In 2012,we published the first special issue on the mechanisms of pain and itch in Neuroscience Bulletin[1],covering peripheral[2,3],central[4],and glial[5]mechanisms.In 2018,the second special issue expanded on these...In 2012,we published the first special issue on the mechanisms of pain and itch in Neuroscience Bulletin[1],covering peripheral[2,3],central[4],and glial[5]mechanisms.In 2018,the second special issue expanded on these topics[6],featuring single-cell profiling and in vivo Ca2+imaging of primary sensory neurons[7,8],and illustrating how nociceptors regulate pain,itch,and infection[9].It also highlighted spinal neurocircuits of pain[10]and itch[11],glial contributions[12],sex differences[13],and supraspinal mechanisms underlying pain and empathy[14,15].Over the past seven years,significant advances have been made in neuroglial and neuroimmune interactions and supraspinal circuits.Thus,this third special issue—comprising one review,eleven original articles,and one research highlight[16,17,18,19,20,21,22,23,24,25,26,27,28]—timely summarizes recent progress in pain and itch research.展开更多
Neuraxial opioids,widely used in obstetric and perioperative pain management,often lead to unwanted itch,reducing patient satisfaction.While theμ-opioid receptor has been implicated in opioid-induced itch,the genetic...Neuraxial opioids,widely used in obstetric and perioperative pain management,often lead to unwanted itch,reducing patient satisfaction.While theμ-opioid receptor has been implicated in opioid-induced itch,the genetic basis for variable itch incidence remains unknown.This study examined 3616 patients receiving epidural opioids,revealing an itch occurrence of 26.55%,with variations among opioid types and gender.Analysis of the OPRM1 gene identified six single-nucleotide polymorphisms,notably rs1799971(A118G),that correlated with opioid-induced itch.Mouse models with an equivalent A112G mutation showed reduced neuraxial opioid-induced itch and light touch-evoked itch,mirroring human findings.The 118G allele demonstrated an anti-itch effect without impacting analgesia,addiction,or tolerance,offering insights for risk stratification and potential anti-itch pretreatment strategies.展开更多
Background:While mild itching may seem harmless,it can worsen over time,necessitating early treatment.Epicutaneous sensitization has recently gained attention.Oral exposure may promote immune tolerance,but ingestion a...Background:While mild itching may seem harmless,it can worsen over time,necessitating early treatment.Epicutaneous sensitization has recently gained attention.Oral exposure may promote immune tolerance,but ingestion after epicutaneous sensitization can trigger severe allergic responses.Therefore,this study focused on the initial stages of allergic symptoms before they become severe and investigated the mechanisms underlying food ingestion-induced mild itching following epicutaneous sensitization.Methods:Female mice were epicutaneously sensitized with ovalbumin(OVA).Scratching behavior was recorded,and serum and tissue samples were collected.Levels of OVA-specific immunoglobulin(Ig)E/IgG1,histamine,and mast cell protease-1(MCPT-1)were measured by ELISA.Histological analysis of skin tissues and immune cell infiltration was performed via staining.Results:OVA challenge following epicutaneous sensitization induced mild itching in the OVA group.Scratching behavior peaked between 1 and 2 h and persisted for 8 h before returning to baseline.This itching was accompanied by dynamic fluctuations in OVA-specific IgE and IgG1,histamine,and MCPT-1 levels.Histological analysis revealed increased epidermal thickness and granulocytic infiltration,particularly of mast cells and eosinophils,within 2 h of OVA challenge.Mast cell and eosinophil migration into the skin tissues was significant,with eosinophil migration into the dermis persisted despite normalization of histamine levels and mast cell degranulation.These results suggest that mast cells and eosinophils play significant roles even in mild itching.Conclusion:This study provides insights into the early immune responses involved in food allergies,contributing to a better understanding of how mild symptoms can progress to more severe reactions.展开更多
The anterior cingulate cortex(ACC)has recently been proposed as a key player in the representation of itch stimuli.However,to date,little is known about the contribution of specific ACC interneuron populations to itch...The anterior cingulate cortex(ACC)has recently been proposed as a key player in the representation of itch stimuli.However,to date,little is known about the contribution of specific ACC interneuron populations to itch processing.Using c-Fos immunolabeling and in vivo Ca2+imaging,we reported that both histamine and chloroquine stimuli-induced acute itch caused a marked enhancement of vasoactive intestinal peptide(VIP)-expressing interneuron activity in the ACC.Behavioral data indicated that optogenetic and chemogenetic activation of these neurons reduced scratching responses related to histaminergic and non-histaminergic acute itch.Similar neural activity and modulatory role of these neurons were seen in mice with chronic itch induced by contact dermatitis.Together,this study highlights the importance of ACC VIP+neurons in modulating itch-related affect and behavior,which may help us to develop novel mechanism-based strategies to treat refractory chronic itch in the clinic.展开更多
