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Sneezing and coughing are primary symptoms of many respiratory viral infections and allergies. It is generally assumed that sneezing and coughing involve common sensory receptors and molecular neurotransmission mechanisms. Here, we show that the nasal mucosa is innervated by several discrete populations of sensory neurons, but only one population (MrgprC11 + MrgprA3 - ) mediates sneezing responses to a multitude of nasal irritants, allergens, and viruses. Although this population also innervates the trachea, it does not mediate coughing, as revealed by our newly established cough model. Instead, a distinct sensory population (somatostatin [SST + ]) mediates coughing but not sneezing, unraveling an unforeseen sensory difference between sneezing and coughing. At the circuit level, sneeze and cough signals are transmitted and modulated by divergent neuropathways. Together, our study reveals the difference in sensory receptors and neurotransmission/modulation mechanisms between sneezing and coughing, offering neuronal drug targets for symptom management in respiratory viral infections and allergies., Competing Interests: Declaration of interests M.J.H. has noncompeting financial interests unrelated to this work and is the Founder of NuPeak Therapeutics Inc., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

During the laser-based directed energy deposition (DED-LB) processing, a WC-12Co composite coating with high hardness and strong wear resistance was successfully prepared on a 316L stainless steel substrate by adopting a high-precision coaxial powder feeding system using a spherical WC-12Co composite powder, which showed a large number of dendritic carbides and herringbone planar crystals on the substrate-binding interface. The influences of laser power on microstructural and mechanical properties (e.g., hardness, friction resistance) of WC-12Co composite surfaces were investigated. The results show that laser power has a significant effect on determining the degree of Co phase melting around the WC particles and the adhesion strength between the matrix and the coating. Lower laser power does not meet the melting requirements of WC particles, thus weakening the molding quality of the composite coating. At high laser power, it is possible to dissolve the WC particles and melt the metal powder between the particles, thus improving the material properties. The laser power increased from 700 W to 1000 W and the average hardness of the coating surface gradually increased from 1166.33 HV to 1395.70 HV, which is about 4-5 times higher than the average hardness of the substrate (about 281.76 HV). In addition, the coatings deposited at 1000 W showed better wear resistance. This work shows that the processing parameters during laser-directed energy deposition can be optimized to prepare WC-12Co composite coatings with excellent mechanical properties.

Cerebral perfusion is functionally regulated by neural mechanisms in addition to the systemic hemodynamic variation, vascular reactivity and cerebral metabolism. Although anesthesia is generally esteemed to suppress the overall brain neural activity and metabolism, a few inhalation anesthetics, such as isoflurane, can increase cerebral perfusion, thus heightening the risks of higher intracranial pressure, bleeding, and brain edema during surgery. With the aid of laser speckle contrast imaging, we observed a transient yet limited effect of cerebral perfusion enhancement in mice from awake to anesthetized conditions with different concentration of isoflurane. Retrograde and antegrade tracing revealed a higher proportion of parasympathetic control more than sympathetic innervation for the blood vessels. Surprisingly, isoflurane directly activated pterygopalatine ganglion (PPG) explants and induced FOS expression in the cholinergic neurons. Chemogenetic activation of cholinergic PPG neurons reduced isoflurane-related cerebral perfusion. On the contrary, ablation of the cholinergic PPG neurons resulted in further enhancement of cerebral perfusion induced by isoflurane. While blocking muscarinic cholinergic receptors resulted in the overall reduction upon isoflurane stimulation, the blockage of nicotinic cholinergic receptors enhanced the isoflurane-induced cerebral perfusion only when PPG neurons exist. Collectively, these results suggest that PPG play important roles in regulating cerebral perfusion under isoflurane inhalation., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Changes in microcirculation lead to the progression of organ pathology in diabetes. Although neuroimmune interactions contribute to a variety of conditions, it is still unclear whether abnormal neural activities affect microcirculation related to diabetes. Using laser speckle contrast imaging, we examined the skin of patients with type 2 diabetes and found that their microvascular perfusion was significantly compromised. This phenomenon was recapitulated in a high-fat-diet-driven murine model of type 2 diabetes-like disease. In this setting, although both macrophages and mast cells were enriched in the skin, only mast cells and associated degranulation were critically required for the microvascular impairment. Sensory neurons exhibited enhanced TRPV1 activities, which triggered mast cells to degranulate and compromise skin microcirculation. Chemical and genetic ablation of TRPV1+ nociceptors robustly improve skin microcirculation status. Substance P (SP) is a neuropeptide and was elevated in the skin and sensory neurons in the context of type 2 diabetes. Exogenous administration of SP resulted in impaired skin microcirculation, whereas neuronal knockdown of SP dramatically prevented mast cell degranulation and consequently improved skin microcirculation. Overall, our findings indicate a neural-mast cell axis underlying skin microcirculation disturbance in diabetes and shed light on neuroimmune therapeutics for diabetes-related complications., (© 2024 by the American Diabetes Association.)

