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Fan Z, Dou B, Wang J, Wu Y, Du S, Li J, Yao K, Li Y, Wang S, Gong Y, Guo Y, Xu Z. Effects and mechanisms of acupuncture analgesia mediated by afferent nerves in acupoint microenvironments. Front Neurosci 2024; 17:1239839. [PMID: 38384495 PMCID: PMC10879281 DOI: 10.3389/fnins.2023.1239839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 09/27/2023] [Indexed: 02/23/2024] Open
Abstract
In the past few decades, the use of acupuncture analgesia in clinical practice has increased worldwide. This is due to its various benefits, including natural alleviation of pain without causing various adverse effects associated with non-steroidal anti-inflammatory drugs (NSAID) and opioids. The acupoint represents the initial site of acupuncture stimulation, where diverse types of nerve fibers located at the acupoint hold significant roles in the generation and transmission of acupuncture-related information. In this study, we analyzed the patterns and mechanisms of acupuncture analgesic mediated by acupoint afferent fibers, and found that acupuncture stimulates acupoints which rapidly and directly induces activation of high-density primary afferent fibers under the acupoints, including myelinated A fibers and unmyelinated C fibers. During acupuncture stimulation at the muscle layer, the analgesic effects can be induced by stimulation of A fiber threshold intensity. At the skin layer, the analgesic effects can only be produced by stimulation of C fiber threshold intensity. Electroacupuncture (EA) activates A fibers, while manual acupuncture (MA) activates both A and C fibers. Furthermore, acupuncture alters acupoint microenvironments, which positively modulates afferent fibers, enhancing the transmission of analgesic signals. In addition to local activation and conduction at acupoints, nerve fibers mediate the transmission of acupuncture information to pain centers. In the spinal cord, acupuncture activates neurons by inducing afferent fiber depolarization, modulating pain gating, inhibiting long-term potentiation (LTP) of the spinal dorsal horn and wide dynamic range (WDR) neuronal activities. At higher nerve centers, acupuncture inhibits neuronal activation in pain-related brain regions. In summary, acupuncture inhibits pain signal transmission at peripheral and central systems by activating different patterns of afferent fibers located on various layers of acupoints. This study provides ideas for enhancing the precise application and clinical translation of acupuncture.
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Affiliation(s)
- Zezhi Fan
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Baomin Dou
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Jiangshan Wang
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Yongjian Wu
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Simin Du
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Jiashan Li
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Kaifang Yao
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Yanwei Li
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Shenjun Wang
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- School of Acupuncture and Moxibustion and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, China
- Tianjin Key Laboratory of Modern Chinese Medicine Theory of Innovation and Application, Tianjin, China
| | - Yinan Gong
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- School of Acupuncture and Moxibustion and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, China
- Tianjin Key Laboratory of Modern Chinese Medicine Theory of Innovation and Application, Tianjin, China
| | - Yi Guo
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, China
- Tianjin Key Laboratory of Modern Chinese Medicine Theory of Innovation and Application, Tianjin, China
| | - Zhifang Xu
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- School of Acupuncture and Moxibustion and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, China
- National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, China
- Tianjin Key Laboratory of Modern Chinese Medicine Theory of Innovation and Application, Tianjin, China
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Abstract
Natural selection has shaped the physiological properties of sensory systems across species, yielding large variations in their sensitivity. Here, we used laser stimulation of skin nociceptors, a widely used technique to investigate pain in rats and humans, to provide a vivid example of how ignoring these variations can lead to serious misconceptions in sensory neuroscience. In 6 experiments, we characterized and compared the physiological properties of the electrocortical responses elicited by laser stimulation in rats and humans. We recorded the electroencephalogram from the surface of the brain in freely moving rats and from the scalp in healthy humans. Laser stimuli elicited 2 temporally distinct responses, traditionally interpreted as reflecting the concomitant activation of different populations of nociceptors with different conduction velocities: small-myelinated Aδ-fibres and unmyelinated C-fibres. Our results show that this interpretation is valid in humans, but not in rats. Indeed, the early response recorded in rats does not reflect the activation of the somatosensory system, but of the auditory system by laser-generated ultrasounds. These results have wide implications: retrospectively, as they prompt for a reconsideration of a large number of previous interpretations of electrocortical rat recordings in basic, preclinical, and pharmacological research, and prospectively, as they will allow recording truly pain-related cortical responses in rats.
