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Sartori BM, Moreira Júnior RE, Paiva IM, Moraes IB, Murgas LDS, Brunialti-Godard AL. Acute ethanol exposure leads to long-term effects on memory, behavior, and transcriptional regulation in the zebrafish brain. Behav Brain Res 2023; 444:114352. [PMID: 36842314 DOI: 10.1016/j.bbr.2023.114352] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 02/02/2023] [Accepted: 02/15/2023] [Indexed: 02/27/2023]
Abstract
Alcohol consumption is associated with alterations in memory and learning processes in humans and animals. In this context, research models such as the zebrafish (Danio rerio) arise as key organisms in behavioral and molecular studies that attempt to clarify alterations in the Central Nervous System (CNS), like those related to alcohol use. Accordingly, we used the zebrafish as a model to evaluate the effects of ethanol on the learning and memory process, as well as its relationship with behavior and transcriptional regulation of lrfn2, lrrk2, grin1a, and bdnf genes in the brain. To this end, for the memory and learning evaluation, we conducted the Novel Object Recognition test (NOR); for behavior, the Novel Tank test; and for gene transcription, qPCR, after 2 h, 24 h, and 8 days of ethanol exposure. As a result, we noticed in the NOR that after 8 days of ethanol exposure, the control group spent more time exploring the novel object than when compared to 2 h post-exposure, indicating that naturally zebrafish remember familiar objects. In animals in the Treatment group, however, no object recognition behavior was observed, suggesting that alcohol affected the learning and memory processes of the animals and stimulated an anxiolytic effect in them. Regarding transcriptional regulation, 24 h after alcohol exposure, we found hyper-regulation of bdnf and, after 8 days, a hypo-regulation of lrfn2 and lrrk2. To conclude, we demonstrated that ethanol exposure may have influenced learning ability and memory formation in zebrafish, as well as behavior and regulation of gene transcription. These data are relevant for further understanding the application of zebrafish in research associated with ethanol consumption and behavior.
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Affiliation(s)
- Barbara Miranda Sartori
- Laboratório de Genética Animal e Humana, Departamento de Genética, Ecologia e Evolução, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Renato Elias Moreira Júnior
- Laboratório de Genética Animal e Humana, Departamento de Genética, Ecologia e Evolução, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Isadora Marques Paiva
- Laboratório de Genética Animal e Humana, Departamento de Genética, Ecologia e Evolução, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil; Centro de Pesquisas em Doenças Inflamatórias (CRID), Faculdade de Medicina de Ribeirão Preto, Departamento de Farmacologia, Universidade de São Paulo (FMRP), Ribeirão Preto, Brazil
| | - Izabela Barbosa Moraes
- Laboratório de Genética Animal e Humana, Departamento de Genética, Ecologia e Evolução, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil; Centro das Ciências Biológicas e da Saúde, Universidade Federal do Oeste da Bahia (UFOB), Barreiras, Brazil
| | - Luis David Solis Murgas
- Biotério Central, Departamento de Medicina Veterinária, Universidade Federal de Lavras (UFLA), Lavras, Brazil
| | - Ana Lúcia Brunialti-Godard
- Laboratório de Genética Animal e Humana, Departamento de Genética, Ecologia e Evolução, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil.
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Aby F, Bouali-Benazzouz R, Landry M, Fossat P. Windup of Nociceptive Flexion Reflex Depends on Synaptic and Intrinsic Properties of Dorsal Horn Neurons in Adult Rats. Int J Mol Sci 2019; 20:ijms20246146. [PMID: 31817540 PMCID: PMC6940907 DOI: 10.3390/ijms20246146] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/20/2019] [Accepted: 12/02/2019] [Indexed: 11/25/2022] Open
Abstract
Windup, a progressive increase in spinal response to repetitive stimulations of nociceptive peripheral fibers, is a useful model to study central sensitization to pain. Windup is expressed by neurons in both the dorsal and ventral horn of the spinal cord. In juvenile rats, it has been demonstrated both in vivo and in vitro that windup depends on calcium-dependent intrinsic properties and their modulation by synaptic components. However, the involvement of these two components in the adults remains controversial. In the present study, by means of electromyographic and extracellular recordings, we show that windup in adults, in vivo, depends on a synaptic balance between excitatory N-methyl-D-aspartate (NMDA) receptors and inhibitory glycinergic receptors. We also demonstrate the involvement of L-type calcium channels in both the dorsal and ventral horn of the spinal cord. These results indicate that windup in adults is similar to juvenile rats and that windup properties are the same regardless of the spinal network, i.e., sensory or motor.
