scholarly journals Involvement of ATP in noxious stimulus-evoked release of glutamate in rat medullary dorsal horn: A microdialysis study

2012 ◽  
Vol 61 (8) ◽  
pp. 1276-1279 ◽  
Author(s):  
Naresh Kumar ◽  
Pavel S. Cherkas ◽  
C.Y. Chiang ◽  
Jonathan O. Dostrovsky ◽  
Barry J. Sessle ◽  
...  
Keyword(s):  
Dorsal Horn ◽  
Noxious Stimulus ◽  
Medullary Dorsal Horn ◽  
Microdialysis Study

Endomorphin-1 and Endomorphin-2 Modulate Responses of Trigeminal Neurons Evoked by N-Methyl-d-Aspartic Acid and Somatosensory Stimuli

2000 ◽  
Vol 83 (6) ◽  
pp. 3570-3574 ◽  
Author(s):  
Xiao-Min Wang ◽  
Kai-Ming Zhang ◽  
Layron O. Long ◽  
Carmina A. Flores ◽  
Sukhbir S. Mokha
Keyword(s):  
Dorsal Horn ◽  
Opioid Receptor ◽  
Inhibitory Effect ◽  
Noxious Stimulus ◽  
Evoked Responses ◽  
Natural Stimulus ◽  
Nociceptive Neurons ◽  
Medullary Dorsal Horn ◽  
Trigeminal Neurons ◽  
Μ Opioid Receptor

The present study investigated the modulation of N-methyl-d-aspartate (NMDA)-evoked and peripheral cutaneous stimulus-evoked responses of trigeminal neurons by endomorphins, endogenous ligands for the μ-opioid receptor. Effects of endomorphins, administered microiontophoretically, were tested on the responses of nociceptive neurons recorded in the superficial and deeper dorsal horn of the medulla (trigeminal nucleus caudalis) in anesthetized rats. Endomorphin-1 and endomorphin-2 predominantly reduced the NMDA-evoked responses, producing an inhibitory effect of 54.1 ± 2.96% (mean ± SE; n = 34, P < 0.001) in 92% (34/37) of neurons and 63.6 ± 3.61% ( n = 32, P< 0.001) in 91% (32/35) of neurons, respectively. The inhibitory effect of endomorphins was modality specific; noxious stimulus-evoked responses were reduced more than nonnoxious stimulus-evoked responses. Naloxone applied at iontophoretic current that blocked the inhibitory effect of [d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin, reduced the peak inhibitory effect of endomorphins on the NMDA- and natural stimulus-evoked responses. We suggest that endomorphins by acting at μ-opioid receptor selectively modulate noxious stimulus-evoked responses in the medullary dorsal horn.

Task-related responses of monkey medullary dorsal horn neurons

1987 ◽  
Vol 57 (1) ◽  
pp. 289-310 ◽  
Author(s):  
G. H. Duncan ◽  
M. C. Bushnell ◽  
R. Bates ◽  
R. Dubner
Keyword(s):  
Dorsal Horn ◽  
Thermal Stimulus ◽  
Behavioral Task ◽  
Related Activity ◽  
Specific Stimulus ◽  
Dorsal Horn Neurons ◽  
Medullary Dorsal Horn ◽  
Successful Execution ◽  
Individual Task ◽  
Sensory Responses

Medullary dorsal horn neurons with trigeminal sensory properties have been previously shown to have additional responses associated with cues relevant to the successful execution of a behavioral task. These “task-related” responses were evoked by environmental cues but were independent of the specific stimulus parameters. We have examined further the characteristics of task-related responses in medullary dorsal horn neurons of three monkeys. Single-unit activity was recorded while the monkeys were performing behavioral tasks that required them to discriminate thermal or visual stimuli for a liquid reward. Forty-five percent (34/75) of the medullary dorsal horn neurons studied exhibited task-related activity that was significantly correlated with the stereotypical behavioral events that occurred during the tasks. Similar events occurring outside of the task produced no response. In addition to the task-related activity of these medullary dorsal horn neurons, responses to mechanical and/or thermal stimuli presented within the neuron's receptive field were demonstrated in 28 of 34 cases. These sensory responses also were evoked by the same stimuli presented outside of the behavioral task. Fifteen of the neurons with task-related responses could be activated antidromically from thalamic stimulating electrodes. Task-related responses were categorized according to their relationship to the three phases of the behavioral trial: trial initiation, trial continuation, and trial termination. Although an individual task-related response was associated with a single behavioral event, most medullary dorsal horn neurons (30/34) exhibited a reproducible pattern of task-related responses that occurred during more than one phase of the trial. Trial-initiation task-related responses were subdivided depending on their correlation with specific events that occurred within that phase of the trial. One-third of the 18 excitatory trial-initiation responses were associated with the visual stimulus that cued the monkey to begin the trial; the remaining two-thirds were associated with the monkey's press of the button that actually initiated the trial. Trial-continuation task-related responses (observed while the monkey waited for a thermal stimulus that triggered a rewarded motor response) were shown to be independent of the actual temperature of the thermal stimulus. In addition these trial-continuation task-related responses were also noted during trials without a thermal stimulus, in which the trigger cue was the onset of a light (in a visual task).(ABSTRACT TRUNCATED AT 400 WORDS)

