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- Kalliomäki, Jarkko, et al.
(författare)
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Intrathecally applied morphine inhibits nociceptive C fiber input to the primary somatosensory cortex (SI) of the rat
- 1998
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Ingår i: Pain. - 0304-3959. ; 77:3, s. 323-329
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Tidskriftsartikel (refereegranskat)abstract
- Nociceptive C fiber input to SI in the halothane-nitrous oxide anesthetized rat was assessed by recording cortical field potentials evoked by noxious thermal cutaneous stimulation with CO2-laser pulses. Morphine topically applied onto the lumbar spinal cord produced a dose-dependent inhibition of nociceptive C fiber input from the hind paw to the contralateral SI. The inhibitory effect of morphine was reversed by naloxone. Potentials evoked by CO2-laser stimulation of the forepaw were unaffected by morphine applied on the lumbar cord, indicating that the effect of morphine was exerted at the segmental level. It is concluded that input from nociceptive C fibers to SI is relayed in the spinal cord and can be inhibited by spinal opioid receptor activation. The present method offers an interesting model of ascending nociceptive transmission to the cerebral cortex. Copyright (C) 1998 International Association for the Study of Pain. Published by Elsevier Science B.V.
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| 2. |
- Larsson, Britt, et al.
(författare)
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The prevalences of cytochrome c oxidase negative and superpositive fibres and ragged-red fibres in the trapezius muscle of female cleaners with and without myalgia and of female healthy controls
- 2000
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Ingår i: Pain. - 1872-6623 .- 0304-3959. ; 84:2-3, s. 379-387
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Tidskriftsartikel (refereegranskat)abstract
- The association of cytochrome c oxidase negative fibres (COX-negative) and ragged-red fibres (RR-fibres) with work related trapezius myalgia has been proposed. Hitherto studies have been small or without control groups. The aim of the present study was to investigate the prevalences of RR-fibres and COX-negative fibres in female cleaners with (n=25) and without (n=23) trapezius myalgia and in clinically healthy female teachers (n=21). The cleaners did mainly floor cleaning requiring monotonous loading on the trapezius muscle. A questionnaire covering background data and aspects of pain (prevalence, duration, intensity and influence on daily living) was answered. Biopsies were obtained from the trapezius muscle by an open surgical technique. The three groups did not differ in prevalence of COX-negative or COX-superpositive (i.e. type-I fibres with extremely strong brownish reaction in both the COX and SDH/COX stainings) fibres. The prevalence of COX-negative fibres was age dependent. Two subgroups of RR-fibres were present when stained for COX; COX-negative (73%) and COX-superpositive (26%) fibres. Forty-two percent of the COX-negative fibres were RR-fibres and 79% of the COX-superpositive were RR-fibres. A significantly (P=0.002) higher proportion of the COX-superpositive fibres in the cleaners were RR-fibres compared to the teachers. Multivariate regression analysis revealed that age, occupation as cleaner and a tender point in the trapezius were significantly associated with increased prevalences of RR-fibres; a cleaner with a tender point had a 4.35 higher prevalence of RR-fibres compared to a teacher without a tender point. No correlations between other pain related variables and prevalence of RR-fibres were noted. In conclusion, RR-fibres but not COX-negative or COX-superpositive fibres were correlated with cleaning work tasks and with a tender point in the trapezius.
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| 3. |
- Sjölund, B. H., et al.
(författare)
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Site of action of antinociceptive acupuncture like nerve stimulation in the spinal rat as visualized by the 14C-2-deoxyglucose method
- 1981
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Ingår i: Pain. - : Ovid Technologies (Wolters Kluwer Health). - 0304-3959. ; 11:Suppl 1, s. 241-241
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Konferensbidrag (refereegranskat)abstract
- Aim: It has been claimed that supraspinal structures are necessary forthe depression of nocifensive behaviour elicited by acupuncture or acupuncturelike (AL) stimulation. However, nocifensive reflexes in the spinal catwere inhibited for long periods by a mechanism releasing opieids on AL conditioning stimulation of groups II-III muscle afferents (Sj~lund and Eriksson, Neurosci.Lett. S3:264:1979). We now present autoradiographic measurements of regional "nervous" activity with the 14C2deoxyglucose method(Sokoloff et al.,J.Neurochem.28:897,1977),indicating that this inhibitionof nociceptive activity occurs in the outer dorsal horn of spinal rats.Methods: Wistar rats were decerebrated and spinalized at C1 under halothane. After curarization, noxious stimuli were given to one hindpaw asbradykinin intracut, or as radiant heat, and 25uC 14C2deoxyglucose was administered. In two test groups, 20min of AL stimulation (needles in ipsilateral sciatic nerve; lOOHz train, duration 70ms, repetition rate 2Hz; intensity 4x twitch threshold) or morphine (img/kg iv) preeeeded the nociceptive stimulation. The autoradiograms were scanned along lines coveringlaminae I-VI of both sides of the lumbar cord.Results: In controls the activity increased ipsilateral to the noxiousstimuli in all the laminae, notably l-III. In rats receiving AL stimulationan increased activity was seen only in the ipsilateral laminae II-IIIwhereas no side to side differences we~e seen in morphine treated rats.Conclusions: Inhibition of nociceptive activity in the rat dorsal horn byopioids seems to occur already in lamina I. The activity in laminae II-IIIafter AL stimulation might be due to interneurones normally responsible forthis inhibition. (Supported by the Swedish MRC, proj.no 05658).
