1
|
Merighi A. Brain-Derived Neurotrophic Factor, Nociception, and Pain. Biomolecules 2024; 14:539. [PMID: 38785946 PMCID: PMC11118093 DOI: 10.3390/biom14050539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/26/2024] [Accepted: 04/26/2024] [Indexed: 05/25/2024] Open
Abstract
This article examines the involvement of the brain-derived neurotrophic factor (BDNF) in the control of nociception and pain. BDNF, a neurotrophin known for its essential role in neuronal survival and plasticity, has garnered significant attention for its potential implications as a modulator of synaptic transmission. This comprehensive review aims to provide insights into the multifaceted interactions between BDNF and pain pathways, encompassing both physiological and pathological pain conditions. I delve into the molecular mechanisms underlying BDNF's involvement in pain processing and discuss potential therapeutic applications of BDNF and its mimetics in managing pain. Furthermore, I highlight recent advancements and challenges in translating BDNF-related research into clinical practice.
Collapse
Affiliation(s)
- Adalberto Merighi
- Department of Veterinary Sciences, University of Turin, 10095 Turin, Italy
| |
Collapse
|
2
|
Smith PA. BDNF in Neuropathic Pain; the Culprit that Cannot be Apprehended. Neuroscience 2024; 543:49-64. [PMID: 38417539 DOI: 10.1016/j.neuroscience.2024.02.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Accepted: 02/20/2024] [Indexed: 03/01/2024]
Abstract
In males but not in females, brain derived neurotrophic factor (BDNF) plays an obligatory role in the onset and maintenance of neuropathic pain. Afferent terminals of injured peripheral nerves release colony stimulating factor (CSF-1) and other mediators into the dorsal horn. These transform the phenotype of dorsal horn microglia such that they express P2X4 purinoceptors. Activation of these receptors by neuron-derived ATP promotes BDNF release. This microglial-derived BDNF increases synaptic activation of excitatory dorsal horn neurons and decreases that of inhibitory neurons. It also alters the neuronal chloride gradient such the normal inhibitory effect of GABA is converted to excitation. By as yet undefined processes, this attenuated inhibition increases NMDA receptor function. BDNF also promotes the release of pro-inflammatory cytokines from astrocytes. All of these actions culminate in the increase dorsal horn excitability that underlies many forms of neuropathic pain. Peripheral nerve injury also alters excitability of structures in the thalamus, cortex and mesolimbic system that are responsible for pain perception and for the generation of co-morbidities such as anxiety and depression. The weight of evidence from male rodents suggests that this preferential modulation of excitably of supra-spinal pain processing structures also involves the action of microglial-derived BDNF. Possible mechanisms promoting the preferential release of BDNF in pain signaling structures are discussed. In females, invading T-lymphocytes increase dorsal horn excitability but it remains to be determined whether similar processes operate in supra-spinal structures. Despite its ubiquitous role in pain aetiology neither BDNF nor TrkB receptors represent potential therapeutic targets.
Collapse
Affiliation(s)
- Peter A Smith
- Neuroscience and Mental Health Institute and Department of Pharmacology, University of Alberta, Edmonton, Canada.
