Sonia Barrón | Universitat de Barcelona (original) (raw)
Papers by Sonia Barrón
L'invention concerne un dispositif d'allaitement (10) comprenant au moins une tetine (100... more L'invention concerne un dispositif d'allaitement (10) comprenant au moins une tetine (100) a appliquer de maniere a entourer au moins partiellement le mamelon maternel, comprenant une ouverture principale (110) a travers laquelle un nourrisson peut etre en contact direct avec le sein de la mere pendant l'allaitement ; et des premier et second trous (120, 130) pour recevoir de maniere reglable un tube d'alimentation (20) a travers ceux-ci de sorte qu'il puisse etre oriente de facon mobile dans l'ouverture principale (110) afin de fournir le produit a proximite du mamelon maternel.
Neuroscience Letters, 1995
Previous studies have shown that ionizing radiation-induced cell death in the developing brain ha... more Previous studies have shown that ionizing radiation-induced cell death in the developing brain has morphological characteristics of apoptosis and is associated with internucleosomal DNA fragmentation. In the present study, we have observed c-Jun induction in cells sensitive to ionizing radiation during the whole process of radiation-induced cell death, and that this expression is accompanied by modifications in the composition of AP-1 complexes: c-Jun/AP-1 activity is highly increased whereas Jun D/AP-1 is slightly decreased. These results show that c-Jun expression and c-Jun/AP-1 activity are induced in the developing brain following ionizing radiation.
Molecular Pharmacology, 2007
UR-1505 is a new molecule, chemically related to salicylic acid with immunomodulator properties, ... more UR-1505 is a new molecule, chemically related to salicylic acid with immunomodulator properties, currently under clinical development for atopic dermatitis. The present work describes the immunomodulatory profile of UR-1505. UR-1505 targets T cells inhibiting their proliferation and cytokine production by blocking NF-AT DNA-binding activity. The effects of UR-1505 (100-300 µM) on T cell proliferation appears to be dependent on the stimulus, since UR-1505 inhibited CD3/CD28-induced T-cell proliferation, increased p27 KIP levels and induces G1/S cell arrest but, interestingly, did not inhibit the JAK/STAT-induced T-cell proliferation. These data suggest that UR-1505 acts by means of a specific mechanism inhibiting T cell activation depending on TCR signalling pathway. Furthermore, the antiproliferative effects of UR-1505 are not consequence of decreased cell viability. In addition to the inhibition of T-cell proliferation, UR-1505 decreased in a dose dependent manner the production of IL-5 and IFN-γ in activated T cells and this effect was produced at transcriptional level. As T-cell proliferation and cytokine production were regulated through NF-AT, we examined the effect of UR-1505 on this transcription factor. According to its effect on IL-5 and IFN-γ mRNA expression, UR-1505 specifically inhibited NF-AT DNA binding without effect on NF-κB and AP-1 activities. The effect of UR-1505 on NF-AT is not attributable to a blockade of nuclear import. In conclusion, UR-1505 is a new immunomodulator agent that specifically inhibits NF-AT activation. As NF-AT regulates the transcription of most genes involved in lymphocyte activation, its selective inactivation results in both decreased T-cell proliferation and cytokine production.
Brain Research, 1993
The anticonvulsant activity of delta-HCH and of a calmodulin antagonist, W-7 were investigated on... more The anticonvulsant activity of delta-HCH and of a calmodulin antagonist, W-7 were investigated on convulsions induced in mice by lindane (ED100 100 mg/kg), by GABAergic antagonists PTZ (ED100 60 mg/kg) and PTX(ED100 4 mg/kg), by calcium channel agonist BAY-K-8644 (ED100 5 mg/kg), by two agonists of excitatory amino acid receptors, kainic acid (ED100 80 mg/kg) and NMDA (ED100 160 mg/kg and by the atypical benzodiazepine Ro 5-4864 (ED100 40 mg/kg). The anticonvulsant activity of a voltage-dependent calcium channel antagonist, nifedipine was also investigated on convulsions induced by Ro 5-4864, BAY-K-8644, kainic acid and NMDA. delta-HCH antagonized lindane- and BAY-K-8644-induced convulsions (ED50 231 (172-309) mg/kg and 148 (142-154) mg/kg, respectively) and at concentrations up to 300 mg/kg failed to antagonize Ro 5-4864, kainic acid and NMDA convulsions. In contrast delta-HCH potentiated PTX-induced seizures. Nifedipine antagonized BAY-K-8644- and kainic acid-induced convulsions (ED50 6.5 (4.3-9.7) mg/kg and 30 (13-70) mg/kg but at concentrations up to 20 mg/kg failed to antagonize Ro 5-4864 and 25% of protection was observed on NMDA-induced convulsions at the highest dose (20 mg/kg). The ED50 of W-7 to antagonize convulsions induced by lindane and BAY-K-8644 were 12 (8-19) mg/kg and 49 (29-85) mg/kg, respectively. Some anticonvulsant effect was observed against PTZ and NMDA but without any dose-dependent anticonvulsant activity. W-7 did not protect against PTX and kainic acid convulsions and 30% of protection was observed against convulsions at the highest dose of W-7 (75 mg/kg).(ABSTRACT TRUNCATED AT 250 WORDS)
Journal of Neurochemistry, 2002