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Geelen S, Guzman DSM, Souza MJ, Cox S, Keuler NS, Paul-Murphy JR. Antinociceptive effects of tramadol hydrochloride after intravenous administration to Hispaniolan Amazon parrots (Amazona ventralis). Am J Vet Res 2013; 74:201-6. [DOI: 10.2460/ajvr.74.2.201] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Granmo M, Jensen T, Schouenborg J. Nociceptive transmission to rat primary somatosensory cortex--comparison of sedative and analgesic effects. PLoS One 2013; 8:e53966. [PMID: 23320109 PMCID: PMC3540052 DOI: 10.1371/journal.pone.0053966] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 12/06/2012] [Indexed: 11/18/2022] Open
Abstract
CO(2)-laser C-fibre evoked cortical potentials (LCEPs) is a potentially useful animal model for studies of pain mechanisms. A potential confounding factor when assessing analgesic effects of systemically administered drugs using LCEP is sedation. This study aims to clarify: 1) the relation between level of anaesthesia and magnitude of LCEP, 2) the effects of a sedative and an analgesic on LCEP and dominant EEG frequency 3) the effects of a sedative and analgesic on LCEP when dominant EEG frequency is kept stable. LCEP and EEG were recorded in isoflurane/nitrous-oxide anaesthetized rats. Increasing isoflurane level gradually reduced LCEPs and lowered dominant EEG frequencies. Systemic midazolam (10 μmol/kg) profoundly reduced LCEP (19% of control) and lowered dominant EEG frequency. Similarly, morphine 1 and 3 mg/kg reduced LCEP (39%, 12% of control, respectively) and decreased EEG frequency. When keeping the dominant EEG frequency stable, midazolam caused no significant change of LCEP. Under these premises, morphine at 3 mg/kg, but not 1 mg/kg, caused a significant LCEP reduction (26% of control). In conclusion, the present data indicate that the sedative effects should be accounted for when assessing the analgesic effects of drug. Furthermore, it is suggested that LCEP, given that changes in EEG induced by sedation are compensated for, can provide information about the analgesic properties of systemically administrated drugs.
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Affiliation(s)
- Marcus Granmo
- Neuronano Research Center, Department of Experimental Medical Sciences, Lund University, Lund, Sweden.
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Shoemaker PA. Neural bistability and amplification mediated by NMDA receptors: Analysis of stationary equations. Neurocomputing 2011. [DOI: 10.1016/j.neucom.2011.04.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Zhang Y, Wang N, Wang JY, Chang JY, Woodward DJ, Luo F. Ensemble encoding of nociceptive stimulus intensity in the rat medial and lateral pain systems. Mol Pain 2011; 7:64. [PMID: 21864358 PMCID: PMC3179932 DOI: 10.1186/1744-8069-7-64] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 08/24/2011] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The ability to encode noxious stimulus intensity is essential for the neural processing of pain perception. It is well accepted that the intensity information is transmitted within both sensory and affective pathways. However, it remains unclear what the encoding patterns are in the thalamocortical brain regions, and whether the dual pain systems share similar responsibility in intensity coding. RESULTS Multichannel single-unit recordings were used to investigate the activity of individual neurons and neuronal ensembles in the rat brain following the application of noxious laser stimuli of increasing intensity to the hindpaw. Four brain regions were monitored, including two within the lateral sensory pain pathway, namely, the ventral posterior lateral thalamic nuclei and the primary somatosensory cortex, and two in the medial pathway, namely, the medial dorsal thalamic nuclei and the anterior cingulate cortex. Neuron number, firing rate, and ensemble spike count codings were examined in this study. Our results showed that the noxious laser stimulation evoked double-peak responses in all recorded brain regions. Significant correlations were found between the laser intensity and the number of responsive neurons, the firing rates, as well as the mass spike counts (MSCs). MSC coding was generally more efficient than the other two methods. Moreover, the coding capacities of neurons in the two pathways were comparable. CONCLUSION This study demonstrated the collective contribution of medial and lateral pathway neurons to the noxious intensity coding. Additionally, we provide evidence that ensemble spike count may be the most reliable method for coding pain intensity in the brain.
