Release Of Substance P Research Articles

GPR35 agonists inhibit TRPA1-mediated colonic nociception through suppression of substance P release.

The development of nonopioid analgesics for the treatment of abdominal pain is a pressing clinical problem. To address this, we examined the expression of Gi/o-coupled receptors, which typically inhibit nociceptor activation, in colonic sensory neurons. This led to the identification of the orphan receptor GPR35 as a visceral analgesic drug target because of its marked coexpression with transient receptor potential ankyrin 1 (TRPA1), a mediator of noxious mechanotransduction in the bowel. Building on in silico docking simulations, we confirmed that the mast cell stabiliser, cromolyn (CS), and phosphodiesterase inhibitor, zaprinast, are agonists at mouse GPR35, promoting the activation of different Gi/o subunits. Pretreatment with either CS or zaprinast significantly attenuated TRPA1-mediated colonic nociceptor activation and prevented TRPA1-mediated mechanosensitisation. These effects were lost in tissue from GPR35-/- mice and were shown to be mediated by inhibition of TRPA1-evoked substance P (SP) release. This observation highlights the pronociceptive effect of SP and its contribution to TRPA1-mediated colonic nociceptor activation and sensitisation. Consistent with this mechanism of action, we confirmed that TRPA1-mediated colonic contractions evoked by SP release were abolished by CS pretreatment in a GPR35-dependent manner. Our data demonstrate that GPR35 agonists prevent the activation and sensitisation of colonic nociceptors through the inhibition of TRPA1-mediated SP release. These findings highlight the potential of GPR35 agonists to deliver nonopioid analgesia for the treatment of abdominal pain.

The Gut Microbial Lipid Metabolite 14(15)-EpETE Inhibits Substance P Release by Targeting GCG/PKA Signaling to Relieve Cisplatin-Induced Nausea and Vomiting in Rats.

Chemotherapy-induced nausea and vomiting (CINV) is a debilitating side effect related to activation of substance P (SP). SP activation can result from dysregulation of the gut-brain axis, and also from activation of protein kinase A signaling (PKA) signaling. In this study, we connected these factors in an attempt to unveil the mechanisms underlying CINV and develop new therapeutic strategies. Female rats were injected with cisplatin (Cis) to induce pica. Fecal samples were collected before/after injection, and subjected to lipid metabolomics analysis. In another portion of pica rats, the PKA inhibitor KT5720 was applied to investigate the involvement of PKA signaling in CINV, while fecal microbiota transplantation (FMT) was implemented to verify the therapeutic effect of the lipid metabolite 14(15)-EpETE. Pica symptoms were recorded, followed by ileal histological examination. The targeting relationship between 14(15)-EpETE and glucagon was determined by bioinformatics. SP and glucagon/PKA signaling in rat ileum, serum, and/or brain substantia nigra were detected by immunohistochemistry, enzyme-linked immunosorbent assay, and/or western blot. The results showed a significantly lower level of 14(15)-EpETE in rat feces after Cis injection. KT5720 treatment alleviated Cis-induced pica symptoms, ileal injury, SP content increase in the ileum, serum, and brain substantia nigra, and ileal PKA activation in rats. The ileal level of glucagon was elevated by Cis in rats. FMT exerted an effect similar to that of KT5720 treatment, relieving the Cis-induced changes, including ileal glucagon/PKA activation in rats. Our findings demonstrate that FMT restores 14(15)-EpETE production, which inhibits SP release by targeting GCG/PKA signaling, ultimately mitigating CINV.

Examination of the Effect of Dimethyl Trisulfide in Acute Stress Mouse Model with the Potential Involvement of the TRPA1 Ion Channel.

