Mechanistic Investigation On Anti-Nociceptive Potential Of Bartogenic Acid Containing Barringtonia Racemosa Fraction In Experimental Models Of Pain

Barringtonia racemosa (B. racemosa) is a tropical medicinal plant possessing interesting biological activities. B. racemosa fruits are traditionally used in India for the treatment of pain, inflammation, and rheumatic conditions. Earlier, we have reported anti-inflammatory activity of ethyl acetate fraction (BREAF) obtained from B. racemosa fruits in animal models of inflammation and delayed-type hypersensitivity. The present study aimed to assess the anti-nociceptive activity of BREAF. Acetic acid-induced writhing test, and hot plate and tail immersion tests were employed to study the effect of BREAF on peripheral and central pain mechanisms, respectively. The involvement of opioid system was confirmed through naloxone antagonism. Formalin induced pain test was performed to assess the effect of BREAF on neurogenic and inflammatory pain components. Capsaicin induced pain models were used to investigate the involvement of transient receptor potential vanilloid 1 receptor. The BREAF reduced writhing episodes and delayed the onset of acetic acid-induced writhings. The raised percentage maximum protective effects by BREAF in hot plate and tail immersion tests suggest the efficacy of BREAF in pain alleviation. A reversal of the analgesic effect of BREAF following naloxone treatment indicates the involvement of opioid receptors. The BREAF also inhibited inflammatory and neurogenic components of formalin-induced pain. The inhibition of capasaicin induced pain to some extent by the BREAF indicates the possibility of involvement of TRPV1 receptors. This study reinforces the traditional use of B. racemosa in the treatment of painful conditions. However, further studies are reasonable to explore the detailed mechanism(s) of the anti-nociceptive action of BREAF.

Effects of transient receptor potential vanillic acid subtype 1 receptor and its modulators on neuropathic pain: research advances / 国际药学研究杂志

Neuropathic pain(NPP)has always been a problem that puzzles the medical community because of its unclear pathogenesis and poor drug treatment. With the development of molecular biology and electrophysiological techniques, studies have shown that the complex pathological mechanism of NPP may be related to the activation of transient receptor potential vanillic acid sub-type 1(TRPV1). TRPV1 receptors are mainly expressed in peripheral sensory neurons, which can detect harmful stimuli in the external and internal environment and transmit information to the central nervous system, thereby playing an important role in peripheral neuropathic pain. TRPV1 modulators exert analgesic effects by blocking the pain transmission function of TRPV1 and have become a potential therapeutic agent in the treatment of NPP. This article reviews TRPV1 receptor-mediated NPP models and the role of TRPV1 modulators in NPP treatment.

Age and Sex Distribution of Chinese Chronic Cough Patients and Their Relationship With Capsaicin Cough Sensitivity

PURPOSE: An older female predominance has been reported among chronic cough patients in Western countries, which is considered to be associated with a higher cough sensitivity in females. However, the characteristics of Chinese chronic cough patients remain unclear. This study aimed to explore the age and sex distribution as well as their relationship with cough reflex sensitivity to capsaicin in Chinese chronic cough patients. METHODS: We analyzed the demographic features of 1,882 consecutive chronic cough patients who attended our cough clinic in Guangzhou, China. Cough sensitivity to capsaicin, which was defined as the lowest concentration of capsaicin causing 5 coughs or more (C5), was measured in 539 of the 1,882 patients and 68 healthy volunteers. RESULTS: The mean age of the patients was 43.0 ± 13.7 years and patients aged <50 years accounted for more than two-thirds of the study population. Around 87% of the patients were never-smokers. The proportion of females (51.5%) was almost equal to that of males (48.5%). The pattern of the age and sex distribution was consistently reflected within most common causes of chronic cough, while a female predominance was shown in patients with cough-variant asthma and patients aged ≥50 years. Female patients had higher cough sensitivity to capsaicin than male patients (log C5: 1.58 ± 0.84 vs. 2.04 ± 0.84 μmol/L, P = 0.001), and patients aged ≥50 years had higher cough sensitivity to capsaicin than patients aged <50 years. CONCLUSIONS: In China, patients with chronic cough have a roughly equal sex distribution and a middle-aged predominance, irrespective of a higher cough sensitivity to capsaicin in females and older patients. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02591550

