1
|
Role of neuroglia in neuropathic pain and depression. Pharmacol Res 2021; 174:105957. [PMID: 34688904 DOI: 10.1016/j.phrs.2021.105957] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/06/2021] [Accepted: 10/20/2021] [Indexed: 12/30/2022]
Abstract
Patients with neuropathic pain induced by nerve injury usually present with co-morbid affective changes, such as depression. Neuroglia was reported to play an important role in the development and maintenance of neuropathic pain both centrally and peripherally. Meanwhile, there have been studies showing that neuroglia participated in the development of depression. However, the specific role of neuroglia in neuropathic pain and depression has not been reviewed comprehensively. Therefore, we summarized the recent findings on the role of neuroglia in neuropathic pain and depression. Based on this review, we found a bridge-like role of neuroglia in neuropathic pain co-morbid with depression. This review may provide therapeutic implications in the treatment of neuropathic pain and offer potential help in the studies of mechanisms in the future.
Collapse
|
2
|
Mohamed AA, Alawna M. The use of passive cable theory to increase the threshold of nociceptors in people with chronic pain. PHYSICAL THERAPY REVIEWS 2020. [DOI: 10.1080/10833196.2020.1853493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Ayman A. Mohamed
- Department of Physiotherapy, Faculty of Health Sciences, Istanbul Gelisim University, Turkey
| | - Motaz Alawna
- Department of Physiotherapy, Faculty of Health Sciences, Istanbul Gelisim University, Turkey
- Department of Physiotherapy and Rehabilitation, Faculty of Allied Medical Sciences, Arab American University, Jenin, Palestin
| |
Collapse
|
3
|
Liu X, Wang G, Ai G, Xu X, Niu X, Zhang M. Selective Ablation of Descending Serotonin from the Rostral Ventromedial Medulla Unmasks Its Pro-Nociceptive Role in Chemotherapy-Induced Painful Neuropathy. J Pain Res 2020; 13:3081-3094. [PMID: 33262643 PMCID: PMC7700091 DOI: 10.2147/jpr.s275254] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/22/2020] [Indexed: 12/22/2022] Open
Abstract
Purpose Chemotherapy-induced painful neuropathy (CIPN) is a severe adverse effect of many anti-neoplastic drugs that is difficult to manage. Serotonin (5-hydroxytryptamine, 5-HT) is an important neurotransmitter in the rostral ventromedial medulla (RVM), which modulates descending spinal nociceptive transmission. However, the influence of the descending 5-HT from the RVM on CIPN is poorly understood. We investigated the role of 5-HT released from descending RVM neurons in a paclitaxel-induced CIPN rat model. Methods CIPN rat model was produced by intraperitoneally injecting of paclitaxel. Pain behavioral assessments included mechanical allodynia and heat hyperalgesia. 5-HT content was analyzed by high-performance liquid chromatography (HPLC). Western blot and immunohistochemistry were used to determine tryptophan hydroxylase (Tph) and c-Fos expression. The inhibitors p-chlorophenylalanine (PCPA) and SB203580 were administrated by stereotaxical RVM microinjection. Ondansetron was injected through intrathecal catheterization. Results The results demonstrated that Tph, the rate-limiting enzyme in 5-HT synthesis, was significantly upregulated in the RVM, and that spinal 5-HT release was increased in CIPN rats. Intra-RVM microinjection of Tph inhibitor PCPA significantly attenuated mechanical and thermal pain behavior through Tph downregulation and decreased spinal 5-HT. Intra-RVM administration of p38 mitogen-activated protein kinase (p38 MAPK) inhibitor SB203580 alleviated paclitaxel-induced pain in a similar manner to PCPA. Intrathecal injection of ondansetron, a 5-HT3 receptor antagonist, partially reversed paclitaxel-induced pain, indicating that 5-HT3 receptors were involved in descending serotoninergic modulation of spinal pain processing. Conclusion The results suggest that activation of the p38 MAPK pathway in the RVM leads to increased RVM Tph expression and descending serotoninergic projection to the spinal dorsal horn and contributes to the persistence of CIPN via spinal 5-HT3 receptors.
