An endogenous capsaicin-like substance with high potency at recombinant and native vanilloid VR1 receptors.

The vanilloid receptor VR1 is a nonselective cation channel that is most abundant in peripheral sensory fibers but also is found in several brain nuclei. VR1 is gated by protons, heat, and the pungent ingredient of "hot" chili peppers, capsaicin. To date, no endogenous compound with potency at this receptor comparable to that of capsaicin has been identified.

Ethanol elicits and potentiates nociceptor responses via the vanilloid receptor-1.

The vanilloid receptor-1 (VR1) is a heat-gated ion channel that is responsible for the burning sensation elicited by capsaicin. A similar sensation is reported by patients with esophagitis when they consume alcoholic beverages or are administered alcohol by injection as a medical treatment. We report here that ethanol activates primary sensory neurons, resulting in neuropeptide release or plasma extravasation in the esophagus, spinal cord or skin.

Tachykinins via Tachykinin NK(2) receptor activation mediate ozone-induced increase in the permeability of the tracheal mucosa in guinea-pigs.

1. Acute exposure to ozone is known to cause airway hyperresponsiveness, which, at least in part, seems to result from an increase in the permeability of the airway mucosa. Recently, we demonstrated that depletion of sensory neuropeptides inhibits the ozone-induced increase in the permeability of the tracheal mucosa in guinea-pigs.

Expression of protease activated receptor-2 (PAR-2) in central airways of smokers and non-smokers.

Background: Protease activated receptor-2 (PAR-2) is a transmembrane G protein coupled receptor preferentially activated by trypsin and tryptase. The protease activated receptors play an important role in most components of injury responses including cell proliferation, migration, matrix remodelling, and inflammation. Cigarette smoking causes an inflammatory process in the central airways, peripheral airways, lung parenchyma, and adventitia of pulmonary arteries.

Neuropeptides: brain messengers of many faces.

Neuropeptides 2001, 2nd Joint Meeting of the European Neuropeptide Club and the American Summer Neuropeptide Conference (11th Annual Meeting). 6-11 May 2001 with Satellite Symposium, Israeli-French Symposium, Israel Ministry of Science, Culture and Sport, 6 May 2001, held at Maale Hachmicha and Tel Aviv University, Israel.

Expression and function of proteinase-activated receptor 2 in human bronchial smooth muscle.

Trypsin and mast cell tryptase cleave proteinase-activated receptor 2 (PAR2) to induce alterations in contraction of airway smooth muscle that have been implicated in asthma in experimental animals. Although tryptase inhibitors are under development for treatment of asthma, little is known about the localization and function of PAR2 in human airways. We detected PAR2 expression in primary cultures of human airway smooth muscle cells using reverse transcriptase/polymerase chain reaction (RT-PCR) and immunofluorescence.

Allergen-induced impairment of bronchoprotective nitric oxide synthesis in asthma.

Background: Endogenous nitric oxide protects against airway hyperresponsiveness (AHR) to bradykinin in mild asthma, whereas AHR to bradykinin is enhanced by inhaled allergens.

Objective: Hypothesizing that allergen exposure impairs bronchoprotective nitric oxide within the airways, we studied the effect of the inhaled nitric oxide synthase (NOS) inhibitor N(G)-monomethyl-L-arginine (L-NMMA) on AHR to bradykinin before and after allergen challenge in 10 subjects with atopic asthma.

Methods: The study consisted of 3 periods (1 diluent and 2 allergen challenges).

The vanilloid receptor (VR1)-mediated effects of anandamide are potently enhanced by the cAMP-dependent protein kinase.

The endogenous cannabinoid receptor ligand, anandamide (AEA), is a full agonist of the vanilloid receptor type 1 (VR1) for capsaicin. Here, we demonstrate that the potency and efficacy of AEA at VR1 receptors can be significantly increased by the concomitant activation of protein kinase A (PKA). In human embryonic kidney (HEK) cells over-expressing human VR1, AEA induces a rise in cytosolic Ca(2+) concentration that is mediated by this receptor.

Factors that determine acetylcholine responsiveness of guinea pig tracheal tubes.

