Medicinal Chemistry, Pharmacology, and Clinical Implications of TRPV1 Receptor Antagonists

TRPV3 facilitates lipolysis and attenuates diet-induced obesity via activation of the NRF2/FSP1 signaling axis

Transient receptor potential vanilloid (TRPV) ion channels play a crucial role in various cellular functions by regulating intracellular Ca2+ levels and have been extensively studied in the context of several metabolic diseases. However, the regulatory effects of TRPV3 in obesity and lipolysis are not well understood. In this study, utilizing a TRPV3 gain-of-function mouse model (TRPV3G568V/G568V), we assessed the metabolic phenotype of both TRPV3G568V/G568V mice and their control littermates, which were randomly assigned to either a 12-week high-fat diet or a control diet. We investigated the potential mechanisms underlying the role of TRPV3 in restraining obesity and promoting lipolysis both in vivo and in vitro. Our findings indicate that a high-fat diet led to significant obesity, characterized by increased epididymal and inguinal white adipose tissue weight and higher fat mass. However, the gain-of-function mutation in TRPV3 appeared to counteract these adverse effects by enhancing lipolysis in visceral fat through the upregulation of the major lipolytic enzyme, adipocyte triglyceride lipase (ATGL). In vitro experiments using carvacrol, a TRPV3 agonist, demonstrated the promotion of lipolysis and antioxidation in 3T3-L1 adipocytes after TRPV3 activation. Notably, carvacrol failed to stimulate Ca2+ influx, lipolysis, and antioxidation in 3T3-L1 adipocytes treated with BAPTA-AM, a cell-permeable calcium chelator. Our results revealed that TRPV3 activation induced the action of transcriptional factor nuclear factor erythroid 2-related factor 2 (NRF2), resulting in increased expression of ferroptosis suppressor protein 1 (FSP1) and superoxide dismutase2 (SOD2). Moreover, the inhibition of NRF2 impeded carvacrol-induced lipolysis and antioxidation in 3T3-L1 adipocytes, with downregulation of ATGL, FSP1, and SOD2. In summary, our study suggests that TRPV3 promotes visceral fat lipolysis and inhibits diet-induced obesity through the activation of the NRF2/FSP1 signaling axis. We propose that TRPV3 may be a potential therapeutic target in the treatment of obesity.

Nanomedicine and voltage-gated sodium channel blockers in pain management: a game changer or a lost cause?

Pain, a complex and debilitating condition affecting millions globally, is a significant concern, especially in the context of post-operative recovery. This comprehensive review explores the complexity of pain and its global impact, emphasizing the modulation of voltage-gated sodium channels (VGSC or NaV channels) as a promising avenue for pain management with the aim of reducing reliance on opioids. The article delves into the role of specific NaV isoforms, particularly NaV 1.7, NaV 1.8, and NaV 1.9, in pain process and discusses the development of sodium channel blockers to target these isoforms precisely. Traditional local anesthetics and selective NaV isoform inhibitors, despite showing varying efficacy in pain management, face challenges in systemic distribution and potential side effects. The review highlights the potential of nanomedicine in improving the delivery of local anesthetics, toxins and selective NaV isoform inhibitors for a targeted and sustained release at the site of pain. This innovative strategy seeks to improve drug bioavailability, minimize systemic exposure, and optimize therapeutic outcomes, holding significant promise for secure pain management and enhancing the quality of life for individuals recovering from surgical procedures or suffering from chronic pain.

Molecular mechanisms of two novel and selective TRPV1 channel activators

Venomous toxins hold immense value as tools in elucidating the intricate structure and underlying mechanisms of ion channels. In this article, we identified of two novel toxins, Hainantoxin-XXI (HNTX-XXI) and Hainantoxin-XXII (HNTX-XXII), derived from the venom of the Chinese spider Ornithoctonus hainana. HNTX-XXI, boasting a molecular weight of 6869.095 Da, comprises 64 amino acid residues and contains 8 cysteines. Meanwhile, HNTX-XXII, with a molecular weight of 8623.732 Da, comprises 77 amino acid residues and contains 12 cysteines. Remarkably, we discovered that both HNTX-XXI and HNTX-XXII possess the ability to activate TRPV1. They activated TRPV1 with EC50 values of 3.6 ± 0.19 μM and 862 ± 56 nM, respectively. Furthermore, the current generated by the activation of TRPV1 by these toxins can be rapidly blocked by ruthenium red. Intriguingly, our analysis revealed that the interaction between HNTX-XXI and TRPV1 is mediated by three key amino acid residues: L465, V469, and D471. Similarly, the interaction between HNTX-XXII and TRPV1 is facilitated by four key amino acid residues: A657, F659, E600, and R601. These findings provide profound insights into the molecular basis of toxin-TRPV1 interactions and pave the way for future research exploring the therapeutic potential of these toxic peptides.

Novel phenylpiperazine derivatives as potent transient receptor potential vanilloid 1 antagonists

Transient receptor potential vanilloid 1 (TRPV1) is a non-selective cation channel, which is considered a highly validated target for pain perception. Repeated activation with agonists to desensitize receptors or use the antagonists can both exert analgesic effects. In this work, two series of novel phenylpiperazine derivatives were designed, synthesized, and evaluated for the in vitro receptor inhibitory activity and in vivo analgesic activity. Among them, L-21 containing sulfonylurea group was identified with potent TRPV1 antagonistic activity and analgesic activity in various pain models. At the same time, L-21 exhibited low risk of hyperthermia side effect. These results indicated that L-21 is a promising candidate for further development of novel TRPV1 antagonist to treat pain.

Novel Alaninamide Derivatives with Drug-like Potential for Development as Antiseizure and Antinociceptive Therapies─In Vitro and In Vivo Characterization

In the present study, a series of original alaninamide derivatives have been designed applying a combinatorial chemistry approach, synthesized, and characterized in the in vivo and in vitro assays. The obtained molecules showed potent and broad-spectrum activity in basic seizure models, namely, the maximal electroshock (MES) test, the 6 Hz (32 mA) seizure model, and notably, the 6 Hz (44 mA) model of pharmacoresistant seizures. Most potent compounds 26 and 28 displayed the following pharmacological values: ED50 = 64.3 mg/kg (MES), ED50 = 15.6 mg/kg (6 Hz, 32 mA), ED50 = 29.9 mg/kg (6 Hz, 44 mA), and ED50 = 34.9 mg/kg (MES), ED50 = 12.1 mg/kg (6 Hz, 32 mA), ED50 = 29.5 mg/kg (6 Hz, 44 mA), respectively. Additionally, 26 and 28 were effective in the ivPTZ seizure threshold test and had no influence on the grip strength. Moreover, lead compound 28 was tested in the PTZ-induced kindling model, and then, its influence on glutamate and GABA levels in the hippocampus and cortex was evaluated by the high-performance liquid chromatography (HPLC) method. In addition, 28 revealed potent efficacy in formalin-induced tonic pain, capsaicin-induced pain, and oxaliplatin- and streptozotocin-induced peripheral neuropathy. Pharmacokinetic studies and in vitro ADME-Tox data proved favorable drug-like properties of 28. The patch-clamp recordings in rat cortical neurons showed that 28 at a concentration of 10 μM significantly inhibited fast sodium currents. Therefore, 28 seems to be an interesting candidate for future preclinical development in epilepsy and pain indications.