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Buvanendran A, Kroin JS, Rajagopal A, Robison SJ, Moric M, Tuman KJ. Oral Ketamine for Acute Pain Management After Amputation Surgery. PAIN MEDICINE 2017; 19:1265-1270. [DOI: 10.1093/pm/pnx229] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Asokumar Buvanendran
- Department of Anesthesiology, Rush University Medical Center, Chicago, Illinois, USA
| | - Jeffrey S Kroin
- Department of Anesthesiology, Rush University Medical Center, Chicago, Illinois, USA
| | - Arvind Rajagopal
- Department of Anesthesiology, Rush University Medical Center, Chicago, Illinois, USA
| | - Sherry J Robison
- Department of Anesthesiology, Rush University Medical Center, Chicago, Illinois, USA
| | - Mario Moric
- Department of Anesthesiology, Rush University Medical Center, Chicago, Illinois, USA
| | - Kenneth J Tuman
- Department of Anesthesiology, Rush University Medical Center, Chicago, Illinois, USA
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Xiao F, Xu W, Feng Y, Fu F, Zhang X, Zhang Y, Wang L, Chen X. Intrathecal magnesium sulfate does not reduce the ED 50 of intrathecal hyperbaric bupivacaine for cesarean delivery in healthy parturients: a prospective, double blinded, randomized dose-response trial using the sequential allocation method. BMC Anesthesiol 2017; 17:8. [PMID: 28095795 PMCID: PMC5240204 DOI: 10.1186/s12871-017-0300-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 01/02/2017] [Indexed: 01/27/2023] Open
Abstract
Background Addition of intrathecal magnesium sulfate to local anesthetics has been reported to potentiate spinal anesthesia and prolong analgesia in parturients. The current study was to determine whether intrathecal magnesium sulfate would reduce the dose of hyperbaric bupivacaine in spinal anesthesia with bupivacaine and sufentanil for cesarean delivery. Methods Sixty healthy parturients undergoing scheduled cesarean delivery were randomly assigned to receive spinal anesthesia with 0.5% hyperbaric bupivacaine and 5 μg sufentanil with either 0.9% sodium chloride (Control group) or 50% magnesium sulfate (50 mg) (Magnesium group). Effective anesthesia was defined as a bilateral T5 sensory block level achieved within 10 min of intrathecal drug administration and no additional epidural anesthetic was required during surgery. Characteristic of spinal anesthesia and the incidence of side effects were observed. The ED50 for both groups was calculated using the Dixon and Massey formula. Results There was no significant difference in the ED50 of bupivacaine between the Magnesium group and the Control group (4.9 mg vs 4.7 mg) (P = 0.53). The duration of spinal anesthesia (183 min vs 148 min, P < 0.001) was longer, the consumption of fentanyl during the first 24 h postoperatively (343 μg vs 550 μg, P < 0.001) was lower in the Magnesium group than that in the Control group. Conclusions Intrathecal magnesium sulfate (50 mg) did not reduce the dose requirement of intrathecal bupivacaine, but can extend the duration of spinal anesthesia with no obvious additional side effects. Trial registration This study was registered with Chinese Clinical Trial Registry (ChiCTR) on 15 Jul. 2014 and was given a trial ID number ChiCTR-TRC-14004954.