Calcium acts as a second messenger and can enter neurons through several types of calcium channel... more Calcium acts as a second messenger and can enter neurons through several types of calcium channel. We sought to determine whether the calcium-dependent mechanisms inducing c-fos expression are identical following activation, by appropriate drugs, of L-type voltage-sensitive calcium channels or NMDA and non-NMDA receptors or following inhibition of the GABAergic system. We used primary cortical neurons and OF1 mice, and the levels of c-fos protein and c-fos mRNA were detected after treatment with the drugs by means of immunocytochemistry and in situ hybridization. The calmodulin antagonist N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) abolished gamma-hexachlorocyclohexane-, Bay K 8644-, pentylenetetrazole-, and kainic acid-induced increases in c-fos expression in cultured neurons. Conversely, W-7 did not affect either NMDA- or picrotoxinin-mediated increases in c-fos expression. In mice, the pattern of protooncogene expression displayed some differences compared with cultured neurons, depending on the treatment. W-7 administered before gamma-hexachlorocyclohexane, Bay K 8644, or pentylenetetrazole blocked the expression of c-fos elicited by these compounds. However, W-7 was not able to abolish c-fos expression induced by picrotoxinin. In the animals treated with W-7 before kainic acid or NMDA administration, c-fos expression was inhibited in cerebral cortex, but it was still present in hippocampus. These results agree with the existence of diverse mechanisms transducing the calcium signals to the nucleus. Calmodulin may mediate neuronal responses depending on the route by which calcium enters the neuron, resulting in activation of different enzymes.
Neurotoxicology, 1994
The anticonvulsant activity of calmodulin antagonist W-7, was investigated on convulsions induced... more The anticonvulsant activity of calmodulin antagonist W-7, was investigated on convulsions induced in mice by the insecticide lindane and by the calcium channel agonist BayK-8644. We also studied the inhibitory effect of W-7 on on c-fos mRNA expression induced by both convulsants. We observed a good correlation between doses and the acute convulsive effects of lindane and BayK-8644. The incidence rate and time to onset were clearly dose-dependent. W-7 antagonized the convulsive effects of lindane and BayK-8644 in all the parameters studied. A significant decrease in the incidence rate and time to onset were observed when they are compared with the values obtained with the ED100 of lindane- and BayK-8644 induced seizures. Both were able to activate the mRNA expression of the proto-oncogene. The pattern of this expression displayed by in situ hybridization was very similar. A dramatic increase was found in dentate gyrus and high levels of mRNA expression also occurring in hippocampal f...
Journal of Neurochemistry, 2002
Primary cortical cultures were used to study the effects of four convulsants on c-fos expression.... more Primary cortical cultures were used to study the effects of four convulsants on c-fos expression. Approximately 30% of the neurons in these cultures displayed c-fos nuclear immunostaining under basal conditions. The addition of tetrodotoxin, nifedipine, or delta-hexachlorocyclohexane produced a significant decrease in c-fos basal values. Lindane (gamma-hexachlorocyclohexane), Bay K 8644, pentylenetetrazole, and picrotoxinin produced a significant increase in c-fos immunoreactivity and in c-fos mRNA expression. Treatment of cells with tetrodotoxin before administration of the convulsant agents lowered c-fos staining below basal levels. In contrast, delta-hexachlorocyclohexane or nifedipine failed to block only the picrotoxin-induced increase. The differential pattern of expression shown by c-fos after these treatments suggests various mechanisms of action for the compounds studied. The results obtained with delta-hexachlorocyclohexane and nifedipine suggest that picrotoxinin activates c-fos expression by calcium-requiring intracellular signaling pathways that are different from those activated by Bay K 8644, pentylenetetrazole, or gamma-hexachlorocyclohexane, which, at least in part, act via L-type calcium channels.
Journal of Microbiological Methods, 1999
Differential agar media for the detection of microbial phytase activity use the disappearance of ... more Differential agar media for the detection of microbial phytase activity use the disappearance of precipitated calcium or sodium phytate as an indication of enzyme activity. When this technique was applied to the study of ruminal bacteria, it became apparent that the method was unable to differentiate between phytase activity and acid production. Strong positive reactions (zones of clearing around microbial colonies) observed for acid producing, anaerobic bacteria, such as Streptococcus bovis, were not corroborated by subsequent quantitative assays. Experimentation revealed that acidic solutions generated false positive results on the selected differential medium. Empirical studies undertaken to find a solution to this limitation determined the false positive results could be eliminated through a two step counterstaining treatment (cobalt chloride and ammonium molybdate / ammonium vanadate) which reprecipitates acid solubilized phytate. This report discusses the application of the developed two step counterstaining treatment for the screening of phytase producing ruminal bacteria as well as its use in phytase zymogram assays.