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Affiliation(s)
- Yang Zhang
- Neuroscience Research Institute and Department of Neurobiology, Peking University Health Science Center, Beijing, China
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Gadotti VM, Zamponi GW. Cellular prion protein protects from inflammatory and neuropathic pain. Mol Pain 2011; 7:59. [PMID: 21843375 PMCID: PMC3170224 DOI: 10.1186/1744-8069-7-59] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 08/16/2011] [Indexed: 11/30/2022] Open
Abstract
Cellular prion protein (PrPC) inhibits N-Methyl-D-Aspartate (NMDA) receptors. Since NMDA receptors play an important role in the transmission of pain signals in the dorsal horn of spinal cord, we thus wanted to determine if PrPC null mice show a reduced threshold for various pain behaviours. We compared nociceptive thresholds between wild type and PrPC null mice in models of inflammatory and neuropathic pain, in the presence and the absence of a NMDA receptor antagonist. 2-3 months old male PrPC null mice exhibited an MK-801 sensitive decrease in the paw withdrawal threshold in response both mechanical and thermal stimuli. PrPC null mice also exhibited significantly longer licking/biting time during both the first and second phases of formalin-induced inflammation of the paw, which was again prevented by treatment of the mice with MK-801, and responded more strongly to glutamate injection into the paw. Compared to wild type animals, PrPC null mice also exhibited a significantly greater nociceptive response (licking/biting) after intrathecal injection of NMDA. Sciatic nerve ligation resulted in MK-801 sensitive neuropathic pain in wild-type mice, but did not further augment the basal increase in pain behaviour observed in the null mice, suggesting that mice lacking PrPC may already be in a state of tonic central sensitization. Altogether, our data indicate that PrPC exerts a critical role in modulating nociceptive transmission at the spinal cord level, and fit with the concept of NMDA receptor hyperfunction in the absence of PrPC.
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Affiliation(s)
- Vinicius M Gadotti
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary T2N 4N1, Canada
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Jensen T, Granmo M, Schouenborg J. Altered nociceptive C fibre input to primary somatosensory cortex in an animal model of hyperalgesia. Eur J Pain 2010; 15:368-75. [PMID: 20947398 DOI: 10.1016/j.ejpain.2010.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 09/15/2010] [Accepted: 09/20/2010] [Indexed: 10/19/2022]
Abstract
Evaluating potentially analgesic effects of drugs and various treatments is critically dependent on valid animal models of pain. Since primary somatosensory (SI) cortex is likely to play an important role in processing sensory aspects of pain, we here assess whether monitoring SI cortex nociceptive C fibre evoked potentials can provide useful information about central changes related to hyperalgesia in rats. Recordings of tactile and CO(2)-laser C fibre evoked potentials (LCEPs) in forelimb and hind limb SI cortex were made 20-24h after UV-B irradiation of the heel at a dose that produced behavioural signs of hyperalgesia. LCEPs from irradiated skin increased significantly in duration but showed no significant change in magnitude, measured as area under curve (AUC). By contrast, LCEPs in hind limb SI cortex from skin sites nearby the irradiated skin showed no increase in duration or onset latency but increased significantly in magnitude after UV-B irradiation. The LCEPs in forelimb or hind limb SI cortex elicited from forelimb skin did not change in magnitude, but were significantly delayed in hind limb SI cortex. Tramadol, a centrally acting analgesic known to reduce hyperalgesia, induced changes that counteracted the changes produced by UV-B irradiation on transmission to SI cortex from the hind paw, but had no significant effect on time course of LCEPs from forelimb skin. Tactile evoked potentials were not affected by UV-B irradiation or tramadol. We conclude that altered sensory processing related to hyperalgesia is reflected in altered LCEPs in SI cortex.
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Affiliation(s)
- Tanja Jensen
- Neuronano Research Center, Section for Neuroscience, Lund University, BMC F10, SE-221 84 Lund, Sweden.
