been therapeutically used for several decades to increase peripheral and cerebral blood flow as well as for the treatment of dementia. The extract contains multiple compounds such as flavonoids and terpenoids that are thought to contribute to its neuroprotective and vasotropic effects. In this review, we summarize the experimental results on the mechanism of neuroprotection induced by standardized extract of Ginkgo biloba leaves (EGb 761) and its constituents. The effects described mostly in animals include those on cerebral blood flow, neurotransmitter systems, cellular redox state and nitric oxide level. Furthermore, we discuss the current status of clinical trials as well as undesired side effects of EGb 761.

Animals↗
PubMed2003

Pharmacological studies supporting the therapeutic use of Ginkgo biloba extract for Alzheimer's disease.

The standardized Ginkgo biloba extract EGb 761(definition see editorial) has been shown to produce neuroprotective effects in different in vivo and in vitro models. Since EGb 761 is a complex mixture containing flavonoid glycosides, terpene lactones (non-flavone fraction) and various other constituents, the question arises as to which of these compounds mediates the protective activity of EGb 761. Previous studies have demonstrated that the non-flavone fraction was responsible for the antihypoxic activity of EGb 761. Thus, we examined the neuroprotective and anti-apoptotic ability of the main constituents of the non-flavone fraction, the ginkgolides A, B, C, J and bilobalide. In focal cerebral ischemia models, the administration of bilobalide (5-20 mg/kg, s. c.) 60 min before ischemia dose-dependently reduced the infarct area in mouse brain and the infarct volume in rat brain 2 days after the onset of the injury. 30 minutes of pretreatment with ginkgolide A (50 mg/kg, s. c.) and ginkgolide B (100 mg/kg, s. c.) reduced the infarct area in the mouse model of focal ischemia. In primary cultures of hippocampal neurons and astrocytes from neonatal rats, ginkgolide B (1 microM) and bilobalide (10 microM) protected the neurons against damage caused by glutamate (1 mM, 1 h) as evaluated by trypan blue staining. In addition, bilobalide (0.1 microM) was able to increase the viability of cultured neurons from chick embryo telencepalon when exposed to cyanide (1 mM, 1h). Furthermore, we attempted to find out whether ginkgolides A, B, and J and bilobalide were also able to inhibit neuronal apoptosis (determined by nuclear staining with Hoechst 33 258 and TUNEL-staining). Ginkgolide B (10 microM), ginkgolide J (100 microM) and bilobalide (1 microM) reduced the apoptotic damage induced by serum deprivation (24h) or treatment with staurosporine (200 nM, 24h) in cultured chick embryonic neurons. Bilobalide (100 microM) rescued cultured rat hippocampal neurons from apoptosis caused by serum deprivation (24h), whereas ginkgolide B (100 microM) and bilobalide (100 microM) reduced apoptotic damage induced by staurosporine (300 nM, 24h). Ginkgolide A failed to affect apoptotic damage neither in serum-deprived nor in staurosporine-treated neurons. The results suggest that some of the constituents of the non-flavone fraction of EGb 761 possess neuroprotective and anti-apoptotic capacity, and that bilobalide is the most potent one. In contrast, ginkgolic acids (100-500 microM) induced neuronal death, which showed features of apoptosis as well as of necrosis, but these constituents were removed from EGb 761 below an amount of 0.0005 %. Taking together, there is experimental evidence for a neuroprotective effect of EGb 761 that agrees with clinical studies showing the efficacy of an oral treatment in patients with mild and moderate dementia.

Alzheimer Disease↗
PubMed2002

Nerve growth factor survival signaling in cultured hippocampal neurons is mediated through TrkA and requires the common neurotrophin receptor P75.