TRPV1 channel in the pathophysiology of epilepsy and its potential as a molecular target for the development of new antiseizure drug candidates

Identification of transient receptor potential cation channel, subfamily V member 1 (TRPV1), also known as capsaicin receptor, in 1997 was a milestone achievement in the research on temperature sensation and pain signalling. Very soon after it became evident that TRPV1 is implicated in a wide array of physiological processes in different peripheral tissues, as well as in the central nervous system, and thereby could be involved in the pathophysiology of numerous diseases. Increasing evidence suggests that modulation of TRPV1 may also affect seizure susceptibility and epilepsy. This channel is localized in brain regions associated with seizures and epilepsy, and its overexpression was found both in animal models of seizures and in brain samples from epileptic patients. Moreover, modulation of TRPV1 on non-neuronal cells (microglia, astrocytes, and/or peripheral immune cells) may have an impact on the neuroinflammatory processes that play a role in epilepsy and epileptogenesis. In this paper, we provide a comprehensive and critical overview of currently available data on TRPV1 as a possible molecular target for epilepsy management, trying to identify research gaps and future directions. Overall, several converging lines of evidence implicate TRPV1 channel as a potentially attractive target in epilepsy research but more studies are needed to exploit the possible role of TRPV1 in seizures/epilepsy and to evaluate the value of TRPV1 ligands as candidates for new antiseizure drugs.

Zhisou powder suppresses airway inflammation in LPS and CS-induced post-infectious cough model mice via TRPA1/TRPV1 channels

ETHNOPHARMACOLOGICAL RELEVANCE

Zhisou Powder (ZSP), a traditional Chinese medicine (TCM) prescription, has been widely used in the clinic for the treatment of post-infectious cough (PIC). However, the exact mechanism is not clear.

AIM OF THE STUDY

The aim of this study was to investigate the ameliorative effect of ZSP on PIC in mice. The possible mechanisms of action were screened based on network pharmacology, and the potential mechanisms were explored through molecular docking and in vivo experimental validation.

MATERIALS AND METHODS

Lipopolysaccharide (LPS) (80μg/50 μL) was used to induce PIC in mice, followed by daily exposure to cigarette smoke (CS) for 30 min for 30 d to establish PIC model. The effects of ZSP on PIC mice were observed by detecting the number of coughs and cough latency, peripheral blood and bronchoalveolar lavage fluid (BALF) inflammatory cell counts, enzyme-linked immunosorbent assay (ELISA), and histological analysis. The core targets and key pathways of ZSP on PIC were analyzed using network pharmacology, and TRPA1 and TRPV1 were validated using RT-qPCR and western blotting assays.

RESULTS

ZSP effectively reduced the number of coughs and prolonged the cough latency in PIC mice. Airway inflammation was alleviated by reducing the expression levels of the inflammatory mediators TNF-α and IL-1β. ZSP modulated the expression of Substance P, Calcitonin gene-related peptide (CGRP), and nerve growth factor (NGF) in BALF. Based on the results of network pharmacology, the mechanism of action of ZSP may exert anti-neurogenic airway-derived inflammation by regulating the expression of TRPA1 and TRPV1 through the natural active ingredients α-spinastero, shionone and didehydrotuberostemonine.

CONCLUSION

ZSP exerts anti-airway inflammatory effects through inhibition of TRPA1/TRPV1 channels regulating neuropeptides to alleviate cough hypersensitivity and has a favorable therapeutic effect on PIC model mice. It provides theoretical evidence for the clinical application of ZSP.

Role of TRPV1 in electroacupuncture-mediated signal to the primary sensory cortex during regulation of the swallowing function

AIMS

Electroacupuncture (EA) at the Lianquan (CV23) could alleviate swallowing dysfunction. However, current knowledge of its neural modulation focused on the brain, with little evidence from the periphery. Transient receptor potential channel vanilloid subfamily 1 (TRPV1) is an ion channel predominantly expressed in sensory neurons, and acupuncture can trigger calcium ion (Ca2+ ) wave propagation through active TRPV1 to deliver signals. The present study aimed to investigate whether TRPV1 mediated the signal of EA to the primary sensory cortex (S1) during regulation of swallowing function.

METHODS

Blood perfusion was evaluated by laser speckle contrast imaging (LSCI), and neuronal activity was evaluated by fiber calcium recording and c-Fos staining. The expression of TRPV1 was detected by RNA-seq analysis, immunofluorescence, and ELISA. In addition, the swallowing function was assessed by in vivo EMG recording and water consumption test.

RESULTS

EA treatment potentiated blood perfusion and neuronal activity in the S1, and this potentiation was absent after injecting lidocaine near CV23. TRPV1 near CV23 was upregulated by EA-CV23. The blood perfusion at CV23 was decreased in the TRPV1 hypofunction mice, while the blood perfusion and the neuronal activity of the S1 showed no obvious change. These findings were also present in post-stroke dysphagia (PSD) mice.

CONCLUSION

The TRPV1 at CV23 after EA treatment might play a key role in mediating local blood perfusion but was not involved in transferring EA signals to the central nervous system (CNS). These findings collectively suggested that TRPV1 may be one of the important regulators involved in the mechanism of EA treatment for improving swallowing function in PSD.

Genus Helleborus: a comprehensive review of phytochemistry, pharmacology and clinical applications

The genus Helleborus belongs to the Ranunculaceae family, distributed in southeastern Europe and western Asia. In folk medicine, it is commonly used as an anti-inflammatory and analgesic medicine for rheumatoid arthritis and bruises. Through reviewing recent articles, it was found that two hundred and twenty-six compounds have been isolated and identified from the genus Helleborus. These compounds include steroids, flavonoids, phenylpropanoids, lignans, anthraquinones, phenolics and others. Among them, the main chemical constituents are steroids. Pharmacological studies show Helleborus has anti-cancer, immunomodulatory, anti-inflammatory, analgesic, anti-hyperglycaemic, antioxidant and antibacterial properties. This article reviews the botany, phytochemistry, pharmacological effects and clinical applications of the genus Helleborus. Hopefully, it will provide a reference for in-depth research and exploitation of the genus Helleborus.

Potential Beneficial Effects of Naringin and Naringenin on Long COVID-A Review of the Literature

Coronavirus disease 2019 (COVID-19) caused a severe epidemic due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Recent studies have found that patients do not completely recover from acute infections, but instead, suffer from a variety of post-acute sequelae of SARS-CoV-2 infection, known as long COVID. The effects of long COVID can be far-reaching, with a duration of up to six months and a range of symptoms such as cognitive dysfunction, immune dysregulation, microbiota dysbiosis, myalgic encephalomyelitis/chronic fatigue syndrome, myocarditis, pulmonary fibrosis, cough, diabetes, pain, reproductive dysfunction, and thrombus formation. However, recent studies have shown that naringenin and naringin have palliative effects on various COVID-19 sequelae. Flavonoids such as naringin and naringenin, commonly found in fruits and vegetables, have various positive effects, including reducing inflammation, preventing viral infections, and providing antioxidants. This article discusses the molecular mechanisms and clinical effects of naringin and naringenin on treating the above diseases. It proposes them as potential drugs for the treatment of long COVID, and it can be inferred that naringin and naringenin exhibit potential as extended long COVID medications, in the future likely serving as nutraceuticals or clinical supplements for the comprehensive alleviation of the various manifestations of COVID-19 complications.

Roadmap for the expression of canonical and extended endocannabinoid system receptors and metabolic enzymes in peripheral organs of preclinical animal models

The endocannabinoid system is widely expressed throughout the body and is comprised of receptors, ligands, and enzymes that maintain metabolic, immune, and reproductive homeostasis. Increasing interest in the endocannabinoid system has arisen due to these physiologic roles, policy changes leading to more widespread recreational use, and the therapeutic potential of Cannabis and phytocannabinoids. Rodents have been the primary preclinical model of focus due to their relative low cost, short gestational period, genetic manipulation strategies, and gold-standard behavioral tests. However, the potential for lack of clinical translation to non-human primates and humans is high as cross-species comparisons of the endocannabinoid system have not been evaluated. To bridge this gap in knowledge, we evaluate the relative gene expression of 14 canonical and extended endocannabinoid receptors in seven peripheral organs of C57/BL6 mice, Sprague-Dawley rats, and non-human primate rhesus macaques. Notably, we identify species- and organ-specific heterogeneity in endocannabinoid receptor distribution where there is surprisingly limited overlap among the preclinical models. Importantly, we determined there were no receptors with identical expression patterns among mice (three males and two females), rats (six females), and rhesus macaques (four males). Our findings demonstrate a critical, yet previously unappreciated, contributor to challenges of rigor and reproducibility in the cannabinoid field, which has implications in hampering progress in understanding the complexity of the endocannabinoid system and development of cannabinoid-based therapies.

