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Biomedical subjects

F Terro

Publications and source records attributed to F Terro.

13 recordsLinked to original sources
PubMed2000

N-methyl-D-aspartate receptor blockade enhances neuronal apoptosis induced by serum deprivation.

Neuronal apoptosis a hallmark of brain development could also be involved in neurodegenerative diseases. Glutamate toxicity is widely proposed as an important factor in the pathogenesis of neurological disorders. We show here that, in rat primary cortical cultures, the blockade of N-methyl-D-aspartate (NMDA) glutamate receptors exacerbated neuronal apoptosis induced by serum deprivation. This effect is observed at early stage of cultures (9 days in vitro (DIV)) and mildly decreases in more mature cultures (13 and 15 DIV). At the opposite, low concentrations of NMDA (5 microM) or glutamate (5 microM) prevented the neuronal apoptosis induced by trophic support withdrawal. In primary cortical cultures, the proapoptotic effect of trophic support removal can be modulated by NMDA receptors depending upon the magnitude of these glutamate receptor activation.

Animals↗
PubMed2000

Markers of apoptosis and models of programmed cell death in Alzheimer's disease.

Alzheimer's disease (AD) is neuropathologically marked by the presence of senile plaques composed of beta-amyloid peptide and by neurofibrillary tangles formed by abnormally phosphorylated tau protein. Many authors have also reported a neuronal loss in affected regions of the brain in AD patients. This neuronal degeneration could be linked to the triggering of intracellular pathways leading to apoptosis. Previous works were focused on the links between neuronal apoptosis and tau and amyloid precursor protein (APP) metabolisms. We have analyzed tau gene expression in primary neuronal cultures submitted to an apoptotic stress produced by excitotoxicity or serum deprivation. Glutamate induces an enhancement of tau gene expression in resistant neurons whereas a reduced expression is noted in apoptotic cells. This decrease is similar to what is observed after trophic support withdrawal in neuronal cultures. Neurons expressing phosphorylated tau are more resistant to experimental apoptosis than neurons positively labeled for dephosphorylated tau protein (AT8/Tau 1 epitope). In vitro apoptotic neurons are able to produce membrane blebbings (strongly immunopositive for APP and amyloidogenic fragments) that are secondary released in the extracellular space. Finally neurons overexpressing human mutated presenilin 1 (M146 L) are more prone to degenerate than neurons overexpressing human wild-type presenilin 1 after apoptosis induction.

Alzheimer Disease↗
PubMed1998

Mild kainate toxicity produces selective motoneuron death with marked activation of CA(2+)-permeable AMPA/kainate receptors.

Motoneuron death could be produced by higher sensitivity to excitoxicity during the development and pathological conditions. We report here that in ventral spinal cord cultures mild kainate exposure (12.5 microM, 20 min or 100 microM, 2.5 min) induced selective cobalt stain of motoneurons, indicating a specific Ca2+ entry through the Ca(2+)-permeable AMPA/kainate receptors. This result was associated with a selective motoneuron death as previously described. In these cultures, motoneuron immunoreactivity for the Ca2+ buffering protein, calretinin was negative. These findings suggest that the selective motoneuron death due to a mild excitotoxic insult could be linked to a marked Ca2+ influx associated with the lack of some Ca2+ buffering proteins.

Animals↗
PubMed1998

Brefeldin A-induced apoptosis is expressed in rat neurons with dephosphorylated tau protein.

Brefeldin A (BFA) is a fungus metabolite (penicillum brefeldanum) that is known to produce the disintegration of the Golgi apparatus in exposed cells, and apoptosis in various cancer cells. This study reports that in rat primary cortical cell cultures BFA also produces apoptosis assessed by the TUNEL method and DAPI (4',6-diemidino-2-phenylindole) staining. The percentages of apoptotic neurons range from 26.9% +/- 8.3 to 43.2 +/- 2.5% in cultures exposed from 4 to 8 h to BFA (10 microg/ml). A double fluorescent staining, using AT8 antibody (phosphorylated tau) or tau1 antibody (dephosphorylated tau) associated with DAPI labeling reveals that tau1 positive neurons are more sensitive to BFA-induced apoptosis compared to AT8 positive neurons. This result and previous results using other apoptosis inducers suggest that tau phosphorylation in the vicinity of the AT8-tau1 epitopes is a marker of resistance or sensitivity to neuronal apoptosis in rat cortical cell cultures.

