ATP acting on P 2Y receptors triggers calcium mobilization in primary cultures of rat neurohypophysial astrocytes (pituicytes)

Troadec, Jean‐Denis; Thirion, Sylvie; Petturiti, Daniel; Bohn, M. T.; Poujeol, Philippe

doi:10.1007/s004240050841

Cited by 39 publications

(36 citation statements)

References 49 publications

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“…duction is mediated by phospholipase C activated after P2Y 1 receptor activation (Troadec et al, 1999). However, in the CA3 interneurons, U-73122, an inhibitor of phospholipase C, did not significantly affect the IPSC frequency increase by 2meSATP at a larger concentration (10 M) than that completely abolishes [Ca 2ϩ ] i changes in the astrocytes (0.5-1 M) (Idestrup and Salter, 1998;Troadec et al, 1999;Koizumi et al, 2002).…”

Section: Activation Of P2y 1 Receptors Activates Inward Currents In Imentioning

confidence: 87%

“…However, in the CA3 interneurons, U-73122, an inhibitor of phospholipase C, did not significantly affect the IPSC frequency increase by 2meSATP at a larger concentration (10 M) than that completely abolishes [Ca 2ϩ ] i changes in the astrocytes (0.5-1 M) (Idestrup and Salter, 1998;Troadec et al, 1999;Koizumi et al, 2002). In the absence and presence of U-73122, IPSC frequency increased from 3.0 Ϯ 1.3 to 8.1 Ϯ 0.7 Hz and from 2.8 Ϯ 1.3 to 8.5 Ϯ 0.9 Hz, respectively (n ϭ 4; p ϭ 0.72), suggesting that increase in IPSC frequency does not involve phospholipase pathways, in a similar manner to that reported for recombinant P2Y 1 receptors expressed in the oocytes, which is linked to unidentified cation conductance (O'Grady et al, 1996).…”

Section: Activation Of P2y 1 Receptors Activates Inward Currents In Imentioning

confidence: 96%

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Direct Excitation of Inhibitory Interneurons by Extracellular ATP Mediated by P2Y₁Receptors in the Hippocampal Slice

Kawamura¹,

Gachet²,

Inoue³

et al. 2004

J. Neurosci.

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ATP is an important cell-to-cell signaling molecule mediating the interactions between astrocytes and neurons in the CNS. In the hippocampal slices, ATP suppresses excitatory transmission mostly through activation of adenosine A 1 receptors, because the ectoenzyme activity for the extracellular breakdown of ATP to adenosine is high in slice preparations in contrast to culture environments. Because the hippocampus is also rich in the expression of P2 receptors activated specifically by ATP, we examined whether ATP modulates neuronal excitability in the acute slice preparations independently of adenosine receptors. Although ATP decreased the frequency of spontaneously occurring EPSCs in the CA3 pyramidal neurons through activation of adenosine A 1 receptors, ATP concurrently increased the frequency of IPSCs in a manner dependent on action potential generation. This effect was mediated by P2Y 1 receptors because (1) 2-methylthio-ATP (2meSATP) was the most potent agonist, (2) 2Ј-deoxy-N 6 -methyladenosine-3Ј,5Ј-bisphosphate diammonium (MRS2179) abolished this effect, and (3) this increase in IPSC frequency was not observed in the transgenic mice lacking P2Y 1 receptor proteins. Application of 2meSATP elicited MRS2179-sensitive time-and voltage-dependent inward currents in the interneurons, which depolarized the cell to firing threshold. Also, it increased [Ca 2ϩ ] i in both astrocytes and interneurons, but, unlike the former effect, the latter was entirely dependent on Ca 2ϩ entry. Thus, in hippocampal slices, in addition to activating A 1 receptors of the excitatory terminals after being converted to adenosine, ATP activates P2Y 1 receptors in the interneurons, which is linked to activation of unidentified excitatory conductance, through mechanisms distinct from those in the astrocytes.

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Section: Activation Of P2y 1 Receptors Activates Inward Currents In Imentioning

confidence: 87%

Section: Activation Of P2y 1 Receptors Activates Inward Currents In Imentioning

confidence: 96%

Direct Excitation of Inhibitory Interneurons by Extracellular ATP Mediated by P2Y₁Receptors in the Hippocampal Slice

Kawamura¹,

Gachet²,

Inoue³

et al. 2004

J. Neurosci.

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“…Cell culture Pituicytes cell cultures were prepared from adult male Wistar rats (150-200 g) and maintained in primary cultures as previously described by Hatton et al [12] and modified by Troadec et al [39]. Briefly, rats were asphyxiated by CO 2 and killed by decapitation with a guillotine following the guidelines laid down by the French/European ethics committee.…”

Section: Methodsmentioning

confidence: 99%

“…The neurohypophysial astrocytes, called pituicytes, are intimately associated with nerve terminals, and we have recently shown that in these cells extracellular ATP induces an increase in the concentration of free cytosolic calcium ([Ca 2+ ] i ) via a P 2Y purinoceptor [39]. The physiological significance of this ATP-induced [Ca 2+ ] i increase in cultured pituicytes remains largely unknown.…”