Glia, 2002
LPA1 (also termed Edg-2 or VZG-1) is a G-protein–coupled receptor for lysophosphatidic acid and i... more LPA1 (also termed Edg-2 or VZG-1) is a G-protein–coupled receptor for lysophosphatidic acid and its gene transcripts have been found selectively expressed by mature myelin-producing cells. We have raised in rabbit a polyclonal antibody against a sequence unique to LPA1 and common to rat, mouse, and human orthologues. In Western blots, LPA1 immunoreactivity appeared as 44–53 kDa bands in extracts from recombinant RH7777 cells expressing LPA1, mouse purified oligodendrocytes, or human white matter, but not from wild-type RH7777 cells or purified astrocytes. In glial cultures, LPA1 immunoreactivity was restricted to oligodendrocytes, appeared at cell membrane and processes, colocalized with myelin basic protein, and appeared before myelin/oligodendrocyte glycoprotein. In slices of rat and human brains, LPA1 immunoreactivity was found in myelinated tracts, as well as in oligodendrocyte somata and their myelinating fibers. Immunoreactivities of LPA1 and myelin basic protein colocalized in the brain, but oligodendrocyte soma showed stronger signals for LPA1 than myelinated fibers, whereas the reverse was true for myelin basic protein. These results strengthen the view that LPA1 is involved in myelin formation or maintenance. GLIA 38:126–136, 2002. © 2002 Wiley-Liss, Inc.
European Journal of Neuroscience, 1998
By screening an olfactory bulb cDNA library using dopamine receptor probes, we isolated the cDNA ... more By screening an olfactory bulb cDNA library using dopamine receptor probes, we isolated the cDNA coding for the rat counterpart of an orphan receptor known as Edg-2, homologous to G protein-coupled receptors. In situ hybridization analysis showed that Edg-2 mRNA expression is restricted to myelinated structures, e.g. corpus callosum or peripheral nerves. A weaker expression in various peripheral organs was also detected in newborns. A 3.8-kb transcript was found at high levels in highly myelinated brain structures and sciatic nerve, and, at lower levels, in poorly myelinated peripheral organs, consistent with its occurrence in Schwann cells in the peripheral nervous system. One hundred percent of Edg-2 mRNA-containing cells in the brain also expressed mRNA encoding myelin-basic-protein, a marker of oligodendrocytes. This restricted olygodendrocytes localization was confirmed by the absence of cellular colocalization of Edg-2 and glial fibrillary acidic protein, an astrocytic marker. During prenatal development, Edg-2 mRNA expression was high in the cortical neuroepithelium and meningeal layer at E16, extended later to other neuroepithelia, and disappeared shortly after birth. During brain postnatal development, Edg-2 mRNA expression in myelinated structures followed a caudo-rostral gradient, similar to that of myelination. Thus, Edg-2 is the first G protein-coupled receptor found to be selectively expressed in myelin-forming cells in the nervous system and its temporal expression pattern is consistent with a dual role (i) in neurogenesis, during embryonic development, and (ii) in myelination and myelin maintenance, during postnatal life.
Molecular and Cellular Neuroscience, 2002
Edg-2 transcripts are not detected during early stages of oligodendroglial development, but are e... more Edg-2 transcripts are not detected during early stages of oligodendroglial development, but are expressed only in mature oligodendrocytes, shortly before the onset of myelination. Lysophosphatidic acid (LPA) has been reported to be a ligand of Edg-2 receptor in different cell types. However, in oligodendroglial cultures, LPA had no effect on survival, maturation, or cytoskeleton organization. In myelinating oligodendrocyte-neuron cocultures, LPA did not influence myelinogenesis. In addition, LPA failed to induce Ca 2؉ mobilization and had no effect on forskolininduced cAMP accumulation. Phosphorylation of the ERK1/ERK2 MAP kinases was the only response elicited by LPA in oligodendrocytes. Therefore, in contrast to other cell types, in which LPA exerts pleiotropic effects, Edg-2-positive postmitotic oligodendrocytes display a restricted responsiveness to LPA.