Nociception is an important physiological process that detects harmful signals and results in pain perception. In this review, we discuss important experimental evidence involving some TRP ion channels as molecular se...Nociception is an important physiological process that detects harmful signals and results in pain perception. In this review, we discuss important experimental evidence involving some TRP ion channels as molecular sensors of chemical, thermal, and mechanical noxious stimuli to evoke the pain and itch sensations. Among them are the TRPA1 channel, members of the vanilloid subfamily （TRPV1, TRPV3, and TRPV4）, and finally members of the melastatin group （TRPM2, TRPM3, and TRPMS）. Given that pain and itch are pro-survival, evolutionarily-honed protective mechanisms, care has to be exercised when developing inhibitory/modulatory com- pounds targeting specific pain/itch-TRPs so that physio- logical protective mechanisms are not disabled to a degree that stimulus-mediated injury can occur. Such events have impeded the development of safe and effective TRPV1- modulating compounds and have diverted substantial resources. A beneficial outcome can be readily accom- plished via simple dosing strategies, and also by incorpo- rating medicinal chemistry design features during compound design and synthesis. Beyond clinical use, where compounds that target more than one channel might have a place and possibly have advantageous features, highly specific and high-potency compounds will be helpful in mechanistic discovery at the structure-function level.展开更多
Toll-like receptors （TLRs） are germline-encoded pattern-recognition receptors that initiate innate immune re- sponses by recognizing molecular structures shared by a wide range of pathogens, known as pathogen-associ...Toll-like receptors （TLRs） are germline-encoded pattern-recognition receptors that initiate innate immune re- sponses by recognizing molecular structures shared by a wide range of pathogens, known as pathogen-associated molecular patterns （PAMPs）. After tissue injury or cellular stress, TLRs also detect endogenous ligands known as danger-associated molecular patterns （DAMPs）. TLRs are expressed in both non-neuronal and neuronal cell types in the central nervous system （CNS） and contribute to both infectious and non-infectious disorders in the CNS. Following tissue insult and nerve injury, TLRs （such as TLR2, TLR3, and TLR4） induce the activation of microglia and astrocytes and the production of the proinflammatory cytokines in the spinal cord, leading to the development and maintenance of inflammatory pain and neu- ropathic pain. In particular, primary sensory neurons, such as nociceptors, express TLRs （e.g., TLR4 and TLR7） to sense exogenous PAMPs and endogenous DAMPs released after tissue injury and cellular stress. These neuronal TLRs are new players in the processing of pain and itch by increasing the excitability of primary sensory neurons. Given the prevalence of chronic pain and itch and the suffering of affected people, insights into TLR signaling in the nervous system will open a new avenue for the management of clinical pain and itch.展开更多
Objective To investigate the role of oxidative stress in itch-indicative scratching behavior in mice, and further- more, to define the cellular and molecular mechanisms underlying oxidative stress-mediated itch. Metho...Objective To investigate the role of oxidative stress in itch-indicative scratching behavior in mice, and further- more, to define the cellular and molecular mechanisms underlying oxidative stress-mediated itch. Methods Scratching behavior was induced by intradermal injection of the oxidants hydrogen peroxide （H202） or tert-butylhydroperoxide （tBHP） into the nape of the neck in mice. The mice were observed for 30 rain. Results Intradermal H202 （0.03%-1%） or tBHP （1-30 pmol） elicited robust scratching behavior, displaying an inverted U-shaped dose-response curve. Naloxone, an opioid receptor antagonist, but not morphine, largely suppressed the oxidant-induced scratching. Chlorpheniramine, a histamine H1 receptor antagonist, blocked histamine- but not oxidant-induced scratching, indicating the involvement of a histamine-independent mechanism in oxidant-evoked itch. Further, resiniferatoxin treatment abolished oxidant-induced scratching, suggesting an essential role of C-fibers. Notably, blockade of transient receptor potential subtype ankyrin 1 （TRPA1） with the selective TRPA1 antagonist HC-030031, or genetic deletion of Trpal but not Trpvl （subfamily V, mem- ber 1） resulted in a profound reduction in H202-evoked scratching. Finally, systemic administration of the antioxidant N- acetyl-L-cysteine or trolox （a water-soluble vitamin E analog） attenuated scratching induced by the oxidants. Conclusion Oxidative stress by different oxidants induces profound scratching behavior, which is largely histamine- and TRPV1- independent but TRPAl-dependent. Antioxidants and TRPA1 antagonists may be used to treat human itch conditions as- sociated with oxidative stress.展开更多