Adrenal Cortex↗
PubMed1998

FK506 antagonizes apoptosis and c-jun protein expression in neuronal cultures.

FK506 is an immunosuppressive drug that binds to FK506 binding protein (FKBPs), a subgroup of cytosolic proteins called immunophillins. Previous works have revealed that FK506 protects neural cells from ischemia or excitotoxicity. Here we report that FK506 (10(-6) M) and not cyclosporine A (10(-6) M) blocks neuronal apoptosis induced by serum deprivation in rat neuronal cultures. In addition the immunohistochemical staining of C-jun protein in deprived cultures is markedly attenuated by FK506. The proportion of C-jun-positive neurons in control cultures, in serum-deprived cultures (48 h) and in serum-deprived cultures exposed to FK506 (10(-6) M) were 12.5%, 56.5% and 16.5%, respectively. The down-regulation of C-jun could play a major role in the anti-apoptotic action of FK506 in stressed neuronal cultures.

Animals↗
PubMed1998

Neuronal apoptosis is associated with a decrease in tau mRNA expression.

Apoptosis is a programmed cell death that occurs during the development of the nervous system and in neurodegenerative disorders. Tau protein is a microtubule-associated protein which promotes microtubule polymerization and stabilization. Apoptosis was induced in primary neuronal cultures by glutamate exposure (200 microM, 15 min) or by serum deprivation, and tau mRNA levels were studied by quantitative in situ hybridization in apoptotic and non apoptotic neurons. Compared to controls, tau mRNA expression was decreased in apoptotic neurons produced by excitotoxicity or trophic support withdrawal. Under these conditions, resistant neurons to apoptosis display either increased tau mRNA levels after glutamate exposure or a stable tau mRNA expression after serum deprivation. In conclusion, in this in vitro model, neurons which are resistant and sensitive to apoptosis can be differentiated according to tau mRNA expression.

Animals↗
PubMed1998

Characterization of human presenilin 1 transgenic rats: increased sensitivity to apoptosis in primary neuronal cultures.

Mutations in the gene for presenilin 1 are causative for the majority of cases of early onset familial Alzheimer's disease. Yet, the physiological function of presenilin 1 and the pathological mechanisms of the mutations leading to Alzheimer's disease are still unknown. To analyse potential pathological effects of presenilin 1 over-expression, we have generated transgenic rats which express high levels of human presenilin 1 protein in the brain. The over-expression of presenilin 1 leads to saturation of its normal processing and to the appearance of full-length protein in the transgenic rat brain. The transgenic protein is expressed throughout the brain and is predominantly found in neuronal cells. Cultured primary cortical neurons derived from these transgenic rats are significantly more sensitive than non-transgenic controls to apoptosis induced by standard culture conditions and to apoptosis induced by trophic factor withdrawal. Furthermore, the observed apoptosis is directly correlated with the expression of the transgenic protein. The results further emphasize the role of presenilin 1 in apoptotic cell death in native neuronal cultures.

Alzheimer Disease↗
PubMed1998

Effects of depolarizing stimuli on calcium homeostasis in cultured rat motoneurones.

Intracellular calcium concentrations in individual rat motoneurones in enriched primary cultures were measured by Indo-1 fluorimetry. Motoneurones in the cultures were characterized morphometrically and by cholineacetyltransferase immunocytochemistry. Depolarization of the cells with glutamic acid or veratridine increased intracellular calcium levels, which returned to baseline only slowly after removal of the depolarizing agent. The use of selective agonists (N-methyl-D-aspartic acid, AMPA, kainic acid, quisqualic acid and 1R-3S-ACPD) and antagonists (MK 801 and CNQX) showed that the excitatory amino acid-evoked responses were mediated by AMPA/kainate receptors rather than by NMDA receptors. Depolarization-evoked calcium transients in motoneurones are blocked by the neuroprotective drug riluzole Calcium transients reflected entry of calcium from without the cell, and their blockade by nitrendipine and lanthanum chloride suggested that this entry took place primarily through voltage-dependent calcium channels. These findings may be relevant for understanding the selective vulnerability of motoneurones to excitotoxicity in amyotrophic lateral sclerosis, and the therapeutic activity of riluzole in the treatment of this disease.

Animals↗
PubMed1997

Neuronal APP accumulates in toxic membrane blebbings.

