Glutamate release evoked by glutamate receptor agonists in cultured chick retina cells: Modulation by arachidonic acid

Duarte, Cristiana; Santos, Paulo F.; Sánchez‐Prieto, José; Carvalho, Arsélio P.

doi:10.1002/(sici)1097-4547(19960515)44:4<363::aid-jnr8>3.0.co;2-a

Cited by 14 publications

(4 citation statements)

References 63 publications

(82 reference statements)

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“…This fits the finding that depletion of internal Ca 2+ stores with CPA also prevents the inhibition of GABA transport by P2Y 1 receptor activation, reinforcing the conclusion that the P2Y 1 /PLC‐induced increase in [Ca 2+ ] i is a necessary step for the P2Y 1 ‐induced negative modulation of GAT activity. A regulatory Ca 2+ ‐dependent mechanism has already been reported to act on neurotransmitter transporters (Nishio et al, ; Parpura et al, ), and to couple to some pathways, like PLA 2 (Chéramy et al, ; Cunha and Ribeiro, ; Duarte et al, ) or CaM (Gadea et al, ; Gonçalves et al, ; Llinás et al, ; Sitges et al, ). These pathways are also induced upon P2Y receptor activation in astrocytes (Bronstein et al, ; Bruner and Murphy, ; Erb et al, ).…”

Section: Discussionmentioning

confidence: 99%

P2Y₁receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes

Jacob

Vaz

Ribeiro

et al. 2014

Glia

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Astrocytes express a variety of purinergic (P2) receptors, involved in astrocytic communication through fast increases in [Ca(2+) ]i . Of these, the metabotropic ATP receptors (P2Y) regulate cytoplasmic Ca(2+) levels through the PLC-PKC pathway. GABA transporters are a substrate for a number of Ca(2+) -related kinases, raising the possibility that calcium signalling in astrocytes impact the control of extracellular levels of the major inhibitory transmitter in the brain. To access this possibility we tested the influence of P2Y receptors upon GABA transport into astrocytes. Mature primary cortical astroglial-enriched cultures expressed functional P2Y receptors, as evaluated through Ca(2+) imaging, being P2Y1 the predominant P2Y receptor subtype. ATP (100 μM, for 1 min) caused an inhibition of GABA transport through either GAT-1 or GAT-3 transporters, decreasing the Vmax kinetic constant. ATP-induced inhibition of GATs activity was still evident in the presence of adenosine deaminase, precluding an adenosine-mediated effect. This, was mimicked by a specific agonist for the P2Y1,12,13 receptor (2-MeSADP). The effect of 2-MeSADP on GABA transport was blocked by the P2 (PPADS) and P2Y1 selective (MRS2179) receptor antagonists, as well as by the PLC inhibitor (U73122). 2-MeSADP failed to inhibit GABA transport in astrocytes where intracellular calcium had been chelated (BAPTA-AM) or where calcium stores were depleted (α-cyclopiazonic acid, CPA). In conclusion, P2Y1 receptors in astrocytes inhibit GABA transport through a mechanism dependent of P2Y1 -mediated calcium signalling, suggesting that astrocytic calcium signalling, which occurs as a consequence of neuronal firing, may operate a negative feedback loop to enhance extracellular levels of GABA.

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Section: Discussionmentioning

confidence: 99%

P2Y₁receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes

Jacob

Vaz

Ribeiro

et al. 2014

Glia

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“…see Refs. [140,141]) and, accordingly, inhibition of this enzyme with p-bromophenacyl bromide prevented DNA fragmentation induced by photosensitization of mouse L5178Y lymphoma cells with AlPc [120]. Although arachidonic acid may also arise from the sequential stimulation of phospholipase C (see above) and diacylglycerol lipase [142], the role of this pathway in PDT-induced cell death has never been investigated.…”

Section: Phopholipase a 2 And Arachidonic Acid Metabolitesmentioning

confidence: 99%

Intracellular signaling mechanisms in photodynamic therapy

Almeida

Manadas

Carvalho

et al. 2004

Biochimica et Biophysica Acta (BBA) - Reviews on Cancer

242

292

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In photodynamic therapy (PDT) a sensitizer, light and oxygen are used to induce death of tumor cells and in the treatment of certain noncancerous conditions. Cell death in PDT may occur by apoptosis or by necrosis, depending on the sensitizer, on the PDT dose and on the cell genotype. Some sensitizers that have been used in PDT are accumulated in the mitochondria, and this may explain their efficiency in inducing apoptotic cell death, both in vitro and in vivo. In this review we will focus on the events that characterize apoptotic death in PDT and on the intracellular signaling events that are set in motion in photosensitized cells. Activation of phospholipases, changes in ceramide metabolism, a rise in the cytosolic free Ca 2 + concentration, stimulation of nitric oxide synthase (NOS), changes in protein phosphorylation and alterations in the activity of transcription factors and on gene expression have all been observed in PDT-treated cells. Although many of these metabolic reactions contribute to the demise process, some of them may antagonize cell death. Understanding the signaling mechanisms in PDT may provide means to modulate the PDT effects at the molecular level and potentiate its antitumor effectiveness. D