Polysulfides are endogenously produced in mammals and generally associated with protective functions. Our aim was to investigate the effect of dimethyl trisulfide (DMTS) in a mouse model of acute stress. DMTS activates transient receptor potential ankyrin 1 (TRPA1) channels and leads to neuropeptide release, potentially that of substance P (SP). We hypothesize that DMTS might inhibit the degrading enzymes of endocannabinoids, so this system was also investigated as another possible pathway for mediating the effects of DMTS. Trpa1 gene wild-type (WT) and knockout (KO) mice were used to confirm the role of the TRPA1 ion channel in mediating the effects of DMTS. C57BL/6J, NK1 gene KO, and Tac1 gene KO mice were used to evaluate the effect of DMTS on the release and expression of SP. Some C57BL/6J animals were treated with AM251, an inhibitor of the cannabinoid CB1 receptor, to elucidate the role of the endocannabinoid system in these processes. Open field test (OFT) and forced swim test (FST) were performed in each mouse strain. A tail suspension test (TST) was performed in Trpa1 WT and KO animals. C-FOS immunohistochemistry was carried out on Trpa1 WT and KO animals. The DMTS treatment increased the number of highly active periods and decreased immobility time in the FST in WT animals, but had no effect on the Trpa1 KO mice. The DMTS administration induced neuronal activation in the Trpa1 WT mice in the stress-related brain areas, such as the locus coeruleus, dorsal raphe nucleus, lateral septum, paraventricular nucleus of the thalamus, and paraventricular nucleus of the hypothalamus. DMTS may have a potential role in the regulation of stress-related processes, and the TRPA1 ion channel may also be involved in mediating the effects of DMTS. DMTS can be an ideal candidate for further study as a potential remedy for stress-related disorders.

MRGPRX2-mediated mast cell activation by substance P from overloaded human tenocytes induces inflammatory and degenerative responses in tendons

Mast cells are immune cells minimally present in normal tendon tissue. The increased abundance of mast cells in tendinopathy biopsies and at the sites of tendon injury suggests an unexplored role of this cell population in overuse tendon injuries. Mast cells are particularly present in tendon biopsies from patients with more chronic symptom duration and a history of intensive mechanical loading. This study, therefore, examined the cross talk between mast cells and human tendon cells in either static or mechanically active conditions in order to explore the potential mechanistic roles of mast cells in overuse tendon injuries. A coculture of isolated human tenocytes and mast cells (HMC-1) combined with Flexcell Tension System for cyclic stretching of tenocytes was used. Additionally, human tenocytes were exposed to agonists and antagonists of substance P (SP) receptors. Mast cell degranulation was assessed by measuring β-hexosaminidase activity. Transwell and cell adhesion assays were used to evaluate mast cell migration and binding to tendon extracellular matrix components (collagen and fibronectin), respectively. Gene expressions were analyzed using real time qRT-PCR. Our results indicate that mechanical stimulation of human tenocytes leads to release of SP which, in turn, activates mast cells through the Mas-related G-protein-coupled receptor X2 (MRGPRX2). The degranulation and migration of mast cells in response to MRGPRX2 activation subsequently cause human tenocytes to increase their expression of inflammatory factors, matrix proteins and matrix metalloproteinase enzymes. These observations may be important in understanding the mechanisms by which tendons become tendinopathic in response to repetitive mechanical stimulation.

Insulin eye drops improve corneal wound healing in STZ-induced diabetic mice by regulating corneal inflammation and neuropeptide release

IntroductionIn recent years, insulin eye drops have attracted increasing attention from researchers and ophthalmologists. The aim of this study was to investigate the efficacy and possible mechanism of action of insulin eye drops in diabetic mice with corneal wounds.MethodsA type 1 diabetes model was induced, and a corneal epithelial injury model of 2.5 mm was established. We used corneal fluorescein staining, hematoxylin-eosin (H-E) staining and the Cochet-Bonnet esthesiometer to examine the process of wound healing. Subsequently, the expression levels of Ki-67, IL-1β, β3-tubulin and neuropeptides, including substance P (SP) and calcitonin gene-related peptide (CGRP), were examined at 72 h after corneal injury.ResultsFluorescein staining demonstrated an acceleration of the recovery of corneal epithelial injury in diabetic mice compared with the saline treatment, which was further evidenced by the overexpression of Ki-67. Moreover, 72 h of insulin application attenuated the expression of inflammatory cytokines and neutrophil infiltration. Remarkably, the results demonstrated that topical insulin treatment enhanced the density of corneal epithelial nerves, as well as neuropeptide SP and CGRP release, in the healing cornea via immunofluorescence staining.ConclusionsOur results indicated that insulin eye drops may accelerate corneal wound healing and decrease inflammatory responses in diabetic mice by promoting nerve regeneration and increasing levels of neuropeptides SP and CGRP.