TWIK2 channel plays a critical role in NLRP3 inflammasome activation and mice deficient in TWIK2 channel are protected from sepsis and inflammatory lung injury. However, inhibitors of TWIK2 channel are currently in an early stage of development, and the molecular determinants underlying the chemical modulation of TWIK2 channel remain unexplored. In this study, we identified NPBA and the synthesized derivative NPBA-4 potently and selectively inhibited TWIK2 channel by using whole-cell patch clamp techniques. Furthermore, the mutation of the last residues of the selectivity filter in both P1 and P2 (i.e., T106A, T214A) of TWIK2 channel substantially abolished the effect of NPBA on TWIK2 channel. Our data suggest that NPBA blocked TWIK2 channel through binding at the bottom of the selectivity filter, which was also supported by molecular docking prediction. Moreover, we found that NPBA significantly suppressed NLRP3 inflammasome activation in macrophages and alleviated LPS-induced endotoxemia and organ injury in vivo. Notably, the protective effects of NPBA against LPS-induced endotoxemia were abolished in Kcnk6 -/- mice. In summary, our study has uncovered a series of novel inhibitors of TWIK2 channel and revealed their distinct molecular determinants interacting TWIK2 channel. These findings provide new insights into the mechanisms of pharmacological action on TWIK2 channel and opportunities for the development of selective TWIK2 channel modulators to treat related inflammatory diseases., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objectives: To compare the pharmacokinetic and safety of the test group capecitabine tablets (0.5 g) and the reference group capecitabine tablets (0.5 g)., Methods: This study was registered at www.chinadrugtrials.org.cn under the registration number CTR20220138. 48 subjects with solid tumor were recruited and randomized to receive either the test group or the reference group at a dose of 2 g per cycle for three cycles of the entire trial., Results: The point estimate of the geometric mean ratio of C max for the subject and reference groups was 1.0670, which was in the range of 80.00%-125.00%. And the upper limit of 95% confidence interval was -0.0450 < 0. The statistics of geometric mean ratio of AUC 0-t and AUC 0-∞ (test group/reference group) and their 90% confidence intervals were in the range of 80.00%-125.00%, thus the test group was bioequivalent to the reference group under the conditions of this postprandial test. There were no major or serious adverse events. Conclusion: The pharmacokinetic profiles of capecitabine under postprandial conditions were consistent between the two groups. The two groups were bioequivalent and had a similar favorable safety profile in Chinese patients with solid tumor.

Pain and itch coding mechanisms in polymodal sensory neurons remain elusive. MrgprD + neurons represent a major polymodal population and mediate both mechanical pain and nonhistaminergic itch. Here, we show that chemogenetic activation of MrgprD + neurons elicited both pain- and itch-related behavior in a dose-dependent manner, revealing an unanticipated compatibility between pain and itch in polymodal neurons. While VGlut2-dependent glutamate release is required for both pain and itch transmission from MrgprD + neurons, the neuropeptide neuromedin B (NMB) is selectively required for itch signaling. Electrophysiological recordings further demonstrated that glutamate synergizes with NMB to excite NMB-sensitive postsynaptic neurons. Ablation of these spinal neurons selectively abolished itch signals from MrgprD + neurons, without affecting pain signals, suggesting a dedicated itch-processing central circuit. These findings reveal distinct neurotransmitters and neural circuit requirements for pain and itch signaling from MrgprD + polymodal sensory neurons, providing new insights on coding and processing of pain and itch., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Single-cell RNA sequencing methods focusing on the 5'-end of transcripts can reveal promoter and enhancer activity and efficiently profile immune receptor repertoire. However, ultra-high-throughput 5'-end single-cell RNA sequencing methods have not been described. We introduce FIPRESCI, 5'-end single-cell combinatorial indexing RNA-Seq, enabling massive sample multiplexing and increasing the throughput of the droplet microfluidics system by over tenfold. We demonstrate FIPRESCI enables the generation of approximately 100,000 single-cell transcriptomes from E10.5 whole mouse embryos in a single-channel experiment, and simultaneous identification of subpopulation differences and T cell receptor signatures of peripheral blood T cells from 12 cancer patients., (© 2023. The Author(s).)

Dry eye disease (DED) is a multifactorial disease with a high prevalence worldwide. Uncomfortable corneal sensations severely affect daily life in DED patients. Hence, corneal neuron injury is a vital pathogenesis in DED. Notably, endoplasmic reticulum stress (ERS) plays a role in peripheral neuron injury. However, the role of ERS in DED corneal neuron injury is still far from being clear. In this study, we established an environmental DED (eDED) model in vivo and a hyperosmotic DED model in vitro . Subsequently, trigeminal ganglion (TG) corneal neurons were retrograde labeled by WGA-Alexa Fluor 555, and fluorescence-activated cell sorting was used to collect targeted corneal neurons for RNA sequencing in mice. Our results revealed that TG corneal neuron injury but not apoptosis in DED. ERS-related genes and proteins were upregulated in TG corneal neurons of the eDED mice. ERS inhibition alleviated TG corneal neuron's ERS-related injury. Therefore, ERS-induced TG corneal neuron injury may be an important pathomechanism and provide a promising therapeutic approach to DED., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhang, Lin, Li, Wu, Yang and Zhou.)

As the largest barrier organ of the body, the skin is highly innervated by peripheral sensory neurons. The major function of these sensory neurons is to transmit sensations of temperature, pain, and itch to elicit protective responses. Inflammatory skin diseases are triggered by the aberrant activation of immune responses. Recently, increasing evidence has shown that the skin peripheral nervous system also acts as a regulator of immune responses, particularly innate immunity, in various skin inflammatory processes. Meanwhile, immune cells in the skin can express receptors that respond to neuropeptides/neurotransmitters, leading to crosstalk between the immune system and nervous system. Herein, we highlight recent advances of such bidirectional neuroimmune interactions in certain inflammatory skin conditions.

Autonomous learning capacity is a key competency that supports teachers' professional development. In this study, a stratified sampling method was used to recruit 396 junior and senior high school mathematics teachers in T city, one of the provincial city in China. A questionnaire with high reliability and validity developed prior to the study by the researchers was employed to measure their autonomous learning capacity and differences across groups. Twelve teachers were then selected for interviews. The results showed satisfactory overall performance. By subdimension, teachers' performance was the best in the development of study plans, followed by evaluation of learning outcomes, while they needed improvement in learning habit formation and proficiency in using learning methods. Furthermore, the analysis of differences across groups indicated that for autonomous learning capacity, female teachers were significantly better than their male peers; junior high school teachers were better compared to those in senior high school; teachers aged 41-50 underperformed those aged 51 and above; teachers who work in rural areas and townships did not perform worse than urban teachers; and those with doctoral degrees did not demonstrate considerable advantage over others. There were no significant differences in the overall autonomous learning capacity across years of teaching and job title groups. However, in the subdimensions, those with 21-30 years of teaching experience had lower proficiency in using learning methods and evaluation of learning outcomes, and teachers with senior titles did not demonstrate expected advantages in learning habit formation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wang, Kang, Li, Zhen, Chen and Huang.)

Inhomogeneous structures with carbon nanotubes (CNTs), reinforced with Cu composite foams as the reinforcing skeletons (CNTs/Cu f ® Cu), have been designed to overcome the paradox between strength and ductility or conductivity in copper matrix composites. The interface between CNTs and the copper matrix is usually weak, due to poor wettability and interaction. In this study, nickel nanoparticles are decorated onto CNTs to improve interfacial bonding. The broader interface transition area between CNTs and copper with Ni 3 C interfacial products formed, and a combination of improved electrical conductivity (95.6% IACS), tensile strength (364.9 MPa), and elongation (40.6%) was achieved for the Ni-decorated CNTs/Cu f ® Cu (Ni-CNTs/Cu f ® Cu). In addition, the strengthening mechanisms are discussed in this study.

Pain emanating from the female reproductive tract is notoriously difficult to treat, and the prevalence of transient pelvic pain has been placed as high as 70%-80% in women surveyed. Although sex hormones, especially estrogen, are thought to underlie enhanced pain perception in females, the underlying molecular and cellular mechanisms are not completely understood. Here, we showed that the pain-initiating TRPA1 channel was required for pain-related behaviors in a mouse model of estrogen-induced uterine pain in ovariectomized female mice. Surprisingly, 2- and 4-hydroxylated estrogen metabolites (2- and 4-HEMs) in the estrogen hydroxylation pathway, but not estrone, estradiol, or 16-HEMs, directly increased nociceptor hyperactivity through TRPA1 and TRPV1 channels, and picomolar concentrations of 2- and 4-hydroxylation estrone (2- or 4-OHE1) could sensitize TRPA1 channel function. Moreover, both TRPA1 and TRPV1 were expressed in uterine-innervating primary nociceptors, and their expression was increased in the estrogen-induced uterine pain model. Importantly, pretreatment with 2- or 4-OHE1 recapitulated estrogen-induced uterine pain-like behaviors, and intraplantar injections of 2- and 4-OHE1 directly produced a TRPA1-dependent mechanical hypersensitivity. Our findings demonstrated that TRPA1 is critically involved in estrogen-induced uterine pain-like behaviors, which may provide a potential drug target for treating female reproductive tract pain.

Background: Although the Mas-related G-protein-coupled receptors (Mrgprs) play essential roles in itch detection, their contribution to allergic contact dermatitis (ACD)-associated itch remains unclear., Objectives: To investigate whether Mrgprs are involved in ACD and whether Mrgprs can be identified as potential therapeutic targets., Methods: Mrgpr-clusterΔ -/- mice and human MrgprX1 (hMrgprX1) transgenic mice were used to evaluate the function of Mrgprs in oxazolone-induced ACD., Results: Utilizing an ACD model, we found that Mrgpr-clusterΔ -/- mice display significantly reduced pruritus. Among 12 Mrgprs deleted in Mrgpr-clusterΔ -/- mice, the expression of MrgprC11 and MrgprA3 was significantly increased in the ACD model, which also innervated the skin and spinal cord at higher-than-normal densities. The proportions of dorsal root ganglia neurons responding to bovine adrenal medulla peptide 8-22 and chloroquine were also remarkably increased in the ACD model, resulting in enhanced itch behaviour. To study the function of human Mrgprs in ACD-induced itch, we used hMrgprX1 transgenic mice, which rescued the severe itch defect of Mrgpr-clusterΔ -/- mice in the ACD model. Remarkably, pharmacological blockade of hMrgprX1 significantly attenuates ACD itch in hMrgprX1 transgenic mouse., Conclusions: Our study provides the first evidence that Mrgprs are involved in ACD-induced chronic itch, which provides new avenues for itch management in ACD., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The research aimed to explore the biological role of p53 protein and long non-coding RNA (lncRNA) taurine upregulated gene 1 (TUG1) in bupivacaine (bup)-induced neurotoxicity. Our work treated dorsal root ganglion (DRG) cells with bup, detected cell viability through CCK-8, apoptosis through TUNEL assays, DeoxyriboNucleic Acid (DNA) damage through γ-H2AX protein and comet assay, including p53 mRNA, protein and TUG1 expression through q-PCR and western blot, furthermore, cell viability and DNA damage were determined after the silencing of p53 and TUG1, biological information and TUG1 FISH combined with p53 protein immunofluorescence (IF) was performed to determine the cellular localization of these molecule. In vivo experiments, we explored the impact of intrathecal injection of bup on p53 mRNA and protein, TUG1, γ-H2AX protein expression. The results showed that bup was available to signally decreased cell viability, promoted apoptosis rate and DNA damage, additionally, bup increased p53 mRNA and protein and TUG1 expression. P53 siRNA and TUG1 siRNA significantly increased DNA damage. Furthermore, bioinformatics analysis and colocalization experiments revealed that the p53 protein is a transcription factor of TUG1, in vivo experiment, intrathecal injection of bup increased the p53 mRNA, p53 protein, TUG1 and γ-H2AX protein in the murine DRG. In this study, it was found p53 and TUG1 promote the repair of the DNA damage induced by bup in murine dorsal root ganglion cells, suggesting a new strategy for the amelioration of bup-induced neurotoxicity.