The role of the common neurotrophin receptor p75 (p75NTR) in neuronal survival and cell death remains controversial. On the one hand, p75NTR provides a positive modulatory influence on nerve growth factor (NGF) signaling through the high affinity neurotrophin receptor TrkA, and hence increases NGF survival signaling. However, p75NTR may also signal independently of TrkA, causing cell death or cell survival, depending on the cell type and stage of development. Here we demonstrate that TrkA is expressed in primary cultures of hippocampal neurons and is activated by NGF within 10 min of exposure. In primary hippocampal cultures neuroprotection by NGF against glutamate toxicity was mediated by NF-kappaB and accompanied by an increased expression of neuroprotective NF-kappaB target genes Bcl-2 and Bcl-xl. In mouse hippocampal cells lacking p75NTR (p75NTR-/-) activation of TrkA by NGF was not detectable. Moreover, neuroprotection by NGF against glutamate toxicity was abolished in p75NTR-/- neurons, and the expression of bcl-2 and bcl-xl was markedly reduced as compared to wildtype cells. NGF increased TrkA phosphorylation in hippocampal neurons and provided protection that required phosphoinositol-3-phosphate (PI3)-kinase activity and Akt phosphorylation, whereas the mitogen-activated protein kinases (MAPK), extracellular-regulated kinases (Erk) 1/2, were not involved. P75NTR signaling independent of TrkA, such as increased neutral sphingomyelinase (NSMase) activity causing enhanced levels of ceramide, were not detected after exposure of hippocampal neurons to NGF. Interestingly, inhibition of sphingosine-kinase blocked the neuroprotective effect of NGF, suggesting that sphingosine-1-phosphate was also involved in NGF-mediated survival in our cultured hippocampal neurons. Overall, our results indicate an essential role for p75NTR in supporting NGF-triggered TrkA signaling pathways mediating neuronal survival in hippocampal neurons.

Animals↗
PubMed2001

3-Ureidopropionate contributes to the neuropathology of 3-ureidopropionase deficiency and severe propionic aciduria: a hypothesis.

3-Ureidopropionate (3-UPA) is a physiologic metabolite in pyrimidine degradation. Pathological accumulation of 3-UPA in body fluids is found in 3-ureidopropionase deficiency and severe forms of propionic aciduria. Both diseases clinically present with a severe neuropathology involving gray and white matter as well as with a dystonic dyskinetic movement disorder. To date nothing is known about the toxic nature of this metabolite. The aim of the present study was to elucidate whether 3-UPA may act as endogenous neurotoxin. Exposure of cultured chick neurons to 3-UPA induced a concentration- and time-dependent neurodegeneration. Neuronal damage was reduced by the antioxidant alpha-tocopherol and the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801. In contrast, the non-NMDA receptor antagonist CNQX, the metabotropic glutamate receptor antagonist L-AP3, and succinate showed no protective effect. Furthermore, 3-UPA elicited an increased production of reactive oxygen species followed by a delayed increase in intracellular calcium concentrations. Activity measurement of single respiratory chain complexes I-V revealed an inhibition of complex V activity, but not of the electron-transferring complexes I-IV by 3-UPA. In contrast, 3-UPA did not affect the mitochondrial beta-oxidation of fatty acids. In conclusion, our results provide strong evidence that 3-UPA acts as endogenous neurotoxin via inhibition of mitochondrial energy metabolism, resulting in the initiation of secondary, energy-dependent excitotoxic mechanisms.

Animals↗
PubMed2001

Ginkgolic acids induce neuronal death and activate protein phosphatase type-2C.

The standardized extract from Ginkgo biloba (EGb 761) is used for the treatment of dementia. Because of allergenic and genotoxic effects, ginkgolic acids are restricted in EGb 761 to 5 ppm. The question arises whether ginkgolic acids also have neurotoxic effects. In the present study, ginkgolic acids caused death of cultured chick embryonic neurons in a concentration-dependent manner, in the presence and in the absence of serum. Ginkgolic acids-induced death showed features of apoptosis as we observed chromatin condensation, shrinkage of the nucleus and reduction of the damage by the protein synthesis inhibitor cycloheximide, demonstrating an active type of cell death. However, DNA fragmentation detected by the terminal-transferase-mediated ddUTP-digoxigenin nick-end labeling (TUNEL) assay and caspase-3 activation, which are also considered as hallmarks of apoptosis, were not seen after treatment with 150 microM ginkgolic acids in serum-free medium, a dose which increased the percentage of neurons with chromatin condensation and shrunken nuclei to 88% compared with 25% in serum-deprived, vehicle-treated controls. This suggests that ginkgolic acid-induced death showed signs of apoptosis as well as of necrosis. Ginkgolic acids specifically increased the activity of protein phosphatase type-2C, whereas other protein phosphatases such as protein phosphatases 1A, 2A and 2B, tyrosine phosphatase, and unspecific acid- and alkaline phosphatases were inhibited or remained unchanged, suggesting protein phosphatase 2C to play a role in the neurotoxic effect mediated by ginkgolic acids.

