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I Lizasoain

Publications and source records attributed to I Lizasoain.

At least 19 recordsLinked to original sources
PubMed2006

TNFR1 mediates increased neuronal membrane EAAT3 expression after in vivo cerebral ischemic preconditioning.

A short ischemic event (ischemic preconditioning) can result in subsequent resistance to severe ischemic injury (ischemic tolerance). Glutamate is released after ischemia and produces cell death. It has been described that after ischemic preconditioning, the release of glutamate is reduced. We have shown that an in vitro model of ischemic preconditioning produces upregulation of glutamate transporters which mediates brain tolerance. We have now decided to investigate whether ischemic preconditioning-induced glutamate transporter upregulation takes also place in vivo, its cellular localization and the mechanisms by which this upregulation is controlled. A period of 10 min of temporary middle cerebral artery occlusion was used as a model of ischemic preconditioning in rat. EAAT1, EAAT2 and EAAT3 glutamate transporters were found in brain from control animals. Ischemic preconditioning produced an up-regulation of EAAT2 and EAAT3 but not of EAAT1 expression. Ischemic preconditioning-induced increase in EAAT3 expression was reduced by the TNF-alpha converting enzyme inhibitor BB1101. Intracerebral administration of either anti-TNF-alpha antibody or of a TNFR1 antisense oligodeoxynucleotide also inhibited ischemic preconditioning-induced EAAT3 up-regulation. Immunohistochemical studies suggest that, whereas the expression of EAAT3 is located in both neuronal cytoplasm and plasma membrane, ischemic preconditioning-induced up-regulation of EAAT3 is mainly localized at the plasma membrane level. In summary, these results demonstrate that in vivo ischemic preconditioning increases the expression of EAAT2 and EAAT3 glutamate transporters the upregulation of the latter being at least partly mediated by TNF-alpha converting enzyme/TNF-alpha/TNFR1 pathway.

ADAM Proteins↗
PubMed2003

Effect of subacute and chronic immobilisation stress on the outcome of permanent focal cerebral ischaemia in rats.

The aim of this study was to determine the effect of mood disorders, including psychological distress and depression, on stroke outcome. Male Fischer rats were exposed to immobilisation stress, an animal paradigm of psychological stress, major depression and post-traumatic stress disorder. Either a subacute (1 h for 7 days) or a chronic (6 h for 21 days) exposure to stress was applied 24 h before permanent middle cerebral artery occlusion (MCAO). Stroke outcome was assessed by measurement of infarct size and behavioural characterisation. Serum glutamate and brain ATP levels as well as brain glutamate transporter function and expression were studied in the search for the molecular mechanisms involved. Subacute stress exposure increased infarct size and decreased behavioural scores after stroke. On the contrary, chronic stress exposure decreased infarct size. Peak serum glutamate levels correlated with infarct size after MCAO. Expression of glutamate transporters was decreased by subacute stress, whereas the expression of EAAT1, a glial glutamate carrier, was increased after the chronic stress protocol. Our results indicate that distinct patterns of stress determine different stroke outcomes, and that expressional changes of brain glutamate transporters, able to affect glutamate release after stroke, are involved.

Adenosine Triphosphate↗
PubMed2003

[Consensus review. Pharmacological neuroprotection in cerebral ischemia: is it still a therapeutic option?].

Our increasing knowledge concerning the pathophysiology of cerebral ischemia is leading to a considerable development of drugs that at various levels block or modify the chain of biochemical processes set off as a consequence of hypoperfusion of cerebral parenchyma. In this zone of ischemic penumbra, the interaction between the neuronal ischemia cascade, the response of the glia and changes in the microcirculation, determine the evolution towards either functional recovery of the ischemic fabric or it necrosis. In various types of animal models, the majority of neuroprotective drugs have been shown to have considerable efficacy. However, this has not been translated into human clinical practice. The identification of persistence of recoverable cerebral tissue, together with the development of new designs of clinical trails better adapted to preclinical experiences and to the features of the drugs concerned, may contribute to an improved applicability of the new drugs in human clinical practice.

Animals↗
PubMed2003

[Experimental headache models].