Bioengineered Smart Nanocarriers for Breast Cancer Treatment: Adorned Carbon-Based Nanocomposites with Silver and Palladium Complexes for Efficient Drug Delivery

Biocompatible and bioactive carbon-based nanocomposites are ingeniously designed and fabricated with the aim of enhancing drug delivery applicability in breast cancer treatment. Reduced graphene oxide (rGO) and multiwalled carbon nanotubes (MWCNTs) are utilized as nanocarriers for increasing penetrability into cells and the loading capacity. What sets our study apart is the strategic incorporation of the two different complexes of silver (AgL2) and palladium (PdL2) with the carboxamide-based ligand C9H7N3OS (L), which have been synthesized and decorated on nanocarriers alongside doxorubicin (DOX) for stabilizing DOX by π-π interactions and hydrogen bonding. Although DOX is a well-known cancer therapy agent, the efficacy of DOX is hindered owing to drug resistance, poor internalization, and limited site specificity. Aside from stabilizing DOX on nanocarriers, our carbon-based nanocarriers are tailored to act as a precision-guided missile, strategically by adorning with target-sensitive complexes. Based on the literature, carboxamide ligands can connect to overexpressed receptors on cancerous cells and inhibit them from proliferation signaling. Also, the complexes have an antibacterial activity that can control the infection caused by decreasing white blood cells and necrosis of cancerous cells. A high-concentration cytotoxicity assay revealed that decorating PdL2 on a DOX-containing nanocarrier not only increased cytotoxicity to breast cancerous cell lines (MDA-MB-231 and MCF-7) but also revealed higher cell viability on a normal cell line (MCF-10A). The drug release screening results showed that the presence of PdL2 led to 72 h correlate release behavior in acidic and physiological pH profiles, while the AgL2-containing nanocomposite showed an analogue behavior for just 6 h and the release of DOX continued and after about 100 h hit the top.

Quantitative Predictive Studies of Multiple Biological Activities of TRPV1 Modulators

TRPV1 channel agonists and antagonists, which have powerful analgesic effects without the addictive qualities associated with traditional analgesics, have become a focus area for the development of novel analgesics. In this study, quantitative structure-activity relationship (QSAR) models for three bioactive endpoints (Ki, IC50, and EC50) were successfully constructed using four machine learning algorithms: SVM, Bagging, GBDT, and XGBoost. These models were based on 2922 TRPV1 modulators and incorporated four types of molecular descriptors: Daylight, E-state, ECFP4, and MACCS. After the rigorous five-fold cross-validation and external test set validation, the optimal models for the three endpoints were obtained. For the Ki endpoint, the Bagging-ECFP4 model had a Q2 value of 0.778 and an R2 value of 0.780. For the IC50 endpoint, the XGBoost-ECFP4 model had a Q2 value of 0.806 and an R2 value of 0.784. For the EC50 endpoint, the SVM-Daylight model had a Q2 value of 0.784 and an R2 value of 0.809. These results demonstrate that the constructed models exhibit good predictive performance. In addition, based on the model feature importance analysis, the influence between substructure and biological activity was also explored, which can provide important theoretical guidance for the efficient virtual screening and structural optimization of novel TRPV1 analgesics. And subsequent studies on novel TRPV1 modulators will be based on the feature substructures of the three endpoints.

The role of TRPV ion channels in adipocyte differentiation: What is the evidence?

Obesity is a complex disorder, and the incidence of obesity continues to rise at an alarming rate worldwide. In particular, the growing incidence of overweight and obesity in children is a major health concern. However, the underlying mechanisms of obesity remain unclear and the efficacy of several approaches for weight loss is limited. As an important calcium-permeable temperature-sensitive cation channel, transient receptor potential vanilloid (TRPV) ion channels directly participate in thermo-, mechano-, and chemosensory responses. Modulation of TRPV ion channel activity can alter the physiological function of the ion channel, leading to neurodegenerative diseases, chronic pain, cancer, and skin disorders. In recent years, increasing studies have demonstrated that TRPV ion channels are abundantly expressed in metabolic organs, including the liver, adipose tissue, skeletal muscle, pancreas, and central nervous system, which has been implicated in various metabolic diseases, including obesity and diabetes mellitus. In addition, as an important process for the pathophysiology of adipocyte metabolism, adipocyte differentiation plays a critical role in obesity. In this review, we focus on the role of TRPV ion channels in adipocyte differentiation to broaden the ideas for prevention and control strategies for obesity.

Progress in the development of TRPV1 small-molecule antagonists: Novel Strategies for pain management

Transient receptor potential vanilloid 1 (TRPV1) channels are widely distributed in sensory nerve endings, the central nervous system, and other tissues, functioning as ion channel proteins responsive to thermal pain and chemical stimuli. In recent years, the TRPV1 receptor has garnered significant interest as a potential therapeutic approach for various pain-related disorders, particularly TRPV1 antagonists. The present review offers a comprehensive, systematic exploration of both first- and second-generation TRPV1 antagonists in the context of pain management. Antagonists are categorized and explicated according to their structural characteristics. Detailed examination of binding modes, structural features, and pharmacological activities, alongside a critical appraisal of the advantages and limitations inherent to typical compounds within each structural category, are undertaken. Detailed discussions of the binding modes, structural features, pharmacological activities, advantages, and limitations of typical compounds within each structural category offer valuable insights and guidance for the future research and development of safer, more effective, and more targeted TRPV1 antagonists.

Insights from molecular dynamics simulations of TRPV1 channel modulators in pain

TRPV1 is a nonselective cation channel vital for detecting noxious stimuli (heat, acid, capsaicin). Its role in pain makes it a potential drug target for chronic pain management, migraines, and related disorders. This review updates molecular dynamics (MD) simulation studies on the TRPV1 channel, focusing on its gating mechanism, ligand-binding sites, and implications for drug design. The article also explores challenges in developing modulators, SAR optimization, and clinical trial studies. Efforts have been undertaken to concisely present MD simulation findings, with a focus on their relevance to drug discovery.

Role of sonic hedgehog signaling pathway in the regulation of ion channels: focus on its association with cardio-cerebrovascular diseases

Sonic hedgehog (SHH) signaling is vital for cell differentiation and proliferation during embryonic development, yet its role in cardiac, cerebral, and vascular pathophysiology is under debate. Recent studies have demonstrated that several compounds of SHH signaling regulate ion channels, which in turn affect the behavior of target cells. Some of these ion channels are involved in the cardio-cerebrovascular system. Here, we first reviewed the SHH signaling cascades, then its interaction with ion channels, and their impact on cardio-cerebrovascular diseases. Considering the complex cross talk of SHH signaling with other pathways that also affect ion channels and their potential impact on the cardio-cerebrovascular system, we highlight the necessity of thoroughly studying the effect of SHH signaling on ion homeostasis, which could serve as a novel mechanism for cardio-cerebrovascular diseases. Activation of SHH signaling influence ion channels activity, which in turn influence ion homeostasis, membrane potential, and electrophysiology, could serve as a novel strategy for cardio-cerebrovascular diseases.