Chronic pain and itch are a pathological operation of the somatosensory system at the levels of primary sensory neurons, spinal cord and brain. Pain and itch are clearly distinct sensations, and recent studies have re...Chronic pain and itch are a pathological operation of the somatosensory system at the levels of primary sensory neurons, spinal cord and brain. Pain and itch are clearly distinct sensations, and recent studies have revealed the separate neuronal pathways that are involved in each sensation. However, the mechanisms by which these sensations turn into a pathological chronic state are poorly understood. A proposed mechanism underlying chronic pain and itch involves abnormal excitability in dorsal horn neurons in the spinal cord. Furthermore, an increasing body of evidence from models of chronic pain and itch has indicated that synaptic hyperexcitability in the spinal dorsal horn might not be a consequence simply of changes in neurons, but rather of multiple alterations in glial cells. Thus, understanding the key roles of glial cells may provide us with exciting insights into the mechanisms of chronicity of pain and itch, and lead to new targets for treating chronic pain and itch.展开更多
Pain and itch are unpleasant sensations that often accompany infections caused by viral, bacterial, parasitic, and fungal pathogens. Recent studies show that sensory neurons are able to directly detect pathogens to me...Pain and itch are unpleasant sensations that often accompany infections caused by viral, bacterial, parasitic, and fungal pathogens. Recent studies show that sensory neurons are able to directly detect pathogens to mediate pain and itch. Nociceptor and pruriceptor neurons respond to pathogen-associated molecular patterns, including Toll-like receptor ligands, N-formyl peptides, and bacterial toxins. Other pathogens are able to silence neuronal activity to produce analgesia during infection. Pain and itch could lead to neuronal modulation of the immune system or behavioral avoidance of future patho- gen exposure. Conversely, pathogens could modulate neuronal signaling to potentiate their pathogenesis and facilitate their spread to other hosts. Defining how pathogens modulate pain and itch has critical implications for sensory neurobiology and our understanding of host- microbe interactions.展开更多
文摘In 2012,we published the first special issue on the mechanisms of pain and itch in Neuroscience Bulletin[1],covering peripheral[2,3],central[4],and glial[5]mechanisms.In 2018,the second special issue expanded on these topics[6],featuring single-cell profiling and in vivo Ca2+imaging of primary sensory neurons[7,8],and illustrating how nociceptors regulate pain,itch,and infection[9].It also highlighted spinal neurocircuits of pain[10]and itch[11],glial contributions[12],sex differences[13],and supraspinal mechanisms underlying pain and empathy[14,15].Over the past seven years,significant advances have been made in neuroglial and neuroimmune interactions and supraspinal circuits.Thus,this third special issue—comprising one review,eleven original articles,and one research highlight[16,17,18,19,20,21,22,23,24,25,26,27,28]—timely summarizes recent progress in pain and itch research.
基金supported by the National Natural Science Foundation of China(32271047)the National Key Research and Development Program of China(2020YFC2008405)+1 种基金The Innovative Research Team of High-level Local Universities in Shanghai,the Natural Science Foundation of Shanghai(22ZR1413800)Shanghai Municipal Science and Technology Major Project(2018SHZDZX01)。
文摘Neuraxial opioids,widely used in obstetric and perioperative pain management,often lead to unwanted itch,reducing patient satisfaction.While theμ-opioid receptor has been implicated in opioid-induced itch,the genetic basis for variable itch incidence remains unknown.This study examined 3616 patients receiving epidural opioids,revealing an itch occurrence of 26.55%,with variations among opioid types and gender.Analysis of the OPRM1 gene identified six single-nucleotide polymorphisms,notably rs1799971(A118G),that correlated with opioid-induced itch.Mouse models with an equivalent A112G mutation showed reduced neuraxial opioid-induced itch and light touch-evoked itch,mirroring human findings.The 118G allele demonstrated an anti-itch effect without impacting analgesia,addiction,or tolerance,offering insights for risk stratification and potential anti-itch pretreatment strategies.
基金supported by JSPS KAKENHI Grant Number(22K11779).