TRPV1 Blocking Alleviates Airway Inflammation and Remodeling in a Chronic Asthma Murine Model

PURPOSE: Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness (AHR), inflammation, and remodeling. There is emerging interest in the involvement of the transient receptor potential vanilloid 1 (TRPV1) channel in the pathophysiology of asthma. This study examined whether TRPV1 antagonism alleviates asthma features in a murine model of chronic asthma. METHODS: BALB/c mice were sensitized to and challenged by ovalbumin to develop chronic asthma. Capsazepine (TRPV1 antagonist) or TRPV1 small interfering RNA (siRNA) was administered in the treatment group to evaluate the effect of TPV1 antagonism on AHR, airway inflammation, and remodeling. RESULTS: The mice displayed increased AHR, airway inflammation, and remodeling. Treatment with capsazepine or TRPV1 siRNA reduced AHR to methacholine and airway inflammation. Type 2 T helper (Th2) cytokines (interleukin [IL]-4, IL-5, and IL-13) were reduced and epithelial cell-derived cytokines (thymic stromal lymphopoietin [TSLP], IL-33, and IL-25), which regulate Th2 cytokine-associated inflammation, were also reduced. Airway remodeling characterized by goblet cell hyperplasia, increased α-smooth muscle action, and collagen deposition was also alleviated by both treatments. CONCLUSIONS: Treatment directed at TRPV1 significantly alleviated AHR, airway inflammation, and remodeling in a chronic asthma murine model. The TRPV1 receptor can be a potential drug target for chronic bronchial asthma.

The functions of P2X3 receptor in inflammatory pain and it's influencial factors / 医学研究生学报

Inflammatory Pain is one of the most common clinical symptom with unclear pathogenesis,which causes difficulty in patien's work and daily life. Previous studies have shown that P2X3 receptor participates in the pathological process of acute and chronic inflammatory pain. This paper focuses on the functions of P2X3 receptor in inflammatory pain and its relationship with TRPV1 receptor,inflammatory mediator and Epac-PKC signal transduction pathway,thereby provides a new thought for research and treatment of this disease.

Esophageal Submucosal Injection of Capsaicin but Not Acid Induces Symptoms in Normal Subjects

BACKGROUND/AIMS: Transient receptor potential vanilloid-1 (TRPV1) is a candidate for mediating acid-induced symptoms in the esophagus. We conducted studies to determine if the presence of acid in the mucosa/submucosa and direct activation of TRPV1 by capsaicin elicited symptoms in normal healthy subjects. We also studied the presence of TRPV1 receptors in the esophagus. METHODS: Unsedated endoscopy was performed on healthy subjects with no symptoms. Using a sclerotherapy needle, normal saline (pH 2.0-7.5) was injected into the mucosa/submucosa, 5 cm above the Z line. In a separate group of healthy subjects, injection of capsaicin and vehicle was also studied. Quality of symptoms was reported using the McGill Pain Questionnaire, and symptom intensity using the visual analogue scale (VAS). Immunohistochemistry was performed on 8 surgical esophagus specimens using TRPV1 antibody. RESULTS: Acid injection either did not elicit or elicited mild symptoms in subjects at all pH solutions. Capsaicin but not the vehicle elicited severe heartburn/chest pain in all subjects. Mean VAS for capsaicin was 91 ± 3 and symptoms lasted for 25 ± 1 minutes. Immunohistochemistry revealed a linear TRPV1 staining pattern between the epithelial layer and the submucosa that extended into the papillae. Eighty-five percent of papillae stained positive for TRPV1 with a mean 1.1 positive papillae per high-powered field. CONCLUSIONS: The mechanism of acid-induced heartburn and chest pain is not the simple interaction of hydrogen ions with afferents located in the esophageal mucosa and submucosa. TRPV1 receptors are present in the lamina propria and their activation induces heartburn and chest pain.