Animals↗
PubMed2001

Intrastriatal administration of 3-hydroxyglutaric acid induces convulsions and striatal lesions in rats.

Glutaryl-CoA dehydrogenase deficiency is an inherited neurometabolic disease complicated by precipitation of acute encephalopathic crises during a vulnerable period of brain development. These crises result in bilateral striatal damage and subsequently a dystonic dyskinetic movement disorder. In previous in vitro studies neuronal damage in this disease has been linked to an excitotoxic mechanism mediated in particular by one of the accumulating metabolites, 3-hydroxyglutaric acid. However, nothing is known about the in vivo effects of this organic acid. In the present study, we used a stereotaxic intrastriatal injection technique to investigate the behavioral and neurotoxic effects of 3-hydroxyglutaric acid exposure in rats. Here, we report that 3-hydroxyglutaric acid induced an increase in convulsion frequency and duration as determined by open field measurement. Nissl-stained coronal sections from treated rats revealed a pale lesion in the striatum following 3-hydroxyglutaric acid exposure. N-methyl-D-aspartate (NMDA) receptor blockade by MK-801 and stimulation of GABA(A) receptors by muscimol prevented the induction of convulsions and striatal damage by 3-hydroxyglutaric acid, whereas blockade of non-NMDA receptors by 6,7-dinitroquinoxaline-2,3-dione (DNQX) was not protective. We conclude that 3-hydroxyglutaric acid induces convulsions and striatal damage via initiation of an imbalance in the excitatory glutamatergic and the inhibitory GABAergic neurotransmission, resulting in an enhanced excitatory input in striatal neurons. These results support the hypothesis of NMDA receptor-mediated excitotoxic cell damage in glutaryl-CoA dehydrogenase deficiency and represent the basis for the development of new neuroprotective treatment strategies.

Acyl Coenzyme A↗
PubMed2001

Retinoic acid reduces apoptosis and oxidative stress by preservation of SOD protein level.

Retinoic acid (RA) has already been shown to exert antiapoptotic and antioxidative activity in various cells. In this study, we determined the effect of RA on the mRNA and protein levels of the Cu-,Zn-superoxide dismutase (SOD-1) and Mn-superoxide dismutase (SOD-2) during staurosporine-induced apoptosis in primary cultures from neonatal rat hippocampus. Exposure to staurosporine (300 nM, 24 h) increased the percentage of apoptotic neurons to 62% compared with 18% in controls. We determined an increase in the reactive oxygen species (ROS) content from 4 up to 48 h after the induction of the injury. Treatment with staurosporine did not significantly change the mRNA levels of SOD-1 and SOD-2. However, the SOD-1 and SOD-2 protein levels markedly decreased 24 and 48 h after the addition of staurosporine. Compared with staurosporine-exposed controls, RA (10 nM)-treated cultures showed a significant increase in neuronal survival, a reduced neuronal ROS content, and enhanced protein levels of SOD-1 and SOD-2 24 and 48 h after the start of the exposure to staurosporine. The results suggest that RA reduced staurosporine-induced oxidative stress and apoptosis by preventing the decrease in the protein levels of SOD-1 and SOD-2, and thus supported the antioxidant defense system.

Animals↗
PubMed2001

Neuroprotective effects of NV-31, a bilobalide-derived compound: evidence for an antioxidative mechanism.

In previous studies we have already shown that the extract of Ginkgo biloba, and some of its constituents, such as ginkgolide B and bilobalide, protected cultured neurons against apoptotic and excitotoxic damage and reduced the infarct volume after focal cerebral ischemia in mice and rats. In this work, we determined the neuroprotective and antioxidative effects of 4-hydroxy-4-tert-butyl-2,3,5,6-tetrahydrothiopyran-1-oxide (NV-31), a stable compound which was synthesized to mimic the pharmacological activity profile of bilobalide. In pure neuronal cultures from chick embryo telencephalon, damage was induced by serum deprivation (24 h) and exposure to staurosporine (200 nM, 24 h) which caused an increase in the percentage of apoptotic neurons from 14 (controls) to 30 and 55%, respectively. NV-31 (1-100 nM) protected dose-dependently chick neurons against both serum deprivation- and staurosporine-induced apoptosis. Similarly, NV-31 (100 nM) reduced staurosporine (300 nM, 24 h)-induced neuronal damage in mixed cultures of neurons and astrocytes from neonatal rat hippocampus. The cellular ROS content increased 6-fold 4 h after serum deprivation as well as 4 h after the exposure to staurosporine and this increase was reduced by 50% in the presence of 10 and 100 nM NV-31, respectively. In mice, a treatment with 10 and 20 mg/kg NV-31 60 min before and immediately after focal cerebral ischemia, respectively, significantly reduced the infarct area compared with vehicle-treated animals. In the present study, we show that NV-31 promotes neuronal survival and we suggest that its antioxidative property contributes to the mechanism of neuroprotection.