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“…Several studies have proposed that ionotropic glutamate receptors, including AMPA/kainate receptors, are important in neuron outgrowth (Cuppini et al, 1999), in the control of protein synthesis at developing synapses (Scheetz et al, 2000), neuronal plasticity on dendritic spines (Fischer et al, 2000) and glutamate neurotoxicity (Xia et al, 1995). Also, studies from our laboratory have shown the importance of glutamate receptors in modulating [Ca 2+ ] i , as well as neurotransmitter release in the chick retina cells (Duarte et al, 1996a;Duarte et al, 1996b;Duarte et al, 1998). However, the expression and activity of AMPA/kainate receptors during retina cell development was not assessed in detail.…”

Section: Introductionmentioning

confidence: 91%

Expression of AMPA/kainate receptors during development of chick embryo retina cells: in vitro versus in vivo studies

Cristóvão

Oliveira

Carvalho

2002

Intl J of Devlp Neuroscience

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The activity and the subunit expression of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/kainate ionotropic glutamate receptors were studied in retina cells developing in chick embryos and in retina cells cultured as retinospheroids, at the same stages of development. In the retinospheroids, the activity of the AMPA/kainate receptors was monitored by following the changes in the intracellular free calcium concentration ([Ca(2+)](i)), in response to AMPA, kainate or to L-glutamate, and the expression of the receptor subunits GluR1, GluR2/3, GluR4 and GluR6/7 was determined in the retinospheroids and in chick retinas by immunodetection using polyclonal antibodies. The changes in [Ca(2+)](i) in response to 400 microM kainate increased from 5h in vitro to 3 days, and remained constant until day 14, whereas the [Ca(2+)](i) in response to 500 microM L-glutamate or 400 microM AMPA increased from 5h in vitro to 3 days, and thereafter decreased slightly until day 14. The [Ca(2+)](i) responses to kainate are mainly due to AMPA receptor stimulation, since the signals were abolished by LY303070, the AMPA receptor antagonist, and were not affected by MK-801, the NMDA receptor antagonist. In retinospheroids, the levels of expression of GluR1 subunit increased from 5h in vitro until day 7, then decreased until day 14. The levels of expression of GluR2/3 and GluR4 subunits increased from 5h in vitro until day 10, and remained constant until day 14. The levels of kainate receptor subunits GluR6/7 increased from 5h in vitro until day 3, and thereafter decreased slightly until day 14. In the retinas, the expression of GluR1 and GluR6/7 subunits increased from day 8 until day 15, and then decreased until day 22 (post-natal 1). The subunits GluR2/3 and GluR4 increased from day 8 until day 18, and remained constant until day 22. The results suggest that AMPA/kainate receptors are expressed at early embryonic stages, although at low levels and before synapse formation (E12). However, the AMPA receptors are not completely functional at the first stage studied since they do not respond to the agonist AMPA. Also, the patterns of AMPA/kainate receptor subunit expression in retinospheroids of chick embryo retina cells cultured in vitro and in retina cells developing in the embryo (in vivo) were similar, indicating that the AMPA/kainate receptor subunits expression in these primary cultures mimics their expression in the developing chick retina.

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Glutamate release evoked by glutamate receptor agonists in cultured chick retina cells: Modulation by arachidonic acid

Cited by 14 publications

References 63 publications

P2Y₁receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes

P2Y₁receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes

Intracellular signaling mechanisms in photodynamic therapy

Expression of AMPA/kainate receptors during development of chick embryo retina cells: in vitro versus in vivo studies

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Glutamate release evoked by glutamate receptor agonists in cultured chick retina cells: Modulation by arachidonic acid

Cited by 14 publications

References 63 publications

P2Y1receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes

P2Y1receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes

Intracellular signaling mechanisms in photodynamic therapy

Expression of AMPA/kainate receptors during development of chick embryo retina cells: in vitro versus in vivo studies

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P2Y₁receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes

P2Y₁receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes