1
|
Kc E, Islam J, Lee G, Park YS. Optogenetic Approach in Trigeminal Neuralgia and Potential Concerns: Preclinical Insights. Mol Neurobiol 2024; 61:1769-1780. [PMID: 37775720 DOI: 10.1007/s12035-023-03652-w] [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: 03/15/2023] [Accepted: 09/11/2023] [Indexed: 10/01/2023]
Abstract
The integration of optogenetics in the trigeminal pain circuitry broadens and reinforces existing pain investigations. Similar to research on spinal neuropathic pain, the exploration of the underlying determinants of orofacial pain is expanding. Optogenetics facilitates more direct, specific, and subtle investigations of the neuronal circuits involved in orofacial pain. One of the most significant concerns of both dentistry and medicine is trigeminal neuralgia (TN) management due to its substantial impact on a patient's quality of life. Our objective is to gather insights from preclinical studies conducted in TN employing an optogenetic paradigm, thereby extending the prospects for in-depth neurobiological research. This review highlights optogenetic research in trigeminal pain circuitry involving TN. We outline the central and peripheral regions associated with pain-that have been investigated using optogenetics in the trigeminal pain circuitry. The study further reports its scope and limitations as well as its potential for future applications from bench to bedside.
Collapse
Affiliation(s)
- Elina Kc
- Program in Neuroscience, Department of Medicine, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Jaisan Islam
- Program in Neuroscience, Department of Medicine, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Gabsang Lee
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- The Solomon H. Snyder, Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Young Seok Park
- Program in Neuroscience, Department of Medicine, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea.
- Department of Neurosurgery, Chungbuk National University Hospital, Cheongju, Republic of Korea.
| |
Collapse
|
2
|
Puja G, Sonkodi B, Bardoni R. Mechanisms of Peripheral and Central Pain Sensitization: Focus on Ocular Pain. Front Pharmacol 2021; 12:764396. [PMID: 34916942 PMCID: PMC8669969 DOI: 10.3389/fphar.2021.764396] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 11/09/2021] [Indexed: 12/14/2022] Open
Abstract
Persistent ocular pain caused by corneal inflammation and/or nerve injury is accompanied by significant alterations along the pain axis. Both primary sensory neurons in the trigeminal nerves and secondary neurons in the spinal trigeminal nucleus are subjected to profound morphological and functional changes, leading to peripheral and central pain sensitization. Several studies using animal models of inflammatory and neuropathic ocular pain have provided insight about the mechanisms involved in these maladaptive changes. Recently, the advent of new techniques such as optogenetics or genetic neuronal labelling has allowed the investigation of identified circuits involved in nociception, both at the spinal and trigeminal level. In this review, we will describe some of the mechanisms that contribute to the perception of ocular pain at the periphery and at the spinal trigeminal nucleus. Recent advances in the discovery of molecular and cellular mechanisms contributing to peripheral and central pain sensitization of the trigeminal pathways will be also presented.
Collapse
Affiliation(s)
- Giulia Puja
- Department of Life Sciences, University of Modena and Reggio Emilia, Emilia-Romagna, Italy
| | - Balazs Sonkodi
- Department of Health Sciences and Sport Medicine, University of Physical Education, Budapest, Hungary
| | - Rita Bardoni
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Emilia-Romagna, Italy
| |
Collapse
|
3
|
Pradier B, McCormick SJ, Tsuda AC, Chen RW, Atkinson AL, Westrick MR, Buckholtz CL, Kauer JA. Properties of neurons in the superficial laminae of trigeminal nucleus caudalis. Physiol Rep 2020; 7:e14112. [PMID: 31215180 PMCID: PMC6581829 DOI: 10.14814/phy2.14112] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 04/24/2019] [Indexed: 02/03/2023] Open
Abstract
The trigeminal nucleus caudalis (TNc) receives extensive afferent innervation from peripheral sensory neurons of the trigeminal ganglion (TG), and is the first central relay in the circuitry underpinning orofacial pain. Despite the initial characterization of the neurons in the superficial laminae, many questions remain. Here we report on electrophysiological properties of 535 superficial lamina I/II TNc neurons. Based on their firing pattern, we assigned these cells to five main groups, including (1) tonic, (2) phasic, (3) delayed, (4) H‐current, and (5) tonic‐phasic neurons, groups that exhibit distinct intrinsic properties and share some similarity with groups identified in the spinal dorsal horn. Driving predominantly nociceptive TG primary afferents using optogenetic stimulation in TRPV1/ChR2 animals, we found that tonic and H‐current cells are most likely to receive pure monosynaptic input, whereas delayed neurons are more likely to exhibit inputs that appear polysynaptic. Finally, for the first time in TNc neurons, we used unsupervised clustering analysis methods and found that the kinetics of the action potentials and other intrinsic properties of these groups differ significantly from one another. Unsupervised spectral clustering based solely on a single voltage response to rheobase current was sufficient to group cells with shared properties independent of action potential discharge pattern, indicating that this approach can be effectively applied to identify functional neuronal subclasses. Together, our data illustrate that cells in the TNc with distinct patterns of TRPV1/ChR2 afferent innervation are physiologically diverse, but can be understood as a few major groups of cells having shared functional properties.
