Inhibition of N-type voltage-activated calcium channels in rat dorsal root ganglion neurons by P2Y receptors is a possible mechanism of ADP-induced analgesia
Inhibition of N-type voltage-activated calcium channels in rat dorsal root ganglion neurons by P2Y receptors is a possible mechanism of ADP-induced analgesia
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DOI：
10.1523/jneurosci.4019-03.2004
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发表时间：
2004-01-28
影响因子：
5.3
通讯作者：
Illes, P
中科院分区：
文献类型：
--
作者：
Gerevich, Z;Borvendeg, SJ;Illes, P
膜片钳记录从小直径大鼠背根神经节（DRG）的神经元保持在文化表现出优先抑制ATP的高电压激活，但不是低电压激活，钙电流（I-Ca）。激动剂作用大小顺序为UTP > ADP > ATP。ATP仅抑制ω-芋螺毒素GVIA敏感的N型电流。P2 Y（1）受体拮抗剂吡哆醛-5-磷酸-6-偶氮苯-2 '，4'-二磺酸（PPADS）和2 '-脱氧-N-6-甲基腺苷-3'，5 '-二磷酸四铵（2'-deoxy-N-6-methyladenosine 3 '，5'-bisphosphate tetramammonium）几乎可消除ATP对细胞的抑制作用。膜片钳记录和免疫细胞化学结合激光共聚焦显微镜都表明功能性P2 X（3）和P2 Y（1）受体在同一DRG神经元上共定位。由于ATP的作用被细胞内鸟苷5 '-O-（2-硫代二磷酸）或施加强去极化预脉冲所抑制，P2 Y（1）受体似乎通过涉及G（q/11）蛋白β-亚基的途径阻断I-Ca。通过减少移液管内EGTA对细胞内Ca 2+浓度（[Ca 2 +]（i））的缓冲效率较低，但未能干扰ATP效应。Fura-2显微荧光分析表明，ATP通过Gal-α介导的胞内钙释放而升高[Ca ~（2+）]（i），同时通过Gbetagamma抑制I-Ca而抑制高钾诱导的[Ca ~（2+）]（i）升高。腺苷5 '-O-（2-硫代二磷酸）抑制背根诱发的多突触群体EPSPs在半横断大鼠脊髓和延长伤害性阈值鞘内应用在甩尾试验。PPADS不能拮抗这些作用。因此，P2 Y受体激活ADP，这是由ATP的酶降解产生的，可能会减少释放谷氨酸从DRG终末在脊髓，从而部分抵消了ATP的致痛作用。
Patch-clamp recordings from small-diameter rat dorsal root ganglion (DRG) neurons maintained in culture demonstrated preferential inhibition by ATP of high-voltage-activated, but not low-voltage-activated, Ca2+ currents (I-Ca). The rank order of agonist potency was UTP > ADP > ATP. ATP depressed the omega-conotoxin GVIA-sensitive N-type current only. Pyridoxal-5-phosphate-6-azophenyl-2', 4'-disulphonic acid (PPADS) and 2'-deoxy-N-6-methyladenosine 3', 5'-bisphosphate tetraammonium, two P2Y(1) receptor antagonists, almost abolished the ATP-induced inhibition. Both patch-clamp recordings and immunocytochemistry coupled with confocal laser microscopy indicated a colocalization of functional P2X(3) and P2Y(1) receptors on the same DRG neurons. Because the effect of ATP was inhibited by intracellular guanosine 5'-O-(2-thiodiphosphate) or by applying a strongly depolarizing prepulse, P2Y(1) receptors appear to block I-Ca by a pathway involving the betagamma subunit of a G(q/11) protein. Less efficient buffering of the intracellular Ca2+ concentration ([Ca2+](i)) by reducing the intrapipette EGTA failed to interfere with the ATP effect. Fura-2 microfluorimetry suggested that ATP raised [Ca2+](i) by a Galpha-mediated release from intracellular pools and simultaneously depressed the high external potassium concentration-induced increase of [Ca2+](i) by inhibiting I-Ca via Gbetagamma. Adenosine 5'-O-(2-thiodiphosphate) inhibited dorsal root-evoked polysynaptic population EPSPs in the hemisected rat spinal cord and prolonged the nociceptive threshold on intrathecal application in the tail-flick assay. These effects were not antagonized by PPADS. Hence, P2Y receptor activation by ADP, which is generated by enzymatic degradation of ATP, may decrease the release of glutamate from DRG terminals in the spinal cord and thereby partly counterbalance the algogenic effect of ATP.