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Modulation of itch and pain signals processing in ventrobasal thalamus by thalamic reticular nucleus. iScience 2022; 25:103625. [PMID: 35106466 PMCID: PMC8786640 DOI: 10.1016/j.isci.2021.103625] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/16/2021] [Accepted: 12/10/2021] [Indexed: 01/03/2023] Open
Abstract
Thalamic reticular nucleus (TRN) is known to be crucial for dynamically modulating sensory processing. Recently, the functional role of TRN in itch and pain sensation processing has drawn much attention. We found that ventrobasal thalamus (VB) neurons exhibited scratching behavior-related and nociceptive behavior-related neuronal activity changes, and most of VB neurons responsive to pruritic stimulus were also activated by nociceptive stimulus. Inhibition of VB could relieve itch-induced scratching behaviors and pathological pain without affecting basal nociceptive thresholds, and activation of VB could facilitate scratching behaviors. Tracing and electrophysiology recording results showed that VB mainly received inhibitory inputs from ventral TRN. Furthermore, optogenetic activation of TRN-VB projections suppressed scratching behaviors, and ablation of TRN enhanced scratching behaviors. In addition, activation of TRN-VB projections relieved the pathological pain without affecting basal nociceptive thresholds. Thus, our study indicates that TRN modulates itch and pain signals processing via TRN-VB inhibitory projections. VB is involved in both itch and pain signals processing Manipulation of VB or TRN-VB inhibitory projections modulates both itch and pain Enhancing the inhibitory tone might be a strategy for treating itch and pain
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Mu D, Sun YG. Circuit Mechanisms of Itch in the Brain. J Invest Dermatol 2021; 142:23-30. [PMID: 34662562 DOI: 10.1016/j.jid.2021.09.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/21/2021] [Accepted: 09/21/2021] [Indexed: 12/12/2022]
Abstract
Itch is an unpleasant somatic sensation with the desire to scratch, and it consists of sensory, affective, and motivational components. Acute itch serves as a critical protective mechanism because an itch-evoked scratching response will help to remove harmful substances invading the skin. Recently, exciting progress has been made in deciphering the mechanisms of itch at both the peripheral nervous system and the CNS levels. Key neuronal subtypes and circuits have been revealed for ascending transmission and the descending modulation of itch. In this review, we mainly summarize the current understanding of the central circuit mechanisms of itch in the brain.
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Affiliation(s)
- Di Mu
- Department of Anesthesiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yan-Gang Sun
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology (CEBSIT), Chinese Academy of Sciences, Shanghai, China; Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China.
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Arimura D, Shinohara K, Takahashi Y, Sugimura YK, Sugimoto M, Tsurugizawa T, Marumo K, Kato F. Primary Role of the Amygdala in Spontaneous Inflammatory Pain- Associated Activation of Pain Networks - A Chemogenetic Manganese-Enhanced MRI Approach. Front Neural Circuits 2019; 13:58. [PMID: 31632244 PMCID: PMC6779784 DOI: 10.3389/fncir.2019.00058] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 08/19/2019] [Indexed: 12/16/2022] Open
Abstract
Chronic pain is a major health problem, affecting 10–30% of the population in developed countries. While chronic pain is defined as “a persistent complaint of pain lasting for more than the usual period for recovery,” recently accumulated lines of evidence based on human brain imaging have revealed that chronic pain is not simply a sustained state of nociception, but rather an allostatic state established through gradually progressing plastic changes in the central nervous system. To visualize the brain activity associated with spontaneously occurring pain during the shift from acute to chronic pain under anesthetic-free conditions, we used manganese-enhanced magnetic resonance imaging (MEMRI) with a 9.4-T scanner to visualize neural activity-dependent accumulation of manganese in the brains of mice with hind paw inflammation. Time-differential analysis between 2- and 6-h after formalin injection to the left hind paw revealed a significantly increased MEMRI signal in various brain areas, including the right insular cortex, right nucleus accumbens, right globus pallidus, bilateral caudate putamen, right primary/secondary somatosensory cortex, bilateral thalamus, right amygdala, bilateral substantial nigra, and left ventral tegmental area. To analyze the role of the right amygdala in these post-formalin MEMRI signals, we repeatedly inhibited right amygdala neurons during this 2–6-h period using the “designer receptors exclusively activated by designer drugs” (DREADD) technique. Pharmacological activation of inhibitory DREADDs expressed in the right amygdala significantly attenuated MEMRI signals in the bilateral infralimbic cortex, bilateral nucleus accumbens, bilateral caudate putamen, right globus pallidus, bilateral ventral tegmental area, and bilateral substantia nigra, suggesting that the inflammatory pain-associated activation of these structures depends on the activity of the right amygdala and DREADD-expressing adjacent structures. In summary, the combined use of DREADD and MEMRI is a promising approach for revealing regions associated with spontaneous pain-associated brain activities and their causal relationships.