| |
Collapse
|
3
|
Dedek A, Xu J, Lorenzo LÉ, Godin AG, Kandegedara CM, Glavina G, Landrigan JA, Lombroso PJ, De Koninck Y, Tsai EC, Hildebrand ME. Sexual dimorphism in a neuronal mechanism of spinal hyperexcitability across rodent and human models of pathological pain. Brain 2022; 145:1124-1138. [PMID: 35323848 PMCID: PMC9050559 DOI: 10.1093/brain/awab408] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/03/2021] [Accepted: 10/15/2021] [Indexed: 12/23/2022] Open
Abstract
The prevalence and severity of many chronic pain syndromes differ across sex, and recent studies have identified differences in immune signalling within spinal nociceptive circuits as a potential mediator. Although it has been proposed that sex-specific pain mechanisms converge once they reach neurons within the superficial dorsal horn, direct investigations using rodent and human preclinical pain models have been lacking. Here, we discovered that in the Freund’s adjuvant in vivo model of inflammatory pain, where both male and female rats display tactile allodynia, a pathological coupling between KCC2-dependent disinhibition and N-methyl-D-aspartate receptor (NMDAR) potentiation within superficial dorsal horn neurons was observed in male but not female rats. Unlike males, the neuroimmune mediator brain-derived neurotrophic factor (BDNF) failed to downregulate inhibitory signalling elements (KCC2 and STEP61) and upregulate excitatory elements (pFyn, GluN2B and pGluN2B) in female rats, resulting in no effect of ex vivo brain-derived neurotrophic factor on synaptic NMDAR responses in female lamina I neurons. Importantly, this sex difference in spinal pain processing was conserved from rodents to humans. As in rodents, ex vivo spinal treatment with BDNF downregulated markers of disinhibition and upregulated markers of facilitated excitation in superficial dorsal horn neurons from male but not female human organ donors. Ovariectomy in female rats recapitulated the male pathological pain neuronal phenotype, with BDNF driving a coupling between disinhibition and NMDAR potentiation in adult lamina I neurons following the prepubescent elimination of sex hormones in females. This discovery of sexual dimorphism in a central neuronal mechanism of chronic pain across species provides a foundational step towards a better understanding and treatment for pain in both sexes.
Collapse
Affiliation(s)
- Annemarie Dedek
- Department of Neuroscience, Carleton University, K1S 5B6 Ontario, Canada.,Neuroscience Program, Ottawa Hospital Research Institute, K1Y 4M9 Ontario, Canada
| | - Jian Xu
- Child Study Center, Yale University School of Medicine, New Haven, CT 06519, USA
| | | | - Antoine G Godin
- CERVO Brain Research Centre, Quebec Mental Health Institute, Quebec G1E 1T2, Canada.,Department of Psychiatry and Neuroscience, Université Laval, Quebec G1V 0A6, Canada
| | - Chaya M Kandegedara
- Department of Neuroscience, Carleton University, K1S 5B6 Ontario, Canada.,Neuroscience Program, Ottawa Hospital Research Institute, K1Y 4M9 Ontario, Canada
| | - Geneviève Glavina
- CERVO Brain Research Centre, Quebec Mental Health Institute, Quebec G1E 1T2, Canada
| | | | - Paul J Lombroso
- Child Study Center, Yale University School of Medicine, New Haven, CT 06519, USA
| | - Yves De Koninck
- CERVO Brain Research Centre, Quebec Mental Health Institute, Quebec G1E 1T2, Canada.,Department of Psychiatry and Neuroscience, Université Laval, Quebec G1V 0A6, Canada
| | - Eve C Tsai
- Neuroscience Program, Ottawa Hospital Research Institute, K1Y 4M9 Ontario, Canada.,Brain and Mind Research Institute, University of Ottawa, Ontario K1N 6N5, Canada.,Department of Surgery, Division of Neurosurgery, The Ottawa Hospital, Ontario K1Y 4E9, Canada
| | - Michael E Hildebrand
- Department of Neuroscience, Carleton University, K1S 5B6 Ontario, Canada.,Neuroscience Program, Ottawa Hospital Research Institute, K1Y 4M9 Ontario, Canada
| |
Collapse
|
4
|