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Affiliation(s)
- Fei Xiao
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Department of Anesthesia, Jiaxing Maternity and Child Care Hospital, Jiaxing, Zhejiang, China
| | - Wenping Xu
- Department of Anesthesia, Jiaxing Maternity and Child Care Hospital, Jiaxing, Zhejiang, China
| | - Ying Feng
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Feng Fu
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaomin Zhang
- Department of Anesthesia, Jiaxing Maternity and Child Care Hospital, Jiaxing, Zhejiang, China
| | - Yinfa Zhang
- Department of Anesthesia, Jiaxing Maternity and Child Care Hospital, Jiaxing, Zhejiang, China
| | - Lizhong Wang
- Department of Anesthesia, Jiaxing Maternity and Child Care Hospital, Jiaxing, Zhejiang, China
| | - Xinzhong Chen
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
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Miranda A, Mickle A, Bruckert M, Kannampalli P, Banerjee B, Sengupta JN. NMDA receptor mediates chronic visceral pain induced by neonatal noxious somatic stimulation. Eur J Pharmacol 2014; 744:28-35. [PMID: 25281204 DOI: 10.1016/j.ejphar.2014.09.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 09/22/2014] [Accepted: 09/23/2014] [Indexed: 12/29/2022]
Abstract
NMDA receptors (NMDAR) are important in the development and maintenance of central sensitization. Our objective was to investigate the role of spinal neurons and NMDAR in the maintenance of chronic visceral pain. Neonatal rats were injected with acidic saline adjusted to pH 4.0 in the gastrocnemius muscle every other day for 12 days. In adult rats, NR1 and NR2B subunits were examined in the lumbo-sacral (LS) spinal cord. A baseline, visceromotor response (VMR) to graded colorectal distension (CRD) was recorded before and after administration of the NMDA antagonist, CGS-19755. Extracellular recordings were performed from CRD-sensitive LS spinal neurons and pelvic nerve afferents (PNA) before and after CGS-19755. Rats that received pH 4.0 saline injections demonstrated a significant increase in the expression NR2B subunits and VMR response to CRD>20 mmHg. CGS-19755 (i.v. or i.t.) had no effect in naïve rats, but significantly decreased the response to CRD in pH 4.0 saline injected rats. CGS-19755 had no effect on the spontaneous firing of SL-A, but decreased that of SL-S. Similarly, CGS-19755 attenuates the responses of SL-S neurons to CRD, but had no effect on SL-A neurons or on the response characteristics of PNA fibers. Neonatal noxious somatic stimulation results in chronic visceral hyperalgesia and sensitizes a specific subpopulation of CRD-sensitive spinal neurons. The sensitization of these SL-S spinal neurons is attenuated by the NMDAR antagonist. The results of this study suggest that spinal NMDARs play an important role in the development of hyperalgesia early in life.
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Affiliation(s)
- Adrian Miranda
- Division of Gastroenterology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, United States.
| | - Aaron Mickle
- Division of Gastroenterology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Mitchell Bruckert
- Division of Gastroenterology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Pradeep Kannampalli
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Banani Banerjee
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Jyoti N Sengupta
- Division of Gastroenterology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, United States; Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, United States
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Jin J, Gong K, Zou X, Wang R, Lin Q, Chen J. The blockade of NMDA receptor ion channels by ketamine is enhanced in developing rat cortical neurons. Neurosci Lett 2013; 539:11-5. [PMID: 23395831 DOI: 10.1016/j.neulet.2013.01.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 12/03/2012] [Accepted: 01/18/2013] [Indexed: 10/27/2022]
Abstract
Ketamine is a non-competitive antagonist of NMDA receptors (NMDARs) commonly used as a dissociative anesthetic in many pediatric procedures. Ketamine acts primarily by blocking NMDA ligand-gated channels. Experimental studies indicate that ketamine administration used for inducing clinically relevant anesthesia can lead to neurotoxic effects, such as apoptosis, selectively on immature brain neurons. However, the underlying mechanisms remain unclear. This study used whole-cell patch-clamp recordings in an in vitro preparation of forebrain slices to analyze pharmacologically the differences in the effects of ketamine administration on the NMDAR channel activity between immature and mature neurons. NMDAR channel activity was recorded in the form of evoked NMDAR-mediated excitatory postsynaptic currents (eEPSCs) from the forebrain of both neonatal and adult rats. Results show that ketamine inhibited eEPSCs in a dose-dependent manner in both immature and mature neurons. However, at each concentration of ketamine applied to the brain slice, a more extensive inhibition could be seen in neonatal neurons than in adult neurons. Further, the blocking effect of ketamine on eEPSCs was measured during the period of 1, 3, and 6h after ketamine washout. Inhibition of eEPSCs in immature neurons was still evident 6h after washout. In contrast, the blockade of eEPSCs in mature neurons recovered completely from the inhibition by ketamine in a time-dependent manner. These results indicate that ketamine produces a greater and longer blocking effect on NMDAR channels in immature neurons than in mature neurons. This differential effect is likely to be a critical link to the higher vulnerability to ketamine-induced neurotoxicity in neurons of the developing brain.