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Affiliation(s)
- Daigo Arimura
- Department of Neuroscience, Jikei University School of Medicine, Tokyo, Japan.,Department of Orthopaedics, Jikei University School of Medicine, Tokyo, Japan.,Center for Neuroscience of Pain, Jikei University School of Medicine, Tokyo, Japan
| | - Kei Shinohara
- Department of Neuroscience, Jikei University School of Medicine, Tokyo, Japan.,Department of Orthopaedics, Jikei University School of Medicine, Tokyo, Japan.,Center for Neuroscience of Pain, Jikei University School of Medicine, Tokyo, Japan
| | - Yukari Takahashi
- Department of Neuroscience, Jikei University School of Medicine, Tokyo, Japan.,Center for Neuroscience of Pain, Jikei University School of Medicine, Tokyo, Japan
| | - Yae K Sugimura
- Department of Neuroscience, Jikei University School of Medicine, Tokyo, Japan.,Center for Neuroscience of Pain, Jikei University School of Medicine, Tokyo, Japan
| | - Mariko Sugimoto
- Department of Neuroscience, Jikei University School of Medicine, Tokyo, Japan.,Center for Neuroscience of Pain, Jikei University School of Medicine, Tokyo, Japan
| | - Tomokazu Tsurugizawa
- Department of Neuroscience, Jikei University School of Medicine, Tokyo, Japan.,Center for Neuroscience of Pain, Jikei University School of Medicine, Tokyo, Japan.,NeuroSpin, CEA-Saclay, Gif-sur-Yvette, France
| | - Keishi Marumo
- Department of Orthopaedics, Jikei University School of Medicine, Tokyo, Japan.,Center for Neuroscience of Pain, Jikei University School of Medicine, Tokyo, Japan
| | - Fusao Kato
- Department of Neuroscience, Jikei University School of Medicine, Tokyo, Japan.,Center for Neuroscience of Pain, Jikei University School of Medicine, Tokyo, Japan
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Neuroimaging of pain in animal models: a review of recent literature. Pain Rep 2019; 4:e732. [PMID: 31579844 PMCID: PMC6728006 DOI: 10.1097/pr9.0000000000000732] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 02/06/2019] [Accepted: 02/12/2019] [Indexed: 01/19/2023] Open
Abstract
Neuroimaging of pain in animals allows us to better understand mechanisms of pain processing and modulation. In this review, we discuss recently published brain imaging studies in rats, mice, and monkeys, including functional magnetic resonance imaging (MRI), manganese-enhanced MRI, positron emission tomography, and electroencephalography. We provide an overview of innovations and limitations in neuroimaging techniques, as well as results of functional brain imaging studies of pain from January 1, 2016, to October 10, 2018. We then discuss how future investigations can address some bias and gaps in the field. Despite the limitations of neuroimaging techniques, the 28 studies reinforced that transition from acute to chronic pain entails considerable changes in brain function. Brain activations in acute pain were in areas more related to the sensory aspect of noxious stimulation, including primary somatosensory cortex, insula, cingulate cortex, thalamus, retrosplenial cortex, and periaqueductal gray. Pharmacological and nonpharmacological treatments modulated these brain regions in several pain models. On the other hand, in chronic pain models, brain activity was observed in regions commonly associated with emotion and motivation, including prefrontal cortex, anterior cingulate cortex, hippocampus, amygdala, basal ganglia, and nucleus accumbens. Neuroimaging of pain in animals holds great promise for advancing our knowledge of brain function and allowing us to expand human subject research. Additional research is needed to address effects of anesthesia, analysis approaches, sex bias and omission, and potential effects of development and aging.