The use of experimental models is so common in most diseases, such as stroke, epilepsy or brain injury, that it does not seem to be necessary to justify in the study of experimental headache models. However, the study of these models was not been possible until 10-15 years ago. Two main reasons made it possible: first, increased basic knowledge about disease mechanisms in the last decade, a requirement necessary before models can be developed and validated; second, the publication of the headache classification of the International Headache Society in 1988 which has permitted an exact diagnosis, avoiding interobserver variability. This review examines the use of animal models to study the neurogenic inflammation described by Moskowitz and those used to study the vascular hypothesis. We have also examined the use of animal experiments to study the neurobiological basis for pain. Finally, we have explored the experimental human headache models not only in sufferers but also in healthy volunteers.

Animals↗
PubMed2001

Implication of TNF-alpha convertase (TACE/ADAM17) in inducible nitric oxide synthase expression and inflammation in an experimental model of colitis.

Tumour necrosis factor-alpha (TNF-alpha) is a pro-inflammatory cytokine which is shed in its soluble form by a disintegrin and metalloproteinase (ADAM) called TNF-alpha convertase (TACE; ADAM17). TNF-alpha plays a role in inflammatory bowel disease (IBD) and is involved in the expression of inducible nitric oxide synthase (iNOS) which has also been implicated in IBD. The study was designed to investigate whether colitis induced by trinitrobenzene sulphonic acid (TNBS) in rats produces an increase in TACE activity and/or expression and whether its pharmacological inhibition reduces TNF-alpha levels, iNOS expression and colonic damage in this model. TNBS (30 mg in 0.4 ml of 50% ethanol) was instilled into the colon of female Wistar rats. Saline or TACE inhibitor BB1101 (10 mg/kg/day) was administered intraperitoneally 5 days after TNBS instillation. On day 10, colons were removed and assessed for pathological score, myeloperoxidase (MPO), NO synthase (NOS), TACE enzymatic activity and protein levels, colonic TNF-alpha and NOx- levels. Instillation of TNBS caused an increase in TACE activity and expression and the release of TNF-alpha. TNBS also resulted in iNOS expression and colonic damage. BB1101 blocked TNBS-induced increase in TACE activity, TNF-alpha release and iNOS expression. Concomitantly, BB1101 ameliorated TNBS-induced colonic damage and inflammation. TNBS causes TNF-alpha release by an increase in TACE activity and expression and this results in the expression of iNOS and subsequent inflammation, suggesting that TACE inhibition may prove useful as a therapeutic means in IBD.

ADAM Proteins↗
PubMed2001

N-(3-(aminomethyl)benzyl)acetamidine, an inducible nitric oxide synthase inhibitor, decreases colonic inflammation induced by trinitrobenzene sulphonic acid in rats.

Gastrointestinal inflammation has been associated with an increased generation of nitric oxide (NO) and the expression of the inducible NO synthase (iNOS). Using an experimental model of colitis induced by trinitrobenzene sulphonic acid (TNBS), we sought to determine whether the administration of N-(3-(Aminomethyl)benzyl)acetamidine (1400W), a specific inhibitor of iNOS, has a beneficial action on the colonic injury. 1400W (0.4 and 2 mg/kg/day) was administered intraperitoneally from day 5 to 10 after intrarectal instillation of TNBS. TNBS led to colonic ulceration and inflammation, an increase of colonic myeloperoxidase activity and the expression of the calcium-independent NOS from days 1 to 15. 1400W reduced the macroscopic damage and the histological changes induced by TNBS as well as the calcium-independent NOS activity and myeloperoxidase activity determined over 30 min after sacrifice. These findings indicate that the expression of iNOS accounts for most of the damage caused by TNBS and that the administration of 1400W after the onset of colitis has a beneficial action on the colonic injury.

Amidines↗
PubMed2001

Up-regulation of TNF-alpha convertase (TACE/ADAM17) after oxygen-glucose deprivation in rat forebrain slices.