TRPM8 inhibits substance P release from primary sensory neurons via PKA/GSK-3beta to protect colonic epithelium in colitis

Transient receptor potential melastatin 8 (TRPM8) is a cold sensory receptor in primary sensory neurons that regulates various neuronal functions. Substance P (SP) is a pro-inflammatory neuropeptide secreted by the neurons, and it aggravates colitis. However, the regulatory role of TRPM8 in SP release is still unclear. Our study aimed to investigate TRPM8’s role in SP release from primary sensory neurons during colitis and clarify the effect of SP on colonic epithelium. We analyzed inflammatory bowel disease patients’ data from the Gene Expression Omnibus dataset. Dextran sulfate sodium (DSS, 2.5%)-induced colitis in mice, mouse dorsal root ganglion (DRG) neurons, ND7/23 cell line, and mouse or human colonic organoids were used for this experiment. Our study found that TRPM8, TAC1 and WNT3A expression were significantly correlated with the severity of ulcerative colitis in patients and DSS-induced colitis in mice. The TRPM8 agonist (menthol) and the SP receptor antagonist (Aprepitant) can attenuate colitis in mice, but the effects were not additive. Menthol promoted calcium ion influx in mouse DRG neurons and inhibited the combination and phosphorylation of PKAca from the cAMP signaling pathway and GSK-3β from the Wnt/β-catenin signaling pathway, thereby inhibiting the effect of Wnt3a-driven β-catenin on promoting SP release in ND7/23 cells. Long-term stimulation with SP inhibited proliferation and enhanced apoptosis in both mouse and human colonic organoids. Conclusively, TRPM8 inhibits SP release from primary sensory neurons by inhibiting the interaction between PKAca and GSK-3β, thereby inhibiting the role of SP in promoting colonic epithelial apoptosis and relieving colitis.

Moxibustion ameliorates visceral hypersensitivity by regulating hypothalamus-spinal cord-colon axis in rats with irritable bowel syndrome with diarrhea.

To observe the effect of moxibustion intervention on the hypothalamus-spinal cord-colon axis of rats with irritable bowel syndrome with diarrhea (IBS-D) and explore the mechanism of moxibustion in improving visceral hypersensitivity in rats with IBS-D. A total of 36 SD rats were randomly divided into normal, model, and moxibustion groups, with 12 rats in each group. The IBS-D model was established by maternal separation + acetic acid stimulation + chronic restraint. Rats of the moxibustion group received bilateral moxibustion on "Tianshu" (ST25) and "Shangjuxu" (ST37) for 15 min, once a day for 7 consecutive days. The body weight, loose stool rate, and minimum threshold volume of abdominal withdrawal reflex (AWR) were measured before and after moxibustion intervention, respectively. The histopathological changes in the colon tissue were observed after HE staining. The number of colonic mucosal mast cells (MCs) was measured by toluidine blue staining. The activation of MCs was determined by tryptase positive expression level and examined by immunohistochemical staining. The content, protein and mRNA expression levels and positive expression levels of corticotropin releasing factor (CRF), substance P (SP), and calcitonin gene-related peptide (CGRP) in the hypothalamus, spinal cord and colon tissues were measured by ELISA, Western blot, real-time fluorescent quantitative PCR and immunofluorescence staining, respectively. Compared with the normal group, the loose stool rate was increased (P<0.01)；the body weight and minimum threshold volume of AWR were decreased (P<0.01)；the inflammatory infiltration of colon tissues was obvious；the number of MCs and positive expression level of tryptase in the colon tissue were increased (P<0.01)；the contents, positive expression le-vels, protein and mRNA expression levels of CRF, SP and CGRP in the hypothalamus, spinal cord and colon tissues were increased (P<0.01, P<0.05) in the model group. After the intervention, compared with the model group, all these indicators showed opposite trends (P<0.01, P<0.05) in the moxibustion group. Moxibustion can improve visceral hypersensitivity in rats with IBS-D, and its mechanism may be related to regulating the hypothalamic-spinal-colon axis to reduce the release of CRF, SP and CGRP, and thus to inhibite MC in colon tissue.

Preliminary Investigation on Efficacy and Safety of Substance P-Coated Stent for Promoting Re-Endothelialization: A Porcine Coronary Artery Restenosis Model.

Current polymer-based drug-eluting stents (DESs) have fundamental issues about inflammation and delayed re-endothelializaton of the vessel wall. Substance-P (SP), which plays an important role in inflammation and endothelial cells, has not yet been applied to coronary stents. Therefore, this study compares poly lactic-co-glycolic acid (PLGA)-based everolimus-eluting stents (PLGA-EESs) versus 2-methacryloyloxyethyl phosphorylcholine (MPC)-based SP-eluting stents (MPC-SPs) in in-vitro and in-vivo models. The morphology of the stent surface and peptide/drug release kinetics from stents were evaluated. The in-vitro proliferative effect of SP released from MPC-SP is evaluated using human umbilical vein endothelial cell. Finally, the safety and efficacy of the stent are evaluated after inserting it into a pig's coronary artery. Similar to PLGA-EES, MPC-SP had a uniform surface morphology with very thin coating layer thickness (2.074μm). MPC-SP showed sustained drug release of SP for over 2weeks. Endothelial cell proliferation was significantly increased in groups treated with SP (n = 3) compared with the control (n = 3) and those with everolimus (n = 3) (SP: 118.9 ± 7.61% vs. everolimus: 64.3 ± 12.37% vs. the control: 100 ± 6.64%, p < 0.05). In the animal study, the percent stenosis was higher in MPC-SP group (n = 7) compared to PLGA-EES group (n = 7) (MPC-SP: 28.6 ± 10.7% vs. PLGA-EES: 16.7 ± 6.3%, p < 0.05). MPC-SP group showed, however, lower inflammation (MPC-SP: 0.3 ± 0.26 vs. PLGA-EES: 1.2 ± 0.48, p < 0.05) and fibrin deposition (MPC-SP: 1.0 ± 0.73 vs. PLGA-EES: 1.5 ± 0.59, p < 0.05) around the stent strut. MPC-SP showed more increased expression of cluster of differentiation 31, suggesting enhanced re-endothelialization. Compared to PLGA-EES, MPC-SP demonstrated more decreased inflammation of the vascular wall and enhanced re-endothelialization and stent coverage. Hence, MPC-SP has the potential therapeutic benefits for the treatment of coronary artery disease by solving limitations of currently available DESs.

Deep electroacupuncture of neurogenic spots attenuates immobilization stress-induced acute hypertension in rats

BackgroundOur previous studies proved that neurogenic inflammatory spots (or neurogenic spots) have the same physiological features as acupuncture points and that neurogenic spot stimulation generates therapeutic effects in various animal models. However, it is unclear how deeply the neurogenic spots should be stimulated to generate therapeutic effects. MethodsThe effects of acupuncture at various needle depths below the neurogenic spot were examined in a rat immobilization stress-induced hypertension (IMH) model. Electroacupuncture was applied to a neurogenic spot at depths of 1, 2, or 3 mm using a concentric bipolar electrode. ResultsElectrical stimulation of the neurogenic spot at a 3-mm depth most effectively lowered blood pressure compared with controls and stimulation at 1- and 2-mm depths, which was inhibited by pretreatment with a local anesthetic lidocaine. Electrical stimulation of the neurogenic spot or injection of substance P (SP) at a 3-mm depth significantly excited the rostral ventrolateral medulla (rVLM) compared with superficial stimulation. Electrical stimulation applied at a 3-mm depth on neurogenic spots dominantly caused c-fos expression from rVLM and ventrolateral periaqueductal gray (vlPAG) in IMH rats. Pretreatment with resiniferatoxin (RTX) injection into the neurogenic spot to ablate SP or calcitonin gene-related peptide (CGRP) prevented the effects of 3-mm neurogenic spot stimulation on blood pressure in IMH rats. Conversely, artificial injection of SP or CGRP generated anti-hypertensive effects in IMH rats. ConclusionOur data suggest that neurogenic spot stimulation at a 3-mm depth generated anti-hypertensive effects through the local release of SP and CGRP and activation of rVLM and vlPAG.

Preparation of co-electrospinning membrane loaded with simvastatin and substance P to accelerate bone regeneration by promoting cell homing, angiogenesis and osteogenesis.

