Neural Mechanisms of Hyperalgesia: Peripheral or Central Sensitization?

Physiology ◽  
1995 ◽  
Vol 10 (6) ◽  
pp. 260-265
Author(s):  
E Carstens
Keyword(s):  
Spinal Cord ◽  
Central Sensitization ◽  
Pain Sensitivity ◽  
Neural Mechanisms ◽  
Neural Processes

Everyone has experienced soreness after an injury. What neural processes underlie this increased pain sensitivity (hyperalgesia)? Recent data indicate that injury triggers an increase in the sensitivity of spinal cord pain-signaling neurons. Nonpainful activation of these sensitized neurons evokes an exaggerated signal interpreted as pain.

scholarly journals Plasmodium berghei-induced malaria decreases pain sensitivity in mice

2021 ◽  
Vol 88 (1) ◽  
Author(s):  
Aboyeji L. Oyewole ◽  
Oluwole Akinola ◽  
Bamidele V. Owoyele
Keyword(s):  
Plasmodium Berghei ◽  
Pain Sensitivity ◽  
Morphological Changes ◽  
Processing System ◽  
Anterior Cingulate ◽  
Immunopositive Cell ◽  
Intact Group ◽  
Malarial Infection ◽  
Swiss Mice ◽  
Neural Processes

Various types of pain were reported by people with Plasmodium falciparum and were mostly attributed to a symptom of malarial infection. Neural processes of pain sensation during malarial infection and their contributions to malaria-related death are poorly understood. Thus, these form the focus of this study. Swiss mice used for this study were randomly divided into two groups. Animals in the first group (Pb-infected group) were inoculated with Plasmodium berghei to induce malaria whilst the other group (intact group) was not infected. Formalin test was used to assess pain sensitivity in both groups and using various antagonists, the possible mechanism for deviation in pain sensitivity was probed. Also, plasma and brain samples collected from animals in both groups were subjected to biochemical and/or histological studies. The results showed that Pb-infected mice exhibited diminished pain-related behaviours to noxious chemical. The observed parasite-induced analgesia appeared to be synergistically mediated via µ-opioid, α2 and 5HT2A receptors. When varied drugs capable of decreasing pain threshold (pro-nociceptive drugs) were used, the survival rate was not significantly different in the Pb-infected mice. This showed little or no contribution of the pain processing system to malaria-related death. Also, using an anti-CD68 antibody, there was no immunopositive cell in the brain to attribute the observed effects to cerebral malaria. Although in the haematoxylin and eosin-stained tissues, there were mild morphological changes in the motor and anterior cingulate cortices. In conclusion, the pain symptom was remarkably decreased in the animal model for malaria, and thus, the model may not be appropriate for investigating malaria-linked pain as reported in humans. This is the first report showing that at a critical point, the malaria parasite caused pain-relieving effects in Swiss mice.

Spinal cord neural activity of patients with fibromyalgia and healthy controls during temporal summation of pain: an fMRI study

2021 ◽  
Vol 126 (3) ◽  
pp. 946-956
Author(s):  
Roland Staud ◽  
Jeff Boissoneault ◽  
Song Lai ◽  
Marlin S. Mejia ◽  
Riddhi Ramanlal ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Chronic Pain ◽  
Neural Activity ◽  
Central Sensitization ◽  
Temporal Summation ◽  
Time Course ◽  
Pain Modulation ◽  
Healthy Controls ◽  
Fmri Study ◽  
Second Pain

“Windup” and its behavioral correlate “temporal-summation-of-second pain” (TSSP) represent spinal cord mechanisms of pain augmentation associated with central sensitization and chronic pain. Fibromyalgia (FM) is a chronic pain disorder, where abnormal TSSP has been demonstrated. We used fMRI to study spinal cord and brainstem activation during TSSP. We characterized the time course of spinal cord and brainstem BOLD activity during TSSP which showed abnormal brainstem activity in patients with FM, possibly due to deficient pain modulation.

scholarly journals Pathophysiology of the lower urinary tract and CNS

2013 ◽  
Vol 5 (5-S2) ◽  
pp. 126
Author(s):  
Christopher Chapple
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Urinary Tract ◽  
Lower Urinary Tract ◽  
Neural Control ◽  
Neural Mechanisms ◽  
The Other ◽  
Bladder Function ◽  
Lower Urinary