Tumour necrosis factor-alpha (TNF-alpha) is a major immunomodulatory and proinflammatory cytokine which is shed in its soluble form by a membrane-anchored zinc protease, identified as a disintegrin and metalloproteinase (ADAM) called TNF-alpha convertase (TACE; ADAM17). The role of this protease in the adult nervous system remains poorly understood. During cerebral ischemia and subsequent reperfusion, expression and release of TNF-alpha have been shown. We have investigated the expression and activity of TACE in an in vitro model of brain ischemia consisting of rat forebrain slices exposed to oxygen-glucose deprivation (OGD). OGD caused the release of TNF-alpha, an effect which was inhibited by a hydroxamate-based metalloprotease inhibitor, BB-3103, with an IC(50) of 0.1 microM, suggesting that TNF-alpha release results selectively from TACE activity. Assay of TACE enzymatic activity on a fluorescein-labelled peptide spanning the cleavage site in pro-TNF-alpha, as well as Western blot and RT-PCR analyses showed that TACE is present in control forebrain and, more interestingly, that TACE expression is increased in OGD-exposed tissue. TACE enzymatic activity from OGD-exposed slices was significantly inhibited by cycloheximide, suggesting that de novo synthesis of TACE contributes to TNF-alpha release after ischaemia. Moreover, it was also inhibited by bisindolylmaleimide I, indicating that TACE activity is regulated by PKC. These findings posed the question of what was its function therein. Among other actions, TNF-alpha has been described to be involved in the expression of inducible nitric oxide synthase (iNOS), a high-output NOS isoform associated to cellular damage, but the link between TNF-alpha release after brain ischaemia and iNOS expression in this condition has not been shown. We have now found that iNOS expression in OGD-subjected brain slices is inhibited by BB-3103 at concentrations below 1 microM, indicating that shedding of TNF-alpha by TACE plays a necessary part in the induction of this NOS isoenzyme after OGD. Taken together, these data demonstrate that (1) TACE/ADAM17 activity accounts for the majority of TNF-alpha shedding after OGD in rat forebrain slices, (2) an increase in TACE expression contributes, at least in part, to the rise in TNF-alpha after OGD and (3) iNOS expression in OGD-subjected brain slices results from TACE activity and subsequent increase in TNF-alpha levels.

ADAM Proteins↗
PubMed2001

Glutathione depletion, lipid peroxidation and mitochondrial dysfunction are induced by chronic stress in rat brain.

Damage to the mitochondrial electron transport chain has been suggested to be an important factor in the pathogenesis of a range of neurodegenerative disorders. We have previously demonstrated that chronic stress induced an increase in nitric oxide (NO) production via an expression of inducible NO synthase (iNOS) in brain. Since it has been demonstrated that NO regulates mitochondrial function, we sought to study the susceptibility of the mitochondrial respiratory chain complexes to chronic restrain stress exposure in brain cortex. In adult male rats, stress (immobilization for six hours during 21 days) inhibits the activities of the first complexes of the mitochondrial respiratory chain (inhibition of 69% in complex I-III and of 67% in complex II-III), without affecting complex IV activity, ATP production and oxygen consumption. The mitochondrial marker citrate synthase is not significantly affected by stress after 21 days, indicating that at this time the mitochondrial structure is still intact. Moreover, the administration of the preferred inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine (400 mg/kg i.p. daily from days 7 to 21 of stress) protects against the inhibition of the activity of complexes of the mitochondrial respiratory chain as well as prevents NO(x)(-) accumulation, lipid peroxidation and glutathione depletion induced by stress. These results suggest that a sustained overproduction of NO via iNOS is responsible, at least in part, of the inhibition of mitochondrial respiratory chain caused by stress and that this pathway also accounts for the oxidative stress found in this situation.

Adenosine Triphosphate↗
PubMed2001

Inducible nitric oxide synthase expression in brain cortex after acute restraint stress is regulated by nuclear factor kappaB-mediated mechanisms.