Glia, 1999
Edg-2 is an heptahelical receptor whose spatio-temporal distribution during rat brain development... more Edg-2 is an heptahelical receptor whose spatio-temporal distribution during rat brain development is consistent with a role in the control of myelination. We have now identified two splice variants of Edg-2 mRNA in rat brain that encode two receptor isoforms differing by a stretch of 18 amino acids in the NH2-terminal extracellular tail of the receptor. Prenatally (i.e., before oligodendrocyte myelination), the two variants detected by selective in situ hybridization are equally abundant, vary in parallel, and remain restricted to proliferative zones in the brain. Postnatally, the long isoform becomes predominant in myelinating structures, where its abundance increases sharply during the period of myelination. In the adult human brain, only the long variant was detected, while in situ hybridization showed it selectively expressed in the white matter and in clusters of cells showing features of oligodendrocytes of the temporal cerebral cortex. Consequently, the human Edg-2 gene was studied to assess its possible contribution in inherited neuropathies. The coding sequence was found to be contained in three exons and to map to chromosome 9q31.3-32 by using radiation hybrid panel and Yeast-Artificial Chromosomes. Two intragenic bi-allelic polymorphisms and a rare mutation were identified. As a first application to molecular genetic studies, they were used to exclude the Edg-2 gene in six families with phenotype of demyelinating Charcot-Marie-Tooth disease of unknown origin.
Molecular Brain Research, 1995
Three different calmodulin genes that encode the same protein have been found in the brain of all... more Three different calmodulin genes that encode the same protein have been found in the brain of all mammalian species so far examined. Little is known about the factors involved in regulating the expression of this gene family in the central nervous system. We have investigated the possibility of differential expression of two calmodulin genes, CaM I and CaM II, which are expressed strongly in neuronal cells in the adult rat brain, after treatment with the 3/ (lindane) and the ~ isomers of the hexachlorocyclohexane (HCH). In this study a decrease of CaM I mRNA (mainly in the 4.0 kb transcript) was found in the cortex of the rats after 24 h of isomer administration. CaM I expression seemed to be more sensitive to ~5 isomer action, whereas the 7 isomer acted mainly at CaM II level. The levels of mRNA of calmodulin CaM II gene were also found to decrease after lindane administration; ~-HCH produced an increase of this transcript. These results were obtained by Northern blot analysis and confirmed by means of in situ hybridization. Our results suggest that levels of neuronal calmodulin mRNA species are modified in response to changes in neuronal activity.
Progress in Neurobiology, 1999
AbstractÐCa 2+ plays a critical role in the normal function of the central nervous system. Howeve... more AbstractÐCa 2+ plays a critical role in the normal function of the central nervous system. However, it can also be involved in the development of dierent neuropathological and neurotoxicological processes. The processing of a Ca 2+ signal requires its union with speci®c intracellular proteins. Calmodulin is a major Ca 2+ -binding protein in the brain, where it modulates numerous Ca 2+ -dependent enzymes and participates in relevant cellular functions. Among the dierent calmodulin-binding proteins, the Ca 2+ / calmodulin-dependent protein kinase II and the phosphatase calcineurin are especially important in the brain because of their abundance and their participation in numerous neuronal functions. We present an overview on dierent works aimed at the study of the Ca 2+ /calmodulin signalling system in the neural response to convulsant agents.
Neuroscience Letters, 1996
The systemic administration of a non-convulsant dose of N-methyl-D-aspartate (NMDA; 75 mg/kg i.p.... more The systemic administration of a non-convulsant dose of N-methyl-D-aspartate (NMDA; 75 mg/kg i.p.), which was associated with motor activation, induced a regional c-fos mRNA expression in the mouse brain. The NMDA-induced c-fos mRNA expression was predominant in the dentate gyrus and in the medial mammillary nucleus and less pronounced in other hippocampal areas, cortical areas, bed nucleus of the stria terminalis and posterior amygdaloid nuclei. It is suggested that the hippocampus and/or the extended amygdala might be involved in the previously hypothesized dopamine-independent NMDA-mediated motor activation mechanism. No increase in c-fos mRNA expression was observed 21 h after reserpine treatment (5 mg/kg s.c.). However, reserpinization induced a significant potentiation of the NMDA-induced c-fos mRNA expression. These results show the existence of a strong and selective aminedependent modulation of NMDA neurotransmission in the brain.
International Journal of Biochemistry & Cell Biology, 2001
Calmodulin (CaM) is a major Ca 2 + -binding protein in the brain, where it plays an important rol... more Calmodulin (CaM) is a major Ca 2 + -binding protein in the brain, where it plays an important role in the neuronal response to changes in the intracellular Ca 2 + concentration. Calmodulin modulates numerous Ca 2 + -dependent enzymes and participates in relevant cellular functions. Among the different CaM-binding proteins, the Ca 2 + /CaM dependent protein kinase II and the phosphatase calcineurin are especially important in the brain because of their abundance and their participation in numerous neuronal functions. Therefore, the role of the Ca 2 + /CaM signalling system in different neurotoxicological or neuropathological conditions associated to alterations in the intracellular Ca 2 + concentration is a subject of interest. We here report different evidences showing the involvement of CaM and the CaM-binding proteins above mentioned in situations of neuronal hyperexcitability induced by convulsant agents. Signal transduction pathways mediated by specific CaM binding proteins warrant future study as potential targets in the development of new drugs to inhibit convulsant responses or to prevent or attenuate the alterations in neuronal function associated to the deleterious increases in the intracellular Ca 2 + levels described in different pathological situations.
