Role of wdr neurons in a hind limb noxious heat evoked flexion withdrawal reflex

Nishioka, Kengo; Harada, Yoshinori; Kitahata, Luke M.; Tsukahara, Sumio; Collins, J. G.

doi:10.1016/0024-3205(94)00477-a

Cited by 10 publications

(3 citation statements)

References 14 publications

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“…lamina V) [60], the actual perception of heat and pressure pain intensity may depend more on afferent activity reaching nociceptive specific (NS) neurons in lamina I [61]. Lamina I neurons are known to project to areas of the insular cortex [62], an important interoceptive area, the functioning of which, in turn, has been demonstrated to be directly affected by SSRIs [63].…”

Section: Discussionmentioning

confidence: 99%

Conditioned Pain Modulation Is Associated with Common Polymorphisms in the Serotonin Transporter Gene

et al. 2011

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BackgroundVariation in the serotonin transporter (5-HTT) gene (SLC6A4) has been shown to influence a wide range of affective processes. Low 5-HTT gene-expression has also been suggested to increase the risk of chronic pain. Conditioned pain modulation (CPM) - i.e. ‘pain inhibits pain’ - is impaired in chronic pain states and, reciprocally, aberrations of CPM may predict the development of chronic pain. Therefore we hypothesized that a common variation in the SLC6A4 is associated with inter-individual variation in CPM. Forty-five healthy subjects recruited on the basis of tri-allelic 5-HTTLPR genotype, with inferred high or low 5-HTT-expression, were included in a double-blind study. A submaximal-effort tourniquet test was used to provide a standardized degree of conditioning ischemic pain. Individualized noxious heat and pressure pain thresholds (PPTs) were used as subjective test-modalities and the nociceptive flexion reflex (NFR) was used to provide an objective neurophysiological window into spinal processing.ResultsThe low, as compared to the high, 5-HTT-expressing group exhibited significantly reduced CPM-mediated pain inhibition for PPTs (p = 0.02) and heat-pain (p = 0.02). The CPM-mediated inhibition of the NFR, gauged by increases in NFR-threshold, did not differ significantly between groups (p = 0.75). Inhibition of PPTs and heat-pain were correlated (Spearman’s rho = 0.35, p = 0.02), whereas the NFR-threshold increase was not significantly correlated with degree of inhibition of these subjectively reported modalities.ConclusionsOur results demonstrate the involvement of the tri-allelic 5-HTTLPR genotype in explaining clinically relevant inter-individual differences in pain perception and regulation. Our results also illustrate that shifts in NFR-thresholds do not necessarily correlate to the modulation of experienced pain. We discuss various possible mechanisms underlying these findings and suggest a role of regulation of 5-HT receptors along the neuraxis as a function of differential 5-HTT-expression.

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Section: Discussionmentioning

confidence: 99%

Conditioned Pain Modulation Is Associated with Common Polymorphisms in the Serotonin Transporter Gene

et al. 2011

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“…The neurons defined wide dynamic range (WDR) neurons seem to be particularly important in mediating the FR and have been shown to be involved in its generation in animals (Nishioka et al, 1995;Schouenborg and Dickenson, 1985;Schouenborg and Kallioma ¨ki, 1990;You et al, 2003;Li and Chen, 2004). These multireceptive neurons, located in lamina Vof the dorsal horn of the spinal cord, are activated by a variety of noxious and innocuous stimuli (Craig, 2003).…”

Section: Spinal Neurons and Interneuronsmentioning

confidence: 99%

The lower limb flexion reflex in humans

Sandrini

Serrao²,

Rossi³

et al. 2005

Progress in Neurobiology

450

422

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“…The flexion reflex (FR) is an objective tool that has already provided information on the human nociceptive pathways (Sandrini et al, 1993a,b). In humans, the FR, a withdrawal reflex, is mediated by a complex network of interneurons at spinal level (Shahani and Young, 1971;Jankowska, 1992;Burke, 1999;Jankowska, 2001), including the wide dynamic range neurons (WDR), and multireceptive neurons located in lamina V of the dorsal horn of the spinal cord (Schouenborg and Dickenson, 1985;Schouenborg and Kalliomaki, 1990;Nishioka et al, 1995;You et al, 2003). The FR consists of an early response, the RII reflex, and a late response, the RIII reflex.…”

Section: Introductionmentioning

confidence: 99%

Cannabinoid‐induced effects on the nociceptive system: A neurophysiological study in patients with secondary progressive multiple sclerosis

Conte

Bettolo

Onesti

et al. 2009

European Journal of Pain

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Although clinical studies show that cannabinoids improve central pain in patients with multiple sclerosis (MS) neurophysiological studies are lacking to investigate whether they also suppress these patients' electrophysiological responses to noxious stimulation. The flexion reflex (FR) in humans is a widely used technique for assessing the pain threshold and for studying spinal and supraspinal pain pathways and the neurotransmitter system involved in pain control. In a randomized, double-blind, placebo-controlled, cross-over study we investigated cannabinoid-induced changes in RIII reflex variables (threshold, latency and area) in a group of 18 patients with secondary progressive MS. To investigate whether cannabinoids act indirectly on the nociceptive reflex by modulating lower motoneuron excitability we also evaluated the H-reflex size after tibial nerve stimulation and calculated the H wave/M wave (H/M) ratio. Of the 18 patients recruited and randomized 17 completed the study. After patients used a commercial delta-9-tetrahydrocannabinol (THC) and cannabidiol mixture as an oromucosal spray the RIII reflex threshold increased and RIII reflex area decreased. The visual analogue scale score for pain also decreased, though not significantly. Conversely, the H/M ratio measured before patients received cannabinoids remained unchanged after therapy. In conclusion, the cannabinoid-induced changes in the RIII reflex threshold and area in patients with MS provide objective neurophysiological evidence that cannabinoids modulate the nociceptive system in patients with MS.

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Role of wdr neurons in a hind limb noxious heat evoked flexion withdrawal reflex

Cited by 10 publications

References 14 publications

Conditioned Pain Modulation Is Associated with Common Polymorphisms in the Serotonin Transporter Gene

Conditioned Pain Modulation Is Associated with Common Polymorphisms in the Serotonin Transporter Gene

The lower limb flexion reflex in humans

Cannabinoid‐induced effects on the nociceptive system: A neurophysiological study in patients with secondary progressive multiple sclerosis

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