Collapse
Affiliation(s)
- Bruno Pradier
- Department of Molecular Pharmacology, Physiology & Biotechnology, Brown University, Carney Institute for Brain Science, Providence, Rhode Island
| | - Samuel J McCormick
- Department of Molecular Pharmacology, Physiology & Biotechnology, Brown University, Carney Institute for Brain Science, Providence, Rhode Island
| | - Ayumi C Tsuda
- Department of Molecular Pharmacology, Physiology & Biotechnology, Brown University, Carney Institute for Brain Science, Providence, Rhode Island
| | - Rudy W Chen
- Department of Molecular Pharmacology, Physiology & Biotechnology, Brown University, Carney Institute for Brain Science, Providence, Rhode Island
| | - Abigail L Atkinson
- Department of Molecular Pharmacology, Physiology & Biotechnology, Brown University, Carney Institute for Brain Science, Providence, Rhode Island
| | - Mollie R Westrick
- Department of Molecular Pharmacology, Physiology & Biotechnology, Brown University, Carney Institute for Brain Science, Providence, Rhode Island
| | - Caroline L Buckholtz
- Department of Molecular Pharmacology, Physiology & Biotechnology, Brown University, Carney Institute for Brain Science, Providence, Rhode Island
| | - Julie A Kauer
- Department of Molecular Pharmacology, Physiology & Biotechnology, Brown University, Carney Institute for Brain Science, Providence, Rhode Island
| |
Collapse
|
4
|
Jarrin S, Finn DP. Optogenetics and its application in pain and anxiety research. Neurosci Biobehav Rev 2019; 105:200-211. [DOI: 10.1016/j.neubiorev.2019.08.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 08/02/2019] [Accepted: 08/11/2019] [Indexed: 12/13/2022]
|
5
|
Kloc ML, Pradier B, Chirila AM, Kauer JA. NMDA receptor activation induces long-term potentiation of glycine synapses. PLoS One 2019; 14:e0222066. [PMID: 31498817 PMCID: PMC6733442 DOI: 10.1371/journal.pone.0222066] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 08/21/2019] [Indexed: 01/12/2023] Open
Abstract
Of the fast ionotropic synapses, glycinergic synapses are the least well understood, but are vital for the maintenance of inhibitory signaling in the brain and spinal cord. Glycinergic signaling comprises half of the inhibitory signaling in the spinal cord, and glycinergic synapses are likely to regulate local nociceptive processing as well as the transmission to the brain of peripheral nociceptive information. Here we have investigated the rapid and prolonged potentiation of glycinergic synapses in the superficial dorsal horn of young male and female mice after brief activation of NMDA receptors (NMDARs). Glycinergic inhibitory postsynaptic currents (IPSCs) evoked with lamina II-III stimulation in identified GABAergic neurons in lamina II were potentiated by bath-applied Zn2+ and were depressed by the prostaglandin PGE2, consistent with the presence of both GlyRα1- and GlyRα3-containing receptors. NMDA application rapidly potentiated synaptic glycinergic currents. Whole-cell currents evoked by exogenous glycine were also readily potentiated by NMDA, indicating that the potentiation results from altered numbers or conductance of postsynaptic glycine receptors. Repetitive depolarization alone of the postsynaptic GABAergic neuron also potentiated glycinergic synapses, and intracellular EGTA prevented both NMDA-induced and depolarization-induced potentiation of glycinergic IPSCs. Optogenetic activation of trpv1 lineage afferents also triggered NMDAR-dependent potentiation of glycinergic synapses. Our results suggest that during peripheral injury or inflammation, nociceptor firing during injury is likely to potentiate glycinergic synapses on GABAergic neurons. This disinhibition mechanism may be engaged rapidly, altering dorsal horn circuitry to promote the transmission of nociceptive information to the brain.