L'invention concerne un dispositif d'allaitement (10) comprenant au moins une tetine (100... more L'invention concerne un dispositif d'allaitement (10) comprenant au moins une tetine (100) a appliquer de maniere a entourer au moins partiellement le mamelon maternel, comprenant une ouverture principale (110) a travers laquelle un nourrisson peut etre en contact direct avec le sein de la mere pendant l'allaitement ; et des premier et second trous (120, 130) pour recevoir de maniere reglable un tube d'alimentation (20) a travers ceux-ci de sorte qu'il puisse etre oriente de facon mobile dans l'ouverture principale (110) afin de fournir le produit a proximite du mamelon maternel.
Neuroscience Letters, 1995
Previous studies have shown that ionizing radiation-induced cell death in the developing brain ha... more Previous studies have shown that ionizing radiation-induced cell death in the developing brain has morphological characteristics of apoptosis and is associated with internucleosomal DNA fragmentation. In the present study, we have observed c-Jun induction in cells sensitive to ionizing radiation during the whole process of radiation-induced cell death, and that this expression is accompanied by modifications in the composition of AP-1 complexes: c-Jun/AP-1 activity is highly increased whereas Jun D/AP-1 is slightly decreased. These results show that c-Jun expression and c-Jun/AP-1 activity are induced in the developing brain following ionizing radiation.
Molecular Pharmacology, 2007
UR-1505 is a new molecule, chemically related to salicylic acid with immunomodulator properties, ... more UR-1505 is a new molecule, chemically related to salicylic acid with immunomodulator properties, currently under clinical development for atopic dermatitis. The present work describes the immunomodulatory profile of UR-1505. UR-1505 targets T cells inhibiting their proliferation and cytokine production by blocking NF-AT DNA-binding activity. The effects of UR-1505 (100-300 µM) on T cell proliferation appears to be dependent on the stimulus, since UR-1505 inhibited CD3/CD28-induced T-cell proliferation, increased p27 KIP levels and induces G1/S cell arrest but, interestingly, did not inhibit the JAK/STAT-induced T-cell proliferation. These data suggest that UR-1505 acts by means of a specific mechanism inhibiting T cell activation depending on TCR signalling pathway. Furthermore, the antiproliferative effects of UR-1505 are not consequence of decreased cell viability. In addition to the inhibition of T-cell proliferation, UR-1505 decreased in a dose dependent manner the production of IL-5 and IFN-γ in activated T cells and this effect was produced at transcriptional level. As T-cell proliferation and cytokine production were regulated through NF-AT, we examined the effect of UR-1505 on this transcription factor. According to its effect on IL-5 and IFN-γ mRNA expression, UR-1505 specifically inhibited NF-AT DNA binding without effect on NF-κB and AP-1 activities. The effect of UR-1505 on NF-AT is not attributable to a blockade of nuclear import. In conclusion, UR-1505 is a new immunomodulator agent that specifically inhibits NF-AT activation. As NF-AT regulates the transcription of most genes involved in lymphocyte activation, its selective inactivation results in both decreased T-cell proliferation and cytokine production.
Brain Research, 1993
The anticonvulsant activity of delta-HCH and of a calmodulin antagonist, W-7 were investigated on... more The anticonvulsant activity of delta-HCH and of a calmodulin antagonist, W-7 were investigated on convulsions induced in mice by lindane (ED100 100 mg/kg), by GABAergic antagonists PTZ (ED100 60 mg/kg) and PTX(ED100 4 mg/kg), by calcium channel agonist BAY-K-8644 (ED100 5 mg/kg), by two agonists of excitatory amino acid receptors, kainic acid (ED100 80 mg/kg) and NMDA (ED100 160 mg/kg and by the atypical benzodiazepine Ro 5-4864 (ED100 40 mg/kg). The anticonvulsant activity of a voltage-dependent calcium channel antagonist, nifedipine was also investigated on convulsions induced by Ro 5-4864, BAY-K-8644, kainic acid and NMDA. delta-HCH antagonized lindane- and BAY-K-8644-induced convulsions (ED50 231 (172-309) mg/kg and 148 (142-154) mg/kg, respectively) and at concentrations up to 300 mg/kg failed to antagonize Ro 5-4864, kainic acid and NMDA convulsions. In contrast delta-HCH potentiated PTX-induced seizures. Nifedipine antagonized BAY-K-8644- and kainic acid-induced convulsions (ED50 6.5 (4.3-9.7) mg/kg and 30 (13-70) mg/kg but at concentrations up to 20 mg/kg failed to antagonize Ro 5-4864 and 25% of protection was observed on NMDA-induced convulsions at the highest dose (20 mg/kg). The ED50 of W-7 to antagonize convulsions induced by lindane and BAY-K-8644 were 12 (8-19) mg/kg and 49 (29-85) mg/kg, respectively. Some anticonvulsant effect was observed against PTZ and NMDA but without any dose-dependent anticonvulsant activity. W-7 did not protect against PTX and kainic acid convulsions and 30% of protection was observed against convulsions at the highest dose of W-7 (75 mg/kg).(ABSTRACT TRUNCATED AT 250 WORDS)
Journal of Neurochemistry, 2002