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Larsson M. Ionotropic glutamate receptors in spinal nociceptive processing. Mol Neurobiol 2009; 40:260-88. [PMID: 19876771 DOI: 10.1007/s12035-009-8086-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 09/29/2009] [Indexed: 02/07/2023]
Abstract
Glutamate is the predominant excitatory transmitter used by primary afferent synapses and intrinsic neurons in the spinal cord dorsal horn. Accordingly, ionotropic glutamate receptors mediate basal spinal transmission of sensory, including nociceptive, information that is relayed to supraspinal centers. However, it has become gradually more evident that these receptors are also crucially involved in short- and long-term plasticity of spinal nociceptive transmission, and that such plasticity have an important role in the pain hypersensitivity that may result from tissue or nerve injury. This review will cover recent findings on pre- and postsynaptic regulation of synaptic function by ionotropic glutamate receptors in the dorsal horn and how such mechanisms contribute to acute and chronic pain.
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Affiliation(s)
- Max Larsson
- Department of Anatomy and Centre for Molecular Biology and Neuroscience, University of Oslo, Norway.
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Cata JP, Weng HR, Chen JH, Dougherty PM. Altered discharges of spinal wide dynamic range neurons and down-regulation of glutamate transporter expression in rats with paclitaxel-induced hyperalgesia. Neuroscience 2006; 138:329-38. [PMID: 16361064 DOI: 10.1016/j.neuroscience.2005.11.009] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Revised: 10/17/2005] [Accepted: 11/08/2005] [Indexed: 01/06/2023]
Abstract
Changes in the signaling of wide dynamic range neurons and the expression of glutamate transporters in the lumbar spinal dorsal horn of rats with Taxol-induced hyperalgesia are detailed in this report. Deep spinal lamina neurons have significantly increased spontaneous activity and after-discharges to noxious mechanical stimuli, increased responses to both skin heating and cooling, and increased after-discharges and abnormal windup to transcutaneous electrical stimuli. The expression of glutamate transporter proteins in the dorsal horn is decreased at the time point corresponding to the physiological changes. These results suggest a state of increased excitability develops in spinal pain-signaling neurons as a consequence of decreased glutamate clearance. These changes in dorsal horn neurobiology likely in turn contribute to the hyper-responsiveness to sensory stimuli seen in animals treated with Taxol and may play a role in the pain seen in cancer patients receiving Taxol.
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Affiliation(s)
- J P Cata
- Department of Anesthesiology and Pain Research, Division of Anesthesiology and Critical Care Medicine, University of Texas-M.D. Anderson Cancer Center, Houston, TX 77030, USA
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Komaki A, Esteky H. Effects of neonatal C-fiber depletion on neocortical long-term potentiation and depression. Brain Res 2005; 1054:135-42. [PMID: 16081053 DOI: 10.1016/j.brainres.2005.06.059] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2005] [Revised: 06/20/2005] [Accepted: 06/25/2005] [Indexed: 11/23/2022]
Abstract
Capsaicin (Cap)-induced depletion of C-fiber afferents results in plasticity of somatosensory system which is manifested as a functional alteration at different levels of the somatosensory pathway. In the present study we examined the effect of Cap-induced neonatal depletion of C-fibers on the induction of long-term potentiation (LTP) and long-term depression (LTD) in the neocortex of freely moving rats. A stimulating electrode was implanted into corpus callosum and a recording electrode was implanted in the somatosensory cortex of control (Con: normal, without electrical stimulation), trained (normal, with electrical stimulation) and Cap-treated (C-fiber depleted, with electrical stimulation) adult rats. Two weeks after the surgery, evoked field potential responses were recorded before, during (12 days) and after (1 month) the induction period of LTP and LTD. The LTP and LTD response characteristics during the time course of recording were compared between different groups. In the train group, LTP and LTD appeared after 3 days of stimulation. LTP magnitude peaked after about 6 days while LTD magnitude peaked in about 12 days. C-fiber depletion postponed the development of LTP and LTD making the highest differential levels of LTP about 6 days after the initiation of LTP induction. The impact of C-fiber depletion on slowing the time course of LTD induction was more prolonged and lasted until day 12 of the initiation of LTD induction. These results suggest that intact C-fibers are necessary for normal plasticity and long-term synaptic modification of the somatosensory system.