The underlying mechanisms by which physical or psychological stress causes neurodegeneration are still unknown. We have demonstrated that the high-output and long-lasting synthesizing source of nitric oxide (NO), inducible NO synthase (iNOS), is expressed in brain cortex during stress and that its overexpression accounts for the neurodegenerative changes seen after 3 weeks of repeated stress. Now we have found that acute stress (restraint for 6 h) increases the activity of a calcium-independent NOS and induces the expression of iNOS in brain cortex in adult male rats. In order to elucidate the possible mechanisms involved in this induction, we studied the role of transcription nuclear factor kappaB (NF-kappaB), which is required for iNOS synthesis. We have observed that an acute restraint stress session stimulates the translocation of the NF-kappaB to the nucleus after 4 h and that the administration of the NF-kappaB inhibitor pyrrolidine dithiocarbamate [PDTC, 75 and 150 mg/kg intraperitoneally (i.p.)] at the onset of stress inhibits the stress-induced increase in iNOS expression. Since glutamate release and subsequent NMDA (N-methyl-D-aspartate) receptor activation has been recognized as an early change after exposure to stressful stimuli, and glutamate has been shown to induce iNOS in brain via a NF-kappaB-dependent mechanism, we studied the possible role of excitatory amino acids in the induction of iNOS in our model. Pretreatment with the NMDA receptor antagonist dizocilpine (MK-801, 0.1 and 0.3 mg/kg i.p.) inhibits the stress-induced NF-kappaB activation as well as the stress-induced increase in iNOS expression. Taken together, these findings indicate that excitatory amino acids and subsequent activation of NF-kappaB account for stress-induced iNOS expression in cerebral cortex, and support a possible neuroprotective role for specific inhibitors in this situation.

Active Transport, Cell Nucleus↗
PubMed2001

Neuroprotective effect of aspirin by inhibition of glutamate release after permanent focal cerebral ischaemia in rats.

Aspirin reduces the size of infarcts after ischaemic stroke. Although this fact has been attributed to its anti-platelet actions, direct neuroprotective effects have also been reported. We have recently demonstrated that aspirin is neuroprotective by inhibiting glutamate release in 'in vitro' models of brain ischaemia, via an increase in ATP production. The present study was designed to determine whether the inhibition of glutamate release induced by aspirin might be protective in a whole-animal model of permanent focal brain ischaemia. Focal brain ischaemia was produced in male adult Fischer rats by occluding both the common carotid and middle cerebral arteries. Central and serum glutamate levels were determined at fixed intervals after occlusion. The animals were then killed and infarct volume was measured. Aspirin (30 mg/kg i.p. administered 2 h before the occlusion) produced a significant reduction in infarct volume, an effect that correlated with the inhibition caused by aspirin on ischaemia-induced increase in brain and serum glutamate concentrations after the onset of the ischaemia. Aspirin also inhibited ischaemia-induced decrease in brain ATP levels. Our present findings show a novel mechanism for the neuroprotective effects of aspirin, which takes place at concentrations in the anti-aggregant-analgesic range, useful in the management of patients with risk of ischaemic events.

Adenosine Triphosphate↗
PubMed2000

Mechanisms of the neuroprotective effect of aspirin after oxygen and glucose deprivation in rat forebrain slices.

Acetylsalicylic acid (ASA, Aspirin) is an anti-inflammatory drug with a wide spectrum of pharmacological activities and multiple sites of action. Apart from its preventive actions against stroke due to its antithrombotic properties, recent data in the literature suggest that high concentrations of ASA also exert direct neuroprotective effects. We have used an in vitro model of brain ischaemia using rat forebrain slices deprived of oxygen and glucose to test ASA neuroprotective properties. We have found that ASA inhibits neuronal damage at concentrations lower than those previously reported (0.1-0.5 mM), and that these effects correlate with the inhibition of excitatory amino acid release, of NF-kappaB translocation to the nucleus and iNOS expression caused by ASA. All of these three mechanisms may mediate the neuroprotective effects of this drug. Our results also show that the effects of ASA are independent of COX inhibition. Taken together, our present findings show that ASA is neuroprotective in an in vitro model of brain ischaemia at doses close to those recommended for its antithrombotic effects.

Animals↗
PubMed2000

Fructose-1,6-bisphosphate inhibits the expression of inducible nitric oxide synthase caused by oxygen-glucose deprivation through the inhibition of glutamate release in rat forebrain slices.