Calcium acts as a second messenger and can enter neurons through several types of calcium channel... more Calcium acts as a second messenger and can enter neurons through several types of calcium channel. We sought to determine whether the calcium-dependent mechanisms inducing c-fos expression are identical following activation, by appropriate drugs, of L-type voltage-sensitive calcium channels or NMDA and non-NMDA receptors or following inhibition of the GABAergic system. We used primary cortical neurons and OF1 mice, and the levels of c-fos protein and c-fos mRNA were detected after treatment with the drugs by means of immunocytochemistry and in situ hybridization. The calmodulin antagonist N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) abolished gamma-hexachlorocyclohexane-, Bay K 8644-, pentylenetetrazole-, and kainic acid-induced increases in c-fos expression in cultured neurons. Conversely, W-7 did not affect either NMDA- or picrotoxinin-mediated increases in c-fos expression. In mice, the pattern of protooncogene expression displayed some differences compared with cultured neurons, depending on the treatment. W-7 administered before gamma-hexachlorocyclohexane, Bay K 8644, or pentylenetetrazole blocked the expression of c-fos elicited by these compounds. However, W-7 was not able to abolish c-fos expression induced by picrotoxinin. In the animals treated with W-7 before kainic acid or NMDA administration, c-fos expression was inhibited in cerebral cortex, but it was still present in hippocampus. These results agree with the existence of diverse mechanisms transducing the calcium signals to the nucleus. Calmodulin may mediate neuronal responses depending on the route by which calcium enters the neuron, resulting in activation of different enzymes.
Neurotoxicology, 1994
The anticonvulsant activity of calmodulin antagonist W-7, was investigated on convulsions induced... more The anticonvulsant activity of calmodulin antagonist W-7, was investigated on convulsions induced in mice by the insecticide lindane and by the calcium channel agonist BayK-8644. We also studied the inhibitory effect of W-7 on on c-fos mRNA expression induced by both convulsants. We observed a good correlation between doses and the acute convulsive effects of lindane and BayK-8644. The incidence rate and time to onset were clearly dose-dependent. W-7 antagonized the convulsive effects of lindane and BayK-8644 in all the parameters studied. A significant decrease in the incidence rate and time to onset were observed when they are compared with the values obtained with the ED100 of lindane- and BayK-8644 induced seizures. Both were able to activate the mRNA expression of the proto-oncogene. The pattern of this expression displayed by in situ hybridization was very similar. A dramatic increase was found in dentate gyrus and high levels of mRNA expression also occurring in hippocampal f...
Journal of Neurochemistry, 2002
Primary cortical cultures were used to study the effects of four convulsants on c-fos expression.... more Primary cortical cultures were used to study the effects of four convulsants on c-fos expression. Approximately 30% of the neurons in these cultures displayed c-fos nuclear immunostaining under basal conditions. The addition of tetrodotoxin, nifedipine, or delta-hexachlorocyclohexane produced a significant decrease in c-fos basal values. Lindane (gamma-hexachlorocyclohexane), Bay K 8644, pentylenetetrazole, and picrotoxinin produced a significant increase in c-fos immunoreactivity and in c-fos mRNA expression. Treatment of cells with tetrodotoxin before administration of the convulsant agents lowered c-fos staining below basal levels. In contrast, delta-hexachlorocyclohexane or nifedipine failed to block only the picrotoxin-induced increase. The differential pattern of expression shown by c-fos after these treatments suggests various mechanisms of action for the compounds studied. The results obtained with delta-hexachlorocyclohexane and nifedipine suggest that picrotoxinin activates c-fos expression by calcium-requiring intracellular signaling pathways that are different from those activated by Bay K 8644, pentylenetetrazole, or gamma-hexachlorocyclohexane, which, at least in part, act via L-type calcium channels.
Journal of Microbiological Methods, 1999
Differential agar media for the detection of microbial phytase activity use the disappearance of ... more Differential agar media for the detection of microbial phytase activity use the disappearance of precipitated calcium or sodium phytate as an indication of enzyme activity. When this technique was applied to the study of ruminal bacteria, it became apparent that the method was unable to differentiate between phytase activity and acid production. Strong positive reactions (zones of clearing around microbial colonies) observed for acid producing, anaerobic bacteria, such as Streptococcus bovis, were not corroborated by subsequent quantitative assays. Experimentation revealed that acidic solutions generated false positive results on the selected differential medium. Empirical studies undertaken to find a solution to this limitation determined the false positive results could be eliminated through a two step counterstaining treatment (cobalt chloride and ammonium molybdate / ammonium vanadate) which reprecipitates acid solubilized phytate. This report discusses the application of the developed two step counterstaining treatment for the screening of phytase producing ruminal bacteria as well as its use in phytase zymogram assays.