The efficacy and neural mechanism of acupuncture therapy in the treatment of visceral hypersensitivity in irritable bowel syndrome

Irritable Bowel Syndrome (IBS) is a complex functional gastrointestinal disorder primarily characterized by chronic abdominal pain, bloating, and altered bowel habits. Chronic abdominal pain caused by visceral Hypersensitivity (VH) is the main reason why patients with IBS seek medication. Significant research effort has been devoted to the efficacy of acupuncture as a non-drug alternative therapy for visceral-hyperalgesia-induced IBS. Herein, we examined the central and peripheral analgesic mechanisms of acupuncture in IBS treatment. Acupuncture can improve inflammation and relieve pain by reducing 5-hydroxytryptamine and 5-HT3A receptor expression and increasing 5-HT4 receptor expression in peripheral intestinal sensory endings. Moreover, acupuncture can also activate the transient receptor potential vanillin 1 channel, block the activity of intestinal glial cells, and reduce the secretion of local pain-related neurotransmitters, thereby weakening peripheral sensitization. Moreover, by inhibiting the activation of N-methyl-D-aspartate receptor ion channels in the dorsal horn of the spinal cord and anterior cingulate cortex or releasing opioids, acupuncture can block excessive stimulation of abnormal pain signals in the brain and spinal cord. It can also stimulate glial cells (through the P2X7 and prokinetic protein pathways) to block VH pain perception and cognition. Furthermore, acupuncture can regulate the emotional components of IBS by targeting hypothalamic-pituitary-adrenal axis-related hormones and neurotransmitters via relevant brain nuclei, hence improving the IBS-induced VH response. These findings provide a scientific basis for acupuncture as an effective clinical adjuvant therapy for IBS pain.

Association between nineteen dietary fatty acids and hearing thresholds: findings from a nationwide survey

INTRODUCTION

Hearing loss is a prevalent health concern, and dietary factors, such as fatty acid intake, may play a role in its development. The current study aimed to investigate the association between the intake of dietary fatty acids and hearing thresholds among U.S. adults.

METHODS

The researchers examined data from the National Health and Nutrition Examination Survey (NHANES), including 7,623 participants with available dietary fatty acid intake and audiometry data. Dietary fatty acid intake was assessed using dietary recalls, and hearing thresholds were measured using pure-tone audiometry. Multivariate linear regression models and smoothing curve fitting were utilized to explore the associations between dietary fatty acid intake and hearing thresholds, adjusting for relevant covariates.

RESULTS

This study reveals a direct association between both low and high frequency pure tone average (PTA) hearing thresholds and the dietary intake of total saturated fatty acids (SFAs) and total polyunsaturated fatty acids (PUFAs). Conversely, the intake of total monounsaturated fatty acids (MUFAs) demonstrates an inverted U-shaped correlation with low-frequency and high-frequency PTA hearing thresholds, having inflection points at 11.91 (energy (%)) and 10.88 (energy (%)), respectively.

CONCLUSION

Dietary intake of certain fatty acids may influence hearing thresholds in adults.

A randomized, double-blinded, placebo-controlled clinical trial of duloxetine hydrochloride enteric-coated tablets in the treatment of refractory chronic cough

INTRODUCTION

Refractory cough, a chronic cough with an unclear diagnosis or poor treatment response. The symptoms are often stubborn and persistent, causing serious complications and lowering the patient's quality of life. Cough hypersensitivity syndrome (CHS) is proposed as a potential cause, and reducing sensory nerve hyperresponsiveness is suggested as an effective treatment. However, current drugs have low efficacy and benefit rates and numerous side effects. This trail proposes using duloxetine, a selective 5-HT and norepinephrine reuptake inhibitor, as a potential treatment for refractory cough, which has shown promise in treating pain and depression. Duloxetine may inhibit pain conduction and oxidative stress in peripheral nerves by inhibiting the activity of TRPV1 channels, which play an important role in the peripheral afferent pathway of refractory cough. Meanwhile, the antidepressant effects of duloxetine may also play a role in the treatment of refractory cough.

METHODS AND ANALYSIS

This is a single-center, prospective, randomized, double-blind, and controlled trial. A total of 98 individuals will be randomized in a 1:1 ratio to duloxetine group and placebo control group (starting with 20 mg QD, increasing 20 mg daily until 20 mg TID). After a screening period, the second stage runs from baseline to the 42nd (last) day of treatment, with follow-up visits on the 3rd, 7th, 14th, 21st, 28th, 35th, 42nd and 49th days. The main end-stage observation indicators include objective cough frequency, cough visual analog scale (VAS), cough symptom score, Leicester Cough Questionnaire (LCQ), and cough evaluation test (CET); the secondary end-stage observation indicators include capsaicin cough sensitivity, Patient Health Questionnaire-9 (PHQ-9), Major Depression Inventory (MDI), the Generalized Anxiety Disorder-7 scale (GAD-7), Life Events Scale (LES-32), induced sputum supernatant. The safety measures will be AEs/SAEs, vital signs, liver and kidney function, fecal occult blood test.

DISCUSSION

This study is the first randomized, double-blind, and controlled clinical trial investigating the use of duloxetine in the treatment of refractory coughs. The study aims to provide a high-quality basis for evaluating the efficacy and safety of duloxetine for this condition.

TRIAL REGISTRATION

Our study was registered in the Chinese Clinical Trials Register ( www.chictr.org.cn/ ) (ChiCTR2000037429) in 28/08/2020.

Pepper Fruit Extracts Show Anti-Proliferative Activity against Tumor Cells Altering Their NADPH-Generating Dehydrogenase and Catalase Profiles

Cancer is considered one of the main causes of human death worldwide, being characterized by an alteration of the oxidative metabolism. Many natural compounds from plant origin with anti-tumor attributes have been described. Among them, capsaicin, which is the molecule responsible for the pungency in hot pepper fruits, has been reported to show antioxidant, anti-inflammatory, and analgesic activities, as well as anti-proliferative properties against cancer. Thus, in this work, the potential anti-proliferative activity of pepper (Capsicum annuum L.) fruits from diverse varieties with different capsaicin contents (California < Piquillo < Padrón < Alegría riojana) against several tumor cell lines (lung, melanoma, hepatoma, colon, breast, pancreas, and prostate) has been investigated. The results showed that the capsaicin content in pepper fruits did not correspond with their anti-proliferative activity against tumor cell lines. By contrast, the greatest activity was promoted by the pepper tissues which contained the lowest capsaicin amount. This indicates that other compounds different from capsaicin have this anti-tumor potentiality in pepper fruits. Based on this, green fruits from the Alegría riojana variety, which has negligible capsaicin levels, was used to study the effect on the oxidative and redox metabolism of tumor cell lines from liver (Hep-G2) and pancreas (MIA PaCa-2). Different parameters from both lines treated with crude pepper fruit extracts were determined including protein nitration and protein S-nitrosation (two post-translational modifications (PTMs) promoted by nitric oxide), the antioxidant capacity, as well as the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX), among others. In addition, the activity of the NADPH-generating enzymes glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), and NADP-isocitrate dehydrogenase (NADP-ICDH) was followed. Our data revealed that the treatment of both cell lines with pepper fruit extracts altered their antioxidant capacity, enhanced their catalase activity, and considerably reduced the activity of the NADPH-generating enzymes. As a consequence, less H₂O₂ and NADPH seem to be available to cells, thus avoiding cell proliferation and possibly triggering cell death in both cell lines.

Targeting dorsal root ganglia and primary sensory neurons for the treatment of chronic pain: an update

INTRODUCTION

Current treatments for chronic pain are inadequate. Here, we provide an update on the new therapeutic strategies that target dorsal root ganglia (DRGs) in the peripheral nervous system for a better and safer treatment of chronic pain.

AREAS COVERED

Despite the complex nature of chronic pain and its underlying mechanisms, we do know that changes in the plasticity and modality of neurons in DRGs play a pivotal role. DRG neurons are heterogenous and offer potential pain targets for different therapeutic interventions. We discuss the last advancements of these interventions, which include the use of systemic and local administrations, selective nerve drug delivery, and gene therapy. In particular, we provide updates and further details on the molecular characterization of primary sensory neurons, new analgesics entering the market, and future gene therapy approaches.

EXPERT OPINION

DRGs and primary sensory neurons are promising targets for chronic pain treatment due to their key role in pain signaling, unique anatomical location, and the potential for different targeted therapeutic interventions.