Boakye PA, Tang SJ, Smith PA. Mediators of Neuropathic Pain; Focus on Spinal Microglia, CSF-1, BDNF, CCL21, TNF-α, Wnt Ligands, and Interleukin 1β. FRONTIERS IN PAIN RESEARCH 2021; 2:698157. [PMID: 35295524 PMCID: PMC8915739 DOI: 10.3389/fpain.2021.698157] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 07/14/2021] [Indexed: 01/04/2023] Open
Abstract
Intractable neuropathic pain is a frequent consequence of nerve injury or disease. When peripheral nerves are injured, damaged axons undergo Wallerian degeneration. Schwann cells, mast cells, fibroblasts, keratinocytes and epithelial cells are activated leading to the generation of an "inflammatory soup" containing cytokines, chemokines and growth factors. These primary mediators sensitize sensory nerve endings, attract macrophages, neutrophils and lymphocytes, alter gene expression, promote post-translational modification of proteins, and alter ion channel function in primary afferent neurons. This leads to increased excitability and spontaneous activity and the generation of secondary mediators including colony stimulating factor 1 (CSF-1), chemokine C-C motif ligand 21 (CCL-21), Wnt3a, and Wnt5a. Release of these mediators from primary afferent neurons alters the properties of spinal microglial cells causing them to release tertiary mediators, in many situations via ATP-dependent mechanisms. Tertiary mediators such as BDNF, tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and other Wnt ligands facilitate the generation and transmission of nociceptive information by increasing excitatory glutamatergic transmission and attenuating inhibitory GABA and glycinergic transmission in the spinal dorsal horn. This review focusses on activation of microglia by secondary mediators, release of tertiary mediators from microglia and a description of their actions in the spinal dorsal horn. Attention is drawn to the substantial differences in the precise roles of various mediators in males compared to females. At least 25 different mediators have been identified but the similarity of their actions at sensory nerve endings, in the dorsal root ganglia and in the spinal cord means there is considerable redundancy in the available mechanisms. Despite this, behavioral studies show that interruption of the actions of any single mediator can relieve signs of pain in experimental animals. We draw attention this paradox. It is difficult to explain how inactivation of one mediator can relieve pain when so many parallel pathways are available.
Collapse
Affiliation(s)
- Paul A. Boakye
- Department of Anesthesiology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Shao-Jun Tang
- Department of Anesthesiology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Peter A. Smith
- Neuroscience and Mental Health Institute and Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
5
|
Chronic BDNF simultaneously inhibits and unmasks superficial dorsal horn neuronal activity. Sci Rep 2021; 11:2249. [PMID: 33500423 PMCID: PMC7838274 DOI: 10.1038/s41598-021-81269-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 01/04/2021] [Indexed: 11/12/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is critically involved in the pathophysiology of chronic pain. However, the mechanisms of BDNF action on specific neuronal populations in the spinal superficial dorsal horn (SDH) requires further study. We used chronic BDNF treatment (200 ng/ml, 5–6 days) of defined-medium, serum-free spinal organotypic cultures to study intracellular calcium ([Ca2+]i) fluctuations. A detailed quantitative analysis of these fluctuations using the Frequency-independent biological signal identification (FIBSI) program revealed that BDNF simultaneously depressed activity in some SDH neurons while it unmasked a particular subpopulation of ‘silent’ neurons causing them to become spontaneously active. Blockade of gap junctions disinhibited a subpopulation of SDH neurons and reduced BDNF-induced synchrony in BDNF-treated cultures. BDNF reduced neuronal excitability assessed by measuring spontaneous excitatory postsynaptic currents. This was similar to the depressive effect of BDNF on the [Ca2+]i fluctuations. This study reveals novel regulatory mechanisms of SDH neuronal excitability in response to BDNF.