Section: Introductionmentioning

confidence: 98%

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Potassium efflux triggered by P2Y purinoceptor activation in cultured pituicytes

Troadec

Thirion

Petturiti

et al. 2000

Pflugers Arch - Eur J Physiol

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We have previously investigated the effects of extracellular ATP on the concentration of free cytosolic calcium ([Ca2+]i) from rat cultured neurohypophysial astrocytes (pituicytes). We demonstrated that ATP acts via a P2Y receptor to increase [Ca2+]i. In the present study, we examine the effect of ATP on K+ efflux using 86Rb+ as an isotopic tracer, in order to characterize the possible presence of a Ca2+-activated K+ conductance and to establish the implications of pituicytes in the regulation of stimulus-secretion coupling. ATP evoked an increase in 86Rb+ efflux from cultured pituicytes. This effect was Ca2+ dependent, as indicated by the unresponsiveness of cells loaded with BAPTA/AM (20 microM). Furthermore, the effect of ATP was mimicked by 2-methylthio-adenosine-5'-triphosphate (2MeSATP), a P2 purinoceptor agonist, and abolished by Reactive Blue 2 (RB-2), a selective P2Y antagonist, implying a role for the P2Y purinoreceptor. A pharmacological study revealed that Ba2+ and tetraethylammonium (TEA), two inhibitors of K+ channels, both strongly reduced the ATP-stimulated 86Rb+ efflux. In addition, the effect of ATP was modulated by different peptidic toxins. Apamin (100 nM), an inhibitor of the small-conductance Ca2+-activated K+ channels, partly blocked ATP-induced 86Rb+ efflux. Leiurus quinquestriatus hebraeus (LQH) scorpion venom (20 microg/ml) and Buthus tamulus (BT) scorpion venom (20-200 microg/ml) inhibited ATP-induced 86Rb+ efflux. The specificity of the effects of the crude venoms was checked using charybdotoxin (100 nM) and iberiotoxin (1 pM), which are the active toxins extracted from the LQH and BT venoms, respectively. These data indicate the involvement of several types of Ca2+-activated K+ channels in the ATP-dependent K+ efflux, and lead to the proposal that, in the neurohypophysis, extracellular ATP released by nerve terminals may act directly on the pituicytes and induce a K+ efflux via a P2Y purinoreceptor.

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DMACM‐Caged Adenosine Nucleotides: Ultrafast Phototriggers for ATP, ADP, and AMP Activated by Long‐Wavelength Irradiation

Geißler¹,

Kresse²,

Wiesner³

et al. 2003

ChemBioChem

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The development of new photocleavable adenosine nucleotides based on the photochemistry of [7-(dimethylamino)coumarin-4-yl]methyl (DMACM) esters is described. The phototriggers liberate adenosine triphosphate (ATP), diphosphate, and monophosphate upon UV/Vis irradiation between 334 and 405 nm. The efficiency of photocleavage at long wavelengths is high as a result of a combination of appropriate quantum yields and intensive absorptivities. By using time-resolved fluorescence spectroscopy, we determined a lower limit of 1.6 x 10(9) s(-1) for the rate constant of the release of ATP from DMACM-caged ATP. The favorable properties of DMACM-caged ATP were confirmed in physiological studies by confocal laser scanning microscopy. We were able to uncage DMACM-caged ATP in cultures of mouse astrocytes and in brain tissue slices from mice and were also able to measure the effect of photoreleased ATP on the cellular response of astrocytes, namely the ability of the ATP to evoke Ca(2+) ion waves.

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ATP acting on P 2Y receptors triggers calcium mobilization in primary cultures of rat neurohypophysial astrocytes (pituicytes)

Cited by 39 publications

References 49 publications

Direct Excitation of Inhibitory Interneurons by Extracellular ATP Mediated by P2Y₁Receptors in the Hippocampal Slice

Direct Excitation of Inhibitory Interneurons by Extracellular ATP Mediated by P2Y₁Receptors in the Hippocampal Slice

Potassium efflux triggered by P2Y purinoceptor activation in cultured pituicytes

DMACM‐Caged Adenosine Nucleotides: Ultrafast Phototriggers for ATP, ADP, and AMP Activated by Long‐Wavelength Irradiation

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ATP acting on P 2Y receptors triggers calcium mobilization in primary cultures of rat neurohypophysial astrocytes (pituicytes)

Cited by 39 publications

References 49 publications

Direct Excitation of Inhibitory Interneurons by Extracellular ATP Mediated by P2Y1Receptors in the Hippocampal Slice

Direct Excitation of Inhibitory Interneurons by Extracellular ATP Mediated by P2Y1Receptors in the Hippocampal Slice

Potassium efflux triggered by P2Y purinoceptor activation in cultured pituicytes

DMACM‐Caged Adenosine Nucleotides: Ultrafast Phototriggers for ATP, ADP, and AMP Activated by Long‐Wavelength Irradiation

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Direct Excitation of Inhibitory Interneurons by Extracellular ATP Mediated by P2Y₁Receptors in the Hippocampal Slice

Direct Excitation of Inhibitory Interneurons by Extracellular ATP Mediated by P2Y₁Receptors in the Hippocampal Slice