Bone regeneration is a complex process that requires the coordination of various biological events. Developing a tissue regeneration membrane that can regulate this cascade of events is challenging. In this study, we aimed to fabricate a membrane that can enrich the damaged area with mesenchymal stem cells, improve angiogenesis, and continuously induce osteogenesis. Our approach involved creating a hierarchical polycaprolactone/gelatin (PCL/GEL) co-electrospinning membrane that incorporated substance P (SP)-loaded GEL fibers and simvastatin (SIM)-loaded PCL fibers. The membrane could initiate a burst release of SP and a slow/sustained release of SIM for over a month. In vitro experiments, including those related to angiogenesis and osteogenesis (e.g., migration, endothelial network formation, alkaline phosphatase activity, mineralization, and gene expression), clearly demonstrated the membrane's superior ability to improve cell homing, revascularization, and osteogenic differentiation. Furthermore, a series of in vivo studies, including immunofluorescence of CD29+/CD90+ double-positive cells and immunohistochemical staining for CD34 and vWF, confirmed the co-electrospinning membrane's ability to enhance MSC migration and revascularization response after five days of implantation. After one month, the Micro-CT and histological (Masson and H&E) results showed accelerated bone regeneration. Our findings suggest that a co-electrospinning membrane with time-tunable drug delivery could advance the development of tissue engineering therapeutic strategies and potentially improve patient outcomes.

3, 3’-diindolylmethane enhances macrophage efferocytosis and subsequently relieves visceral pain via the AhR/Nrf2/Arg-1-mediated arginine metabolism pathway

Background3, 3’-diindolylmethane (DIM), a classical aryl hydrocarbon receptor (AhR) agonist, has been shown to relieve neuropathic pain, but few studies have reported the efficacy of DIM in visceral pain under colitis condition. PurposeThis study aimed to investigate the effect and mechanism of DIM on visceral pain under colitis condition. MethodsCytotoxicity was performed using the MTT assay. RT-qPCR and ELISA assays were applied to determine the expression and release of algogenic substance P (SP), nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). Flow cytometry was used to examine the apoptosis and efferocytosis. The expression of Arg-1-arginine metabolism-related enzymes was detected using western blotting assays. ChIP assays were used to examine the binding of Nrf2 to Arg-1. Mouse models of dextran sulfate sodium (DSS) were established to illustrate the effect of DIM and validate the mechanism in vivo. ResultsDIM did not directly affect expressions and release of algogenic SP, NGF and BDNF in enteric glial cells (EGCs). However, when co-cultured with DIM-pre-treated RAW264.7 cells, the release of SP and NGF was decreased in lipopolysaccharides-stimulated EGCs. Furthermore, DIM increased the number of PKH67+ F4/80+ cells in the co-culture system of EGCs and RAW264.7 cells in vitro and alleviated visceral pain under colitis condition by regulating levels of SP and NGF as well as values of electromyogram (EMG), abdominal withdrawal reflex (AWR) and tail-flick latency (TFL) in vivo, which was significantly inhibited by efferocytosis inhibitor. Subsequently, DIM was found to down-regulate levels of intracellular arginine, up-regulate levels of ornithine, putrescine and Arg-1 but not extracellular arginine or other metabolic enzymes, and polyamine scavengers reversed the effect of DIM on efferocytosis and release of SP and NGF. Moving forward, Nrf2 transcription and the binding of Nrf2 to Arg-1-0.7 kb was enhanced by DIM, AhR antagonist CH223191 abolished the promotion of DIM on Arg-1 and efferocytosis. Finally, nor-NOHA validated the importance of Arg-1-dependent arginine metabolism in DIM-alleviated visceral pain. ConclusionDIM enhances macrophage efferocytosis in an arginine metabolism-dependent manner via “AhR-Nrf2/Arg-1” signals and inhibits the release of SP and NGF to relieve visceral pain under colitis condition. These findings provide a potential therapeutic strategy for the treatment of visceral pain in patients with colitis.

Synaptotagmin 9 Modulates Spontaneous Neurotransmitter Release in Striatal Neurons by Regulating Substance P Secretion.

Synaptotagmin 9 (SYT9) is a tandem C2 domain Ca2+ sensor for exocytosis in neuroendocrine cells; its function in neurons remains unclear. Here, we show that, in mixed-sex cultures, SYT9 does not trigger rapid synaptic vesicle exocytosis in mouse cortical, hippocampal, or striatal neurons, unless it is massively overexpressed. In striatal neurons, loss of SYT9 reduced the frequency of spontaneous neurotransmitter release events (minis). We delved into the underlying mechanism and discovered that SYT9 was localized to dense-core vesicles that contain substance P (SP). Loss of SYT9 impaired SP release, causing the observed decrease in mini frequency. This model is further supported by loss of function mutants. Namely, Ca2+ binding to the C2A domain of SYT9 triggered membrane fusion in vitro, and mutations that disrupted this activity abolished the ability of SYT9 to regulate both SP release and mini frequency. We conclude that SYT9 indirectly regulates synaptic transmission in striatal neurons by controlling SP release.SIGNIFICANCE STATEMENT Synaptotagmin 9 (SYT9) has been described as a Ca2+ sensor for dense-core vesicle (DCV) exocytosis in neuroendocrine cells, but its role in neurons remains unclear, despite widespread expression in the brain. This article examines the role of SYT9 in synaptic transmission across cultured cortical, hippocampal, and striatal neuronal preparations. We found that SYT9 regulates spontaneous neurotransmitter release in striatal neurons by serving as a Ca2+ sensor for the release of the neuromodulator substance P from DCVs. This demonstrates a novel role for SYT9 in neurons and uncovers a new field of study into neuromodulation by SYT9, a protein that is widely expressed in the brain.

Ambient ozone, and urban PM2.5 co-exposure, aggravate allergic asthma via transient receptor potential vanilloid 1-mediated neurogenic inflammation

Allergic asthma is the most common pulmonary inflammatory disease, and epidemiological studies have revealed that PM2.5 or ambient ozone (O3) exposure contribute to the higher prevalence of allergic asthma. Current experimental evidence focus principally on the pathogenic effect of exposure to a single air pollutant, ignoring the possible synergistic effect of combined exposure to a mix of these pollutants, which is a more realistic scenario. In this study, allergic mice and a nociceptor antagonist were used to explore the mechanisms of co-exposure to these two important air pollutants. Compared with exposure to either PM2.5 or O3, combined exposure to both greatly aggravated allergic asthma in a dose dependent manner, including increased airway hyperresponsiveness, goblet cell metaplasia, more severe airway inflammation and higher oxidative stress levels. In addition, co-exposure in the allergic mice resulted in elevation of the expression of transient receptor potential vanilloid 1 (TRPV1), and of the production of substance P (SP), which exacerbated lung inflammation by neurogenic inflammation. TRPV1 antagonist (capsazepine, CPZ) treatment for the co-exposed allergic mice, markedly attenuated TRPV1 expression and SP release, and reduced airway inflammation and oxidative damage, further alleviating airway hyperresponsiveness. We conclude that neuro-immune interactions might be involved in PM2.5 and O3 co-exposure aggravated allergic asthma.

Evaluation of substance P and bradykinin levels in nasal secretions of patients with nasal polyposis with and without sensitivity to non-steroidal anti-inflammatory drugs.

ObjectiveThe role of neurogenic inflammation in pathogenesis of chronic rhinitis is well known. However, very little is known about its importance in pathogenesis of nasal polyposis (NP), especially in form of NP which appears as a part of aspirin‐exacerbated respiratory disease (AERD). The aim of this study was to examine the concentrations of neuropeptides substance P (SP) and bradykinin (BK) in nasal secretions of patients with NP.MethodsFourteen patients with NP as a part of AERD with mild persistent asthma, 14 patients with NP without aspirin sensitivity, and 14 control subjects without nasal inflammation (C) entered this cross‐sectional study. Clinical parameters (symptoms, endoscopic, and radiological findings) were assessed. The concentrations of SP and BK were measured in the nasal secretion samples using commercial human enzyme immunoassay kits.ResultsThe concentration of SP in nasal secretions was significantly higher in NP patients without aspirin sensitivity and AERD patients compared to controls (p = .022; p < .0001, respectively), but higher in AERD than in non‐AERD patients (p = .018). The level of BK in nasal fluid was higher in non‐AERD and AERD NP patients than in controls (p < .0001; p < .0001, respectively), but also higher in AERD than in non‐AERD patients (p < .0001). We found high positive correlations between BK in nasal fluid and Lund–Mackay computed tomography (CT) score in both non‐AERD and AERD groups of NP patients.ConclusionOur results suggest more intense release of SP and BK from the nasal mucosa in patients with AERD than in patients with NP who do not have aspirin sensitivity. The strong correlation between concentration of BK in nasal secretions and CT score suggests that BK in nasal fluid could be used as a marker for disease severity as measured by the Lund–Mackay score.