Collapse
|
6
|
Polli A, Ghosh M, Bakusic J, Ickmans K, Monteyne D, Velkeniers B, Bekaert B, Godderis L, Nijs J. DNA Methylation and Brain-Derived Neurotrophic Factor Expression Account for Symptoms and Widespread Hyperalgesia in Patients With Chronic Fatigue Syndrome and Comorbid Fibromyalgia. Arthritis Rheumatol 2020; 72:1936-1944. [PMID: 32562379 DOI: 10.1002/art.41405] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 06/07/2020] [Indexed: 12/16/2022]
Abstract
OBJECTIVE The epigenetics of neurotrophic factors holds the potential to unravel the mechanisms underlying the pathophysiology of complex conditions such as chronic fatigue syndrome (CFS). This study was undertaken to explore the role of brain-derived neurotrophic factor (BDNF) genetics, epigenetics, and protein expression in patients with both CFS and comorbid fibromyalgia (CFS/FM). METHODS A repeated-measures study was conducted in 54 participants (28 patients with CFS/FM and 26 matched healthy controls). Participants underwent a comprehensive assessment, including questionnaires, sensory testing, and blood withdrawal. Serum BDNF (sBDNF) protein levels were measured using enzyme-linked immunosorbent assay, while polymorphism and DNA methylation were measured in blood using pyrosequencing technology. To assess the temporal stability of the measures, participants underwent the same assessment twice within 4 days. RESULTS Repeated-measures mixed linear models were used for between-group analysis, with mean differences and 95% confidence intervals (95% CIs) shown. Compared to controls, serum BNDF was higher in patients with CFS/FM (F = 15.703; mean difference 3.31 ng/ml [95% CI 1.65, 4.96]; P = 0.001), whereas BDNF DNA methylation in exon 9 was lower (F = 7.543; mean difference -2.16% [95% CI -3.93, -0.83]; P = 0.007). BDNF DNA methylation was mediated by the Val66Met (rs6265) polymorphism. Lower methylation in the same region predicted higher sBDNF levels (F = 7.137, β = -0.408 [95% CI -0.711, -0.105]; P = 0.009), which in turn predicted participants' symptoms (F = 14.410, β = 3.747 [95% CI 1.79, 5.71]; P = 0.001) and widespread hyperalgesia (F = 4.147, β = 0.04 [95% CI 0.01, 0.08]; P = 0.044). CONCLUSION Our findings indicate that sBDNF levels are elevated in patients with CFS/FM and that BDNF methylation in exon 9 accounts for the regulation of protein expression. Altered BDNF levels might represent a key mechanism explaining CFS/FM pathophysiology.
Collapse
Affiliation(s)
- Andrea Polli
- Vrije Universiteit Brussel, Brussels, Belgium, Katholieke Universiteit Leuven, Leuven, Belgium, and Scientific Research Foundation, Flanders, Belgium
| | - Manosij Ghosh
- Katholieke Universiteit Leuven, Leuven, Belgium, and Scientific Research Foundation, Flanders, Belgium
| | | | - Kelly Ickmans
- Vrije Universiteit Brussel and University Hospital Brussels, Brussels, Belgium, and Scientific Research Foundation, Flanders, Belgium
| | | | | | - Bram Bekaert
- University Hospitals Leuven, and Katholieke Universiteit Leuven, Leuven, Belgium
| | - Lode Godderis
- Katholieke Universiteit Leuven, Leuven, Belgium, and External Service for Prevention and Protection at Work, IDEWE, Heverlee, Belgium
| | - Jo Nijs
- Vrije Universiteit Brussel, Brussels, Belgium, and University Hospital Brussels, Brussels, Belgium
| |
Collapse
|
7
|
Boakye PA, Rancic V, Whitlock KH, Simmons D, Longo FM, Ballanyi K, Smith PA. Receptor dependence of BDNF actions in superficial dorsal horn: relation to central sensitization and actions of macrophage colony stimulating factor 1. J Neurophysiol 2019; 121:2308-2322. [PMID: 30995156 DOI: 10.1152/jn.00839.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Peripheral nerve injury elicits an enduring increase in the excitability of the spinal dorsal horn. This change, which contributes to the development of neuropathic pain, is a consequence of release and prolonged exposure of dorsal horn neurons to various neurotrophins and cytokines. We have shown in rats that nerve injury increases excitatory synaptic drive to excitatory neurons but decreases drive to inhibitory neurons. Both effects, which contribute to an increase in dorsal horn excitability, appear to be mediated by microglia-derived BDNF. We have used multiphoton Ca2+ imaging and whole cell recording of spontaneous excitatory postsynaptic currents in defined-medium organotypic cultures of GAD67-GFP+ mice spinal cord to determine the receptor dependence of these opposing actions of BDNF. In mice, as in rats, BDNF enhances excitatory transmission onto excitatory neurons. This is mediated via presynaptic TrkB and p75 neurotrophin receptors and exclusively by postsynaptic TrkB. By contrast with findings from rats, in mice BDNF does not decrease excitation of inhibitory neurons. The cytokine macrophage colony-stimulating factor 1 (CSF-1) has also been implicated in the onset of neuropathic pain. Nerve injury provokes its de novo synthesis in primary afferents, its release in spinal cord, and activation of microglia. We now show that CSF-1 increases excitatory drive to excitatory neurons via a BDNF-dependent mechanism and decreases excitatory drive to inhibitory neurons via BDNF-independent processes. Our findings complete missing steps in the cascade of events whereby peripheral nerve injury instigates increased dorsal horn excitability in the context of central sensitization and the onset of neuropathic pain. NEW & NOTEWORTHY Nerve injury provokes synthesis of macrophage colony-stimulating factor 1 (CSF-1) in primary afferents and its release in the dorsal horn. We show that CSF-1 increases excitatory drive to excitatory dorsal horn neurons via BDNF activation of postsynaptic TrkB and presynaptic TrkB and p75 neurotrophin receptors. CSF-1 decreases excitatory drive to inhibitory neurons via a BDNF-independent processes. This completes missing steps in understanding how peripheral injury instigates central sensitization and the onset of neuropathic pain.