Bupivacaine (BP) is a commonly clinically used local anesthetic (LA). Current studies suggest that neurological complications are increased in diabetic patients after LA application, but the molecular mechanism is poorly understood. LA-induced autophagy and neuronal injury have been reported. We hypothesized that a high-glucose environment aggravates BP-induced autophagic damage. Mouse dorsal root ganglion (DRG) neurons were treated with BP in a high-glucose environment, and the results showed that reactive oxygen species (ROS) levels increased, autophagy was activated, autophagy flux was blocked, and cell viability decreased. Pretreatment with the ROS scavenger N-acetyl-cysteine (NAC) attenuated ROS-mediated autophagy regulation. Moreover, the expression of the long noncoding RNA (lncRNA) taurine upregulated gene 1 (TUG1) increased, and NAC and TUG1 siRNA inhibited the expression of TUG1/mammalian target of rapamycin (mTOR) in DRGs treated with BP in a high-glucose environment. Intriguingly, contrary to previous reports on a positive effect on neurons, we found that rapamycin, an autophagy activator, and chloroquine, an autophagy and lysosome inhibitor, both exacerbated autophagic damage. These data suggest that a high-glucose environment exacerbated BP induced ROS-dependent autophagic damage in DRG neurons through the TUG1/mTOR signaling pathway, which provides a theoretical basis and target for the clinical prevention and treatment of BP neurotoxicity in diabeties., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

N-of-1 trials are randomized controlled clinical trials conducted exclusively on a single patient. The ultimate aim of N-of-1 trials is to optimize a strategy in a particular individual. Chronic pain is a common but refractory clinical problem. Its diverse etiologies and broad variations among patients often lead to the requirement of individualizing medicine. Thus, chronic pain represents a classical condition for N-of-1 clinical trials. Studies have indicated that N-of-1 benefits patients with chronic pain, multiple comorbidities, and uncertain variations during therapies; however, this approach it is not yet adopted as the first choice in pain clinics. To dissect the current status of N-of-1 in chronic pain management, as well as the limitations for its implementation, we herein studied all N-of-1 studies related to chronic pain by searching three major databases (PubMed, ClinicalTrial.gov, Cochrane Library) for publications between 1985 and 2020. Of 35 eligibility papers, 19 were selected for analysis. Results confirmed that N-of-1 trials have solved the refractory cases including osteoarthritis, chronic musculoskeletal pain, and neuropathic pain; however, none of the trials dealt with cancer pain. Longer time and more efforts are needed from investigators when carrying out N-of-1 trials, which inevitably result in implementation difficulties. Of note, all recruited trials were conducted in developed countries. As mobile devices have been introduced and protocols improve, renewed interest in the implementation of N-of-1 trials will occur. Collectively, a previously underestimated conflict between "precision medicine" and "poor implementation" has put N-of-1 in a challenging position for chronic pain management., (© 2021. The Author(s).)

Sneezing is a vital respiratory reflex frequently associated with allergic rhinitis and viral respiratory infections. However, its neural circuit remains largely unknown. A sneeze-evoking region was discovered in both cat and human brainstems, corresponding anatomically to the central recipient zone of nasal sensory neurons. Therefore, we hypothesized that a neuronal population postsynaptic to nasal sensory neurons mediates sneezing in this region. By screening major presynaptic neurotransmitters/neuropeptides released by nasal sensory neurons, we found that neuromedin B (NMB) peptide is essential for signaling sneezing. Ablation of NMB-sensitive postsynaptic neurons in the sneeze-evoking region or deficiency in NMB receptor abolished the sneezing reflex. Remarkably, NMB-sensitive neurons further project to the caudal ventral respiratory group (cVRG). Chemical activation of NMB-sensitive neurons elicits action potentials in cVRG neurons and leads to sneezing behavior. Our study delineates a peptidergic pathway mediating sneezing, providing molecular insights into the sneezing reflex arc., Competing Interests: Declaration of interests The authors declare no competing interests. B.S.K. has noncompeting financial interests unrelated to this work and has served as a consultant for AbbVie, ABRAX Japan, Almirall, Cara Therapeutics, Maruho, Menlo Therapeutics, Pfizer, and Third Rock Ventures. He has participated on the advisory board for Almirall, Boehringer Ingelheim, Cara Therapeutics, Kiniksa Pharmaceuticals, Menlo Therapeutics, Regeneron Pharmaceuticals, Sanofi Genzyme, and Trevi Therapeutics. He is also founder, chief scientific officer, and stockholder of Nuogen Pharma and stockholder of Locus Biosciences., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Carbon nanotubes (CNTs) reinforced double-layered Cu-Ni composite foams (Cu-Ni/CNT foams) were prepared through chemical plating and electrodeposition, for the purpose of combining enhanced mechanical and electromagnetic shielding properties. The microstructure characterization revealed a quite uniform dispersion of the CNTs embedded in the metal layers, even after heat treatments. The property testing showed the compressive strength, energy absorption capacity and electromagnetic shielding effectiveness (SE) of Cu-Ni/CNTs foams were significantly improved, as compared to Cu-Ni foams. The heat treatments of the composite foams resulted in an interdiffusion of the Cu and Ni layers, causing an increase of compressive strength and a slight decrease of average SE. The possible mechanisms of the property evolution are discussed.

Itch is an evolutionarily conserved sensation that facilitates expulsion of pathogens and noxious stimuli from the skin. However, in organ failure, cancer, and chronic inflammatory disorders such as atopic dermatitis (AD), itch becomes chronic, intractable, and debilitating. In addition to chronic itch, patients often experience intense acute itch exacerbations. Recent discoveries have unearthed the neuroimmune circuitry of itch, leading to the development of anti-itch treatments. However, mechanisms underlying acute itch exacerbations remain overlooked. Herein, we identify that a large proportion of patients with AD harbor allergen-specific immunoglobulin E (IgE) and exhibit a propensity for acute itch flares. In mice, while allergen-provoked acute itch is mediated by the mast cell-histamine axis in steady state, AD-associated inflammation renders this pathway dispensable. Instead, a previously unrecognized basophil-leukotriene (LT) axis emerges as critical for acute itch flares. By probing fundamental itch mechanisms, our study highlights a basophil-neuronal circuit that may underlie a variety of neuroimmune processes., Competing Interests: Declaration of interests B.S.K. has served as a consultant for AbbVie, ABRAX Japan, Almirall, AstraZeneca, Cara Therapeutics, Daewoong Pharmaceutical, Incyte, LEO Pharma, Lilly, Maruho, Menlo Therapeutics, OM Pharma, Pfizer, and Third Rock Ventures. He has also participated on the advisory board for Almirall, Boehringer Ingelheim, Cara Therapeutics, Kiniksa Pharmaceuticals, Menlo Therapeutics, Regeneron Pharmaceuticals, Sanofi Genzyme, and Trevi Therapeutics. He is stockholder of Locus Biosciences. All other authors declare that they have no relevant conflicts of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Transient receptor potential vanilloid type 1 (TRPV1) is a nonselective cation channel that is intensively expressed in the peripheral nerve system and involved in a variety of physiological and pathophysiological processes in mammals. Its activity is of great significance in transmitting pain or itch signals from peripheral sensory neurons to the central nervous system. The alteration or hypersensitivity of TRPV1 channel is well evidenced under various pathological conditions. Moreover, accumulative studies have revealed that TRPV1-expressing (TRPV1 + ) sensory neurons mediate the neuroimmune crosstalk by releasing neuropeptides to innervated tissues as well as immune cells. In the central projection, TRPV1 + terminals synapse with the secondary neurons for the transmission of pain and itch signalling. The intense involvement of TRPV1 and TRPV1 + neurons in pain and itch makes it a potential pharmaceutical target. Over decades, the basis of TRPV1 channel structure, the nature of its activity, and its modulation in pathological processes have been broadly studied and well documented. Herein, we highlight the role of TRPV1 and its associated neurons in sensing pain and itch. The fundamental understandings of TRPV1-involved nociception, pruriception, neurogenic inflammation, and cell-specific modulation will help bring out more effective strategies of TRPV1 modulation in treating pain- and itch-related diseases., (© 2021. Springer Nature Singapore Pte Ltd.)

Background: Bupivacaine (BP) is commonly used as a local anaesthetic(LA) in the clinic, but it can also cause neurotoxicity, especially in patients with diabetes. Previous studies have found that high-glucose environments can aggravate BP-induced DNA damage in nerve cells. Ku70 is subunit of the DNA damage repair enzyme DNA-PK. This study was designed to determine whether high-glucose conditions enhance BP neurotoxicity and DNA damage by inhibiting Ku70 expression., Methods: We examined the effect of BP on apoptosis and DNA damage in murine dorsal root ganglion (DRG) neurons under hyperglycaemic conditions. Untreated DRG cells and DRG cells pretreated with NU7441, a DNA-PK inhibitor, were cultured for 3 days under normal culture conditions or with 50 mM glucose, and the cells were then treated with BP for 3 h. DNA damage was investigated via comet assays, the ratio of early to late apoptotic cells was assessed by Annexin V-FITC/PI staining, and cell viability was measured by CCK-8 assays. The protein expression levels of DNA-PK, Ku70, Bax, Bcl-2 and γH2ax were measured by immunofluorescence or Western blotting., Results: Compared to its effect under normal culture conditions, BP treatment led to decreased cell viability and increased DNA damage in DRG cells grown under high-glucose conditions. The rate of DRG cell apoptosis and the expression of γH2ax, the ratio of Bax to Bcl-2 also increased under the high-glucose conditions. Furthermore, Ku70 expression was inhibited. The DNA-PK inhibitor, NU7441, could significantly inhibit DNA-PK and Ku70 expression, simultaneously further aggravating BP-induced apoptosis and DNA damage under high-glucose conditions., Conclusion: These data indicate that hyperglycaemia may enhance BP-induced neurotoxicity and DNA damage by inhibiting the DNA repair protein Ku70., (Copyright © 2019 Elsevier B.V. All rights reserved.)

As a protective mechanism, the cornea is sensitive to noxious stimuli. Here, we show that in mice, a high proportion of corneal TRPM8 + cold-sensing fibers express the heat-sensitive TRPV1 channel. Despite its insensitivity to cold, TRPV1 enhances membrane potential changes and electrical firing of TRPM8 + neurons in response to cold stimulation. This elevated neuronal excitability leads to augmented ocular cold nociception in mice. In a model of dry eye disease, the expression of TRPV1 in TRPM8 + cold-sensing fibers is increased, and results in severe cold allodynia. Overexpression of TRPV1 in TRPM8 + sensory neurons leads to cold allodynia in both corneal and non-corneal tissues without affecting their thermal sensitivity. TRPV1-dependent neuronal sensitization facilitates the release of the neuropeptide substance P from TRPM8 + cold-sensing neurons to signal nociception in response to cold. Our study identifies a mechanism underlying corneal cold nociception and suggests a potential target for the treatment of ocular pain.

Although TWIK-related spinal cord K + (TRESK) channel is expressed in all primary afferent neurons in trigeminal ganglia (TG) and dorsal root ganglia (DRG), whether TRESK activity regulates trigeminal pain processing is still not established. Dominant-negative TRESK mutations are associated with migraine but not with other types of pain in humans, suggesting that genetic TRESK dysfunction preferentially affects the generation of trigeminal pain, especially headache. Using TRESK global knock-out mice as a model system, we found that loss of TRESK in all TG neurons selectively increased the intrinsic excitability of small-diameter nociceptors, especially those that do not bind to isolectin B4 (IB4 - ). Similarly, loss of TRESK resulted in hyper-excitation of the small IB4 - dural afferent neurons but not those that bind to IB4 (IB4 + ). Compared with wild-type littermates, both male and female TRESK knock-out mice exhibited more robust trigeminal nociceptive behaviors, including headache-related behaviors, whereas their body and visceral pain responses were normal. Interestingly, neither the total persistent outward current nor the intrinsic excitability was altered in adult TRESK knock-out DRG neurons, which may explain why genetic TRESK dysfunction is not associated with body and/or visceral pain in humans. We reveal for the first time that, among all primary afferent neurons, TG nociceptors are the most vulnerable to the genetic loss of TRESK. Our findings indicate that endogenous TRESK activity regulates trigeminal nociception, likely through controlling the intrinsic excitability of TG nociceptors. Importantly, we provide evidence that genetic loss of TRESK significantly increases the likelihood of developing headache., (Copyright © 2019 Guo et al.)

Background: It was reported that prolonging the injection time or diluting administration can reduce the incidence of opioid-induced cough. However, the incidence of sufentanil-induced cough (SIC) via a standardized infusion rate is unclear. A mechanical dropper is an infusion filtering device commonly used for intravenous degassing; it can also be used to administer special drugs due to its temporary storage and dilution effect. This study assesses the effectiveness of administration via mechanical dropper on SIC., Methods: Two hundred patients undergoing general anesthesia were enrolled. Patients received sufentanil at a strength of 0.3 μg·kg - 1 either via T-connector (group C) or by mechanical dropper (group M) at 1 ml·s - 1 . Cough severity was graded as none (0), mild (1-2), moderate (3-5), or severe (> 5), and the incidence of SIC was evaluated for 5 min after the start of sufentanil injection. Other adverse reactions such as hypotension, hypertension, bradycardia, tachycardia, hypoxemia, vomiting, and aspiration during the induction period of general anesthesia were also observed. The primary outcome was the incidence of SIC. The secondary outcomes were the severity of SIC and other adverse reactions., Results: The incidence of SIC in group M was significantly lower than that in group C (2% versus 21%, P = 0.000), and the prevalence of moderately severe coughing was also statistically different (none in group M versus 11% in group C, P = 0.001). However, there were no statistical differences in the incidence of other adverse reactions between two groups (P > 0.05)., Conclusion: Sufentanil application via mechanical dropper can significantly alleviate the occurrence of SIC during the induction phase of total intravenous general anesthesia. This method is simple, safe, and reliable, and has wide prospective application for clinical use., Trial Registration: Chinese Clinical Trial Register, ChiCTR-IOR-17011561 . Registered on 3 June 2017.

Itch and pain are refractory symptoms of many ocular conditions. Ocular itch is generated mainly in the conjunctiva and is absent from the cornea. In contrast, most ocular pain arises from the cornea. However, the underlying mechanisms remain unknown. Using genetic axonal tracing approaches, we discover distinct sensory innervation patterns between the conjunctiva and cornea. Further genetic and functional analyses in rodent models show that a subset of conjunctival-selective sensory fibers marked by MrgprA3 expression, rather than corneal sensory fibers, mediates ocular itch. Importantly, the actions of both histamine and nonhistamine pruritogens converge onto this unique subset of conjunctiva sensory fibers and enable them to play a key role in mediating itch associated with allergic conjunctivitis. This is distinct from skin itch, in which discrete populations of sensory neurons cooperate to carry itch. Finally, we provide proof of concept that selective silencing of conjunctiva itch-sensing fibers by pruritogen-mediated entry of sodium channel blocker QX-314 is a feasible therapeutic strategy to treat ocular itch in mice. Itch-sensing fibers also innervate the human conjunctiva and allow pharmacological silencing using QX-314. Our results cast new light on the neural mechanisms of ocular itch and open a new avenue for developing therapeutic strategies.

Background: With the development of painless diagnosis and treatment, remifentanil, a synthetic opioid agonist, is increasingly used in gastroscopy for its rapid, short-term, and potent analgesic effect. However, the dosage of remifentanil used in endoscopy is unclear. Index of consciousness (IOC) is a new anesthesia depth-monitoring indicator that can be divided into index of consciousness 1 (IOC 1 ) and index of consciousness 2 (IOC 2 ); IOC 1 is used for estimating a patient's sedation state, whereas IOC 2 reflects analgesic depth. We hypothesized that combining with IOC 1 and IOC 2 monitoring may be helpful to identify an optimal remifentanil dosage in gastroscopic polypectomy., Methods: One hundred twenty patients scheduled for gastroscopic polypectomy were enrolled and were randomly assigned to remifentanil 2 ng/mL (group R2), 4 ng/mL (group R4), or 6 ng/mL (group R6), and 40 cases were in each group. During the anesthesia period, remifentanil was kept at the initial given concentration but propofol was adjusted according to IOC 1 . The primary outcomes were the dosage of propofol and remifentanil. The secondary outcomes were the variety of IOC 1 and IOC 2 , patients' awakening time, and peri-operative adverse reactions such as hypotension, hypertension, bradycardia, tachycardia, body movements, hypoxemia, therapy interruption, nausea, vomiting, aspiration, and intra-operative awareness., Results: With the increasing dosage of remifentanil, the propofol dosage and patients' awakening time decreased significantly, the morbidity of hypertension and body movements also declined, but the incidence of hypotension, bradycardia, and hypoxemia rose. In group R2, the value of IOC 2 remained above 50 during the treatment. However, IOC 2 dropped to below 30 at the beginning of the gastroscopy in group R6, and there was statistical difference in hypoxemia between groups R2 and R6 (P <0.05)., Conclusions: With the help of IOC monitoring, we found that a target concentration of remifentanil 4 ng/mL is comparatively ideal in patients under gastroscopic polypectomy., Trial Registration: Chinese Clinical Trial Register: ChiCTR-OOD-16009489 , on October 19, 2016.