Collapse
Affiliation(s)
- Xijiang Liu
- Department of Anesthesiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, People's Republic of China
| | - Gongming Wang
- Department of Anesthesiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, People's Republic of China
| | - Geyi Ai
- Department of Anesthesiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, People's Republic of China
| | - Xiqiang Xu
- Department of Orthopedics, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, People's Republic of China
| | - Xinhuan Niu
- Department of Anesthesiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, People's Republic of China
| | - Mengyuan Zhang
- Department of Anesthesiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan 250021, People's Republic of China
| |
Collapse
|
4
|
Castellanos LCS, Rozenfeld P, Gatto RG, Reisin RC, Uchitel OD, Weissmann C. Upregulation of ASIC1a channels in an in vitro model of Fabry disease. Neurochem Int 2020; 140:104824. [DOI: 10.1016/j.neuint.2020.104824] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/20/2020] [Accepted: 07/30/2020] [Indexed: 01/01/2023]
|
5
|
Feng JH, Lee HJ, Suh HW. The Molecular Signatures of Acute-immobilization-induced Antinociception and Chronic-immobilization-induced Antinociceptive Tolerance. Exp Neurobiol 2019; 28:670-678. [PMID: 31902155 PMCID: PMC6946116 DOI: 10.5607/en.2019.28.6.670] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 11/22/2019] [Accepted: 11/26/2019] [Indexed: 12/15/2022] Open
Abstract
In the present study, the productions of antinociception induced by acute and chronic immobilization stress were compared in several animal pain models. In the acute immobilization stress model (up to 1 hr immobilization), the antinociception was produced in writhing, tail-flick, and formalin-induced pain models. In chronic immobilization stress experiment, the mouse was enforced into immobilization for 1 hr/day for 3, 7, or 14 days, then analgesic tests were performed. The antinociceptive effect was gradually reduced after 3, 7 and 14 days of immobilization stress. To delineate the molecular mechanism involved in the antinociceptive tolerance development in the chronic stress model, the expressions of some signal molecules in dorsal root ganglia (DRG), spinal cord, hippocampus, and the hypothalamus were observed in acute and chronic immobilization models. The COX-2 in DRG, p-JNK, p-AMPKα1, and p-mTOR in the spinal cord, p-P38 in the hippocampus, and p-AMPKα1 in the hypothalamus were elevated in acute immobilization stress, but were reduced gradually after 3, 7 and 14 days of immobilization stress. Our results suggest that the chronic immobilization stress causes development of tolerance to the antinociception induced by acute immobilization stress. In addition, the COX-2 in DRG, p-JNK, p-AMPKα1, and p-mTOR in the spinal cord, p-P38 in the hippocampus, and p-AMPKα1 in the hypothalamus may play important roles in the regulation of antinociception induced by acute immobilization stress and the tolerance development induced by chronic immobilization stress.
Collapse
Affiliation(s)
- Jing-Hui Feng
- Department of Pharmacology and Institute of Natural Medicine, College of Medicine, Hallym University, Chuncheon 24252, Korea
| | - Hee-Jung Lee
- Department of Pharmacology and Institute of Natural Medicine, College of Medicine, Hallym University, Chuncheon 24252, Korea
| | - Hong-Won Suh
- Department of Pharmacology and Institute of Natural Medicine, College of Medicine, Hallym University, Chuncheon 24252, Korea
| |
Collapse
|
6
|
Fiore NT, Austin PJ. Peripheral Nerve Injury Triggers Neuroinflammation in the Medial Prefrontal Cortex and Ventral Hippocampus in a Subgroup of Rats with Coincident Affective Behavioural Changes. Neuroscience 2019; 416:147-167. [DOI: 10.1016/j.neuroscience.2019.08.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 06/25/2019] [Accepted: 08/02/2019] [Indexed: 12/14/2022]
|
7
|
Zhao C, Zhao J, Yang Q, Ye Y. Cobra neurotoxin produces central analgesic and hyperalgesic actions via adenosine A 1 and A 2A receptors. Mol Pain 2018; 13:1744806917720336. [PMID: 28758541 PMCID: PMC5542074 DOI: 10.1177/1744806917720336] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cobra neurotoxin, a short-chain peptide isolated from snake venom of Naja naja atra, showed both a central analgesic effect and a hyperalgesic effect in mice tests. In order to explore mechanisms, a hypothesis is put forward that cobra neurotoxin takes effect through adenosine receptor pathway. The central effects of cobra neurotoxin were evaluated using the hot plate test (a model of acute pain) and the spinal cord injury (a model of central pain) in mice and using A1 receptor antagonist (DPCPX) and A2A receptor antagonist (ZM241385); behaviors were scored and signal molecules such as reactive oxygen species and adenosine triphosphate levels and mitogen-activated protein kinases/extracellular signal-regulated protein kinase expression were measured. Low dose of cobra neurotoxin (25 µg/kg) had analgesic effects which were inhibited by DPCPX, while high dose of cobra neurotoxin (100 µg/kg) had hyperalgesic effects which were blocked by ZM241385. Cobra neurotoxin reduced reactive oxygen species and increased adenosine triphosphate in brain tissues, and extracellular signal-regulated protein kinase expression was markedly inhibited by cobra neurotoxin. Cobra neurotoxin may take effect through mitogen-activated protein kinases/extracellular signal-regulated protein kinase pathway inhibition by activating adenosine A1Rs and cause changes of reactive oxygen species and adenosine triphosphate through feedback mechanisms. Overdose cobra neurotoxin further activates the adenosine A2ARs to generate pain sensitization. This research proposes a new central analgesic mechanism of cobra neurotoxin and discloses dual regulation of pain.
Collapse
Affiliation(s)
- Chuang Zhao
- Department of Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, China
| | - Jun Zhao
- Department of Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, China
| | - Qian Yang
- Department of Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, China
| | - Yong Ye
- Department of Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, China
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, Guangzhou, China
- Yong Ye, Department of Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
| |
Collapse
|
8
|
Yu LN, Sun LH, Wang M, Yan M. Research progress of the role and mechanism of extracellular signal-regulated protein kinase 5 (ERK5) pathway in pathological pain. J Zhejiang Univ Sci B 2017; 17:733-741. [PMID: 27704743 DOI: 10.1631/jzus.b1600188] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Extracellular signal-regulated protein kinase 5 (ERK5), also known as big mitogen-activated protein kinase 1 (MAPK1), is an important member of ERK family, which is a subfamily of the large MAPK family. ERK5 is expressed in many tissues, including the dorsal root ganglion (DRG) neurons and the spinal cord. In this review, we focus on elaborating ERK5-associated pathway in pathological pain, in which the ERK5/CREB (cyclic adenosine monophosphate (cAMP)-response element-binding protein) pathway plays a crucial role in the transduction of pain signal and contributes to pain hypersensitivity. ERK5 activation in the spinal dorsal horn occurs mainly in microglia. The activation of ERK5 can be mediated by N-methyl-D-aspartate (NMDA) receptors. We also elaborate the relationship between ERK5 activation and nerve growth factor-tyrosine kinase A (NGF-TrkA), and the connection between ERK5 activation and brain-derived neurotrophic factor (BDNF) in pathological pain in detail.
Collapse
Affiliation(s)
- Li-Na Yu
- Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China
| | - Li-Hong Sun
- Jiangsu Province Key Laboratory of Anesthesiology, Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221000, China
| | - Min Wang
- Jiangsu Province Key Laboratory of Anesthesiology, Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221000, China
| | - Min Yan
- Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China.,Jiangsu Province Key Laboratory of Anesthesiology, Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221000, China
| |
Collapse
|
9
|
Yang Q, Yan C, Yin C, Gong Z. Serotonin Activated Hepatic Stellate Cells Contribute to Sex Disparity in Hepatocellular Carcinoma. Cell Mol Gastroenterol Hepatol 2017; 3:484-499. [PMID: 28462385 PMCID: PMC5403976 DOI: 10.1016/j.jcmgh.2017.01.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 01/05/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Hepatocellular carcinoma (HCC) occurs more frequently and aggressively in men than in women. Although sex hormones are believed to play a critical role in this disparity, the possible contribution of other factors largely is unknown. We aimed to investigate the role of serotonin on its contribution of sex discrepancy during HCC. METHODS By using an inducible zebrafish HCC model through hepatocyte-specific transgenic krasV12 expression, differential rates of HCC in male and female fish were characterized by both pharmaceutical and genetic interventions. The findings were validated further in human liver disease samples. RESULTS Accelerated HCC progression was observed in krasV12-expressing male zebrafish and male fish liver tumors were found to have higher hepatic stellate cell (HSC) density and activation. Serotonin, which is essential for HSC survival and activation, similarly were found to be synthesized and accumulated more robustly in males than in females. Serotonin-activated HSCs could promote HCC carcinogenesis and concurrently increase serotonin synthesis via transforming growth factor (Tgf)b1 expression, hence contributing to sex disparity in HCC. Analysis of liver disease patient samples showed similar male predominant serotonin accumulation and Tgfb1 expression. CONCLUSIONS In both zebrafish HCC models and human liver disease samples, a predominant serotonin synthesis and accumulation in males resulted in higher HSC density and activation as well as Tgfb1 expression, thus accelerating HCC carcinogenesis in males.
Collapse
Key Words
- EGFP, enhanced green fluorescence protein
- Gfap, glial fibrillary acidic protein
- HCC, hepatocellular carcinoma
- HSC, hepatic stellate cell
- Htr2b, 5-hydoxytryptamine receptor 2B
- IF, immunofluorescence
- IHC, immunohistochemistry
- Kras
- Liver Cancer
- P-Tph1, phosphorylated tryptophan hydroxylase 1
- PCR, polymerase chain reaction
- TGF, transforming growth factor
- TGFB1
- Tph1, tryptophan hydroxylase 1
- WT, wild type
- Zebrafish
- cDNA, complementary DNA
- dox, doxycycline
- α-SMA, α-smooth muscle actin
Collapse
Affiliation(s)
- Qiqi Yang
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Chuan Yan
- Department of Biological Sciences, National University of Singapore, Singapore
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
| | - Chunyue Yin
- Division of Gastroenterology, Hepatology and Nutrition, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio
| | - Zhiyuan Gong
- Department of Biological Sciences, National University of Singapore, Singapore
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
| |
Collapse
|
10
|
Pomierny B, Fuxe K, Krzyżanowska W, Regulska M, Broniowska Ż, Budziszewska B. Participation of protein kinases in cytotoxic and proapoptotic effects of ethylene glycol ethers and their metabolites in SH-SY5Y cells. Toxicol In Vitro 2016; 36:153-163. [PMID: 27497993 DOI: 10.1016/j.tiv.2016.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 07/16/2016] [Accepted: 08/02/2016] [Indexed: 11/24/2022]
Abstract
Ethylene glycol ethers (EGEs) are compounds widely used in many branches of industry. Their toxicological profile in the peripheral tissues is relatively well described, but little is known about their action on the central nervous system (CNS). In this study, we evaluated the effect of 2-ethoxyethanol (EE), 2-butoxyethanol (BE), 2-phenoxyethanol (PHE) and their metabolites on necrotic (estimated by cell viability and lactate dehydrogenase release) and apoptotic (caspase-3 activity and mitochondrial membrane potential) processes and reactive oxygen species' (ROS) production in human neuroblastoma (SH-SY5Y) cells. We have shown that, similar to the peripheral tissues, EGE metabolites in most of the performed assays revealed greater potential to damage than the parent compounds in the CNS cells. Subsequently, we investigated the participation of some selected protein kinases in the degenerative activity of PHE and its main metabolite, phenoxyacetic acid (PHA). It has been found that a GSK3β inhibitor weakened the damaging effects of PHE and PHA in each of the performed assays. Furthermore, the kinases, p38-MAPK, JNK-MAPK and PKC, had a significant role in the cytotoxic and proapoptotic effects of PHA. These results indicate that the neurotoxic effect of EGEs may stem from their impact on many intracellular signal transduction pathways.
Collapse
Affiliation(s)
- Bartosz Pomierny
- Department of Biochemical Toxicology, Chair of Toxicology, Faculty of Pharmacy, Medical College, Jagiellonian University, Medyczna 9, PL 30-688 Kraków, Poland; Department of Neuroscience, Karolinska Institutet, Retzius väg 8, Stockholm, Sweden.