The occurence of plasma membrane blebbings is an early cytotoxic event, associated with the reorganization of cytoskeletal proteins, the alteration of interactions between the plasma membrane and the underlying cytoskeleton. The blebbing formation remains poorly understood but the involvement of cytosolic Ca2+ and the production of free radicals may contribute to this cellular phenomenom. The amyloid precursor protein (APP), is a transmembrane protein that can be cleaved to produce the beta amyloid peptide (Abeta) which accumulates in brain senile plaques of Alzheimer's disease. Our study reveals that the exposure of rat and human (hNT) neuronal cultures to a mild concentration of the excitotoxin NMDA slowly induces perturbations of the neuronal cytoskeleton and the occurence of plasma membrane blebbings. An immunocytochemical study using four different APP antibodies demonstrates that these membrane blebs are also associated with a redistribution and an accumulation of cellular APP. This phenomenon is linked to a Ca2+-influx through NMDA-receptors since it is prevented by the NMDA antagonist MK801 or by Ca2+-depleted conditions. In conclusion this study shows that neuronal degeneration induced by slow excitotoxicity, is associated with the presence of APP-accumulating blebs, that can be secondly released in the extracellular region.

Amyloid beta-Protein Precursor↗
PubMed1996

Antioxidant drugs block in vitro the neurotoxicity of CSF from patients with amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a progressive neurological disease characterized by upper and lower motoneurone degeneration. Excitotoxicity and oxidative stress have been proposed as possible aetiological factors. We measured the neuronal death induced in rat cortical cell cultures by CSF taken from seven ALS patient and seven control subjects with lumbar radiculopathies. Cultures were exposed to CSF for 48 h at a dilution of 1:4. Some cultures were also exposed to antioxidant drugs, the free radical scavenger vitamin E (250 microM) and the xanthine oxidase inhibitor allopurinol (50 microM), alone or combined. The mean neuronal death rate was 31.8 +/- 3.4% in cultures exposed to ALS CSF and 10.9 +/- 1.8% in cultures exposed to control CSF. The cytotoxicity of ALS CSF was partially blocked by vitamin E (21.6 +/- 3%) or by allopurinol (18.6 +/- 2.7%). The combination of these two antioxidants reduced the toxicity from 31.8 +/- 3.4% to 10.6 +/- 1.7%. The present work suggests that neurotoxicity induced by CSF from patients with ALS indirectly involves free radicals. A combination of allopurinol and vitamin E may be useful in ALS therapy.

Adult↗
PubMed1996

Phosphorylated neurofilament expression and resistance to kainate toxicity.

Antibodies directed against phosphorylated neurofilaments, which are major proteins of the neuronal cytoskeleton, usually do not label neuronal cell bodies except in some neurological diseases. In the present study, we show that in rat cortical cell cultures exposed to kainate there is an inverse relation between neuronal survival and the proportion of neuronal cell bodies stained by a monoclonal antibody (clone SMI31) that recognizes extensively phosphorylated neurofilament proteins (150 kDa and 200 kDa). The immunoblot analysis also revealed an increase in 150-kDa phosphorylated neurofilament expression in kainate-treated cell cultures. Furthermore, the direct quantification of viable neurons SMI31-immunopositive or immunonegative in perikarya showed that the majority of neurons resistant to kainate toxicity expressed phosphorylated neurofilaments in their cell bodies. The percentage of viable neurons displaying SMI31-immunoreactivity in their cell bodies increased from 14.7% in control cultures to 30.0% in cultures treated with 10 microM kainate. These data suggest that phosphorylated neurofilament expression is associated with a reduced cell vulnerability to excitotoxicity induced by kainate.

Animals↗
PubMed1996

NMDA antagonist blockade of AT8 tau immunoreactive changes in neuronal cultures.

Antagonists at four distinct regulatory sites on the N-methyl-D-aspartate (NMDA) receptor were tested for their ability to attenuate NMDA-mediated chronic excitotoxicity and the consequences on AT8 tau immunoreactivity in neuronal cultures. Excitotoxicity was monitored in cultures by diacetate fluorescein staining. Immunoreactivity of tau phosphorylated at serine 202 was quantified by laser confocal microscopy. The NMDA-receptor antagonists MK801, AP7 and 7-chlorokynurenate significantly blocked NMDA-induced cell death and significantly reduced AT8 tau immunoreactivity. NMDA antagonism by the polyamine site antagonist, ifenprodil, did not completely reverse the increase in AT8 tau immunolabeling induced by NMDA and did not completely protect NMDA-sensitive neurons, suggesting an heterogeneity in the NMDA receptor population.

2-Amino-5-phosphonovalerate↗