Background: Physical cooling of the eye surface relieves ocular discomfort, but translating this event to drug treatment of dry eye discomfort not been studied. Here, we synthesized a water-soluble TRPM8 receptor agonist called cryosim-3 (C3, 1-diisopropylphosphorylnonane) which selectively activates TRPM8 (linked to cooling) but not TRPV1 or TRPA1 (linked to nociception) and tested C3 in subjects with mild forms of dry eye disease., Methods: A set of 1-dialkylphosphoryalkanes were tested for activation of TRPM8, TRPV1 and TRPA1 receptors in transfected cells. The bioactivity profiles were compared by perioral, topical, and intravenous delivery to anesthetized rats. The selected lead candidate C3 or vehicle (water) was applied with a cotton gauze pad to upper eyelids of patients with dry eye disease (n = 30). Cooling sensation, tear film break-up time (TBUT), basal tear secretion, and corneal staining were evaluated. C3 was then applied four times daily for 2 weeks to patients using a pre-loaded single unit applicator containing 2 mg/mL of C3 in water (n = 20) or water only. TBUT, basal tear secretion, and corneal staining, and three questionnaires surveys of ocular discomfort (VAS scale, OSDI, and CVS symptoms) were analyzed before and at 1 and 2 weeks thereafter., Results: C3 was a selective and potent TRPM8 agonist without TRPV1 or TRPA1 activity. In test animals, the absence of shaking behavior after C3 perioral administration made it the first choice for further study. C3 increased tear secretion in an animal model of dry eye disease and did not irritate when wiped on eyes of volunteers. C3 singly applied (2 mg/ml) produced significant cooling in <5 min, an effecting lasting 46 min with an increase in tear secretion for 60 min. C3 applied for 2 weeks also significantly increased basal tear secretion with questionnaire surveys of ocular discomfort indices clearly showing improvement of symptoms at 1 and 2 weeks. No complaints of irritation or pain were reported by any subject., Conclusions: C3 is a promising candidate for study of TRPM8 function on the eye surface and for relief of dry eye discomfort., Trial Registration: ISRCTN24802609 and ISRCTN13359367 . Registered 23 March 2015 and 2 September 2015.

The aim of this study was to examine the effects of phentolamine on severe hand, foot and mouth disease (HFMD) combined with pulmonary edema (PE). From May 2008 to December 2012, 53 children with severe HFMD plus PE were enrolled in the treatment group, receiving phentolamine intravenously at a loading dose of 5 µg/kg/min. The control group comprised 52 children with the same disease who did not receive phentolamine infusion. Data concerning creatine kinase (CK), CK-MB, cardiac troponin I (cTnI), heart rate, systolic blood pressure (SBP) and the duration of ventilation dependence and hospitalization were collected. Adverse events were also recorded. It was found that the phentolamine-treated patients exhibited significantly lower CK, CK-MB and cTnI levels, heart rate and SBP than the controls (P<0.01 for all parameters). The average duration of ventilator dependence and hospitalization was significantly shorter (P<0.01) in the phentolamine group than in the control group. It was also found that the overall mortality rate was lower in the phentolamine group (5.8%) than in the control group (11.5%). No adverse events were observed in either group. Thus, these results offer preliminary evidence that phentolamine reduces mortality and relieves the symptoms of EV71-induced PE. Phentolamine is a potential therapeutic agent for this highly lethal disorder.

Frankincense and myrrh are widely used in clinics as a pair of herbs to obtain a synergistic effect for relieving pain. To illuminate the analgesia mechanism of frankincense and myrrh, we assessed its effect in a neuropathic pain mouse model. Transient receptor potential vanilloid 1 (TRPV1) plays a crucial role in neuropathic pain and influences the plasticity of neuronal connectivity. We hypothesized that the water extraction of frankincense and myrrh (WFM) exerted its analgesia effect by modulating the neuronal function of TRPV1. In our study, WFM was verified by UHPLC-TQ/MS assay. In vivo study showed that nociceptive response in mouse by heat and capsaicin induced were relieved by WFM treatment. Furthermore, thermal hypersensitivity and mechanical allodynia were also alleviated by WFM treatment in a chronic constriction injury (CCI) mouse model. CCI resulted in increased TRPV1 expression at both the mRNA and protein levels in predominantly small-to-medium neurons. However, after WFM treatment, TRPV1 expression was reverted in real-time PCR, Western blot, and immunofluorescence experiments. Calcium response to capsaicin was also decreased in cultured DRG neurons from CCI model mouse after WFM treatment. In conclusion, WFM alleviated CCI-induced mechanical allodynia and thermal hypersensitivity via modulating TRPV1.