A number of aspects of neural control are potentially important inthe control of bladder function, including both sensory and motorand peripheral and central pathways. It is likely that a combinationof disorders of both central and peripheral neural mechanisms isimportant in the genesis of urgency and the other symptoms of theoveractive bladder (OAB). Given the number of potential pathwaysinvolved, potential pharmacologic targets for OAB exist in the CNS(central nervous system; cerebral cortex, midbrain, spinal cord)and periphery (LUT; lower urinary tract). Antimuscarinics are stillthe mainstay of OAB treatment, but there are also a number ofother potentially efficacious drugs that may also provide benefitagainst the neurologic components of OAB. This review discussesthe impact of neurological abnormalities on lower urinary tractsymptoms and the potential for treatments targeting these pathwaysto improve symptoms.

Neural mechanisms of intersegmental coordination in lamprey: local excitability changes modify the phase coupling along the spinal cord

1992 ◽  
Vol 67 (2) ◽  
pp. 373-388 ◽  
Author(s):  
T. Matsushima ◽  
S. Grillner
Keyword(s):  
Spinal Cord ◽  
Forward Direction ◽  
Neural Mechanisms ◽  
Cycle Duration ◽  
Phase Lag ◽  
High Concentration ◽  
Caudal Portion ◽  
Bath Application ◽  
Ventral Roots

1. To elucidate the neural mechanisms responsible for coordinating undulatory locomotor movements, the intersegmental phase lag was analyzed from ventral roots along the spinal cord during fictive swimming. It was induced by bath application of N-methyl-D-aspartate (NMDA) in in vitro preparations of lamprey spinal cord, while the excitability of different segments were modified. The phase lag between consecutive segments during normal forward swimming is 1% of the cycle duration in a broad range of values. Rostral segments are activated before more caudal ones. 2. Under control conditions, whole preparations (12-24 segment long; n = 22) were perfused with NMDA solutions of the same concentration (100-150 microM). The intersegmental phase lag values varied in a continuous range with a single peak around a median value of forward +0.74% per segment (range: forward +2.23% to backward -0.97%). 3. To examine whether excitability differences along the spinal cord could modify the intersegmental phase lag, different levels of excitatory amino acids (NMDA) were applied to spinal cord preparations positioned in a partitioned chamber. Different portions of the cord could be perfused separately by NMDA solutions of different concentrations (50-150 microM). If rostral segments were perfused with the higher NMDA solution, the lag was inevitably in the forward direction. Conversely, if the caudal portion was perfused with the higher NMDA solution, caudally located ventral roots became activated before the rostral ventral roots in a caudorostral succession, thus reversing the direction of the fictive swimming wave to propagate as during backward swimming. If the middle portion was perfused by the highest NMDA solution, this portion instead became leading, and the activity propagated from this point in both the rostral and the caudal directions. The portion located in the pool with highest NMDA concentration always gave rise to a "leading" segment. 4. When a portion of the preparation was perfused with an NMDA solution of a high concentration (75-150 microM), the cycle duration was close to that recorded when the whole preparation was perfused with the same high NMDA solution. The ensemble cycle duration is, therefore, largely determined by the leading segment. 5. The phase lag changes were not restricted to the region around the barrier separating pools with different NMDA solutions.(ABSTRACT TRUNCATED AT 400 WORDS)

Rhythmic sympathetic nerve discharges in an in vitro neonatal rat brain stem-spinal cord preparation

1999 ◽  
Vol 87 (3) ◽  
pp. 1066-1074 ◽  
Author(s):  
Chun-Kuei Su
Keyword(s):  
Spinal Cord ◽  
Ascorbic Acid ◽  
Brain Stem ◽  
Sympathetic Nerve ◽  
Power Spectral Analysis ◽  
Neural Mechanisms ◽  
Neonatal Rat ◽  
Root Activity ◽  
Superior Cerebellar Artery