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| 6. |
- Amandusson, Åsa, 1974-, et al.
(författare)
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Estrogen-induced alterations of spinal cord enkephalin gene expression
- 1999
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Ingår i: Pain. - : Elsevier. - 0304-3959 .- 1872-6623. ; 83:2, s. 243-248
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Tidskriftsartikel (refereegranskat)abstract
- Enkephalin-synthesizing neurons in the super®cial laminae of the spinal and trigeminal dorsal horn are critical components of the endogenous pain-modulatory system. We have previously demonstrated that these neurons display intracellular estrogen receptors, suggesting that estrogen can potentially influence their enkephalin expression. By using Northern blot, we now show that a bolus injection of estrogen results in a rapid increase in spinal cord enkephalin mRNA levels in ovariectomized female rats. Thus, 4 h after estrogen administration the enkephalin mRNA-expression in the lumbar spinal cord was on average 68% higher (P , 0:05) than in control animals injected with vehicle only. A small increase in the amount of enkephalin mRNA was also seen after 8 h (P , 0:05), whereas no difference between estrogen-injected and control animals was found after 24 h or at time periods shorter than 4 h. Taken together with the previous anatomical data, the present findings imply that estrogen has an acute effect on spinal opioid levels in areas involved in the transmission of nociceptive information.
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| 7. |
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| 9. |
- Berglund, Birgitta, et al.
(författare)
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Quantitative and qualitative perceptual analysis of cold dysesthesia and hyperalgesia in fibromyalgia.
- 2002
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Ingår i: Pain. - : Ovid Technologies (Wolters Kluwer Health). - 0304-3959 .- 1872-6623. ; 96:1-2, s. 177-87
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Tidskriftsartikel (refereegranskat)abstract
- Somatosensory perception thresholds, perceived intensity, and quality of perceptions were assessed in 20 women with fibromyalgia syndrome (FMS) and in 20 healthy age-matched female controls. All patients and controls scaled perceived intensity and described perceived quality of randomized thermal (Thermotest) and tactile (von Frey filaments) stimulation. Perceived intensity was scaled by free-number magnitude estimation and interindividual comparability was accomplished by Master Scaling. Perceived quality was assessed by choosing verbal descriptors from a list. Thenar was used as a reference for each modality tested. All patients were able to reliably scale perceived intensity at thenar, as well as in pain-affected body areas. Perception thresholds for cold pain, heat pain, cold-pain tolerance and heat-pain tolerance were significantly lower in patients than controls. For cold and tactile stimulation, the master scaled perceived intensities were significantly higher in patients' pain-affected areas, whereas for warmth/heat stimulation, the intensities were significantly lower. In the qualitative perceptual analysis the most striking and significant finding was the aberration of cold-evoked perceptions in all patients: most stimuli in the range of 30-10 degrees C were reported as heat or other paresthetic or dysesthetic perceptions. The perceptual quality of warmth, and of touch, did not differ from the controls. Another aberration was observed in the nociceptive range of thermal and of tactile stimulation as significantly more frequent pain-related descriptors than in controls. This indicates a general nociceptive facilitation in addition to the lower thermal pain thresholds. The combination of cold hyperesthesia, cold dysesthesia, and multimodal hyperalgesia suggests a selective pathophysiology at a particular level of integration, possibly in the insular cortex. It is suggested that the aberrations revealed by the supraliminal sensory evaluation may be generic for FMS. Particularly, the aberrations established in all patients for perceived quality and intensity in the cold sensory channel may be an additional diagnostic criterion.
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