Animals↗
PubMed2001

Adaptive plasticity in tachykinin and tachykinin receptor expression after focal cerebral ischemia is differentially linked to gabaergic and glutamatergic cerebrocortical circuits and cerebrovenular endothelium.

To test the hypothesis of an involvement of tachykinins in destabilization and hyperexcitation of neuronal circuits, gliosis, and neuroinflammation during cerebral ischemia, we investigated cell-specific expressional changes of the genes encoding substance P (SP), neurokinin B (NKB), and the tachykinin/neurokinin receptors (NK1, NK2, and NK3) after middle cerebral artery occlusion (MCAO) in the rat. Our analysis by quantitative in situ hybridization, immunohistochemistry, and confocal microscopy was concentrated on cerebrocortical areas that survive primary infarction but undergo secondary damage. Here, SP-encoding preprotachykinin-A and NK1 mRNA levels and SP-like immunoreactivity were transiently increased in GABAergic interneurons at 2 d after MCAO. Coincidently, MCAO caused a marked expression of SP and NK1 in a subpopulation of glutamatergic pyramidal cells, and in some neurons SP and NK1 mRNAs were coinduced. Elevated levels of the NKB-encoding preprotachykinin-B mRNA and of NKB-like immunoreactivity at 2 and 7 d after MCAO were confined to GABAergic interneurons. In parallel, the expression of NK3 was markedly downregulated in pyramidal neurons. MCAO caused transient NK1 expression in activated cerebrovenular endothelium within and adjacent to the infarct. NK1 expression was absent from activated astroglia or microglia. The differential ischemia-induced plasticity of the tachykinin system in distinct inhibitory and excitatory cerebrocortical circuits suggests that it may be involved in the balance of endogenous neuroprotection and neurotoxicity by enhancing GABAergic inhibitory circuits or by facilitating glutamate-mediated hyperexcitability. The transient induction of NK1 in cerebrovenular endothelium may contribute to ischemia-induced edema and leukocyte diapedesis. Brain tachykinin receptors are proposed as potential drug targets in stroke.

Animals↗
PubMed2001

TGF-beta1 inhibits caspase-3 activation and neuronal apoptosis in rat hippocampal cultures.

The effect of TGF-beta1 on apoptosis varies depending on the cell type, the kind of stimulus and the experimental conditions. The present study attempted to identify whether TGF-beta1 can prevent neuronal apoptosis and interrupt caspase-3 activation in rat primary hippocampal cultures after staurosporine treatment. TGF-beta1 at the concentration of 1 and 10 ng/ml significantly reduced neuronal damage as detected by trypan blue exclusion. Nuclear staining with Hoechst 33258 and TUNEL-staining further demonstrated that TGF-beta1 at the same concentration range effectively diminished neuronal apoptosis 24 h after staurosporine treatment, whereas 0.1 ng/ml of TGF-beta1 did not. Furthermore, TGF-beta1 (1 and 10 ng/ml) markedly inhibited the activation of caspase-3 induced by staurosporine as demonstrated by both caspase-3 activity assay and Western blotting. This study provides evidence that TGF-beta1 is able to efficiently inhibit caspase-3 activation, and thereby protects cultured hippocampal neurons against apoptosis.

Animals↗
PubMed2001

Beta(2)-adrenoceptor stimulation enhances latent transforming growth factor-beta-binding protein-1 and transforming growth factor-beta1 expression in rat hippocampus after transient forebrain ischemia.