Fructose-1,6-bisphosphate (FBP) is a glycolytic pathway intermediate with a neuroprotective action in animal models of brain ischaemia. We addressed the question of whether FBP acts through inhibiting inducible nitric oxide synthase (iNOS) expression via reduction of glutamate release, since we have recently demonstrated that glutamate is involved in the expression of iNOS. FBP (5 mM) added to the incubation solution of rat forebrain slices subjected to oxygen-glucose deprivation (OGD) inhibited glutamate release significantly (around 40%). FBP also inhibited the induction of the calcium-independent NOS activity and reduced the levels of iNOS protein in rat forebrain slices subjected to OGD. We conclude that the action of FBP by reducing glutamate release and iNOS expression, both of which have been implicated in cell damage, is a reason for further evaluation of FBP as a neuroprotectant.

Amino Acids, Essential↗
PubMed2000

Up-regulation of neuronal NO synthase immunoreactivity in opiate dependence and withdrawal.

RATIONALE: Nitric oxide (NO) has been postulated to contribute significantly to analgesic effects of opiates as well as to the development of tolerance and physical dependence to morphine. OBJECTIVE: The present study was undertaken to determine the effect of chronic morphine treatment and abstinence on the expression of neuronal NO synthase (neuronal NOS, nNOS) in several brain regions of mice. METHODS: Seven days after the implantation of a 75 mg morphine pellet, adult male CD1 mice received a SC dose of 1 mg/kg naloxone. Fifteen minutes after the naloxone injection, brains were removed and nNOS expression was studied by using immunohistochemical methods. RESULTS: Morphine-dependence produced an increase in the number of nNOS-positive cells in the main and accessory olfactory bulb, olfactory nuclei, cerebellum, locus coeruleus, medulla oblongata (nucleus of the solitary tract and prepositus hypoglossal nucleus), and a decrease in nNOS immunoreactivity in hypothalamus. The administration of naloxone to morphine-dependent mice to induce abstinence increased nNOS immunoreactivity in the hypothalamus and locus coeruleus. CONCLUSIONS: These results indicate that the chronic treatment with morphine leads to alterations in nNOS expression in important regions implicated in the physical tolerance and dependence to opiates and suggest the use of specific inhibitors of this isoform in these conditions.

Animals↗
PubMed2000

Implication of glutamate in the expression of inducible nitric oxide synthase after oxygen and glucose deprivation in rat forebrain slices.

Nitric oxide synthesis by inducible nitric oxide synthase (iNOS) has been postulated to contribute to ischemia-reperfusion neurotoxicity. The expression of this enzyme has been demonstrated in cells present in the postischemic brain. The mechanisms of iNOS expression after cerebral ischemia are a subject of current research. We therefore decided to investigate whether glutamate, which is released in ischemia and is implicated in neurotoxicity, might be involved in the mechanisms by which oxygen and glucose deprivation (OGD) leads to the expression of iNOS in rat forebrain slices. In this model, we have shown previously that 20 min of OGD causes the expression of iNOS. We have now found that the NMDA receptor antagonist MK-801 blocks the expression of iNOS, suggesting that the activation of the NMDA subtype of glutamate receptor is implicated in the mechanisms that lead to the expression of this isoform. Moreover, we have found that glutamate alone could trigger the induction process, as shown by the appearance of a Ca(2+)-independent NOS activity and by the detection of iNOS mRNA and protein in slices exposed to glutamate. Glutamate-dependent iNOS expression was concentration-dependent and was blocked by EGTA and by the inhibitors of nuclear factor kappaB (NF-kappaB) activation pyrrolidine dithiocarbamate and MG132. In addition, glutamate induced NF-kappaB translocation to the nucleus, an effect that was inhibited by MG132. Taken together, our data suggest that activation of NMDA receptors by glutamate released in ischemia is involved in the expression of iNOS in rat forebrain slices via a Ca(2+)-dependent activation of the transcription factor NF-kappaB. To our knowledge, this is the first report showing an implication of excitatory amino acids in the expression of iNOS caused by ischemia.

Animals↗
PubMed2000

Chronic stress induces the expression of inducible nitric oxide synthase in rat brain cortex.