Collapse
Affiliation(s)
- Paul A Boakye
- Neuroscience and Mental Health Institute, University of Alberta , Edmonton , Canada
| | - Vladimir Rancic
- Neuroscience and Mental Health Institute, University of Alberta , Edmonton , Canada.,Department of Physiology, University of Alberta , Edmonton , Canada
| | - Kerri H Whitlock
- Neuroscience and Mental Health Institute, University of Alberta , Edmonton , Canada
| | - Danielle Simmons
- Department of Neurology and Neurological Sciences, Stanford University , Stanford, California
| | - Frank M Longo
- Department of Neurology and Neurological Sciences, Stanford University , Stanford, California
| | - Klaus Ballanyi
- Neuroscience and Mental Health Institute, University of Alberta , Edmonton , Canada.,Department of Physiology, University of Alberta , Edmonton , Canada
| | - Peter A Smith
- Neuroscience and Mental Health Institute, University of Alberta , Edmonton , Canada.,Department of Pharmacology, University of Alberta , Edmonton , Canada
| |
Collapse
|
8
|
Spinal Plasticity and Behavior: BDNF-Induced Neuromodulation in Uninjured and Injured Spinal Cord. Neural Plast 2016; 2016:9857201. [PMID: 27721996 PMCID: PMC5046018 DOI: 10.1155/2016/9857201] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 07/27/2016] [Accepted: 08/10/2016] [Indexed: 12/26/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophic factor family of signaling molecules. Since its discovery over three decades ago, BDNF has been identified as an important regulator of neuronal development, synaptic transmission, and cellular and synaptic plasticity and has been shown to function in the formation and maintenance of certain forms of memory. Neural plasticity that underlies learning and memory in the hippocampus shares distinct characteristics with spinal cord nociceptive plasticity. Research examining the role BDNF plays in spinal nociception and pain overwhelmingly suggests that BDNF promotes pronociceptive effects. BDNF induces synaptic facilitation and engages central sensitization-like mechanisms. Also, peripheral injury-induced neuropathic pain is often accompanied with increased spinal expression of BDNF. Research has extended to examine how spinal cord injury (SCI) influences BDNF plasticity and the effects BDNF has on sensory and motor functions after SCI. Functional recovery and adaptive plasticity after SCI are typically associated with upregulation of BDNF. Although neuropathic pain is a common consequence of SCI, the relation between BDNF and pain after SCI remains elusive. This article reviews recent literature and discusses the diverse actions of BDNF. We also highlight similarities and differences in BDNF-induced nociceptive plasticity in naïve and SCI conditions.