Glucose-Dependent Insulinotropic Polypeptide and Substance P Mediate Emetic Response Induction by Masked Trichothecene Deoxynivalenol-3-Glucoside through Ca2+ Signaling.

Deoxynivalenol (DON), the most naturally-occurring trichothecenes, may affect animal and human health by causing vomiting as a hallmark of food poisoning. Deoxynivalenol-3-glucoside (D3G) usually co-occurs with DON as its glucosylated form and is another emerging food safety issue in recent years. However, the toxicity of D3G is not fully understood compared to DON, especially in emetic potency. The goals of this research were to (1) compare emetic effects to D3G by oral and intraperitoneal (IP) routes and relate emetic effects to brain-gut peptides glucose-dependent insulinotropic polypeptide (GIP) and substance P (SP) in mink; (2) determine the roles of calcium-sensing receptor (CaSR) and transient receptor potential (TRP) channel in D3G’s emetic effect. Both oral and IP exposure to D3G elicited marked emetic events. This emetic response corresponded to an elevation of GIP and SP. Blocking the GIP receptor (GIPR) diminished emetic response induction by GIP and D3G. The neurokinin 1 receptor (NK-1R) inhibitor Emend® restrained the induction of emesis by SP and D3G. Importantly, CaSR antagonist NPS-2143 or TRP channel antagonist ruthenium red dose-dependently inhibited both D3G-induced emesis and brain-gut peptides GIP and SP release; cotreatment with both antagonists additively suppressed both emetic and brain-gut peptide responses to D3G. To summarize, our findings demonstrate that activation of CaSR and TRP channels contributes to D3G-induced emesis by mediating brain-gut peptide exocytosis in mink.

The excitatory effect of hydrogen sulfide on rat colonic muscle contraction and the underlying mechanism

H2S is a well-known relaxant regulator in muscle contraction but little attention has been paid to its excitatory effect on colonic motility. To investigate the excitation of H2S on rat colonic contraction and the underlying mechanism, the muscle contractile activity was assessed by an organ bath system, the level of substance P (SP) in the colon was detected using enzyme immunoassay kits, L-type Ca2+ channel currents (ICa,L) and large conductance Ca2+-activated K+ channel currents (IBK) in smooth muscle cells (SMCs) were measured by patch-clamp electrophysiology. The results show that the H2S donor NaHS (100 μM) reversed the relaxation of the NO donor SNP on colonic muscle contraction. Pretreatment with the TRPV1 antagonist and the neurokinin receptor antagonists attenuated the NaHS-induced excitation. Incubation of colon with NaHS increased the SP level. In freshly isolated SMCs, NaHS exerted a biphasic effect on ICa,L and concentration-dependently inhibited the IBK. And 100 μM NaHS partially reversed the SNP-induced changes in ICa,L and IBK. We concluded that exogenous H2S exerts a potential excitatory effect on colonic motility, which may be achieved by activating SP release from afferent nerves in combination with a direct activation of ICa,L and suppression of IBK in SMCs.

Participation of transient receptor potential vanilloid 1 in the analgesic effect of duloxetine for paclitaxel induced peripheral neuropathic pain

Painful peripheral neuropathy is a common dose-limiting side effect of chemotherapeutic paclitaxel (PTX) treatment. The American Society of Clinical Oncology (ASCO) recommends duloxetine (DUL) as a promising treatment alternative for chemotherapy-induced peripheral neuropathic pain. However, this recommendation lacks a robust theoretical basis and supporting data. To elucidate the involvement of transient receptor potential vanilloid 1 (TRPV1) in the analgesic effect of DUL for PTX-induced neuropathic pain, TRPV1 expression in the lumbar dorsal root ganglion (DRG) and spinal cord was evaluated following intraperitoneal administration of PTX (2 mg/kg/day) for four alternate days in rats. Western blot and immunohistochemistry suggested that a cumulative dosage of PTX (8 mg/kg) upregulated TRPV1 expression in the lumbar DRG and spinal dorsal horn (SDH) at day 14 post treatment. TRPV1 upregulation in the DRG was mainly expressed in calcitonin gene-related peptide (CGRP) and IB-4 positive small-size sensory neurons. Additionally, PTX increased CGRP and substance P (SP) expression in the DRG and SDH, induced SDH microglia and astrocyte activation, and upregulated spinal tumor necrosis factor-α (TNF-α) but not IL-1β or IL-10 expression. Behavioral detection showed that PTX-related mechanical and thermal hyperalgesia was significantly inhibited by consecutive administration of DUL 20 mg/kg/day greater than 10 mg/kg/day for 5 days starting at day 10 post PTX injection. Furthermore, DUL (20 mg/kg/day) for 5 days markedly ameliorated PTX-induced TRPV1, CGRP, and SP upregulation in the DRG and SDH, and mitigated PTX-induced spinal cord glia activation and TNF-α expression. Moreover, the pharmacological blockade of TRPV1 resulted in an analgesic effect on PTX-induced hyperalgesia. Collectively, these results suggest that DUL alleviates PTX-induced peripheral neuropathic pain by suppressing TRPV1 upregulation in the lumbar DRG and SDH, which is followed by a reduction in CGRP and SP release, as well as spinal glia activation and TNF-α expression.