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Affiliation(s)
- Jianhui Jin
- Institute for Biomedical Sciences of Pain, Capital Medical University, Beijing, China
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A Translational Study of the Effects of Ketamine and Pregabalin on Temporal Summation of Experimental Pain. Reg Anesth Pain Med 2011; 36:585-91. [DOI: 10.1097/aap.0b013e31822b0db0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Sanders RD, Xu J, Shu Y, Fidalgo A, Ma D, Maze M. General anesthetics induce apoptotic neurodegeneration in the neonatal rat spinal cord. Anesth Analg 2008; 106:1708-11. [PMID: 18499598 DOI: 10.1213/ane.0b013e3181733fdb] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Exposure to anesthetics triggers apoptotic neurodegeneration in the neonatal rat brain; whether neuronal apoptosis also occurs in the spinal cord, a crucial target for analgesic and anesthetic drugs, is unknown. METHODS We exposed 7-day-old rats were exposed to air or 75% nitrous oxide + 0.75% isoflurane in oxygen for 6 h (n = 19 per group). Caspase-3 immunoreactivity was evaluated in the lumbar spinal cord at the end of the gas exposure (n = 3 per group). Developmental nociceptive responses were tested using tail flick latencies on postnatal days 8, 15, and 30 (n = 3 per group). Motor responses were evaluated using the rotarod on postnatal day 30 (n = 7 per group). RESULTS Isoflurane plus nitrous oxide increased the numbers of caspase-3 positive neurons in the spinal cord (P < 0.01). Despite a preponderance of the injury in the ventral horn of the spinal cord, motor impairment did not occur (P > 0.05). No functional effect on nociception was observed at the three developmental stages tested (P > 0.05). CONCLUSIONS Anesthesia induces apoptosis in the neonatal rat spinal cord; however, the functional consequences of this injury, if any, remain obscure. Neither motor nor nociceptive responses were affected by anesthetic treatment. Nonetheless, further investigation is required as regional anesthetic techniques may also trigger neuroapoptosis in the spinal cord with unknown potency.
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Affiliation(s)
- Robert D Sanders
- Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College London, Chelsea & Westerminster Hospital, London, UK
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Ng KP, Antognini JF. Isoflurane and Propofol Have Similar Effects on Spinal Neuronal Windup at Concentrations that Block Movement. Anesth Analg 2006; 103:1453-8. [PMID: 17122222 DOI: 10.1213/01.ane.0000247732.33602.f5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND We investigated the actions of isoflurane and propofol on neuronal windup in the spinal cord of intact rats. We hypothesized that propofol would depress windup more than isoflurane. METHODS In a cross-over design, rats received 0.8 and 1.2 minimum alveolar concentration (MAC) isoflurane and 0.8 and 1.2 ED50 (effective dose(50%)) of propofol, as recordings were made from single units in the lumbar cord (n = 13). Electrical stimuli were applied (20 stimuli at 0.1, 1, and 3 Hz). Neuronal responses were analyzed for those occurring in the C-fiber range (100-400 ms after each stimulus), combined C-fiber and afterdischarge range (100-1000 ms) and the 100-333 ms range for the 3 Hz stimuli. Absolute windup was also calculated (the sum of action potentials for 20 stimuli - 20 x response to the first stimulus). RESULTS At 1 Hz, total action potentials (mean, standard error) summed across the 20 stimuli (100-1000 ms range) were 571 +/- 106 and 742 +/- 214 for isoflurane (at 0.8 and 1.2 MAC) and 586 +/- 148 and 641 +/- 143 for propofol (at 0.8 and 1.2 ED50), respectively (P = NS); corresponding values for the 0.1 Hz stimuli were 345 +/- 104, 370 +/- 108, 430 +/- 86, and 403 +/- 106 (P = NS), and for the 3 Hz stimuli (100-333 ms range) were 266 +/- 66, 333 +/- 76, 343 +/- 85, and 252 +/- 72 (P = NS). Absolute windup in the 100-1000 ms range was greater for 1.2 MAC isoflurane at 1 Hz (445 +/- 82, P < 0.01), when compared with absolute windup at 0.8 MAC isoflurane and 0.8 and 1.2 ED50 propofol (232 +/- 31, 88 +/- 65, and 210 +/- 41, respectively). CONCLUSIONS These data suggest that isoflurane and propofol have similar effects on neuronal windup in the spinal cord, although there was enhanced absolute windup at 1.2 MAC isoflurane for the 1 Hz stimulus.