Glia, 2002
LPA1 (also termed Edg-2 or VZG-1) is a G-protein–coupled receptor for lysophosphatidic acid and i... more LPA1 (also termed Edg-2 or VZG-1) is a G-protein–coupled receptor for lysophosphatidic acid and its gene transcripts have been found selectively expressed by mature myelin-producing cells. We have raised in rabbit a polyclonal antibody against a sequence unique to LPA1 and common to rat, mouse, and human orthologues. In Western blots, LPA1 immunoreactivity appeared as 44–53 kDa bands in extracts from recombinant RH7777 cells expressing LPA1, mouse purified oligodendrocytes, or human white matter, but not from wild-type RH7777 cells or purified astrocytes. In glial cultures, LPA1 immunoreactivity was restricted to oligodendrocytes, appeared at cell membrane and processes, colocalized with myelin basic protein, and appeared before myelin/oligodendrocyte glycoprotein. In slices of rat and human brains, LPA1 immunoreactivity was found in myelinated tracts, as well as in oligodendrocyte somata and their myelinating fibers. Immunoreactivities of LPA1 and myelin basic protein colocalized in the brain, but oligodendrocyte soma showed stronger signals for LPA1 than myelinated fibers, whereas the reverse was true for myelin basic protein. These results strengthen the view that LPA1 is involved in myelin formation or maintenance. GLIA 38:126–136, 2002. © 2002 Wiley-Liss, Inc.
European Journal of Neuroscience, 1998
By screening an olfactory bulb cDNA library using dopamine receptor probes, we isolated the cDNA ... more By screening an olfactory bulb cDNA library using dopamine receptor probes, we isolated the cDNA coding for the rat counterpart of an orphan receptor known as Edg-2, homologous to G protein-coupled receptors. In situ hybridization analysis showed that Edg-2 mRNA expression is restricted to myelinated structures, e.g. corpus callosum or peripheral nerves. A weaker expression in various peripheral organs was also detected in newborns. A 3.8-kb transcript was found at high levels in highly myelinated brain structures and sciatic nerve, and, at lower levels, in poorly myelinated peripheral organs, consistent with its occurrence in Schwann cells in the peripheral nervous system. One hundred percent of Edg-2 mRNA-containing cells in the brain also expressed mRNA encoding myelin-basic-protein, a marker of oligodendrocytes. This restricted olygodendrocytes localization was confirmed by the absence of cellular colocalization of Edg-2 and glial fibrillary acidic protein, an astrocytic marker. During prenatal development, Edg-2 mRNA expression was high in the cortical neuroepithelium and meningeal layer at E16, extended later to other neuroepithelia, and disappeared shortly after birth. During brain postnatal development, Edg-2 mRNA expression in myelinated structures followed a caudo-rostral gradient, similar to that of myelination. Thus, Edg-2 is the first G protein-coupled receptor found to be selectively expressed in myelin-forming cells in the nervous system and its temporal expression pattern is consistent with a dual role (i) in neurogenesis, during embryonic development, and (ii) in myelination and myelin maintenance, during postnatal life.
Molecular and Cellular Neuroscience, 2002
Edg-2 transcripts are not detected during early stages of oligodendroglial development, but are e... more Edg-2 transcripts are not detected during early stages of oligodendroglial development, but are expressed only in mature oligodendrocytes, shortly before the onset of myelination. Lysophosphatidic acid (LPA) has been reported to be a ligand of Edg-2 receptor in different cell types. However, in oligodendroglial cultures, LPA had no effect on survival, maturation, or cytoskeleton organization. In myelinating oligodendrocyte-neuron cocultures, LPA did not influence myelinogenesis. In addition, LPA failed to induce Ca 2؉ mobilization and had no effect on forskolininduced cAMP accumulation. Phosphorylation of the ERK1/ERK2 MAP kinases was the only response elicited by LPA in oligodendrocytes. Therefore, in contrast to other cell types, in which LPA exerts pleiotropic effects, Edg-2-positive postmitotic oligodendrocytes display a restricted responsiveness to LPA.