Beyond Thermal Sensation: Roles of Transient Receptor Potential Vanilloid Subfamily Member 1 and Spicy Food in Cardiometabolic Diseases

Beyond Thermal Sensation: Roles of Transient Receptor Potential Vanilloid Subfamily Member 1 and Spicy Food in Cardiometabolic Diseases

Pentobarbital may protect against neurogenic inflammation after surgery via inhibition of substance P release from peripheral nerves of rats

The inflammatory response related to surgery is considered surgical inflammation. Most anesthetic agents directly or indirectly suppress the immune response. However, the intravenous anesthetics pentobarbital and ketamine were reported to inhibit the lipopolysaccharide-induced inflammatory response such as cytokines formation. Neurogenic inflammation is inflammation originating from the local release of inflammatory mediators, such as substance P (SP), by primary afferent neurons after noxious stimuli like surgery. Thus, in this study, we examined whether pentobarbital and ketamine suppress SP release from cultured dorsal root ganglion (DRG) neurons. DRG cells were dissected from male Wistar rats. Released SP was measured by radioimmunoassay. We demonstrated that higher concentrations of pentobarbital (100–1,000 μM) significantly inhibited capsaicin (100 nM)-induced, but not high K+ (50 mM)-induced, SP release from DRG cells, although a high concentration of ketamine (1 mM) did not. This study revealed that pentobarbital functions between the activation of vanilloid receptor subtype 1 (TRPV1) receptors, to which capsaicin selectively binds, and the opening of voltage-operated Ca2+ channels (VOCC) in the nerve endings. Therefore, the anti-inflammatory action of pentobarbital is mediated through different mechanisms than those of ketamine. Thus, the inhibitory effect of pentobarbital on SP release from peripheral terminals may protect against neurogenic inflammation after surgery.

Tachykinins amplify the action of capsaicin on central histaminergic neurons

Substance P (SP), a product of the tachykinin 1 (Tac1) gene, is expressed in many hypothalamic neurons. Its wake-promoting potential could be mediated through histaminergic (HA) neurons of the tuberomamillary nucleus (TMN), where functional expression of neurokinin receptors (NKRs) waits to be characterized. As in the process of nociception in the peripheral nervous system (PNS) capsaicin-receptor (transient potential vanilloid 1: TRPV1) signalling is amplified by local release of histamine and SP, we tested the involvement of tachykinins in the capsaicin-induced long-lasting enhancement (LLEcaps) of HA neurons firing by investigating selective neurokinin receptor ligands in the hypothalamic mouse brain slice preparation using patch-clamp recordings in cell-attached mode combined with single-cell RT-PCR. We report that the majority of HA neurons respond to SP (EC50 3 nM), express the SP precursor tachykinin 1 (Tac1) gene and at least one of the neurokinin receptors. Responses to selective agonists of three known neurokinin receptors were sensitive to corresponding antagonists. LLEcaps was significantly impaired by the neurokinin receptor antagonists, indicating that in hypothalamus, as in the PNS, release of tachykinins downstream to TRPV1 activation is able to boost the release of histamine. The excitatory action of SP on histaminergic neurons adds another pathway to the noradrenergic and orexinergic ones to synergistically enhance cortical arousal. We show NK1R to play a prominent role on HA neurons and thus the control of wakefulness.