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Affiliation(s)
- Kevin P Ng
- Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, California 95616, USA
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Yamamoto S, Honda M, Tanabe M, Ono H. Spinal ventral root after-discharges as a pain index: Involvement of NK-1 and NMDA receptors. Brain Res 2006; 1082:115-23. [PMID: 16507302 DOI: 10.1016/j.brainres.2006.01.097] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 01/23/2006] [Accepted: 01/25/2006] [Indexed: 10/25/2022]
Abstract
Nociceptive signals are transmitted to the spinal dorsal horn via primary afferent fibers, and the signals induce withdrawal reflexes by activating spinal motoneurons in the ventral horn. Therefore, nociceptive stimuli increase motoneuronal firing and ventral root discharges. This study was aimed to develop a method for the study of pain mechanisms and analgesics by recording ventral root discharges. Spinalized rats were laminectomized in the lumbo-sacral region. The fifth lumbar ventral root was sectioned and placed on a pair of wire electrodes. Multi unit efferent discharges from the ventral root were increased by mechanical stimulation using a von Frey hair applied to the plantar surface of the hindpaw. The low-intensity mechanical stimuli increased the discharges during stimulation (during-discharges) without increasing the discharges after cessation of stimulation (after-discharges), and the high-intensity mechanical stimuli increased both during- and after-discharges. Pretreatment with resiniferatoxin, an ultrapotent analogue of capsaicin, halved during-discharges and eliminated after-discharges, suggesting that after-discharges are generated by heat- and mechanosensitive polymodal nociceptors. Ezlopitant, a neurokinin-1 (NK-1) receptor antagonist, but not its inactive enantiomer, selectively reduced the after-discharges. Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, preferentially reduced the after-discharges, demonstrating that NK-1 and NMDA receptors mediate the after-discharges. Morphine reduced the after-discharges without affecting during-discharges. By contrast, mephenesin, a centrally acting muscle relaxant, reduced both during- and after-discharges. There results suggest that simultaneous recordings of during- and after-discharges are useful to study pain mechanisms and analgesics as well as to discriminate the analgesic effects from the side effects such as muscle relaxant effects.
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Affiliation(s)
- Shohei Yamamoto
- Laboratory of CNS Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Nagoya 467-8603, Japan
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Caudle RM, Perez FM, Del Valle-Pinero AY, Iadarola MJ. Spinal cord NR1 serine phosphorylation and NR2B subunit suppression following peripheral inflammation. Mol Pain 2005; 1:25. [PMID: 16137337 PMCID: PMC1208948 DOI: 10.1186/1744-8069-1-25] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Accepted: 09/02/2005] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Spinal cord N-methyl-D-aspartate (NMDA) receptors are intimately involved in the development and maintenance of central sensitization. However, the mechanisms mediating the altered function of the NMDA receptors are not well understood. In this study the role of phosphorylation of NR1 splice variants and NR2 subunits was examined following hind paw inflammation in rats. We further examined the level of expression of these proteins following the injury. RESULTS Lumbar spinal cord NR1 subunits were found to be phosphorylated on serine residues within two hours of the induction of hind paw inflammation with carrageenan. The enhanced NR1 serine phosphorylation reversed within six hours. No phosphorylation on NR1 threonine or tyrosine residues was observed. Likewise, no NR2 subunit phosphorylation was observed on serine, threonine or tyrosine residues. An analysis of NR1 and NR2 protein expression demonstrated no change in the levels of NR1 splice variants or NR2A following the inflammation. However, spinal cord NR2B expression was depressed by the hind paw inflammation. The expression of NR2B remained depressed for more than one week following initiation of the inflammation. CONCLUSION These data suggest that NR1 serine phosphorylation leads to an initial increase in NMDA receptor activity in the spinal cord following peripheral injury. The suppression of NR2B expression suggests compensation for the enhanced nociceptive activity. These data indicate that spinal cord NMDA receptors are highly dynamic in the development, maintenance and recovery from central sensitization following an injury. Thus, chronic pain therapies targeted to NMDA receptors should be designed for the exact configuration of NMDA receptor subunits and post-translational modifications present during specific stages of the disease.