Roadmap For The Expression Of Canonical and Extended Endocannabinoid System Receptors and Proteins in Peripheral Organs of Preclinical Animal Models

The endocannabinoid system is widely expressed throughout the body and is comprised of receptors, ligands, and enzymes that maintain metabolic, immune, and reproductive homeostasis. Increasing interest in the endocannabinoid system has arisen due to these physiologic roles, policy changes leading to more widespread recreational use, and the therapeutic potential of Cannabis and phytocannabinoids. Rodents have been the primary preclinical model of focus due to their relative low cost, short gestational period, genetic manipulation strategies, and gold-standard behavioral tests. However, the potential for lack of clinical translation to non-human primates and humans is high as cross-species comparisons of the endocannabinoid system has not been evaluated. To bridge this gap in knowledge, we evaluate the relative gene expression of 14 canonical and extended endocannabinoid receptors in seven peripheral organs of C57/BL6 mice, Sprague-Dawley rats, and non-human primate rhesus macaques. Notably, we identify species- and organ-specific heterogeneity in endocannabinoid receptor distribution where there is surprisingly limited overlap among the preclinical models. Importantly, we determined there were only five receptors (CB2, GPR18, GPR55, TRPV2, and FAAH) that had identical expression patterns in mice, rats, and rhesus macaques. Our findings demonstrate a critical, yet previously unappreciated, contributor to challenges of rigor and reproducibility in the cannabinoid field, which has profound implications in hampering progress in understanding the complexity of the endocannabinoid system and development of cannabinoid-based therapies.

5-Alkoxy-1-aryl-3-polyfluoroalkylpyrazoles with Antinociceptive Activity: Partial Agonists of TRPV1 Ion Channels

Chemoselective O-alkylation of 1-aryl-3-polyfluoroalkylpyrazol-5-oles under basic conditions resulted in a series of 5-alkoxypyrazoles (26 derivatives). They showed an acceptable ADME profile (in silico) and can be considered as drug-like. In experiments in vivo (CD-1 mice), it was found that the obtained compounds do not have toxic properties at a dose of more than 150 mg/kg (for most compounds at a dose of >300 mg/kg, and for lead compounds - >600 mg/kg). 22 Compounds from this series demonstrated from moderate to high analgesic effects (28-104 % at 1 h and 37-109 % at 2 h after administration) in vivo in the hot plate test (SD rats, 15 mg/kg, intraperitoneal (ip)). The lead compound was 4-([1-phenyl-3-(trifluoromethyl)pyrazol-5-yl]oxy)butan-1-ol, which not only increased the latent period in the hot plate test by 103 % at both measurement points but also showed a pronounced analgesic effect under conditions of capsaicin-induced nociception (CD-1 mice, 15 mg/kg, ip). According to molecular modeling, all synthesized compounds can interact with the TRPV1 ion channel. This biological target was confirmed in in vitro experiments on Chinese hamster ovary cells expressing rTRPV1. 5-Alkoxypyrazoles were partial agonists of the TRPV1 ion channel in various degree, and the most active was the same pyrazole as in in vivo tests.

TRPV1 inhibition overcomes cisplatin resistance by blocking autophagy-mediated hyperactivation of EGFR signaling pathway

Cisplatin resistance along with chemotherapy-induced neuropathic pain is an important cause of treatment failure for many cancer types and represents an unmet clinical need. Therefore, future studies should provide evidence regarding the mechanisms of potential targets that can overcome the resistance as well as alleviate pain. Here, we show that the emergence of cisplatin resistance is highly associated with EGFR hyperactivation, and that EGFR hyperactivation is arisen by a transcriptional increase in the pain-generating channel, TRPV1, via NANOG. Furthermore, TRPV1 promotes autophagy-mediated EGF secretion via Ca²⁺ influx, which activates the EGFR-AKT signaling and, consequentially, the acquisition of cisplatin resistance. Importantly, TRPV1 inhibition renders tumors susceptible to cisplatin. Thus, our findings indicate a link among cisplatin resistance, EGFR hyperactivation, and TRPV1-mediated autophagic secretion, and implicate that TRPV1 could be a crucial drug target that could not only overcome cisplatin resistance but also alleviate pain in NANOG⁺ cisplatin-resistant cancer.

Human TRPV1 structure and inhibition by the analgesic SB-366791

Pain therapy has remained conceptually stagnant since the opioid crisis, which highlighted the dangers of treating pain with opioids. An alternative addiction-free strategy to conventional painkiller-based treatment is targeting receptors at the origin of the pain pathway, such as transient receptor potential (TRP) ion channels. Thus, a founding member of the vanilloid subfamily of TRP channels, TRPV1, represents one of the most sought-after pain therapy targets. The need for selective TRPV1 inhibitors extends beyond pain treatment, to other diseases associated with this channel, including psychiatric disorders. Here we report the cryo-electron microscopy structures of human TRPV1 in the apo state and in complex with the TRPV1-specific nanomolar-affinity analgesic antagonist SB-366791. SB-366791 binds to the vanilloid site and acts as an allosteric hTRPV1 inhibitor. SB-366791 binding site is supported by mutagenesis combined with electrophysiological recordings and can be further explored to design new drugs targeting TRPV1 in disease conditions.

Inhibiting degradation of 2-arachidonoylglycerol as a therapeutic strategy for neurodegenerative diseases

Endocannabinoids are endogenous lipid signaling mediators that participate in a variety of physiological and pathological processes. 2-Arachidonoylglycerol (2-AG) is the most abundant endocannabinoid and is a full agonist of G-protein-coupled cannabinoid receptors (CB1R and CB2R), which are targets of Δ⁹-tetrahydrocannabinol (Δ⁹-THC), the main psychoactive ingredient in cannabis. While 2-AG has been well recognized as a retrograde messenger modulating synaptic transmission and plasticity at both inhibitory GABAergic and excitatory glutamatergic synapses in the brain, growing evidence suggests that 2-AG also functions as an endogenous terminator of neuroinflammation in response to harmful insults, thus maintaining brain homeostasis. Monoacylglycerol lipase (MAGL) is the key enzyme that degrades 2-AG in the brain. The immediate metabolite of 2-AG is arachidonic acid (AA), a precursor of prostaglandins (PGs) and leukotrienes. Several lines of evidence indicate that pharmacological or genetic inactivation of MAGL, which boosts 2-AG levels and reduces its hydrolytic metabolites, resolves neuroinflammation, mitigates neuropathology, and improves synaptic and cognitive functions in animal models of neurodegenerative diseases, including Alzheimer's disease (AD), multiple sclerosis (MS), Parkinson's disease (PD), and traumatic brain injury (TBI)-induced neurodegenerative disease. Thus, it has been proposed that MAGL is a potential therapeutic target for treatment of neurodegenerative diseases. As the main enzyme hydrolyzing 2-AG, several MAGL inhibitors have been identified and developed. However, our understanding of the mechanisms by which inactivation of MAGL produces neuroprotective effects in neurodegenerative diseases remains limited. A recent finding that inhibition of 2-AG metabolism in astrocytes, but not in neurons, protects the brain from TBI-induced neuropathology might shed some light on this unsolved issue. This review provides an overview of MAGL as a potential therapeutic target for neurodegenerative diseases and discusses possible mechanisms underlying the neuroprotective effects of restraining degradation of 2-AG in the brain.

Cannabinoids And Cannabinoid-Like Compounds: Biochemical Characterization And Pharmacological Perspectives

Publication interest in cannabinoids, including phytocannabinoids, endogenous cannabinoids, synthetic cannabinoids and cannabinomimetic compounds, is due to the therapeutic potential of these compounds in inflammatory pathology. Since recent years, scientific interest was focused on compounds with cannabinomimetic activity. The therapeutic use of phytocannabinoids and endocannabinoids is somewhat limited due to unresolved issues of dosing, toxicity and safety in humans, while cannabinoid-like compounds combine similar therapeutic effects with a high confirmed safety. Targets for endocannabinoids and phytocannabinoids are endocannabinoid receptors 1 and 2, G protein-coupled receptors (GPCRs), peroxisome proliferator-activated receptors (PPARs), and transient receptor potential ion channels (TRPs). Non-endocannabinoid N-acylethanolamines do not interact with cannabinoid receptors and exhibit agonist activity towards non-cannabinoid receptors, such as PPARs, GPCRs and TRPs. This literature review includes contemporary information on the biological activity, metabolism and pharmacological properties of cannabinoids and cannabinoid-like compounds, as well as their receptors. We established that only a few studies were devoted to the relationship of non-endocannabinoid N-acylethanolamines with non-cannabinoid receptors, such as PPARs, GPCRs, and also with TRPs. We have focused on issues that were insufficiently covered in the published sources in order to identify gaps in existing knowledge and determine the prospects for scientific research.