Descending inhibitory influences from periaqueductal gray, nucleus raphe magnus, and adjacent reticular formation. II. Effects on medullary dorsal horn nociceptive and nonnociceptive neurons

1983 ◽  
Vol 49 (4) ◽  
pp. 948-960 ◽  
Author(s):  
J. O. Dostrovsky ◽  
Y. Shah ◽  
B. G. Gray
Keyword(s):  
Dorsal Horn ◽  
Dynamic Range ◽  
Periaqueductal Gray ◽  
Nucleus Raphe Magnus ◽  
Nucleus Reticularis ◽  
Medullary Dorsal Horn ◽  
Significant Difference ◽  
Raphe Magnus ◽  
Somatosensory Responses ◽  
Wdr Neurons

1. This study examined the inhibitory effects elicited by brain stem stimulation on the somatosensory responses of trigeminal medullary dorsal horn (subnucleus caudalis of the spinal trigeminal nucleus) neurons. Single-unit extracellular recordings were obtained in chloralose-anesthetized cats. Neurons were classified as wide dynamic range (WDR), nociceptive specific (NS), or low-threshold mechanoreceptive (LTM). Conditioning stimuli were delivered to the periaqueductal gray (PAG), nucleus cuneiformis (CU), nucleus raphe magnus (NRM), nucleus reticularis gigantocellularis (NGC), and nucleus reticularis magnocellularis (NMC). 2. Over 97% of the neurons tested could be inhibited by stimulation in all regions except PAG. Stimulation in the PAG inhibited 91% of the neurons tested. There was no statistically significant difference in the incidence of inhibition of WDR and NS nociceptive (noci) neurons and the LTM nonnociceptive (nonnoci) neurons. 3. Mean stimulation intensities necessary to produce inhibition were determined for each neuron from each stimulation site. The current thresholds necessary to inhibit the responses of noci neurons were found to be significantly lower, on the average, than those of nonnoci neurons at stimulation sites in the PAG, CU, and NGC. 4. Inhibition of the responses of WDR neurons required a lower mean current than for NS neurons but was statistically significant only for PAG and NGC. Thresholds for inhibiting the responses of NS neurons were similar to those for inhibiting the responses of LTM neurons for all regions except CU, where LTM thresholds were markedly but not significantly higher. 5. Stimulation thresholds were found to be lowest in NMC, while in NGC, NRM, and CU they were all similar and slightly higher. Stimulation in the PAG required the highest currents to produce inhibition. 6. These results indicate that stimulation in NRM and PAG not only inhibits the responses of noci neurons but also those of nonnoci neurons. Furthermore, stimulation in reticular regions adjacent to NRM and PAG is frequently even more effective in inhibiting the responses of both noci and nonnoci neurons. In addition, WDR neurons are more effectively inhibited than NS or LTM neurons. These results are compared with those obtained using similar methods in cat lumbar dorsal horn.

Cholecystokinin concentrations and peptide immunoreactivity in the intact and deafferented medullary dorsal horn of the rat

1992 ◽  
Vol 326 (1) ◽  
pp. 22-43 ◽  
Author(s):  
Mark F. Jacquin ◽  
Margery C. Beinfeld ◽  
Nicolas L. Chiaia ◽  
Daniel S. Zahm
Keyword(s):  
Dorsal Horn ◽  
Medullary Dorsal Horn
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