Collapse
Affiliation(s)
- Michelle L. Kloc
- Dept. of Pharmacology, Physiology and Biotechnology, Brown Institute for Brain Science, Brown University, Providence, RI, United States of America
| | - Bruno Pradier
- Dept. of Pharmacology, Physiology and Biotechnology, Brown Institute for Brain Science, Brown University, Providence, RI, United States of America
| | - Anda M. Chirila
- Dept. of Pharmacology, Physiology and Biotechnology, Brown Institute for Brain Science, Brown University, Providence, RI, United States of America
| | - Julie A. Kauer
- Dept. of Pharmacology, Physiology and Biotechnology, Brown Institute for Brain Science, Brown University, Providence, RI, United States of America
- * E-mail: ,
| |
Collapse
|
6
|
RGS4 Maintains Chronic Pain Symptoms in Rodent Models. J Neurosci 2019; 39:8291-8304. [PMID: 31308097 DOI: 10.1523/jneurosci.3154-18.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 05/02/2019] [Accepted: 06/27/2019] [Indexed: 12/26/2022] Open
Abstract
Regulator of G-protein signaling 4 (RGS4) is a potent modulator of G-protein-coupled receptor signal transduction that is expressed throughout the pain matrix. Here, we use genetic mouse models to demonstrate a role of RGS4 in the maintenance of chronic pain states in male and female mice. Using paradigms of peripheral inflammation and nerve injury, we show that the prevention of RGS4 action leads to recovery from mechanical and cold allodynia and increases the motivation for wheel running. Similarly, RGS4KO eliminates the duration of nocifensive behavior in the second phase of the formalin assay. Using the Complete Freud's Adjuvant (CFA) model of hindpaw inflammation we also demonstrate that downregulation of RGS4 in the adult ventral posterolateral thalamic nuclei promotes recovery from mechanical and cold allodynia. RNA sequencing analysis of thalamus (THL) from RGS4WT and RGS4KO mice points to many signal transduction modulators and transcription factors that are uniquely regulated in CFA-treated RGS4WT cohorts. Ingenuity pathway analysis suggests that several components of glutamatergic signaling are differentially affected by CFA treatment between RGS4WT and RGS4KO groups. Notably, Western blot analysis shows increased expression of metabotropic glutamate receptor 2 in THL synaptosomes of RGS4KO mice at time points at which they recover from mechanical allodynia. Overall, our study provides information on a novel intracellular pathway that contributes to the maintenance of chronic pain states and points to RGS4 as a potential therapeutic target.SIGNIFICANCE STATEMENT There is an imminent need for safe and efficient chronic pain medications. Regulator of G-protein signaling 4 (RGS4) is a multifunctional signal transduction protein, widely expressed in the pain matrix. Here, we demonstrate that RGS4 plays a prominent role in the maintenance of chronic pain symptoms in male and female mice. Using genetically modified mice, we show a dynamic role of RGS4 in recovery from symptoms of sensory hypersensitivity deriving from hindpaw inflammation or hindlimb nerve injury. We also demonstrate an important role of RGS4 actions in gene expression patterns induced by chronic pain states in the mouse thalamus. Our findings provide novel insight into mechanisms associated with the maintenance of chronic pain states and demonstrate that interventions in RGS4 activity promote recovery from sensory hypersensitivity symptoms.
Collapse
|