Long-term exposure to stress has detrimental effects on several brain functions in many species, including humans, and leads to neurodegenerative changes. However, the underlying neural mechanisms by which stress causes neurodegeneration are still unknown. We have investigated the role of endogenously released nitric oxide (NO) in this phenomenon and the possible induction of the inducible NO synthase (iNOS) isoform. In adult male rats, stress (immobilization for 6 h during 21 days) increases the activity of a calcium-independent NO synthase and induces the expression of iNOS in cortical neurons as seen by immunohistochemical and western blot analysis. Three weeks of repeated immobilization increases immunoreactivity for nitrotyrosine, a nitration product of peroxynitrite. Repeated stress causes accumulation of the NO metabolites NO2+ NO3- (NOx-) accumulation in cortex, and these changes occur in parallel with lactate dehydrogenase (LDH) release and impairment of glutamate uptake in synaptosomes. Administration of the selective iNOS inhibitor aminoguanidine (400 mg/kg i.p. daily from days 7 to 21 of stress) prevents NOx- accumulation in cortex, LDH release, and impairment of glutamate uptake in synaptosomes. Taken together, these findings indicate that a sustained overproduction of NO via iNOS expression may be responsible, at least in part, for some of the neurodegenerative changes caused by stress and support a possible neuroprotective role for specific iNOS inhibitors in this situation.

Animals↗
PubMed1999

Neuroprotective effects of DETA-NONOate, a nitric oxide donor, on hydrogen peroxide-induced neurotoxicity in cortical neurones.

Nitric oxide (NO) has been proposed to exert neuroprotective actions against oxidative damage acting directly as an antioxidant; in addition, it has also been suggested that NO might be cytoprotective by increasing cyclic GMP concentrations via activation of soluble guanylate cyclase. In this context, we have previously shown that cyclic GMP elevations confer cytoprotection against the neurotoxicity induced by SIN-1 in the presence of superoxide dismutase, conditions in which cell death seems to be a consequence of hydrogen peroxide (H2O2) formation. We have now found that H2O2 (20-100 microM) causes neurotoxicity in 1-week-old rat cortical neurones and that this effect is inhibited by the NO donor DETA-NONOate (1-10 microM). We have also found that 1H-[1,2,4]oxadiazolo[4,3,-alpha]quinoxalin-1-one (ODQ), a selective inhibitor of soluble guanylate cyclase, reverses the effect induced by DETA-NONOate, and that this action of ODQ is mimicked by 8-(4-chlorophenylthio)guanosine-3',5'-monophosphorothioate (Rp-8-pCPT-cGMPS), an inhibitor of cyclic GMP-dependent protein kinase, suggesting that the pathway affording protection involves activation of this kinase by cyclic GMP elevations. Simultaneously, ODQ inhibits the elevation of cyclic GMP concentrations induced by DETA-NONOate (1-3 microM) in cortical cells. Finally, we have also shown that the cyclic GMP mimetic, 8-bromoguanosine 3':5'-cyclic monophosphate (8-Br-cyclic GMP) inhibits the neurotoxicity induced by H2O2 (30-40 microM). Taken together, these data demonstrate that NO-induced cyclic GMP elevations confer cytoprotection against H2O2-induced neuronal cell death.

Animals↗
PubMed1999

Use of brain slices in the study of pathogenic role of inducible nitric oxide synthase in cerebral ischemia-reperfusion.

We have recently demonstrated that inducible nitric oxide synthase (iNOS) is expressed in rat forebrain slices exposed to oxygen and glucose deprivation (OGD). Now, we have found that the expression of iNOS after OGD is time-dependent since 20 min of OGD produces the appearance of iNOS at earlier times than 10 min of OGD. OGD also causes neurotoxicity in this model, as revealed by the increase in excitatory amino acid, neuron specific enolase and lactate dehydrogenase (LDH) efflux to the incubation solution. Finally, the administration of the NMDA receptor antagonist MK-801 (100 nM) inhibits both the expression of iNOS and the release of LDH. Our findings demonstrate that this method may be considered an useful in vitro model of ischemia-reperfusion to determine the therapeutic role of neuroprotective tools.

Animals↗