文摘Background:While mild itching may seem harmless,it can worsen over time,necessitating early treatment.Epicutaneous sensitization has recently gained attention.Oral exposure may promote immune tolerance,but ingestion after epicutaneous sensitization can trigger severe allergic responses.Therefore,this study focused on the initial stages of allergic symptoms before they become severe and investigated the mechanisms underlying food ingestion-induced mild itching following epicutaneous sensitization.Methods:Female mice were epicutaneously sensitized with ovalbumin(OVA).Scratching behavior was recorded,and serum and tissue samples were collected.Levels of OVA-specific immunoglobulin(Ig)E/IgG1,histamine,and mast cell protease-1(MCPT-1)were measured by ELISA.Histological analysis of skin tissues and immune cell infiltration was performed via staining.Results:OVA challenge following epicutaneous sensitization induced mild itching in the OVA group.Scratching behavior peaked between 1 and 2 h and persisted for 8 h before returning to baseline.This itching was accompanied by dynamic fluctuations in OVA-specific IgE and IgG1,histamine,and MCPT-1 levels.Histological analysis revealed increased epidermal thickness and granulocytic infiltration,particularly of mast cells and eosinophils,within 2 h of OVA challenge.Mast cell and eosinophil migration into the skin tissues was significant,with eosinophil migration into the dermis persisted despite normalization of histamine levels and mast cell degranulation.These results suggest that mast cells and eosinophils play significant roles even in mild itching.Conclusion:This study provides insights into the early immune responses involved in food allergies,contributing to a better understanding of how mild symptoms can progress to more severe reactions.
基金supported by grants from the National Natural Science Foundation of China(82271243 and 82101318)Shaanxi Province Key Research and Development Plan(2024SF-ZDCYL-01-13)+1 种基金the support funding from Fourth Military Medical University(2024JC005,2020AXJHHJ,and XJZT24JC27)Liaoning Provincial Joint Science and Technology Program(2023-MSLH-345).
文摘The anterior cingulate cortex(ACC)has recently been proposed as a key player in the representation of itch stimuli.However,to date,little is known about the contribution of specific ACC interneuron populations to itch processing.Using c-Fos immunolabeling and in vivo Ca2+imaging,we reported that both histamine and chloroquine stimuli-induced acute itch caused a marked enhancement of vasoactive intestinal peptide(VIP)-expressing interneuron activity in the ACC.Behavioral data indicated that optogenetic and chemogenetic activation of these neurons reduced scratching responses related to histaminergic and non-histaminergic acute itch.Similar neural activity and modulatory role of these neurons were seen in mice with chronic itch induced by contact dermatitis.Together,this study highlights the importance of ACC VIP+neurons in modulating itch-related affect and behavior,which may help us to develop novel mechanism-based strategies to treat refractory chronic itch in the clinic.
基金supported by the National Institutes of Health,USA(DE018549,UL1TR001117,P30AR066527,and AR48182 to WL,AR48182-S1 to WL as co-investigatorF33DE024668 and K12DE022793 to YC)+1 种基金the US Department of Defense(W81XWH-13-1-0299 to WL)the Harrington Discovery Institute,Cleveland OH(to WL)
文摘Nociception is an important physiological process that detects harmful signals and results in pain perception. In this review, we discuss important experimental evidence involving some TRP ion channels as molecular sensors of chemical, thermal, and mechanical noxious stimuli to evoke the pain and itch sensations. Among them are the TRPA1 channel, members of the vanilloid subfamily （TRPV1, TRPV3, and TRPV4）, and finally members of the melastatin group （TRPM2, TRPM3, and TRPMS）. Given that pain and itch are pro-survival, evolutionarily-honed protective mechanisms, care has to be exercised when developing inhibitory/modulatory com- pounds targeting specific pain/itch-TRPs so that physio- logical protective mechanisms are not disabled to a degree that stimulus-mediated injury can occur. Such events have impeded the development of safe and effective TRPV1- modulating compounds and have diverted substantial resources. A beneficial outcome can be readily accom- plished via simple dosing strategies, and also by incorpo- rating medicinal chemistry design features during compound design and synthesis. Beyond clinical use, where compounds that target more than one channel might have a place and possibly have advantageous features, highly specific and high-potency compounds will be helpful in mechanistic discovery at the structure-function level.
