Diane
14-06-2008, 11:39 AM
I found a free access journal called Purinergic Signalling (http://www.springerlink.com/content/r27706254163/?p=b101f4210cb24fa5ab7910fd0b82674e&pi=0) (which I'm sure must have come about as a result of all the work Geoffrey Burnstock (http://www.somasimple.com/forums/showthread.php?t=5521) has done on this whole topic (http://www.somasimple.com/forums/showthread.php?t=5520)..)
Anyway, here is an article (from 2005) from that journal discussing changes in the ATP receptors in spinal cord microglia: ATP receptors in pain sensation: Involvement of spinal microglia and P2X4 receptors (http://www.springerlink.com/content/k8h667rwh3rt7726/fulltext.pdf) (a 6-page pdf).
It helps clarify the differences between (mere) neurogenic pain and neuropathic pain. It seems endogenous ATP (as opposed to extracellular) can be problematic in a pain scenario. Or rather an unusual expression of receptors for it.
ATP receptors in pain sensation: Involvement of spinal microglia and P2X4 receptors
Kazuhide Inoue, Makoto Tsuda & Schuichi Koizumi
Abstract
There is abundant evidence that extracellular ATP and other nucleotides have an important role in pain signaling at both the periphery and in the CNS. At first, it was thought that ATP was simply involved in acute pain, since ATP is released from damaged cells and excites directly primary sensory neurons by activating their receptors. However, neither blocking P2X/Y receptors pharmacologically nor suppressing the expression of P2X/Y receptors molecularly in sensory neurons or in the spinal cord had an effect on acute physiological pain. The focus of attention now is on the possibility that endogenous ATP and its receptor system might be activated in pathological pain states, particularly in neuropathic pain. Neuropathic pain is often a consequence of nerve injury through surgery, bone compression, diabetes or infection. This type of pain can be so severe that even light touching can be intensely painful; unfortunately, this state is generally resistant to currently available treatments. An important advance in our understanding of the mechanisms involved in neuropathic pain has been made by a recent work demonstrating the crucial role of ATP receptors (i.e., P2X3 and P2X4 receptors). In this review, we summarize the role of ATP receptors, particularly the P2X4 receptor, in neuropathic pain. The expression of P2X4 receptors in the spinal cord is enhanced in spinal microglia after peripheral nerve injury, and blocking pharmacologically and suppressing molecularly P2X4 receptors produce a reduction of the neuropathic pain behaviour. Understanding the key roles of ATP receptors including P2X4 receptors may lead to new strategies for the management of neuropathic pain.
Anyway, here is an article (from 2005) from that journal discussing changes in the ATP receptors in spinal cord microglia: ATP receptors in pain sensation: Involvement of spinal microglia and P2X4 receptors (http://www.springerlink.com/content/k8h667rwh3rt7726/fulltext.pdf) (a 6-page pdf).
It helps clarify the differences between (mere) neurogenic pain and neuropathic pain. It seems endogenous ATP (as opposed to extracellular) can be problematic in a pain scenario. Or rather an unusual expression of receptors for it.
ATP receptors in pain sensation: Involvement of spinal microglia and P2X4 receptors
Kazuhide Inoue, Makoto Tsuda & Schuichi Koizumi
Abstract
There is abundant evidence that extracellular ATP and other nucleotides have an important role in pain signaling at both the periphery and in the CNS. At first, it was thought that ATP was simply involved in acute pain, since ATP is released from damaged cells and excites directly primary sensory neurons by activating their receptors. However, neither blocking P2X/Y receptors pharmacologically nor suppressing the expression of P2X/Y receptors molecularly in sensory neurons or in the spinal cord had an effect on acute physiological pain. The focus of attention now is on the possibility that endogenous ATP and its receptor system might be activated in pathological pain states, particularly in neuropathic pain. Neuropathic pain is often a consequence of nerve injury through surgery, bone compression, diabetes or infection. This type of pain can be so severe that even light touching can be intensely painful; unfortunately, this state is generally resistant to currently available treatments. An important advance in our understanding of the mechanisms involved in neuropathic pain has been made by a recent work demonstrating the crucial role of ATP receptors (i.e., P2X3 and P2X4 receptors). In this review, we summarize the role of ATP receptors, particularly the P2X4 receptor, in neuropathic pain. The expression of P2X4 receptors in the spinal cord is enhanced in spinal microglia after peripheral nerve injury, and blocking pharmacologically and suppressing molecularly P2X4 receptors produce a reduction of the neuropathic pain behaviour. Understanding the key roles of ATP receptors including P2X4 receptors may lead to new strategies for the management of neuropathic pain.