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Follansbee T, Le Chang H, Iodi Carstens M, Guan Y, Carstens E, Dong X. Optotagging and characterization of GABAergic rostral ventromedial medulla (RVM) neurons. Mol Pain 2024; 20:17448069241270295. [PMID: 39054310 DOI: 10.1177/17448069241270295] [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] [Indexed: 07/27/2024] Open
Abstract
The transmission of nociceptive and pruriceptive signals in the spinal cord is greatly influenced by descending modulation from brain areas such as the rostral ventromedial medulla (RVM). Within the RVM three classes of neurons have been discovered which are relevant to spinal pain modulation, the On, Off, and Neutral cells. These neurons were discovered due to their functional response to nociceptive stimulation. On cells are excited, Off cells are inhibited, and Neutral cells have no response to noxious stimulation. Since these neurons are identified by functional response characteristics it has been difficult to molecularly identify them. In the present study, we leverage our ability to perform optotagging within the RVM to determine whether RVM On, Off, and Neutral cells are GABAergic. We found that 27.27% of RVM On cells, 47.37% of RVM Off cells, and 42.6% of RVM Neutral cells were GABAergic. These results demonstrate that RVM On, Off, and Neutral cells represent a heterogeneous population of neurons and provide a reliable technique for the molecular identification of these neurons.
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Affiliation(s)
- Taylor Follansbee
- Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Henry Le Chang
- Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Mirela Iodi Carstens
- Department of Neurobiology, Physiology, and Behavior, University of California Davis, Davis, CA, USA
| | - Yun Guan
- Department of Neurological Surgery, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Earl Carstens
- Department of Neurobiology, Physiology, and Behavior, University of California Davis, Davis, CA, USA
| | - Xinzhong Dong
- Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, USA
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Ke Wang W, Cesnakova L, Goldsack JC, Dunn J. Defining digital measurement of scratching during sleep, or “Nocturnal Scratch”: A review of the literature (Preprint). J Med Internet Res 2022; 25:e43617. [PMID: 37071460 PMCID: PMC10155092 DOI: 10.2196/43617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 12/22/2022] [Accepted: 03/25/2023] [Indexed: 03/29/2023] Open
Abstract
BACKGROUND Digital sensing solutions represent a convenient, objective, relatively inexpensive method that could be leveraged for assessing symptoms of various health conditions. Recent progress in the capabilities of digital sensing products has targeted the measurement of scratching during sleep, traditionally referred to as nocturnal scratching, in patients with atopic dermatitis or other skin conditions. Many solutions measuring nocturnal scratch have been developed; however, a lack of efforts toward standardization of the measure's definition and contextualization of scratching during sleep hampers the ability to compare different technologies for this purpose. OBJECTIVE We aimed to address this gap and bring forth unified measurement definitions for nocturnal scratch. METHODS We performed a narrative literature review of definitions of scratching in patients with skin inflammation and a targeted literature review of sleep in the context of the period during which such scratching occurred. Both searches were limited to English language studies in humans. The extracted data were synthesized into themes based on study characteristics: scratch as a behavior, other characterization of the scratching movement, and measurement parameters for both scratch and sleep. We then developed ontologies for the digital measurement of sleep scratching. RESULTS In all, 29 studies defined inflammation-related scratching between 1996 and 2021. When cross-referenced with the results of search terms describing the sleep period, only 2 of these scratch-related papers also described sleep-related variables. From these search results, we developed an evidence-based and patient-centric definition of nocturnal scratch: an action of rhythmic and repetitive skin contact movement performed during a delimited time period of intended and actual sleep that is not restricted to any specific time of the day or night. Based on the measurement properties identified in the searches, we developed ontologies of relevant concepts that can be used as a starting point to develop standardized outcome measures of scratching during sleep in patients with inflammatory skin conditions. CONCLUSIONS This work is intended to serve as a foundation for the future development of unified and well-described digital health technologies measuring nocturnal scratching and should enable better communication and sharing of results between various stakeholders taking part in research in atopic dermatitis and other inflammatory skin conditions.
