What is the contribution of the NMDA receptor to the production of pain? Glutamate that is released from primary afferent fibers acts upon two major receptor types in the dorsal horn: the AMPA and the NMDA receptors. Under normal conditions, the NMDA receptor is blocked by the presence of a magnesium ion in the channel. …
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primary and secondary hyperalgesia Primary hyperalgesia refers to the sensitization process that enhances “pain” transmission via a peripheral mechanism. For example, in the setting of inflammation, there is synthesis of arachidonic acid, which is acted upon to produce prostaglandins. These lipid mediators in turn act on the terminals of primary afferent nociceptors and lower their …
How are substance P and calcitonin gene-related peptide implicated in the phenomenon of neurogenic inflammation? Cell bodies in the dorsal root ganglion synthesize substance P and CGRP and transport these peptides by axoplasmic transport both to the central and peripheral terminals of the primary afferents. The peptides are stored in the periphery and can be …
What is neurogenic inflammation? Neurogenic inflammation refers to the inflammation that is produced by the peripheral release of substances from the nervous system—in particular, from small-diameter primary afferent fibers. Although most studies emphasize the contribution of the primary afferent C fibers, there is also evidence for a contribution of sympathetic postganglionic terminals. The primary afferents …
Phenomenon of referred pain A very likely explanation for the phenomenon of referred pain relates to the convergence of visceral and somatic afferent input to wide dynamic range neurons of lamina V. As a result of the convergence, injury-induce increased activity of visceral afferent nociceptors is interpreted by the brain as having arisen from the …
How is the spinal cord influenced by peripheral nerve injury? Peripheral nerve injury was originally thought to only functionally disconnect the periphery from the spinal cord. Because the dorsal root ganglion is not injured when the peripheral nerve is damaged, neither anatomical nor biochemical changes in the proximal limb of the dorsal root or in …
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What is substance P saporin, and how might it be used to treat chronic pain? When substance P is released from primary afferent nociceptors, it binds to the neurokinin-1 (NK1) receptor that is located on large numbers of “pain” transmission neurons, many of which are located in lamina I of the superficial dorsal horn. Although …