Acetylcholine administered to the inside of epithelium-denuded tracheal tubes did cause a potent contraction (2486+/-120 mg). In contrast, a response was hardly observed in tissues with an intact epithelial layer (674+/-81 mg), which was due to both the synthesis of nitric oxide and the activity of acetylcholinesterase, since the contractions to acetylcholine were significantly enhanced after preincubation with N(omega)-nitro-L-arginine methyl ester (L-NAME) or physostigmine (1374+/-65 and 1120+/-65 mg, respectively). In addition, the suppressive effect was caused by the barrier function of the epithelial layer, since preincubation of epithelium-denuded tissues with physostigmine significantly increased the pD2 value for acetylcholine (7.

Comparison of prazosin, terazosin and tamsulosin: functional and binding studies in isolated prostatic and vascular human tissues.

Background: Terazosin and tamsulosin are drugs currently used in the treatment of benign prostatic hypertrophy (BPH). The potency of these two alpha(1) receptor antagonists and that of prazosin to inhibit contractions induced by noradrenaline and the binding of [(3)H]-prazosin in human prostate and four different human arterial and venous vessels (saphenous and umbilical veins, renal and mesenteric arteries) was studied.

Methods: By bioassay and binding studies, we examined the receptor affinities of different alpha(1) receptor antagonists in different human tissues.

Substance p.

This article provides a brief overview of the history of substance P from its discovery in the 1930s to the present day. The development of substance P receptor agonists and antagonists, and more recently the employment of transgenic mice, provide a framework to explore the functional role of substance P. Chronic inflammation and pain are associated with a number of diseases, and it has been proposed that substance P, released from primary afferent nerve endings play a role in these conditions.

Role of peripheral N-methyl-D-aspartate (NMDA) receptors in visceral nociception in rats.

Background & Aims: N-methyl-D-aspartate (NMDA) receptors are ligand-gated ion channels that have an important role in long-term potentiation and memory processing in the central nervous system. The aims in this study were to determine whether NMDA receptors are expressed in the peripheral nervous system and identify their role in mediating behavioral pain responses to colonic distention in the normal gut.

Methods And Results: Immunohistochemical localization of the NR1 subunit showed that NMDA receptors are expressed on the cell bodies and peripheral terminals of primary afferent nerves innervating the colon.

NK1 receptor stimulation causes contraction and inositol phosphate increase in medium-size human isolated bronchi.

Although contraction of human isolated bronchi is mediated mainly by tachykinin NK2 receptors, NK1 receptors, via prostanoid release, contract small-size (approximately 1 mm in diameter) bronchi. Here, we have investigated the presence and biological responses of NK1 receptors in medium-size (2-5 mm in diameter) human isolated bronchi. Specific staining was seen in bronchial sections with an antibody directed against the human NK1 receptor.

Anandamide excites central terminals of dorsal root ganglion neurons via vanilloid receptor-1 activation.

Recently, the cannabinoid (CB) receptor agonist anandamide (AEA) has been shown to excite perivascular terminals of primary sensory neurons via activation of the vanilloid receptor-1 (VR-1). To determine whether AEA stimulates central terminals of these neurons, via VR-1 activation, we studied the release of calcitonin gene-related peptide (CGRP)- and substance P (SP)-like immunoreactivities (LI) from slices of rat dorsal spinal cord. Mobilization of Ca(2+) in rat dorsal root ganglion (DRG) neurons in culture was also studied.

Neutral endopeptidase terminates substance P-induced inflammation in allergic contact dermatitis.

Sensory nerve-derived neuropeptides such as substance P demonstrate a number of proinflammatory bioactivities, but less is known about their role in inflammatory skin disease. The cell surface metalloprotease neutral endopeptidase (NEP) is the principal proteolytic substance P-degrading enzyme. This study tests the hypothesis that the absence of NEP results in dysregulated inflammatory skin responses.

Evidence that PAR-1 and PAR-2 mediate prostanoid-dependent contraction in isolated guinea-pig gallbladder.

We have investigated the ability of protease-activated receptor-1 (PAR-1), PAR-2, PAR-3 and PAR-4 agonists to induce contractile responses in isolated guinea-pig gallbladder. Thrombin, trypsin, mouse PAR-1 activating (SFLLRN-NH(2)) peptide, and mouse PAR-2 activating (SLIGRL-NH(2)) and human PAR-2 activating (SLIGKV-NH(2)) peptides produced a concentration-dependent contractile response. Mouse PAR-4 activating (GYPGKF-NH(2)) peptide, the mouse PAR-1 reverse (NRLLFS-NH(2)) peptide, the mouse PAR-2 reverse (LRGILS-NH(2)) and human PAR-2 reverse (VKGILS-NH(2)) peptides caused negligible contractile responses at the highest concentrations tested.