To understand the origination of sympathetic nerve discharge (SND), I developed an in vitro brain stem-spinal cord preparation from neonatal rats. Ascorbic acid (3 mM) was added into the bath solution to increase the viability of preparations. At 24°C, rhythmic SND (recorded from the splanchnic nerve) was consistently observed, but it became quiescent at <16°C. Respiratory-related SND (rSND) was discernible and was well correlated with C4 root activity. Power spectral analysis of SND revealed a dominant 2-Hz oscillation. In most preparations (86%), such oscillation was persistent, whereas it only slightly reduced its magnitude after isolation from the brain stem. The removal of neural structures rostral to the superior cerebellar artery (equivalent to the level of facial nuclei) reduced rSND, increased tonic SND, but did not affect the temporal coupling between SND and C4 root activity. Our data suggest a prominent contribution of SND from the neural mechanisms confined within the neonatal rat spinal cord. This ascorbic acid-enhanced in vitro preparation is a very useful model to study neural mechanisms underlying sympathorespiratory integration.

scholarly journals Cutaneous stimulation evokes long-lasting excitation of spinal interneurons in the turtle

1990 ◽  
Vol 64 (4) ◽  
pp. 1134-1148 ◽  
Author(s):  
S. N. Currie ◽  
P. S. Stein
Keyword(s):  
Spinal Cord ◽  
Receptive Field ◽  
Action Potential ◽  
Receptive Fields ◽  
Neural Mechanisms ◽  
Cutaneous Afferents ◽  
Cutaneous Stimulation ◽  
Single Action ◽  
Single Action Potential ◽  
Stimulation Of

1. We demonstrated multisecond increases in the excitability of the rostral-scratch reflex in the turtle by electrically stimulating the shell at sites within the rostral-scratch receptive field. To examine the cellular mechanisms for these multisecond increases in scratch excitability, we recorded from single cutaneous afferents and sensory interneurons that responded to stimulation of the shell within the rostral-scratch receptive field. A single segment of the midbody spinal cord (D4, the 4th postcervical segment) was isolated in situ by transecting the spinal cord at the segment's anterior and posterior borders. The isolated segment was left attached to its peripheral nerve that innervates part of the rostral-scratch receptive field. A microsuction electrode (4-5 microns ID) was used to record extracellularly from the descending axons of cutaneous afferents and interneurons in the spinal white matter at the posterior end of the D4 segment. 2. The turtle shell is innervated by slowly and rapidly adapting cutaneous afferents. All cutaneous afferents responded to a single electrical stimulus to the shell with a single action potential. Maintained mechanical stimulation applied to the receptive field of some slowly adapting afferents produced several seconds of afterdischarge at stimulus offset. We refer to the cutaneous afferent afterdischarge caused by mechanical stimulation of the shell as "peripheral afterdischarge." 3. Within the D4 spinal segment there were some interneurons that responded to a brief mechanical stimulus within their receptive fields on the shell with short afterdischarge and others that responded with long afterdischarge. Short-afterdischarge interneurons responded to a single electrical pulse to a site in their receptive fields either with a brief train of action potentials or with a single action potential. Long-afterdischarge interneurons responded to a single electrical shell stimulus with up to 30 s of afterdischarge. Long-afterdischarge interneurons also exhibited strong temporal summation in response to a pair of electrical shell stimuli delivered up to several seconds apart. Because all cutaneous afferents responded to an electrical shell stimulus with a single action potential, we conclude that electrically evoked afterdischarge in interneurons was produced by neural mechanisms in the spinal cord; we refer to this type of afterdischarge as "central afterdischarge." 4. These results demonstrate that neural mechanisms for long-lasting excitability changes in response to cutaneous stimulation reside in a single segment of the spinal cord. Cutaneous interneurons with long afterdischarge may serve as cellular loci for multise

Association between Pain Sensitivity, Central Sensitization, and Functional Disability in Adolescents With Joint Hypermobility

2018 ◽  
Vol 42 ◽  
pp. 34-38 ◽  
Author(s):  
Elizabeth A. Bettini ◽  
Ki Moore ◽  
Yunfei Wang ◽  
Pamela S. Hinds ◽  
Julia C. Finkel
Keyword(s):  
Central Sensitization ◽  
Pain Sensitivity ◽  
Functional Disability ◽  
Joint Hypermobility
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