基金supported by the US National Institutes of Health (R01-DE17794, R01-NS54362 and R01-NS67686)
文摘Toll-like receptors （TLRs） are germline-encoded pattern-recognition receptors that initiate innate immune re- sponses by recognizing molecular structures shared by a wide range of pathogens, known as pathogen-associated molecular patterns （PAMPs）. After tissue injury or cellular stress, TLRs also detect endogenous ligands known as danger-associated molecular patterns （DAMPs）. TLRs are expressed in both non-neuronal and neuronal cell types in the central nervous system （CNS） and contribute to both infectious and non-infectious disorders in the CNS. Following tissue insult and nerve injury, TLRs （such as TLR2, TLR3, and TLR4） induce the activation of microglia and astrocytes and the production of the proinflammatory cytokines in the spinal cord, leading to the development and maintenance of inflammatory pain and neu- ropathic pain. In particular, primary sensory neurons, such as nociceptors, express TLRs （e.g., TLR4 and TLR7） to sense exogenous PAMPs and endogenous DAMPs released after tissue injury and cellular stress. These neuronal TLRs are new players in the processing of pain and itch by increasing the excitability of primary sensory neurons. Given the prevalence of chronic pain and itch and the suffering of affected people, insights into TLR signaling in the nervous system will open a new avenue for the management of clinical pain and itch.
基金supported by grants from the US National Institutes of Health (R01-DE17794,R01-NS54362 and R01-NS67686)
文摘Objective To investigate the role of oxidative stress in itch-indicative scratching behavior in mice, and further- more, to define the cellular and molecular mechanisms underlying oxidative stress-mediated itch. Methods Scratching behavior was induced by intradermal injection of the oxidants hydrogen peroxide （H202） or tert-butylhydroperoxide （tBHP） into the nape of the neck in mice. The mice were observed for 30 rain. Results Intradermal H202 （0.03%-1%） or tBHP （1-30 pmol） elicited robust scratching behavior, displaying an inverted U-shaped dose-response curve. Naloxone, an opioid receptor antagonist, but not morphine, largely suppressed the oxidant-induced scratching. Chlorpheniramine, a histamine H1 receptor antagonist, blocked histamine- but not oxidant-induced scratching, indicating the involvement of a histamine-independent mechanism in oxidant-evoked itch. Further, resiniferatoxin treatment abolished oxidant-induced scratching, suggesting an essential role of C-fibers. Notably, blockade of transient receptor potential subtype ankyrin 1 （TRPA1） with the selective TRPA1 antagonist HC-030031, or genetic deletion of Trpal but not Trpvl （subfamily V, mem- ber 1） resulted in a profound reduction in H202-evoked scratching. Finally, systemic administration of the antioxidant N- acetyl-L-cysteine or trolox （a water-soluble vitamin E analog） attenuated scratching induced by the oxidants. Conclusion Oxidative stress by different oxidants induces profound scratching behavior, which is largely histamine- and TRPV1- independent but TRPAl-dependent. Antioxidants and TRPA1 antagonists may be used to treat human itch conditions as- sociated with oxidative stress.
基金supported by JSPS KAKENHI Grant Numbers 15H02522the Core Research for Evolutional Science and Technology(CREST)program+3 种基金the Practical Research Project for Allergic Diseases and Immunology(Research on Allergic Diseases and Immunology)from Japan Agency for Medical Research and Developmentthe Toray Science FoundationTakeda Science FoundationThe Nakatomi Foundation
文摘Chronic pain and itch are a pathological operation of the somatosensory system at the levels of primary sensory neurons, spinal cord and brain. Pain and itch are clearly distinct sensations, and recent studies have revealed the separate neuronal pathways that are involved in each sensation. However, the mechanisms by which these sensations turn into a pathological chronic state are poorly understood. A proposed mechanism underlying chronic pain and itch involves abnormal excitability in dorsal horn neurons in the spinal cord. Furthermore, an increasing body of evidence from models of chronic pain and itch has indicated that synaptic hyperexcitability in the spinal dorsal horn might not be a consequence simply of changes in neurons, but rather of multiple alterations in glial cells. Thus, understanding the key roles of glial cells may provide us with exciting insights into the mechanisms of chronicity of pain and itch, and lead to new targets for treating chronic pain and itch.
基金supported by funding from the National Institutes of Health(NCCIH DP2AT009499 and MAID K22AI114810),USA
文摘Pain and itch are unpleasant sensations that often accompany infections caused by viral, bacterial, parasitic, and fungal pathogens. Recent studies show that sensory neurons are able to directly detect pathogens to mediate pain and itch. Nociceptor and pruriceptor neurons respond to pathogen-associated molecular patterns, including Toll-like receptor ligands, N-formyl peptides, and bacterial toxins. Other pathogens are able to silence neuronal activity to produce analgesia during infection. Pain and itch could lead to neuronal modulation of the immune system or behavioral avoidance of future patho- gen exposure. Conversely, pathogens could modulate neuronal signaling to potentiate their pathogenesis and facilitate their spread to other hosts. Defining how pathogens modulate pain and itch has critical implications for sensory neurobiology and our understanding of host- microbe interactions.