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Affiliation(s)
- Robert M Caudle
- Department of Oral and Maxillofacial Surgery and Diagnostic Sciences, University of Florida College of Dentistry, Gainesville, FL 32610, USA
- Department of Neuroscience, University of Florida College of Medicine, McKnight Brain Institute, Gainesville, FL 32610, USA
| | - Federico M Perez
- Department of Oral and Maxillofacial Surgery and Diagnostic Sciences, University of Florida College of Dentistry, Gainesville, FL 32610, USA
| | - Arseima Y Del Valle-Pinero
- Department of Neuroscience, University of Florida College of Medicine, McKnight Brain Institute, Gainesville, FL 32610, USA
| | - Michael J Iadarola
- Pain and Neurosensory Mechanisms Branch, National Institutes of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
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Cuellar JM, Montesano PX, Antognini JF, Carstens E. Application of nucleus pulposus to L5 dorsal root ganglion in rats enhances nociceptive dorsal horn neuronal windup. J Neurophysiol 2005; 94:35-48. [PMID: 15744012 DOI: 10.1152/jn.00762.2004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Herniation of the nucleus pulposus (NP) from lumbar intervertebral discs commonly results in radiculopathic pain possibly through a neuroinflammatory response. NP sensitizes dorsal horn neuronal responses, but it is unknown whether this reflects a central or peripheral sensitization. To study central sensitization, we tested if NP enhances windup--the progressive increase in the response of a nociceptive spinal neuron to repeated electrical C-fiber stimulation--a phenomenon that may partly account for temporal summation of pain. Single-unit recordings were made from wide dynamic range (WDR; n = 36) or nociceptive-specific (NS; n = 8) L5 dorsal horn neurons in 44 isoflurane-anesthetized rats. Subcutaneous electrodes delivered electrical stimuli (20 pulses, 3 times the C-fiber threshold, 0.5 ms) to the receptive field on the hindpaw. Autologous NP was harvested from a tail disc and placed onto the L5 dorsal root ganglion after recording of baseline responses (n = 22). Controls had saline applied similarly (n = 22). Electrical stimulus trains (0.1, 0.3, and 1 Hz; 5-min interstimulus interval) were repeated every 30 min for 3-6 h after each treatment. The total number of evoked spikes (summed across all 20 stimuli) to 0.1 Hz was enhanced 3 h after NP, mainly in the after-discharge (AD) period (latency > 400 ms). Total responses to 0.3 and 1.0 Hz were also enhanced at > or = 60 min after NP in both the C-fiber (100- to 400-ms latency) and AD periods, whereas the absolute windup (C-fiber + AD - 20 times the initial response) increased at > or = 90 min after treatment. In saline controls, windup was not enhanced at any time after treatment for any stimulus frequency, although there was a trend toward enhancement at 0.3 Hz. These results are consistent with NP-induced central sensitization. Mechanical responses were not significantly enhanced after saline or NP treatment. We speculate that inflammatory agents released from (or recruited by) NP affect the dorsal root ganglion (and/or are transported to cord) to enhance primary afferent excitation of nociceptive dorsal horn neurons.
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Affiliation(s)
- J M Cuellar
- Section of Neurobiology, Physiology and Behavior, University of California, Davis, 1 Shields Ave., Davis, California 95616, USA
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Abstract
The dorsal horn of the spinal cord is a key relay in the transmission of sensory information to the brain. Furthermore, this circuitry of spinal-cord neurons, and hence the spinal processing of sensory information, is subject to a great deal of plasticity, both pharmacological and physiological, in persistent pain states. This chapter describes in detail the procedure by which the activity and pharmacological modulation of these dorsal-horn neurons can be recorded in vivo in anesthetized rats, allowing a comprehensive study of spinal sensory processing in an intact and integrated system. The chapter covers the surgical preparation of the animal for electrophysiological recording; isolating and recording the activity of a single dorsal-horn neuron; and identifying the type of dorsal-horn neuron recorded by characterizing the neuronal response to a variety of peripheral stimuli. The study of these neuronal responses in a variety of persistent pain states, such as carrageenan-induced inflammation and neuropathy induced by L5/L6 spinal nerve ligation, together with the study of their pharmacological modulation by locally or systemically administered drugs, is also described.