Novel dual-target μ‑opioid and TRPV1 ligands as potential pharmacotherapeutics for pain management

Currently, the development of effective analgesic drugs with few side effects remains a great challenge. Studies have suggested that multi-target drug treatments show high efficacy and reduced side effects compared to single-target drug therapies. In this work, we designed and synthesized two series of novel MOR/TRPV1 dual active ligands in which the phenylpiperidine group or the N-phenyl-N-(piperidin-4-yl) propionamide group as the MOR pharmacophore was fused to the benzylpiperazinyl urea-based TRPV1 pharmacophore. In particular, compound 5a exhibited promising dual pharmacological activity for MOR (EC₅₀ = 53.7 nM) and TRPV1 (IC₅₀ = 32.9 nM) in vitro. In formalin tests, compound 5a showed potent, dose-dependent in vivo analgesic activity in both the 1st and 2nd phases. Gratifyingly, compound 5a did not cause the side effects of hyperthermia and analgesic tolerance. Consistent with its in vitro activity, compound 5a also simultaneously agonized MOR and antagonized TRPV1 in vivo. Further studies on compound 5a showed acceptable pharmacokinetic properties and brain permeability. Furthermore, molecular docking studies showed that compound 5a tightly bound to the active pockets of hMOR and hTRPV1, respectively. Overall, this work shows the promise in discovering new analgesic treatments through the strategy of simultaneously targeting MOR and TRPV1 with a single molecule.

Synthesis and biological evaluation of N-(benzene sulfonyl)acetamide derivatives as anti-inflammatory and analgesic agents with COX-2/5-LOX/TRPV1 multifunctional inhibitory activity

In this study, a series of structurally novel N-(benzene sulfonyl) acetamide derivatives were designed, synthesized, and biologically evaluated as COX-2/5-LOX/TRPV1 multitarget inhibitors for anti-inflammatory and analgesic therapy. Among them, 9a and 9b displayed favorable COX-2 (9a IC₅₀ = 0.011 μM, 9b IC₅₀ = 0.023 μM), 5-LOX (9a IC₅₀ = 0.046 μM, 9b IC₅₀ = 0.31 μM) and TRPV1 (9a IC₅₀ = 0.008 μM, 9b IC₅₀ = 0.14 μM) inhibitory activities. The pharmacokinetic (PK) study of 9a in SD rats at the dosage of 10 mg/kg demonstrated a high oral exposure, an acceptable clearance and a favorable bioavailability (Cmax = 5807.18 ± 2657.83 ng/mL, CL = 3.24 ± 1.47 mL/min/kg, F = 96.8 %). Further in vivo efficacy studies illustrated that 9a was capable of ameliorating formalin-induced pain and inhibiting capsaicin-induced ear edema.

First-in-Class Dual Hybrid Carbonic Anhydrase Inhibitors and Transient Receptor Potential Vanilloid 1 Agonists Revert Oxaliplatin-Induced Neuropathy

Here, we report for the first time a series of compounds potentially useful for the management of oxaliplatin-induced neuropathy (OINP) able to modulate the human Carbonic Anhydrases (hCAs) as well as the Transient Receptor Potential Vanilloid 1 (TRPV1). All compounds showed effective in vitro inhibition activity toward the main hCAs involved in such a pathology, whereas selected items reported moderate agonism of TRPV1. X-ray crystallographic experiments assessed the binding modes of the two enantiomers (R)-37a and (S)-37b within the hCA II cleft. Although the tails assumed diverse orientations, no appreciable effects were observed for their hCA II affinity. Similarly, the activity of (R)-39a and (S)-39b on TRPV1 was not influenced by the stereocenters. In vivo evaluation of the most promising derivatives (R)-12a, (R)-37a, and the two enantiomers (R)-39a, (S)-39b revealed antihypersensitivity effects in a mouse model of OINP with potent and persistent effect up to 75 min after administration.

The transient receptor potential channels in rheumatoid arthritis: Need to pay more attention

Rheumatoid arthritis (RA) is characterized by the augment of vascular permeability, increased inflammatory cells infiltration, dysregulated immune cells activation, pannus formation and unbearable pain hyperalgesia. Ca²⁺ affect almost every aspect of cellular functions, involving cell migration, signal transduction, proliferation, and apoptosis. Transient receptor potential channels (TRPs) as a type of non-selective permeable cation channels, can regulate Ca²⁺ entry and intracellular Ca²⁺ signal in cells including immune cells and neurons. Researches have demonstrated that TRPs in the mechanisms of inflammatory diseases have achieved rapid progress, while the roles of TRPs in RA pathogenesis and pain hyperalgesia are still not well understood. To solve this problem, this review presents the evidence of TRPs on vascular endothelial cells in joint swelling, neutrophils activation and their trans-endothelial migration, as well as their bridging role in the reactive oxygen species/TRPs/Ca²⁺/peptidyl arginine deiminases networks in accelerating citrullinated proteins formation. It also points out the distinct functions of TRPs subfamilies expressed in the nervous systems of joints in cold hyperalgesia and neuro-inflammation mutually influenced inflammatory pain in RA. Thus, more attention could be paid on the impact of TRPs in RA and TRPs are useful in researches on the molecular mechanisms of anti-inflammation and analgesic therapeutic strategies.

Endocannabinoid-Binding Receptors as Drug Targets

Cannabis plant has been used from ancient times with therapeutic purposes for treating human pathologies, but the identification of the cellular and molecular mechanisms underlying the therapeutic properties of the phytocannabinoids, the active compounds in this plant, occurred in the last years of the past century. In the late 1980s and early 1990s, seminal studies demonstrated the existence of cannabinoid receptors and other elements of the so-called endocannabinoid system. These G protein-coupled receptors (GPCRs) are a key element in the functions assigned to endocannabinoids and appear to serve as promising pharmacological targets. They include CB₁, CB₂, and GPR55, but also non-GPCRs can be activated by endocannabinoids, like ionotropic receptor TRPV₁ and even nuclear receptors of the PPAR family. Their activation, inhibition, or simply modulation have been associated with numerous physiological effects at both central and peripheral levels, which may have therapeutic value in different human pathologies, then providing a solid experimental explanation for both the ancient medicinal uses of Cannabis plant and the recent advances in the development of cannabinoid-based specific therapies. This chapter will review the scientific knowledge generated in the last years around the research on the different endocannabinoid-binding receptors and their signaling mechanisms. Our intention is that this knowledge may help readers to understand the relevance of these receptors in health and disease conditions, as well as it may serve as the theoretical basis for the different experimental protocols to investigate these receptors and their signaling mechanisms that will be described in the following chapters.

TRP Channels: Recent Development in Translational Research and Potential Therapeutic Targets in Migraine

Migraine is a chronic neurological disorder that affects approximately 12% of the population. The cause of migraine headaches is not yet known, however, when the trigeminal system is activated, neuropeptides such as calcitonin gene-related peptide (CGRP) and substance P (SP) are released, which cause neurogenic inflammation and sensitization. Advances in the understanding of migraine pathophysiology have identified new potential pharmacological targets. In recent years, transient receptor potential (TRP) channels have been the focus of attention in the pathophysiology of various pain disorders, including primary headaches. Genetic and pharmacological data suggest the role of TRP channels in pain sensation and the activation and sensitization of dural afferents. In addition, TRP channels are widely expressed in the trigeminal system and brain regions which are associated with the pathophysiology of migraine and furthermore, co-localize several neuropeptides that are implicated in the development of migraine attacks. Moreover, there are several migraine trigger agents known to activate TRP channels. Based on these, TRP channels have an essential role in migraine pain and associated symptoms, such as hyperalgesia and allodynia. In this review, we discuss the role of the certain TRP channels in migraine pathophysiology and their therapeutic applicability.