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Affiliation(s)
- Will Ke Wang
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
| | | | | | - Jessilyn Dunn
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
- Department of Biostatistics & Bioinformatics, Duke University, Durham, NC, United States
- The Duke Clinical Research Institute, Durham, NC, United States
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Follansbee T, Domocos D, Nguyen E, Nguyen A, Bountouvas A, Velasquez L, Iodi Carstens M, Takanami K, Ross SE, Carstens E. Inhibition of itch by neurokinin 1 receptor (Tacr1) -expressing ON cells in the rostral ventromedial medulla in mice. eLife 2022; 11:69626. [PMID: 35972457 PMCID: PMC9381038 DOI: 10.7554/elife.69626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 08/04/2022] [Indexed: 12/03/2022] Open
Abstract
The rostral ventromedial medulla (RVM) is important in descending modulation of spinal nociceptive transmission, but it is unclear if the RVM also modulates spinal pruriceptive transmission. RVM ON cells are activated by noxious algesic and pruritic stimuli and are pronociceptive. Many RVM-spinal projection neurons express the neurokinin-1 receptor (Tacr1), and ON-cells are excited by local administration of substance P (SP). We hypothesized that Tacr1-expressing RVM ON cells exert an inhibitory effect on itch opposite to their pronociceptive action. Intramedullary microinjection of SP significantly potentiated RVM ON cells and reduced pruritogen-evoked scratching while producing mild mechanical sensitization. Chemogenetic activation of RVM Tacr1-expressing RVM neurons also reduced acute pruritogen-evoked scratching. Optotagging experiments confirmed RVM Tacr1-expressing neurons to be ON cells. We conclude that Tacr1-expressing ON cells in RVM play a significant role in the modulation of pruriceptive transmission.
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Affiliation(s)
- Taylor Follansbee
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, United States.,Department of Neuroscience, Johns Hopkins University, Baltimore, United States
| | - Dan Domocos
- Department of Anatomy, Animal Physiology and Biophysics, University of Bucharest, Bucharest, Romania
| | - Eileen Nguyen
- Pittsburgh Center for Pain Research and Department of Neurobiology, University of Pittsburgh, Pittsburgh, United States
| | - Amanda Nguyen
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, United States
| | - Aristea Bountouvas
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, United States
| | - Lauren Velasquez
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, United States
| | - Mirela Iodi Carstens
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, United States
| | - Keiko Takanami
- Department of Environmental Life Science, National Nara Women University, Nara, Japan
| | - Sarah E Ross
- Pittsburgh Center for Pain Research and Department of Neurobiology, University of Pittsburgh, Pittsburgh, United States
| | - Earl Carstens
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, United States
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Meeuwis SH, van Middendorp H, Lavrijsen APM, Veldhuijzen DS, Evers AWM. Open- and Closed-Label Placebo and Nocebo Suggestions About a Sham Transdermal Patch. Psychosom Med 2021; 83:33-42. [PMID: 32969962 PMCID: PMC7748039 DOI: 10.1097/psy.0000000000000862] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 07/21/2020] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Placebo effects may occur when it is known that an inert substance is given (i.e., open-label placebo). It is not yet clear whether these effects are similar to concealed (i.e., closed-label) placebo effects for itch or whether nocebo effects can be induced under open-label conditions. METHODS Healthy volunteers (n = 112) were randomized to an open-label (I) or closed-label (II) positive suggestions group, or an open-label (III) or closed-label (IV) negative suggestions group. Participants were told, as cover story, that a transdermal caffeine patch would be applied that positively influences cognitive abilities and, as a side effect, positively or negatively (depending on group allocation) influences itch. Participants in the open-label groups were given a rationale explaining placebo and nocebo effect mechanisms. Itch (the primary outcome) was induced at baseline and postsuggestions by histamine iontophoresis. RESULTS Analyses of variance revealed significantly lower itch in the positive compared with the negative suggestions groups for both open- and closed-label contexts (all, p ≤ .008, Cohen d ≥ 0.47). Self-rated skin response was less severe after positive versus negative suggestions (all, p ≤ .017, Cohen d ≥ 0.33), but no effects on physical skin response were found (all, p ≥ .23, Cohen d ≤ 0.30). CONCLUSIONS Itch can be reduced by positive compared with negative suggestions under both open- and closed-label conditions. These findings indicate that open-label suggestions may potentially be a tool to use placebo effects for self-reported outcomes in clinical practice, for example, by explaining the role of expectancy in treatment. It needs to be investigated further under which circumstances an open-label rationale may impact placebo and nocebo effects.Trial Registration:www.trialregister.nl; NTR7174.