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, Stockholm, Sweden.
| | - Weronika Krzyżanowska
- Department of Biochemical Toxicology, Chair of Toxicology, Faculty of Pharmacy, Medical College, Jagiellonian University, Medyczna 9, PL 30-688 Kraków, Poland.
| | - Magdalena Regulska
- Department of Experimental Neuroendocrynology, Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, PL 31-343 Kraków, Poland.
| | - Żaneta Broniowska
- Department of Biochemical Toxicology, Chair of Toxicology, Faculty of Pharmacy, Medical College, Jagiellonian University, Medyczna 9, PL 30-688 Kraków, Poland.
| | - Bogusława Budziszewska
- Department of Biochemical Toxicology, Chair of Toxicology, Faculty of Pharmacy, Medical College, Jagiellonian University, Medyczna 9, PL 30-688 Kraków, Poland; Department of Experimental Neuroendocrynology, Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, PL 31-343 Kraków, Poland.
| |
Collapse
|
11
|
Activation of extracellular signal-regulated kinase1/2 in the medial prefrontal cortex contributes to stress-induced hyperalgesia. Mol Neurobiol 2014; 50:1013-23. [PMID: 24799176 DOI: 10.1007/s12035-014-8707-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 04/01/2014] [Indexed: 01/07/2023]
Abstract
Stressful stimuli can exacerbate persistent pain disorder. However, the underlying mechanism is still unknown. Here, to reveal the underlying mechanism for stressful stimuli-induced hyperalgesia in chronic pain, we investigated the effect of extracellular signal-regulated kinase1/2 (ERK1/2) activation on pain hypersensitivity using single-prolonged stress (SPS) model, complete Freund's adjuvant (CFA) model and SPS + CFA model. The experimental results revealed significantly reduced paw withdrawal threshold in the SPS, CFA, and SPS + CFA group compared with the control group. However, the increased phosphorylation of ERK1/2 in the medial prefrontal cortex (mPFC) was observed in the SPS- or SPS + CFA-exposed group but not the CFA group compared with control group. There was also a significant increase in mPFC ERK1/2 phosphorylation and mechanical allodynia after SPS + CFA treatment compared to SPS or CFA treatment alone. Furthermore, inhibiting ERK1/2 phosphorylation by microinjection of U0126, a MAPK kinase (MEK) inhibitor, into the mPFC attenuated SPS + CFA- and SPS- but not CFA-induced mechanical allodynia, anxiety-like behavior, and cognitive impairments. These results suggest that the activation of ERK1/2 in the mPFC may contribute to the process of stress-induced cognitive and emotional disorders, leading to an increase in pain sensitivity.
Collapse
|
12
|
Borges GS, Berrocoso E, Ortega-Alvaro A, Mico JA, Neto FL. Extracellular signal-regulated kinase activation in the chronic constriction injury model of neuropathic pain in anaesthetized rats. Eur J Pain 2012; 17:35-45. [PMID: 23055268 DOI: 10.1002/j.1532-2149.2012.00181.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2012] [Indexed: 12/18/2022]
Abstract
BACKGROUND The role of extracellular signal-regulated kinases (ERKs) in nociception has been explored in the last years. While in spinal cord their activation is frequently correlated with pain or acute noxious stimuli, supraspinally, this association is not so evident and remains unclear. This study aims to evaluate ERK1/2 activation in the spinal cord and brainstem nuclei upon neuropathy and/or an additional mechanical stimulus. METHODS Acute noxious mechanical stimulation was applied in the left hindpaw of anaesthetized SHAM-operated and chronic constriction injured (CCI, neuropathic pain model) rats. Other SHAM or CCI rats did not receive any stimulus. Immunohistochemistry against the phosphorylated isoforms of ERK1/2 (pERK1/2) was performed in lumbar spinal cord and brainstem sections to assess ERK1/2 activation. RESULTS In the spinal cord, stimulation promoted an increase in pERK1/2 expression in the superficial dorsal horn of SHAM rats. No significant effects were caused by CCI alone. At supraspinal level, changes in ERK1/2 activation induced by CCI were observed in A5, locus coeruleus (LC), raphe obscurus (ROb), raphe magnus, dorsal raphe (DRN), lateral reticular and paragigantocellularis nucleus. CCI increased pERK1/2 expression in all these nuclei, with exception of LC, where a significant decrease was verified. Mechanical noxious stimulation of CCI rats decreased pERK1/2 expression in ROb and DRN, but no further changes were detected in either SHAM- or CCI-stimulated animals. CONCLUSION ERK1/2 are differentially activated in the spinal cord and in selected brainstem nuclei implicated in nociception, in response to an acute noxious stimulus and/or to a neuropathic pain condition.
Collapse
Affiliation(s)
- G S Borges
- Departamento de Biologia Experimental, Centro de Investigação Médica-Faculdade de Medicina (CIM-FMUP), Universidade do Porto, Porto, Portugal
| | | | | | | | | |
Collapse
|