Nociceptive Processing

2019 ◽  
pp. 26-40
Author(s):  
Cynthia L. Renn ◽  
Susan G. Dorsey
Keyword(s):  
Peripheral Nerve ◽  
Spinal Dorsal Horn ◽  
Inhibitory Interneurons ◽  
Molecular Signaling ◽  
Nucleus Raphe Magnus ◽  
Spinal Dorsal ◽  
Molecular Events ◽  
Pain Pathways ◽  
Raphe Magnus ◽  
Nociceptive Processing

Chapter 2 describes the molecular events associated with pain signaling. The mechanisms associated with chemical, thermal, and mechanical pain signaling in the peripheral nerve endings are detailed. Molecular signaling mechanisms occurring in the spinal dorsal horn, including the primary afferent nociceptor, the inhibitory interneurons, and the descending on-cells and off-cells projecting from the nucleus raphe magnocellularis are described. Persistent increases in pain signaling resulting from inflammatory mediators are explained with reference to specific molecules. Signaling events at supraspinal levels, such as the thalamus, cortex, periaqueductal gray, and nucleus raphe magnus, including cannabinoids, opioids, and noradrenergic and serotonergic neurotransmitter events, are described as critical to pain pathways with relevance to potential pain therapies.

19. A comparison of visceral and noxious somatic influences on neurons in rat nucleus raphe magnus

1985 ◽  
Vol 308 (1136) ◽  
pp. 425-425
Keyword(s):  
Urinary Bladder ◽  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Diffuse Noxious Inhibitory Controls ◽  
Nucleus Raphe Magnus ◽  
Spinal Dorsal ◽  
Raphe Magnus ◽  
Noxious Stimuli

The activities of certain neurons in the spinal dorsal horn can be depressed by widespread noxious stimuli (Le Bars et al. 1979), A phenomenon usually referred to as ‘diffuse noxious inhibitory controls’ (d.n.i.c.). Similar effects have been demonstrated following distension of the urinary bladder or colon (Cadden, this meeting). D.n.i.c. are thought to be mediated by a pathway which relays in the medullary nucleus raphe magnus (n.r.m.) (Dickenson et al. 1980). The aims of the present study were to determine whether neurons in n.r.m. could be influenced by visceral and somatic stimuli that produce d.n.i.c., and whether any such neurons have spinally projecting axons.

scholarly journals Prior perineural or neonatal treatment with capsaicin does not alter the development of spinal microgliosis induced by peripheral nerve injury

2020 ◽  
Author(s):  
Ivett Dorina Szeredi ◽  
Gábor Jancsó ◽  
Orsolya Oszlács ◽  
Péter Sántha
Keyword(s):  
Peripheral Nerve ◽  
Dorsal Horn ◽  
Nerve Injury ◽  
Peripheral Nerve Injury ◽  
Spinal Dorsal Horn ◽  
Primary Afferents ◽  
Primary Afferent ◽  
Spinal Dorsal ◽  
C Fiber ◽  
Spinal Afferents

Abstract Peripheral nerve injury is associated with spinal microgliosis which plays a pivotal role in the development of neuropathic pain behavior. Several agents of primary afferent origin causing the microglial reaction have been identified, but the type(s) of primary afferents that release these mediators are still unclear. In this study, specific labeling of C-fiber spinal afferents by lectin histochemistry and selective chemodenervation by capsaicin were applied to identify the type(s) of primary afferents involved in the microglial response. Comparative quantitative morphometric evaluation of the microglial reaction in central projection territories of intact and injured peripheral nerves in the superficial (laminae I and II) and deep (laminae III and IV) spinal dorsal horn revealed a significant, about three-fold increase in microglial density after transection of the sciatic or the saphenous nerve. Prior perineural treatment of these nerves with capsaicin, resulting in a selective defunctionalization of C-fiber afferent fibers failed to affect spinal microgliosis. Similarly, peripheral nerve injury-induced increase in microglial density was unaffected in rats treated neonatally with capsaicin known to result in a near-total loss of C-fiber dorsal root fibers. Perineural treatment with capsaicin per se did not evoke a significant increase in microglial density. These observations indicate that injury-induced spinal microgliosis may be attributed to phenotypic changes in injured myelinated primary afferent neurons, whereas the contribution of C-fiber primary sensory neurons to this neuroimmune response is negligible. Spinal myelinated primary afferents may play a hitherto unrecognized role in regulation of neuroimmune and perisynaptic microenvironments of the spinal dorsal horn.

scholarly journals Kappa opioid receptors in the central amygdala modulate spinal nociceptive processing through an action on amygdala CRF neurons

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Guangchen Ji ◽  
Volker Neugebauer
Keyword(s):  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Facilitatory Effect ◽  
Functional Coupling ◽  
Kappa Opioid ◽  
Positive Direction ◽  
Dorsal Horn Neurons ◽  
Spinal Dorsal ◽  
Nociceptive Processing ◽  
Spinal Dorsal Horn Neurons

Abstract The amygdala plays an important role in the emotional-affective aspects of behaviors and pain, but can also modulate sensory aspect of pain (“nociception”), likely through coupling to descending modulatory systems. Here we explored the functional coupling of the amygdala to spinal nociception. We found that pharmacological activation of neurons in the central nucleus of the amygdala (CeA) increased the activity of spinal dorsal horn neurons; and this effect was blocked by optogenetic silencing of corticotropin releasing factor (CRF) positive CeA neurons. A kappa opioid receptor (KOR) agonist (U-69,593) was administered into the CeA by microdialysis. KOR was targeted because of their role in averse-affective behaviors through actions in limbic brain regions. Extracellular single-unit recordings were made of CeA neurons or spinal dorsal horn neurons in anesthetized transgenic Crh-Cre rats. Neurons responded more strongly to noxious than innocuous stimuli. U-69,593 increased the responses of CeA and spinal neurons to innocuous and noxious mechanical stimulation of peripheral tissues. The facilitatory effect of the agonist was blocked by optical silencing of CRF-CeA neurons though light activation of halorhodopsin expressed in these neurons by viral-vector. The CRF system in the amygdala has been implicated in aversiveness and pain modulation. The results suggest that the amygdala can modulate spinal nociceptive processing in a positive direction through CRF-CeA neurons and that KOR activation in the amygdala (CeA) has pro-nociceptive effects.

Convergent Nociceptive Input to Spinal Dorsal Horn Neurons After Peripheral Nerve Injury

2014 ◽  
Vol 40 (3) ◽  
pp. 438-445 ◽  
Author(s):  
Ryuji Terayama ◽  
Noriko Kishimoto ◽  
Yuya Yamamoto ◽  
Kotaro Maruhama ◽  
Hiroki Tsuchiya ◽  
...  
Keyword(s):  
Peripheral Nerve ◽  
Dorsal Horn ◽  
Nerve Injury ◽  
Peripheral Nerve Injury ◽  
Spinal Dorsal Horn ◽  
Dorsal Horn Neurons ◽  
Spinal Dorsal ◽  
Spinal Dorsal Horn Neurons ◽  
Nociceptive Input
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