Collapse
|
9
|
Rusanescu G, Mao J. Immature spinal cord neurons are dynamic regulators of adult nociceptive sensitivity. J Cell Mol Med 2015. [PMID: 26223362 PMCID: PMC4594677 DOI: 10.1111/jcmm.12648] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Chronic pain is a debilitating condition with unknown mechanism. Nociceptive sensitivity may be regulated by genetic factors, some of which have been separately linked to neuronal progenitor cells and neuronal differentiation. This suggests that genetic factors that interfere with neuronal differentiation may contribute to a chronic increase in nociceptive sensitivity, by extending the immature, hyperexcitable stage of spinal cord neurons. Although adult rodent spinal cord neurogenesis was previously demonstrated, the fate of these progenitor cells is unknown. Here, we show that peripheral nerve injury in adult rats induces extensive spinal cord neurogenesis and a long-term increase in the number of spinal cord laminae I–II neurons ipsilateral to injury. The production and maturation of these new neurons correlates with the time course and modulation of nociceptive behaviour, and transiently mimics the cellular and behavioural conditions present in genetically modified animal models of chronic pain. This suggests that the number of immature neurons present at any time in the spinal cord dorsal horns contributes to the regulation of nociceptive sensitivity. The continuous turnover of these neurons, which can fluctuate between normal and injured states, is a dynamic regulator of nociceptive sensitivity. In support of this hypothesis, we find that promoters of neuronal differentiation inhibit, while promoters of neurogenesis increase long-term nociception. TrkB agonists, well-known promoters of nociception in the short-term, significantly inhibit long-term nociception by promoting the differentiation of newly produced immature neurons. These findings suggest that promoters of neuronal differentiation may be used to alleviate chronic pain.
Collapse
Affiliation(s)
- Gabriel Rusanescu
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Jianren Mao
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
10
|
Exercise therapy normalizes BDNF upregulation and glial hyperactivity in a mouse model of neuropathic pain. Pain 2015; 156:504-513. [DOI: 10.1097/01.j.pain.0000460339.23976.12] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
|
11
|
Smith PA. BDNF: No gain without pain? Neuroscience 2014; 283:107-23. [DOI: 10.1016/j.neuroscience.2014.05.044] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 05/16/2014] [Accepted: 05/21/2014] [Indexed: 12/22/2022]
|
12
|
Biggs JE, Boakye PA, Ganesan N, Stemkowski PL, Lantero A, Ballanyi K, Smith PA. Analysis of the long-term actions of gabapentin and pregabalin in dorsal root ganglia and substantia gelatinosa. J Neurophysiol 2014; 112:2398-412. [DOI: 10.1152/jn.00168.2014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The α2δ-ligands pregabalin (PGB) and gabapentin (GBP) are used to treat neuropathic pain. We used whole cell recording to study their long-term effects on substantia gelatinosa and dorsal root ganglion (DRG) neurons. Spinal cord slices were prepared from embryonic day 13 rat embryos and maintained in organotypic culture for >5 wk (neuronal age equivalent to young adult rats). Exposure of similarly aged DRG neurons (dissociated and cultured from postnatal day 19 rats) to GBP or PGB for 5–6 days attenuated high-voltage-activated calcium channel currents (HVA ICa). Strong effects were seen in medium-sized and in small isolectin B4-negative (IB4−) DRG neurons, whereas large neurons and small neurons that bound isolectin B4 (IB4+) were hardly affected. GBP (100 μM) or PGB (10 μM) were less effective than 20 μM Mn2+ in suppression of HVA ICa in small DRG neurons. By contrast, 5–6 days of exposure to these α2δ-ligands was more effective than 20 μM Mn2+ in reducing spontaneous excitatory postsynaptic currents at synapses in substantia gelatinosa. Spinal actions of gabapentinoids cannot therefore be ascribed to decreased expression of HVA Ca2+ channels in primary afferent nerve terminals. In substantia gelatinosa, 5–6 days of exposure to PGB was more effective in inhibiting excitatory synaptic drive to putative excitatory neurons than to putative inhibitory neurons. Although spontaneous inhibitory postsynaptic currents were also attenuated, the overall long-term effect of α2δ-ligands was to decrease network excitability as monitored by confocal Ca2+ imaging. We suggest that selective actions of α2δ-ligands on populations of DRG neurons may predict their selective attenuation of excitatory transmission onto excitatory vs. inhibitory neurons in substantia gelatinosa.