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Urch CE, Dickenson AH. Neuronal Nitric Oxide Synthase Modulation of Dorsal Horn Neuronal Responses in the Rat: A Developmental Study. Dev Neurosci 2003; 25:301-7. [PMID: 14614256 DOI: 10.1159/000073506] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2002] [Accepted: 04/15/2003] [Indexed: 11/19/2022] Open
Abstract
Nitric oxide (NO) is a diffusible chemical messenger functionally linked to N-methyl-D-aspartate (NMDA) receptor activity and has been shown to be involved in modulating numerous pathways in the central nervous system. In order to investigate the role of the neuronal NO synthase type I (nNOS)/NO system in the postnatal development of dorsal horn nociceptive pathways in rats, the specific nNOS inhibitor 7-nitroindazole sodium salt (7-NI) and the non-specific NOS inhibitor nitro-L-arginine methyl ester (L-NAME) were applied spinally at postnatal days (P) 14, 21, 28 and >56 (adult) and their effects on neuronal responses were compared. In response to a train of 16 noxious electrical stimuli, the wide dynamic range neurones in the deep dorsal horn showed a dose-dependent inhibition of C-fibre-evoked response, post-discharge and windup to both 7-NI and L-NAME. No difference between any age group was observed with either agent on these responses. However, the effect of both 7-NI and L-NAME on the primary evoked response, a measure of the events occurring pre-synaptic and intrinsic to the neurone recorded, was significantly different between the P14 and older age groups. nNOS is known to be expressed later in postnatal development than the NMDA receptor and from the results presented here, it is fully mature and functional from P14 onwards. The subtle differences in attenuation of the primary evoked response at P14 compared with older ages may reflect the immaturity of the dorsal horn and in particular the incomplete development of intrinsic and descending inhibitory controls.
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Affiliation(s)
- C E Urch
- Department of Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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Urch CE, Dickenson AH. In vivo single unit extracellular recordings from spinal cord neurones of rats. BRAIN RESEARCH. BRAIN RESEARCH PROTOCOLS 2003; 12:26-34. [PMID: 12928042 DOI: 10.1016/s1385-299x(03)00068-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A method for in vivo single unit extracellular recordings from the dorsal horn of rat or mouse spinal cords is described. This method allows the complex, dynamic and plastic circuitry of the dorsal horn to be explored in various models and situations. Briefly, the spinal cord is exposed in deeply anaesthetised animals and a recording electrode is inserted into the dorsal horn. To isolate a neurone the electrode is moved incrementally through the cord whilst the ipsilateral hindpaw (receptive field) is stimulated with a light tap. The neurone can then be characterised according to its depth, latency of Abeta-, Adelta- and C-fibre responses and its response to natural (brush, heat, pressure) and electrical stimulation. The neuronal response is captured, filtered, amplified and displayed via an oscilloscope and speakers, and fed through to a computer where the responses can be integrated and displayed in numerous formats. This basic technique can be adapted to record from animals of various ages, to investigate alterations in spinal processing, suprapsinal influences, receptive field size and so on, and to assess the impact of therapeutic or other interventions. A key issue is that this type of approach, unlike behavioural assessment that relies on threshold measures, allows quantitative measures of suprathreshold activity, closer to the clinical situation.
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Affiliation(s)
- C E Urch
- Department of Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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Guo H, Huang LY. Alteration in the voltage dependence of NMDA receptor channels in rat dorsal horn neurones following peripheral inflammation. J Physiol 2001; 537:115-23. [PMID: 11711566 PMCID: PMC2278919 DOI: 10.1111/j.1469-7793.2001.0115k.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
1. It has been proposed that the activation of NMDA receptors and upregulation of protein kinase C (PKC) underlie the exaggerated and persistent pain experienced in the inflammatory state. However, there is no direct evidence to show that inflammation alters the function of NMDA receptors. 2. We examined the voltage-dependent properties of NMDA receptor channels in rat dorsal horn neurones that receive sensory inputs from an inflamed hindpaw. 3. Peripheral inflammation was induced by injections of complete Freund's adjuvant (CFA). Membrane currents were measured using the perforated patch-clamp technique. 4. After CFA treatment, the current-voltage relationship of NMDA receptor channels was shifted in the hyperpolarized direction. This resulted in enhanced NMDA responses at negative potentials. 5. The change was mediated by PKC because the voltage shift was blocked by the selective PKC inhibitors chelerythrine and bisindolylmaleimide I. 6. Furthermore, the Mg(2+) blockade of NMDA receptors was reduced. This reduction could account for the shift in the voltage dependence of NMDA receptor channels. 7. These results indicate that NMDA receptor channel characteristics in the dorsal horn are altered by inflammation, and that the changes observed could contribute to the hyperalgesia and allodynia associated with tissue injury.
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Affiliation(s)
- H Guo
- Marine Biomedical Institute, University of Texas Medical Branch, Galveston, TX 77555-1069, USA
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