Transient Receptor Potential Vanilloid 1 Expression and Functionality in MCF-7 Cells: A Preliminary Investigation / 한국유방암학회지

PURPOSE: Transient receptor potential vanilloid 1 (TRPV1) is a nonselective cation channel belonging to the transient receptor potential family, and it is expressed in different neoplastic tissues. Its activation is associated with regulation of cancer growth and progression. The aim of this research was to study the expression and pharmacological characteristics of TRPV1 in cells derived from human breast cancer MCF-7 cells. METHODS: TRPV1 presence was assessed by binding studies and Western blotting. Receptor binding characteristics were evaluated through competition assays, while 3-(4,5-dimethylthiazol-2-yl)-2,5,-dipheyltetrazolium bromide reduction assays were performed to confirm an early hypothesis regarding the modulation of cancer cell proliferation. The functionality of TRPV1 was evaluated by measuring Ca2+ uptake in the presence of increasing concentrations of TRPV1 agonists and antagonists. RESULTS: Binding studies identified a single class of TRPV1 (Bmax 1,492+/-192 fmol/mg protein), and Western blot showed a signal at 100 kDa corresponding to the molecular weight of human TRPV1. Among the different tested agonists and antagonists, anandamide (Ki: 2.8x10(-11) M) and 5-iodoresiniferatoxin (5-I-RTX) (Ki: 5.6x10(-11) M) showed the highest degrees of affinity for TRPV1, respectively. All tested TRPV1 agonists and antagonists caused a significant (panandamide>capsaicin and 5-I-RTX=capsazepine, respectively. CONCLUSION: These data indicate that both TRPV1 agonists and antagonists induce significant inhibition of MCF-7 cell growth. Even though the mechanisms involved in the antiproliferative effects of TRPV1 agonists and antagonists should be further investigated, it has been suggested that agonists cause desensitization of the receptor, leading to alteration in Ca2+-influx regulation. By contrast, antagonists cause a functional block of the receptor with consequent fatal dysregulation of cell homeostasis.

Are Rice and Spicy Diet Good for Functional Gastrointestinal Disorders?

Rice- and chili-containing foods are common in Asia. Studies suggest that rice is completely absorbed in the small bowel, produces little intestinal gas and has a low allergenicity. Several clinical studies have demonstrated that rice-based meals are well tolerated and may improve gastrointestinal symptoms in functional gastrointestinal disorders (FGID). Chili is a spicy ingredient commonly use throughout Asia. The active component of chili is capsaicin. Capsaicin can mediate a painful, burning sensation in the human gut via the transient receptor potential vanilloid-1 (TRPV1). Recently, the TRPV1 expressing sensory fibers have been reported to increase in the gastrointestinal tract of patients with FGID and visceral hypersensitivity. Acute exposure to capsaicin or chili can aggravate abdominal pain and burning in dyspepsia and IBS patients. Whereas, chronic ingestion of natural capsaicin agonist or chili has been shown to decrease dyspeptic and gastroesophageal reflux disease (GERD) symptoms. The high prevalence of spicy food in Asia may modify gastrointestinal burning symptoms in patients with FGID. Studies in Asia demonstrated a low prevalence of heartburn symptoms in GERD patients in several Asian countries. In conclusion rice is well tolerated and should be advocated as the carbohydrate source of choice for patients with FGID. Although, acute chili ingestion can aggravate abdominal pain and burning symptoms in FGID, chronic ingestion of chili was found to improve functional dyspepsia and GERD symptoms in small randomized, controlled studies.