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Najafi P, Dufor O, Ben Salem D, Misery L, Carré JL. Itch processing in the brain. J Eur Acad Dermatol Venereol 2020; 35:1058-1066. [PMID: 33145804 DOI: 10.1111/jdv.17029] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 09/17/2020] [Accepted: 10/02/2020] [Indexed: 01/04/2023]
Abstract
Itch is a sensation defined as the urge to scratch. The central mechanisms of itch are being increasingly studied. These studies are usually based on experimental itch induction methods, which can be classified into the following categories: histamine-induced, induction by other non-histamine chemicals (e.g. cowhage), physically induced (e.g. electrical) and mentally induced (e.g. audio-visual). Because pain has been more extensively studied, some extrapolations to itch can be proposed and verified by experiments. Recent studies suggest that the itch-processing network in the brain could be disrupted in certain diseases. This disruption could be related to the implication of new regions or the exclusion of already engaged brain regions from itch-processing network in the brain.
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Affiliation(s)
| | - O Dufor
- LIEN, Univ Brest, Brest, France.,LabISEN Yncréa Ouest ISEN, Brest, France
| | - D Ben Salem
- Univ Brest, LaTIM, INSERM, UMR 1101, Brest, France.,University Hospital of Brest, Brest, France
| | - L Misery
- LIEN, Univ Brest, Brest, France.,University Hospital of Brest, Brest, France
| | - J-L Carré
- LIEN, Univ Brest, Brest, France.,University Hospital of Brest, Brest, France
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Wolters F, Peerdeman KJ, Evers AW. Placebo and Nocebo Effects Across Symptoms: From Pain to Fatigue, Dyspnea, Nausea, and Itch. Front Psychiatry 2019; 10:470. [PMID: 31312148 PMCID: PMC6614509 DOI: 10.3389/fpsyt.2019.00470] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 06/13/2019] [Indexed: 01/06/2023] Open
Abstract
Placebo and nocebo effects are, respectively, the helpful and harmful treatment effects that do not arise from active treatment components. These effects have thus far been researched most often in pain. It is not yet clear to what extent these findings from pain can be generalized to other somatic symptoms. This review investigates placebo and nocebo effects in four other highly prevalent symptoms: dyspnea, fatigue, nausea, and itch. The role of learning mechanisms (verbal suggestions, conditioning) in placebo and nocebo effects on various outcomes (self-reported, behavioral, and physiological) of these different somatic symptoms is explored. A search of experimental studies indicated that, as in pain, the combination of verbal suggestion and conditioning is generally more effective than suggestion alone for evoking placebo and nocebo effects. However, conditioning appears more and verbal suggestions less relevant in symptoms other than pain, with the exception of placebo effects on fatigue and nocebo effects on itch. Physiological measures, such as heart rate, lung function, or gastric activity, are rarely affected even when self-reported symptoms are. Neurobiological correlates are rarely investigated, and few commonalities appear across symptoms. Expectations generally predict placebo and nocebo effects for dyspnea and itch but seem less involved in fatigue and nausea. Individual characteristics do not consistently predict placebo or nocebo effects across symptoms or studies. In sum, many conclusions deriving from placebo and nocebo pain studies do appear to apply to other somatic symptoms, but a number of important differences exist. Understanding what type of learning mechanisms for which symptom are most likely to trigger placebo and nocebo effects is crucial for generalizing knowledge for research and therapies across symptoms and can help clinicians to optimize placebo effects in practice.
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Affiliation(s)
- Fabian Wolters
- Health, Medical and Neuropsychology Unit, Institute of Psychology, Faculty of Social and Behavioral Sciences, Leiden University, Leiden, Netherlands
- Leiden Institute for Brain and Cognition, Leiden University, Leiden, Netherlands
| | - Kaya J. Peerdeman
- Health, Medical and Neuropsychology Unit, Institute of Psychology, Faculty of Social and Behavioral Sciences, Leiden University, Leiden, Netherlands
- Leiden Institute for Brain and Cognition, Leiden University, Leiden, Netherlands
| | - Andrea W.M. Evers
- Health, Medical and Neuropsychology Unit, Institute of Psychology, Faculty of Social and Behavioral Sciences, Leiden University, Leiden, Netherlands
- Leiden Institute for Brain and Cognition, Leiden University, Leiden, Netherlands
- Department of Psychiatry, Leiden University Medical Center, Leiden, Netherlands
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