Immunoregulatory Role of the Mechanosensitive Ion Channel Piezo1 in Inflammation and Cancer

Piezo1 was originally identified as a mechanically activated, nonselective cation ion channel, with significant permeability to calcium ions, is evolutionally conserved, and is involved in the proliferation and development of various types of cells, in the context of various types of mechanical or innate stimuli. Recently, our study and work by others have reported that Piezo1 from all kinds of immune cells is involved in regulating many diseases, including infectious inflammation and cancer. This review summarizes the recent progress made in understanding the immunoregulatory role and mechanisms of the mechanical receptor Piezo1 in inflammation and cancer and provides new insight into the biological significance of Piezo1 in regulating immunity and tumors.

Dietary Capsaicin: A Spicy Way to Improve Cardio-Metabolic Health?

Today's sedentary lifestyle with too much food and too little exercise has made metabolic syndrome a pandemic. Metabolic syndrome is a major risk factor for type-2 diabetes and cardiovascular disease. New knowledge of medical and nutraceutical intervention in the early stages of metabolic syndrome is central to prevent these deadly complications. People who eat chili pepper on a regular basis seem to stay healthier and live longer than those who do not. Animal experiments suggest a therapeutic potential for dietary capsaicin, the active principle in hot chili pepper, to reduce the risk of developing metabolic syndrome. This is an attractive theory since capsaicin has been a culinary staple for thousands of years, and is generally deemed safe when consumed in hedonically acceptable doses. The broad expression of the capsaicin receptor TRPV1 in metabolically active tissues lends experimental support to this theory. This review critically evaluates the available experimental and clinical evidence for and against dietary capsaicin being an effective dietary means to improve cardio-metabolic health. It comes to the conclusion that although a chili pepper-rich diet is associated with a reduced risk of dying due to cardiovascular disease, dietary capsaicin has no clear effect on blood glucose or lipid profiles. Therefore, the reduced mortality risk may reflect the beneficial action of digested capsaicin on gut microbiota.

The triple function of the capsaicin-sensitive sensory neurons: In memoriam János Szolcsányi

This paper is dedicated to the memory of János Szolcsányi (1938-2018), an outstanding Hungarian scientist. Among analgesics that act on pain receptors, he identified capsaicin as a selective lead molecule. He studied the application of capsaicin and revealed several physiological (pain, thermoregulation) and pathophysiological (inflammation, gastric ulcer) mechanisms. He discovered a new neuroregulatory system without sensory efferent reflex and investigated its pharmacology. The authors of this review are his former Ph.D. students who carried out their doctoral work in Szolcsányi's laboratory between 1985 and 2010 and report on the scientific results obtained under his guidance. His research group provided evidence for the triple function of the peptidergic capsaicin-sensitive sensory neurons including classical afferent function, local efferent responses, and remote, hormone-like anti-inflammatory, and antinociceptive actions. They also proposed somatostatin receptor type 4 as a promising drug target for the treatment of pain and inflammation. They revealed that neonatal capsaicin treatment caused no acute neuronal death but instead long-lasting selective ultrastructural and functional changes in B-type sensory neurons, similar to adult treatment. They described that lipid raft disruption diminished the agonist-induced channel opening of the TRPV1, TRPA1, and TRPM8 receptors in native sensory neurons. Szolcsányi's group has developed new devices for noxious heat threshold measurement: an increasing temperature hot plate and water bath. This novel approach proved suitable for assessing the thermal antinociceptive effects of analgesics as well as for analyzing peripheral mechanisms of thermonociception.

Bioflavonoid exerts analgesic and anti-inflammatory effects via transient receptor potential 1 channel in a rat model

BACKGROUND

Pain is an uncomfortable sensation in the body. Kaempferol is a flavonoid with antinociceptive effects. Transient receptor potential (TRP) channels have been characterized in the sensory system.

OBJECTIVE

This study evaluated the central antinociceptive effect of Kaempferol and possible mechanisms of action of transient receptor potential cation channel subfamily V member 1 (TRPV1).

METHODS

Capsaicin as a TRPV agonist (5 μg/μL, intracerebroventricular [ICV]) and capsazepine as its antagonist (10 μg/μL, icv) were used to test the analgesic effect of kaempferol (1.5 mg, ICV). Morphine (10 μg, ICV) was used as a positive control. The other groups were treated with a combination of kaempferol and capsaicin, kaempferol and capsazepine, and capsaicin and capsazepine. The cannula was implanted in the cerebroventricular area. The tail-flick, acetic acid, and formalin tests were used to assess analgesic activity. For evaluation of antiinflammatory effect, the formalin-induced rat paw edema was used.

RESULTS

Kaempferol significantly decreased pain in the acute pain models, including the tail-flick and the first phase of the formalin test. In the late phase of the formalin test, as a valid model of nociception, capsazepine inhibited the antinociceptive effect of kaempferol.

CONCLUSIONS

Kaempferol has an analgesic effect in the acute pain model and can affect inflammatory pain. Also, the TRPV1 channel plays a role in the antinociceptive activity of kaempferol.

Recent Developments on the Roles of Calcium Signals and Potential Therapy Targets in Cervical Cancer

Intracellular calcium (Ca²⁺) concentration ([Ca²⁺]i) is implicated in proliferation, invasion, and metastasis in cancerous tissues. A variety of oncologic therapies and some candidate drugs induce their antitumor effects (in part or in whole) through the modulation of [Ca²⁺]i. Cervical cancer is one of most common cancers among women worldwide. Recently, major research advances relating to the Ca²⁺ signals in cervical cancer are emerging. In this review, we comprehensively describe the current progress concerning the roles of Ca²⁺ signals in the occurrence, development, and prognosis of cervical cancer. It will enhance our understanding of the causative mechanism of Ca²⁺ signals in cervical cancer and thus provide new sights for identifying potential therapeutic targets for drug discovery.

Role of TRPV1 in respiratory disease and association with traditional Chinese medicine: A literature review

Transient receptor potential vanilloid type 1 (TRPV1), involved in multiple pathophysiological processes including inflammation, is a thermally activated, non-selective cation channel. It has been identified that TRPV1 is highly involved in some common respiratory diseases including allergic rhinitis, asthma, chronic obstructive pulmonary disease, and pulmonary infection by participating in neurogenic and immunogenic inflammation, sensitization, and oxidative stress. In recent years, the hypothesis of transient receptor potential (TRP) has been introduced in studies on the theory of five flavors and four properties of Chinese medicinal. However, the hypothesis is undetermined due to the multi-component and multi-target characteristics of Chinese medicinal. This study describes the relations between TRPV1 and four types of respiratory diseases based on the literature in recent five years. In the meantime, the therapeutic effect of Chinese medicinal by intervening TRPV1 was reviewed, in an attempt to provide certain evidence for future studies on the medicinal property-effect relationship, mechanism of drug action, the syndrome differentiation in traditional Chinese medicine (TCM) for respiratory diseases and to help for new drug development.

Discovery of Potent and Selective Transient Receptor Potential Vanilloid 1 (TRPV1) Agonists with Analgesic Effects In Vivo Based on the Functional Conversion Induced by Altering the Orientation of the Indazole Core

Transient receptor potential vanilloid 1 (TRPV1) is a promising target for developing antinociceptive agents. Here, we report the synthesis of N-indazole-4-aryl piperazine carboxamide analogues as TRPV1 modulators. The structure-activity relationship (SAR) reveals that substituting indazole at the 5-/6-position leads to TRPV1 agonism, whereas the 4- and 7-positions of indazole obtain mild antagonism and loss of activity, respectively. The whole-cell clamp patch assay shows that 28 is a potent and selective TRPV1 agonist and it relieves inflammatory and thermal pain by desensitizing the native TRPV1 current in the dorsal root ganglion (DRG) in mice. Additionally, site-directed mutagenesis combined with molecular docking shows an important hydrogen interaction between Arg557 and the indazole of 28. Taken together, our findings provide insight into TRPV1 agonism-antagonism conversion based on the interaction between indazole and Arg557, which provides a strategy to obtain new TRPV1 agonists by structural modification of antagonists. Compound 28 may be used as a lead compound for further optimization.