Glia, 1999
Edg-2 is an heptahelical receptor whose spatio-temporal distribution during rat brain development... more Edg-2 is an heptahelical receptor whose spatio-temporal distribution during rat brain development is consistent with a role in the control of myelination. We have now identified two splice variants of Edg-2 mRNA in rat brain that encode two receptor isoforms differing by a stretch of 18 amino acids in the NH2-terminal extracellular tail of the receptor. Prenatally (i.e., before oligodendrocyte myelination), the two variants detected by selective in situ hybridization are equally abundant, vary in parallel, and remain restricted to proliferative zones in the brain. Postnatally, the long isoform becomes predominant in myelinating structures, where its abundance increases sharply during the period of myelination. In the adult human brain, only the long variant was detected, while in situ hybridization showed it selectively expressed in the white matter and in clusters of cells showing features of oligodendrocytes of the temporal cerebral cortex. Consequently, the human Edg-2 gene was studied to assess its possible contribution in inherited neuropathies. The coding sequence was found to be contained in three exons and to map to chromosome 9q31.3-32 by using radiation hybrid panel and Yeast-Artificial Chromosomes. Two intragenic bi-allelic polymorphisms and a rare mutation were identified. As a first application to molecular genetic studies, they were used to exclude the Edg-2 gene in six families with phenotype of demyelinating Charcot-Marie-Tooth disease of unknown origin.
Molecular Brain Research, 1995
Three different calmodulin genes that encode the same protein have been found in the brain of all... more Three different calmodulin genes that encode the same protein have been found in the brain of all mammalian species so far examined. Little is known about the factors involved in regulating the expression of this gene family in the central nervous system. We have investigated the possibility of differential expression of two calmodulin genes, CaM I and CaM II, which are expressed strongly in neuronal cells in the adult rat brain, after treatment with the 3/ (lindane) and the ~ isomers of the hexachlorocyclohexane (HCH). In this study a decrease of CaM I mRNA (mainly in the 4.0 kb transcript) was found in the cortex of the rats after 24 h of isomer administration. CaM I expression seemed to be more sensitive to ~5 isomer action, whereas the 7 isomer acted mainly at CaM II level. The levels of mRNA of calmodulin CaM II gene were also found to decrease after lindane administration; ~-HCH produced an increase of this transcript. These results were obtained by Northern blot analysis and confirmed by means of in situ hybridization. Our results suggest that levels of neuronal calmodulin mRNA species are modified in response to changes in neuronal activity.
Progress in Neurobiology, 1999
AbstractÐCa 2+ plays a critical role in the normal function of the central nervous system. Howeve... more AbstractÐCa 2+ plays a critical role in the normal function of the central nervous system. However, it can also be involved in the development of dierent neuropathological and neurotoxicological processes. The processing of a Ca 2+ signal requires its union with speci®c intracellular proteins. Calmodulin is a major Ca 2+ -binding protein in the brain, where it modulates numerous Ca 2+ -dependent enzymes and participates in relevant cellular functions. Among the dierent calmodulin-binding proteins, the Ca 2+ / calmodulin-dependent protein kinase II and the phosphatase calcineurin are especially important in the brain because of their abundance and their participation in numerous neuronal functions. We present an overview on dierent works aimed at the study of the Ca 2+ /calmodulin signalling system in the neural response to convulsant agents.
Neuroscience Letters, 1996
The systemic administration of a non-convulsant dose of N-methyl-D-aspartate (NMDA; 75 mg/kg i.p.... more The systemic administration of a non-convulsant dose of N-methyl-D-aspartate (NMDA; 75 mg/kg i.p.), which was associated with motor activation, induced a regional c-fos mRNA expression in the mouse brain. The NMDA-induced c-fos mRNA expression was predominant in the dentate gyrus and in the medial mammillary nucleus and less pronounced in other hippocampal areas, cortical areas, bed nucleus of the stria terminalis and posterior amygdaloid nuclei. It is suggested that the hippocampus and/or the extended amygdala might be involved in the previously hypothesized dopamine-independent NMDA-mediated motor activation mechanism. No increase in c-fos mRNA expression was observed 21 h after reserpine treatment (5 mg/kg s.c.). However, reserpinization induced a significant potentiation of the NMDA-induced c-fos mRNA expression. These results show the existence of a strong and selective aminedependent modulation of NMDA neurotransmission in the brain.
International Journal of Biochemistry & Cell Biology, 2001
Calmodulin (CaM) is a major Ca 2 + -binding protein in the brain, where it plays an important rol... more Calmodulin (CaM) is a major Ca 2 + -binding protein in the brain, where it plays an important role in the neuronal response to changes in the intracellular Ca 2 + concentration. Calmodulin modulates numerous Ca 2 + -dependent enzymes and participates in relevant cellular functions. Among the different CaM-binding proteins, the Ca 2 + /CaM dependent protein kinase II and the phosphatase calcineurin are especially important in the brain because of their abundance and their participation in numerous neuronal functions. Therefore, the role of the Ca 2 + /CaM signalling system in different neurotoxicological or neuropathological conditions associated to alterations in the intracellular Ca 2 + concentration is a subject of interest. We here report different evidences showing the involvement of CaM and the CaM-binding proteins above mentioned in situations of neuronal hyperexcitability induced by convulsant agents. Signal transduction pathways mediated by specific CaM binding proteins warrant future study as potential targets in the development of new drugs to inhibit convulsant responses or to prevent or attenuate the alterations in neuronal function associated to the deleterious increases in the intracellular Ca 2 + levels described in different pathological situations.