Background: Phosphoinositide-3-kinase (PI3K)/protein kinase B (Akt) pathway activation may promote neuronal survival via neuroprotection during inflammation after cerebral ischemia. In this study, we investigated whether IV pretreatment with emulsified isoflurane (EI) could decrease ischemic brain injury related to the PI3K/Akt pathway., Methods: Male Sprague-Dawley rats received different doses of IV EI (1, 2, 4, or 8 mL/kg/h) or Intralipid (8 mL/kg/h) for 30 minutes (n = 6-12 per group), followed by middle cerebral artery occlusion (MCAO) for 100 minutes to induce transient focal ischemia. The neurologic score and infarct volume were measured 48 hours after MCAO. Immunostaining, Western blot analysis, and an enzyme-linked immunosorbent assay were used to assess EI effects on the cell inflammatory response, high-mobility group box-1 release, and phosphorylated Akt (expression. LY294002, a PI3K inhibitor, was also infused into the ventricular space before EI to determine the effect of EI., Results: Four milliliters per kilogram per hour of EI reduced the infarct size (21.08 ± 11.24 vs 37.09 ± 10.46, P = 0.006), improved neurologic scores after MCAO (1.13 ± 0.48 vs 1.95 ± 0.65, P = 0.015), significantly reinforced neuronal survival (982.7 ± 364.4 vs 439.8 ± 278.4, P = 0.036), and inhibited CD68 macrophage/macroglial infiltration in the ischemic core (188.2 ± 49.1 vs 282 ± 49.4, P = 0.018) compared with the vehicle group. In the EI pretreatment group, the serum high-mobility group box-1 concentration (3.62 ± 0.72 vs 5.73 ± 0.65, P < 0.001) was decreased, and the cerebral phosphorylated Akt level (50.33 ± 4.73 vs 37.5 ± 3.11, P = 0.007) was increased at 48 hours, which was inhibited by LY294002 compared with the vehicle group (5.31 ± 0.72 vs 5.73 ± 0.65, P = 0.216; 43.00 ± 4.84 vs 37.5 ± 3.11, P = 0.091)., Conclusions: These findings suggest that EI pretreatment protects against ischemic brain injury via the inhibition of cerebral inflammation and is associated with the PI3K-Akt pathway in rats with MCAO. This drug may be a novel therapeutic agent for patients after stroke.

Chronic itch (pruritus) is an important clinical problem. However, the underlying molecular basis has yet to be understood. The Transient Receptor Potential Vanilloid 1 channel is a heat-sensitive cation channel expressed in primary sensory neurons and involved in both thermosensation and pain, but its role in chronic itch remains elusive. Here, we for the first time revealed an increased innervation density of Transient Receptor Potential Vanilloid 1-expressing sensory fibers in the skin afflicted with chronic itch. Further analysis indicated that this phenomenon is due to an expansion of Transient Receptor Potential Vanilloid 1-expressing sensory neurons under chronic itch conditions. As a functional correlates of this neuronal expansion, we observed an enhanced neuronal responsiveness to capsaicin under the dry skin conditions. Importantly, the neuronal hypersensitivity to capsaicin results in itch, rather than pain sensation, suggesting that the up-regulated Transient Receptor Potential Vanilloid 1 underlies the pain-to-itch switch under chronic itchy conditions. The study shows that there are different mechanisms of chronic pain and itching, and Transient Receptor Potential Vanilloid 1 plays an important role in chronic itch., (© The Author(s) 2016.)

Background: Isoflurane is a potent volatile anesthetic; however, it evokes airway irritation and neurogenic constriction through transient receptor potential (TRP) A1 channels and sensitizes TRPV1 channels, which colocalizes with TRPA1 in most of the vagal C-fibers innervating the airway. However, little is known about the precise effects of these two channels on the respiratory function during isoflurane anesthesia., Methods: By using a rodent behavioral model and whole-body plethysmograph, the authors examined the response of Trpa1 and Trpv1 mice to isoflurane anesthesia and monitored their respiratory functions during anesthesia., Results: This study showed that Trpa1 mice (n = 9), but not Trpv1 mice (n = 11), displayed a shortened induction latency compared with wild-type mice (n = 10) during isoflurane anesthesia (33 ± 2.0 s in wild-type and 33 ± 3.8 s in Trpv1 vs. 17 ± 1.8 in Trpa1 at 2.2 minimum alveolar concentrations). By contrast, their response to the nonpungent volatile anesthetic sevoflurane is indistinguishable from wild-type mice (24 ± 3.6 s in wild-type vs. 26 ± 1.0 s in Trpa1 at 2.4 minimum alveolar concentrations). The authors discovered that Trpa1 mice inhaled more anesthetic but maintained better respiratory function. Further respiration pattern analysis revealed that isoflurane triggered nociceptive reflexes and led to prolonged resting time between breaths during isoflurane induction as well as decreased dynamic pulmonary compliance, an indicator of airway constriction, throughout isoflurane anesthesia in wild-type and Trpv1 mice, but not in Trpa1 mice., Conclusion: Activation of TRPA1 by isoflurane negatively affects anesthetic induction latency by altering respiratory patterns and impairing pulmonary compliance.

A series of Arg-Phe-NH2 peptidomimetics containing an Arg mimetic were synthesized and tested as agonists of human MrgX1, rat MrgC, and mouse MrgC11 receptors. As predicted from the previously established species specificity, these peptidomimetics were found to be devoid of MrgX1 agonist activity. In contrast, these compounds acted as agonists of MrgC and/or MrgC11 with varying degrees of potency. These new peptidomimetics should complement the existing small molecule human MrgX1 agonists and enhance our ability to assess the therapeutic utility of targeting Mrg receptors in rodent models., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The recent research progress of the utilization of natural drugs for the treatment of liver fibrosis in China and other countries was reviewed. Forty reported remedies were summarized and classified into 3 categories, that is, the single herbal drugs (rhizome, leaf, fruit, bark, peel, flower, whole plants, and oil), traditional Chinese medicine prescriptions and animal drugs. The future directions of the R&D of new natural drugs against liver fibrosis were discussed and some suggestions were provided.