A review on synthetic strategy, molecular pharmacology of indazole derivatives, and their future perspective

With different nitrogen-containing heterocyclic moieties, Indazoles earn one of the places among the top investigated molecules in medicinal research. Indazole, an important fused aromatic heterocyclic system containing benzene and pyrazole ring with a chemical formula of C₇ H₆ N₂ , is also called benzopyrazole. Indazoles consist of three tautomeric forms in which 1H-tautomers (indazoles) and 2H-tautomers (isoindazoles) exist in all phases. The tautomerism in indazoles greatly influences synthesis, reactivity, physical and even the biological properties of indazoles. The thermodynamic internal energy calculation of these tautomers points view 1H-indazole as the predominant and stable form over 2H-indazole. The natural source of indazole is limited and exists in alkaloidal nature (i.e., nigellidine, nigeglanine, nigellicine, etc.) found from Nigella plants. Some of the FDA-approved drugs like Axitinib, Entrectinib, Niraparib, Benzydamine, and Granisetron are being used to treat renal cell cancer, non-small cell lung cancer (NSCLC), epithelial ovarian cancer, chronic inflammation, chemotherapy-induced nausea, vomiting, and many more uses. Besides all these advantages regarding its biological activity, the main issue about indazoles is the less abundance in plant sources, and their synthetic derivatives also often face problems with low yield. In this review article, we discuss its chemistry, tautomerism along with their effects, different schematics for the synthesis of indazole derivatives, and their different biological activities.

Capsaicin for Weight Control: “Exercise in a Pill” (or Just Another Fad)?

Medical management of obesity represents a large unmet clinical need. Animal experiments suggest a therapeutic potential for dietary capsaicin, the pungent ingredient in hot chili peppers, to lose weight. This is an attractive theory since capsaicin has been a culinary staple for thousands of years and is generally deemed safe when consumed in hedonically acceptable, restaurant-like doses. This review critically evaluates the available experimental and clinical evidence for and against capsaicin as a weight control agent and comes to the conclusion that capsaicin is not a magic “exercise in a pill”, although there is emerging evidence that it may help restore a healthy gut microbiota.

Structure-Based Virtual Screening Identifies Novobiocin, Montelukast, and Cinnarizine as TRPV1 Modulators with Anticonvulsant Activity In Vivo

The transient receptor potential vanilloid 1 (TRPV1) receptor is a nonselective cation channel, known to be involved in the regulation of many important physiological and pathological processes. In the last few years, it has been proposed as a promising target to develop novel anticonvulsant compounds. However, thermoregulatory effects associated with the channel inhibition have hampered the path for TRPV1 antagonists to become marketed drugs. In this regard, we conducted a structure-based virtual screening campaign to find potential TRPV1 modulators among approved drugs, which are known to be safe and thermally neutral. To this end, different docking models were developed and validated by assessing their pose and score prediction powers. Novobiocin, montelukast, and cinnarizine were selected from the screening as promising candidates for experimental testing and all of them exhibited nanomolar inhibitory activity. Moreover, the in vivo profiles showed promising results in at least one of the three models of seizures tested.

New Phenylglycinamide Derivatives with Hybrid Structure as Candidates for New Broad-Spectrum Anticonvulsants

In the present study, a focused combinatorial chemistry approach was applied to merge structural fragments of well-known TRPV1 antagonists with a potent anticonvulsant lead compound, KA-104, that was previously discovered by our group. Consequently, a series of 22 original compounds has been designed, synthesized, and characterized in the in vivo and in vitro assays. The obtained compounds showed robust in vivo antiseizure activity in the maximal electroshock (MES) test and in the 6 Hz seizure model (using both 32 and 44 mA current intensities). The most potent compounds 53 and 60 displayed the following pharmacological profile: ED₅₀ = 89.7 mg/kg (MES), ED₅₀ = 29.9 mg/kg (6 Hz, 32 mA), ED₅₀ = 68.0 mg/kg (6 Hz, 44 mA), and ED₅₀ = 73.6 mg/kg (MES), ED₅₀ = 24.6 mg/kg (6 Hz, 32 mA), and ED₅₀ = 56.3 mg/kg (6 Hz, 44 mA), respectively. Additionally, 53 and 60 were effective in the ivPTZ seizure threshold and had no influence on the grip strength and body temperature in mice. The in vitro binding and functional assays indicated a multimodal mechanism of action for 53 and 60. These molecules, beyond TRPV1 antagonism, inhibited calcium currents and fast sodium currents in patch-clamp assays. Further studies proved beneficial in vitro ADME-Tox properties for 53 and 60 (i.e., high metabolic stability, weak influence on CYPs, no neurotoxicity, etc.). Overall, 53 and 60 seem to be interesting candidates for future preclinical development in epilepsy and pain indications due to their interaction with the TRPV1 channel.

Ocular Surface Ion-Channels Are Closely Related to Dry Eye: Key Research Focus on Innovative Drugs for Dry Eye

Abundant ion-channels, including various perceptual receptors, chloride channels, purinergic receptor channels, and water channels that exist on the ocular surface, play an important role in the pathogenesis of dry eye. Channel-targeting activators or inhibitor compounds, which have shown positive effects in in vivo and in vitro experiments, have become the focus of the dry eye drug research and development, and individual compounds have been applied in clinical experimental treatment. This review summarized various types of ion-channels on the ocular surface related to dry eye, their basic functions, and spatial distribution, and discussed basic and clinical research results of various channel receptor regulatory compounds. Therefore, further elucidating the relationship between ion-channels and dry eye will warrant research of dry eye targeted drug therapy.

SGK1-targeted TRPV1 regulates bladder smooth muscle cell proliferation due to BOO in mice via NFAT2

OBJECTIVE

Bladder outlet obstruction (BOO) is a type of chronic disease that is mainly caused by benign prostatic hyperplasia. Previous studies discovered the involvements of both SGK1 and NFAT2 in the proliferation of smooth muscle cells after BOO. However, the relationship between these two molecules is yet to be explored. Thus, this study explored the specific mechanism of the SGK1-NFAT2 signaling pathway in mouse BOO-mediated BSMC proliferation in vivo and in vitro.

MATERIALS AND METHODS

In vivo experiments were performed by suturing 1/2 of the external urethra of female BALB/C mice to cause BOO for 2 weeks. In vitro, MBSMCs were treated with dexamethasone (Dex) or dexamethasone + SB705498 for 12 hours and were transfected with SGK1 siRNA for 48 hours. The expression and distribution of SGK1, TRPV1, NFAT2, and PCNA were measured by Western blotting, polymerase chain reaction and immunohistochemistry. The relationship between SGK1 and TRPV1 was analyzed by immunoprecipitation. The proliferation of MBSMCs was examined by EdU and CCK-8 assays. Bladder weight, smooth muscle thickness and collagen deposition in mice after 2 weeks of BOO were examined.

RESULTS

Bladder weight, smooth muscle thickness, the collagen deposition ratio and the expression of SGK1, TRPV1, NFAT2, and PCNA were significantly increased in mice after 2 weeks of BOO. Compared with the control, 10 μM Dex promoted the expression of these four molecules and the proliferation of MBSMCs. After inhibiting TRPV1, only the expression of SGK1 was not affected, and the proliferation of MBSMCs was inhibited. After silencing SGK1, the expression of these four molecules and the proliferation of MBSMCs decreased. CoIP suggested that SGK1 acted directly on TRPV1.

CONCLUSION

In this study, SGK1 targeted TRPV1 to regulate the proliferation of MBSMCs mediated by BOO in mice through NFAT2 and then affected the process of bladder remodeling after BOO. This finding may provide a strategy for BOO drug target screening. This article is protected by copyright. All rights reserved.