A protective capacity of transforming growth factor-beta1 (TGF-beta1) against various insults inducing neurone cell death in vitro and in vivo has been well established. We have recently shown the rapid up-regulation and persistent expression of TGF-beta1 in surviving CA1 pyramidal cells after cerebral ischemia suggesting an endogenous mechanism of neuroprotection by this multifunctional cytokine. In the present study, we demonstrated that intraperitoneal administration of clenbuterol, a lipophilic beta(2)-adrenoceptor agonist, caused an increase in TGF-beta1 expression in non-ischemic rats and further enhanced TGF-beta1 protein levels in rat CA1 pyramidal neurones after transient forebrain ischemia. In the hippocampus neuroprotection by clenbuterol (0.5 mg/kg) was accompanied by increased TGF-beta1 immunoreactivity as early as 3 h, and remained elevated up to 2 days after ischemia. The corresponding increased TGF-beta1 mRNA levels after ischemia were not further enhanced by clenbuterol, suggesting post-transcriptional regulation of TGF-beta1 protein after beta(2)-adrenoceptor stimulation. In saline-treated rats latent TGF-beta-binding protein-1 (LTBP-1) immunoreactivity was moderately elevated 3 and 6 h after ischemia, and returned to control levels after 1 day of reperfusion. In parallel with the up-regulation of TGF-beta1 immunoreactivity, LTBP-1 levels in the hippocampus were considerably increased by clenbuterol from 3 h to 2 days after ischemia. Our data demonstrate a concomitant increase in LTBP-1 and TGF-beta1 expression in the ischemic hippocampus after stimulation of beta(2)-adrenoceptors.

Adrenergic beta-Agonists↗
PubMed2001

Effect of 5-hydroxytryptamine 1A receptor agonist BAY X 3702 on BCL-2 and BAX proteins level in the ipsilateral cerebral cortex of rats after transient focal ischaemia.

The proto-oncogene B-cell lymphoma protein 2 (BCL-2) and its homologues are important modulators of cellular survival after transient brain ischaemia. In the present study we used western blotting to elucidate if the stimulation of 5-hydroxytryptamine 1A type receptors with their agonist BAY X 3702 results in regulation of BCL-2 family proteins. Treatment with BAY X 3702 resulted in elevated BCL-2 protein level in the ipsilateral cerebral cortex of animals as early as at 6 and 12 h of reperfusion, this effect becoming more pronounced at 24 h. BAY X 3702 administration caused no change in BCL-2-associated protein X content during reperfusion. The effect of BAY X 3702 on the level of death-inhibiting protein BCL-2 in the brain during ischaemia/reperfusion could contribute to the neuroprotective potency of the drug.

Animals↗
PubMed2001

Potentiation of 3-hydroxyglutarate neurotoxicity following induction of astrocytic iNOS in neonatal rat hippocampal cultures.

Neuronal damage in glutaryl-CoA dehydrogenase deficiency (GDD) has previously been addressed to N-methyl-D-aspartate (NMDA) receptor-mediated neurotoxicity of the accumulating neurotoxic metabolite 3-hydroxyglutarate. However, acute encephalopathic crises in GDD patients are typically precipitated by febrile illness or even routine vaccinations, suggesting a potentiating role of inflammatory cytokines. In the present study we investigated the effect of interleukin-1beta and interferon-gamma on 3-hydroxyglutarate toxicity in rat cortical astrocyte cultures and neonatal rat hippocampal cultures. A cotreatment of both culture systems with interleukin-1beta and interferon-gamma induced the protein expression of astrocytic inducible nitric oxide synthase (iNOS), resulting in increased nitric oxide (NO) production. Cytokine pretreatment alone had no effect on cell viability but potentiated 3-hydroxyglutarate neurotoxicity. NOS inhibition by aminoguanidine and L-NAME prevented an iNOS-mediated potentiation of 3-hydroxyglutarate neurotoxicity but failed to protect neurons against 3-hydroxyglutarate alone. In contrast, superoxide dismutase/catalase as well as MK-801 prevented toxicity of 3-hydroxyglutarate alone as well as its potentiation by iNOS, supporting a central role of NMDA receptor stimulation with subsequently increased superoxide anion production. It is concluded that the potentiation of 3-hydroxyglutarate neurotoxicity is most probably due to an induction of astrocytic iNOS and concomitantly increased NO production, enabling enhanced peroxynitrite formation. Thus, we provide evidence for a neuroimmunological approach to the precipitation of acute encephalopathic crises in GDD by inflammatory cytokines.

Animals↗