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Affiliation(s)
- Alireza Komaki
- Research Center for Brain and Cognitive Sciences, Shaheed Beheshti University of Medical Sciences, Tehran, Iran.
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Barter L, Dominguez CL, Carstens E, Antognini JF. The effect of isoflurane and halothane on electroencephalographic activation elicited by repetitive noxious c-fiber stimulation. Neurosci Lett 2005; 382:242-7. [PMID: 15925098 DOI: 10.1016/j.neulet.2005.03.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2004] [Revised: 02/02/2005] [Accepted: 03/11/2005] [Indexed: 11/17/2022]
Abstract
Windup is the progressive increase in neuronal response to a repetitive noxious stimulus. This response is most often observed in the spinal cord, but it is unclear how this response is manifested in supraspinal structures. We investigated the effects of isoflurane and halothane on electroencephalographic responses to repetitive noxious electrical stimuli (20 pulses at 0.1, 1 and 3 Hz) applied to the tail in rats. Halothane and isoflurane concentrations were adjusted to 0.8 and 1.2 minimum alveolar concentration (MAC), where MAC is the concentration needed to prevent gross and purposeful movement in 50% of animals. At 0.8 MAC halothane, the 3 Hz stimulus caused electroencephalographic (EEG) activation primarily by increasing the median edge frequency (MEF), while at 1.2 MAC halothane the spectral edge frequency (SEF) was increased by the 1 and 3 Hz stimuli, and the MEF was increased by the 3 Hz stimuli. At 0.8 MAC isoflurane, the 1 and 3 Hz stimuli evoked EEG activation by increasing the MEF and SEF, while at 1.2 MAC only the MEF was increased by the 1 Hz stimulus. No EEG activation occurred with the 0.1 Hz repetitive stimulus with either isoflurane or halothane. These data suggest that repetitive electrical stimulation normally associated with windup in spinal neurons can evoke EEG activation.
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Affiliation(s)
- Linda Barter
- Department of Anesthesiology and Pain Medicine, University of California, Davis, CA 95616, USA
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Petersson P, Granmo M, Schouenborg J. Properties of an Adult Spinal Sensorimotor Circuit Shaped Through Early Postnatal Experience. J Neurophysiol 2004; 92:280-8. [PMID: 14985408 DOI: 10.1152/jn.00063.2004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During development, information about the three-dimensional shape and mechanical properties of the body is laid down in the synaptic connectivity of sensorimotor systems through adaptive mechanisms. This functional adaptation occurs through alteration of connection properties. Here, we characterize the differences between strong and weak connections in the nociceptive withdrawal reflex in adult decerebrate spinal rats, representing the preserved end product of the developmental adaptation process. Stronger excitatory reflex connections from the skin onto a muscle had relatively higher gain in their input-output relations, shorter onset latencies (up to ∼150 ms) and lower trial-to-trial variability in relation to response amplitude (SD ∼ mean1/2) than weaker pathways. Although inhibitory and excitatory nociceptive receptive fields of a muscle overlap to some degree, the results indicate that the inhibitory input is not a major determinant of the gain distribution within the excitatory receptive field and vice versa. The N-methyl-d-aspartate (NMDA) receptor antagonist, d-2-amino-5-phosphonovalerate (0.1–1 μg), applied topically on the spinal cord reduced the gain, whereas the response amplitude was mainly reduced by an absolute number by the alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor antagonist, 6-nitro-7-sulfamoylbenzo(f)quinoxaline-2,3-dione (1–10 μg). The results indicate that NMDA receptors have a critical role in gain regulation in the nociceptive withdrawal reflex system. It is suggested that after normal postnatal experience-dependent adaptation, the number of connections from a given skin site onto the reflex encoding interneurons is a major determinant of the difference in gain.
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Affiliation(s)
- Per Petersson
- Section for Neurophysiology, Department of Physiological, University of Lund, Sweden.
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