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Xie B, Li XY. Inflammatory mediators causing cutaneous chronic itch in some diseases via transient receptor potential channel subfamily V member 1 and subfamily A member 1. J Dermatol 2018; 46:177-185. [PMID: 30588658 PMCID: PMC6590237 DOI: 10.1111/1346-8138.14749] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 11/19/2018] [Indexed: 12/23/2022]
Abstract
Chronic itch with an itch–scratch vicious circle is a significant problem in a large amount of diseases. Some of these diseases, such as psoriasis, atopic dermatitis, prurigo nodularis, Sézary syndrome, uremic pruritus, diabetes and jaundice, are common. For a very long time, chronic itch has been a thorny problem with few effective treatments. Because of this, itch researchers and dermatologists seek to find the mechanisms among chronic itch, inflammatory cytokines and neurons. As an immediate area of research focus, we are going to find the peripheral cross‐talk between neurons and skin cells. Two receptors, named transient receptor potential channel vanilloid 1 and transient receptor potential channel ankyrin transmembrane protein 1, have been shown to play important roles in chronic itch. Many advances have been made so far this decade. This review talks about the updated mechanism of itch‐related inflammatory cytokines via transient receptor potential channels in cutaneous chronic itch and corresponding diseases. The search for itch‐related inflammatory mediators and the structure of transient receptor potential channels this decade could deepen our understanding of the mechanism of itch and help us find more treatments of chronic itch in the future.
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Affiliation(s)
- Bo Xie
- Department of Pharmacology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, China
| | - Xin-Yu Li
- Department of Pharmacology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, China
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Cloyd RA, Koren SA, Abisambra JF. Manganese-Enhanced Magnetic Resonance Imaging: Overview and Central Nervous System Applications With a Focus on Neurodegeneration. Front Aging Neurosci 2018; 10:403. [PMID: 30618710 PMCID: PMC6300587 DOI: 10.3389/fnagi.2018.00403] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 11/23/2018] [Indexed: 12/16/2022] Open
Abstract
Manganese-enhanced magnetic resonance imaging (MEMRI) rose to prominence in the 1990s as a sensitive approach to high contrast imaging. Following the discovery of manganese conductance through calcium-permeable channels, MEMRI applications expanded to include functional imaging in the central nervous system (CNS) and other body systems. MEMRI has since been employed in the investigation of physiology in many animal models and in humans. Here, we review historical perspectives that follow the evolution of applied MRI research into MEMRI with particular focus on its potential toxicity. Furthermore, we discuss the more current in vivo investigative uses of MEMRI in CNS investigations and the brief but decorated clinical usage of chelated manganese compound mangafodipir in humans.
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Affiliation(s)
- Ryan A Cloyd
- Department of Physiology, University of Kentucky, Lexington, KY, United States.,College of Medicine, University of Kentucky, Lexington, KY, United States.,Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
| | - Shon A Koren
- Department of Physiology, University of Kentucky, Lexington, KY, United States.,Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States.,Department of Neuroscience & Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, United States
| | - Jose F Abisambra
- Department of Physiology, University of Kentucky, Lexington, KY, United States.,Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States.,Department of Neuroscience & Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, United States.,Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY, United States
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Upadhyay J, Geber C, Hargreaves R, Birklein F, Borsook D. A critical evaluation of validity and utility of translational imaging in pain and analgesia: Utilizing functional imaging to enhance the process. Neurosci Biobehav Rev 2018; 84:407-423. [PMID: 28807753 PMCID: PMC5729102 DOI: 10.1016/j.neubiorev.2017.08.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 05/22/2017] [Accepted: 08/04/2017] [Indexed: 02/07/2023]
Abstract
Assessing clinical pain and metrics related to function or quality of life predominantly relies on patient reported subjective measures. These outcome measures are generally not applicable to the preclinical setting where early signs pointing to analgesic value of a therapy are sought, thus introducing difficulties in animal to human translation in pain research. Evaluating brain function in patients and respective animal model(s) has the potential to characterize mechanisms associated with pain or pain-related phenotypes and thereby provide a means of laboratory to clinic translation. This review summarizes the progress made towards understanding of brain function in clinical and preclinical pain states elucidated using an imaging approach as well as the current level of validity of translational pain imaging. We hypothesize that neuroimaging can describe the central representation of pain or pain phenotypes and yields a basis for the development and selection of clinically relevant animal assays. This approach may increase the probability of finding meaningful new analgesics that can help satisfy the significant unmet medical needs of patients.
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Affiliation(s)
| | - Christian Geber
- Department of Neurology, University Medical Centre Mainz, Mainz, Germany; DRK Schmerz-Zentrum Mainz, Mainz, Germany
| | - Richard Hargreaves
- Center for Pain and the Brain, United States; Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston Harvard Medical School, Boston, MA 02115, United States
| | - Frank Birklein
- Department of Neurology, University Medical Centre Mainz, Mainz, Germany
| | - David Borsook
- Center for Pain and the Brain, United States; Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston Harvard Medical School, Boston, MA 02115, United States.
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