Collapse
Affiliation(s)
- James E. Biggs
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada; and
| | - Paul A. Boakye
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | - Naren Ganesan
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | | | - Aquilino Lantero
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada; and
| | - Klaus Ballanyi
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Peter A. Smith
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada; and
| |
Collapse
|
13
|
Ziemlińska E, Kügler S, Schachner M, Wewiór I, Czarkowska-Bauch J, Skup M. Overexpression of BDNF increases excitability of the lumbar spinal network and leads to robust early locomotor recovery in completely spinalized rats. PLoS One 2014; 9:e88833. [PMID: 24551172 PMCID: PMC3925164 DOI: 10.1371/journal.pone.0088833] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 01/16/2014] [Indexed: 02/05/2023] Open
Abstract
Strategies to induce recovery from lesions of the spinal cord have not fully resulted in clinical applications. This is a consequence of a number of impediments that axons encounter when trying to regrow beyond the lesion site, and that intraspinal rearrangements are subjected to. In the present study we evaluated (1) the possibility to improve locomotor recovery after complete transection of the spinal cord by means of an adeno-associated (AAV) viral vector expressing the neurotrophin brain-derived neurotrophic factor (BDNF) in lumbar spinal neurons caudal to the lesion site and (2) how the spinal cord transection and BDNF treatment affected neurotransmission in the segments caudal to the lesion site. BDNF overexpression resulted in clear increases in expression levels of molecules involved in glutamatergic (VGluT2) and GABAergic (GABA, GAD65, GAD67) neurotransmission in parallel with a reduction of the potassium-chloride co-transporter (KCC2) which contributes to an inhibitory neurotransmission. BDNF treated animals showed significant improvements in assisted locomotor performance, and performed locomotor movements with body weight support and plantar foot placement on a moving treadmill. These positive effects of BDNF local overexpression were detectable as early as two weeks after spinal cord transection and viral vector application and lasted for at least 7 weeks. Gradually increasing frequencies of clonic movements at the end of the experiment attenuated the quality of treadmill walking. These data indicate that BDNF has the potential to enhance the functionality of isolated lumbar circuits, but also that BDNF levels have to be tightly controlled to prevent hyperexcitability.
Collapse
Affiliation(s)
| | - Sebastian Kügler
- Center of Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
| | - Melitta Schachner
- Center for Neuroscience, Shantou University Medical College, Shantou, China
| | - Iwona Wewiór
- Nencki Institute of Experimental Biology, Warsaw, Poland
| | | | | |
Collapse
|
14
|
Zhang H, Zhang H, Dougherty PM. Dynamic effects of TNF-α on synaptic transmission in mice over time following sciatic nerve chronic constriction injury. J Neurophysiol 2013; 110:1663-71. [PMID: 23864372 DOI: 10.1152/jn.01088.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Nerve injury-induced central sensitization can manifest as an increase in excitatory synaptic transmission and/or as a decrease in inhibitory synaptic transmission in spinal dorsal horn neurons. Cytokines such as tumor necrosis factor-α (TNF-α) are induced in the spinal cord under various injury conditions and contribute to neuropathic pain. In this study we examined the effect of TNF-α in modulating excitatory and inhibitory synaptic input to spinal substantia gelatinosa (SG) neurons over time in mice following chronic constriction injury (CCI) of the sciatic nerve. Whole cell patch-clamp studies from SG neurons showed that TNF-α enhanced overall excitability of the spinal cord early in time following nerve injury 3 days after CCI compared with that in sham control mice. In contrast, the effects of TNF were blunted 14 days after CCI in nerve-injured mice compared with sham surgery mice. Immunohistochemical staining showed that the expression of TNF-α receptor 1 (TNFR1) was increased at 3 days but decreased at 14 days following CCI in the ipsilateral vs. the contralateral spinal cord dorsal horn. These results suggest that TNF-α acting at TNFR1 is important in the development of neuropathic pain by facilitating excitatory synaptic signaling in the acute phases after nerve injury but has a reduced effect on spinal neuron signaling in the later phases of nerve injury-induced pain. Failure of the facilatory effects of TNF-α on excitatory synaptic signaling in the dorsal horn to resolve following nerve injury may be an important component in the transition between acute and chronic pain conditions.
Collapse
Affiliation(s)
- Hongmei Zhang
- Department of Anesthesia and Pain Medicine Research, The University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | | | | |
Collapse
|