The role of spinal P2X receptors in different pain states
| Type of pain | P2X Receptor Agonist or Antagonist (i.t. Application) | Model, Species | Response (Modulation or Induction) | Blockade by Antagonist (i.t. Application) | Reference | |
|---|---|---|---|---|---|---|
| Acute pain | Agonists | α,β-meATP, 2-methylthio ATP | Tail-flick model, rat | Withdrawal latency (↓) | Suramin, Evans blue | Driessen et al., 1994 |
| α,β-meATP | Thermal nociceptive threshold testing, mouse | Withdrawal threshold (↓) and thermal hyperalgesia | PPADS, TNP-ATP or desensitization by pretreatment with α,β-meATP | Tsuda et al., 1999b | ||
| β,γ-meATP, but not α,β-meATP | Electrophysiological recordings in anesthetized rat | C-fiber-evoked responses of spinal dorsal horn neurons (↑) | Stanfa et al., 2000 | |||
| Antagonists or desensitizing agonists | Suramin, Evans blue, reactive blue, trypan blue, but not PPADS | Tail-flick model, rat | Withdrawal latency (↑) | Driessen et al., 1994 | ||
| Reactive red 2 | Electrophysiological recordings in anesthetized rat | C-fiber-evoked activity of thalamic neurons (↓) | Driessen et al., 1998 | |||
| PPADS | Tail-flick and hot-plate tests, rat | Withdrawal latency (N.E.) | Li et al., 1998 | |||
| PPADS, TNP-ATP or desensitization by pretreatment with α,β-meATP | Capsaicin and formalin tests, mouse | Capsaicin- and formalin- (early phase) induced nociception (↓) | Tsuda et al., 1999a | |||
| Suramin, PPADS | Electrophysiological recordings in anesthetized rat | C-fiber-evoked responses of spinal dorsal horn neurons (N.E.) | Stanfa et al., 2000 | |||
| Inflammatory pain | Antagonists or desensitizing agonists | Desensitization by pretreatment with α,β-meATP | Formalin test, rat | Nociceptive behavior (N.E.) | Driessen et al., 1994 | |
| Suramin | Formalin test, rat | Nociceptive behavior (↓) | Driessen et al., 1994 | |||
| PPADS, but not TNP-ATP | Formalin test, mouse | Late phase of nociceptive behavior (↓) | Tsuda et al., 1999a | |||
| Suramin, PPADS | Electrophysiological recordings in anesthetized rats with carrageenan-induced paw inflammation | C-fiber-evoked responses of spinal dorsal horn neurons (↓) | Stanfa et al., 2000 | |||
| Neuropathic pain | Antagonists | PPADS | Thermal nociceptive threshold testing in rats with PCI | Thermal hyperalgesia in animals (N.E.) | Liu and Tracey, 2000 | |
| Suramin, PPADS | Electrophysiological recordings in anesthetized rats with SNL | C-fiber-evoked responses of spinal dorsal horn neurons (N.E.) | Stanfa et al., 2000 | |||
i.t., intrathecal; PCI, partial constriction injury of the sciatic nerve; SNL, lumbar 5/6 spinal nerve ligation; ↑, potentiation or induction; ↓, inhibition; N.E., no effect.