Clinical pharmacology of oral cotinine.

Cotinine is the major proximate metabolite of nicotine. The aims of our study were to assess the pharmacokinetics of oral cotinine comparing the use of saliva and plasma concentrations, and to characterize the subjective and cardiovascular effects of oral cotinine in nonsmokers. The clearance and half-life of cotinine measured using plasma or saliva concentrations were similar.

Presence and bronchomotor activity of protease-activated receptor-2 in guinea pig airways.

The protease activated receptor-2 (PAR-2) belongs to a family of G-protein-coupled receptors that are activated by proteolysis. Trypsin cleaves PAR-2, exposing an N-terminal tethered ligand (SLIGRL) that activates the receptor. Messenger RNA (mRNA) for PAR-2 was found in guinea pig airway tissue by reverse transcription-polymerase chain reaction, and PAR-2 was found by immunohistochemistry in airway epithelial and smooth-muscle cells.

Role of nitric oxide and septide-insensitive NK(1) receptors in bronchoconstriction induced by aerosolised neurokinin A in guinea-pigs.

The tachykinin, neurokinin A (NKA), contracts guinea-pig airways both in vitro and in vivo, preferentially activating smooth muscle NK(2) receptors, although smooth muscle NK(1) receptors may also contribute. In vitro evidence suggests that NKA activates epithelial NK(1) receptors, inducing the release of nitric oxide (NO) and subsequent smooth muscle relaxation. A number of selective NK(1) receptor agonists have been reported to activate both smooth muscle and epithelial NK(1) receptors, however septide appears only to activate smooth muscle NK(1) receptors.

Agonists of proteinase-activated receptor 2 induce inflammation by a neurogenic mechanism.

Trypsin and mast cell tryptase cleave proteinase-activated receptor 2 and, by unknown mechanisms, induce widespread inflammation. We found that a large proportion of primary spinal afferent neurons, which express proteinase-activated receptor 2, also contain the proinflammatory neuropeptides calcitonin gene-related peptide and substance P. Trypsin and tryptase directly signal to neurons to stimulate release of these neuropeptides, which mediate inflammatory edema induced by agonists of proteinase-activated receptor 2.

The distribution of neurokinin-1 and neurokinin-2 receptors in human central airways.

The precise locations of neurokinin (NK)-1 and NK-2 receptors in human airways, and their role in airway inflammatory diseases, have not been carefully examined. To determine the distribution of NK-1 and NK-2 receptors in human central airways, and to determine whether their distribution was different in smokers, we examined surgical specimens from patients undergoing lung resection for limited lung lesions. We mapped NK-1 and NK-2 receptors in four groups of subjects: four asymptomatic nonsmokers, seven asymptomatic smokers, seven symptomatic smokers with normal lung function, and eight symptomatic smokers with chronic airflow limitation.

Detection of nitric oxide release induced by bradykinin in guinea pig trachea and main bronchi using a porphyrinic microsensor.

Indirect evidence using nitric oxide (NO) synthase (NOS) inhibitors suggests that in guinea-pig airways bradykinin releases bronchoprotective NO. In this study, using a recently developed electrochemical method of NO measurement based on a porphyrinic microsensor, we investigated whether bradykinin releases NO from guinea-pig airways and whether the epithelium is the main source of NO. Further, the Ca(2+)-dependence of bradykinin-induced NO release was assessed stimulating airway preparations with bradykinin in Ca(2+)-free conditions.

Neutral endopeptidase (EC 3.4.24.11) terminates colitis by degrading substance P.

Neurogenic inflammation is regulated by sensory nerves and characterized by extravasation of plasma proteins and infiltration of neutrophils from post-capillary venules and arteriolar vasodilatation. Although it is well established that substance P (SP) interacts with the neurokinin 1 receptor (NK1R) to initiate neurogenic inflammation, the mechanisms that terminate inflammation are unknown. We examined whether neutral endopeptidase (NEP), a cell-surface enzyme that degrades SP in the extracellular fluid, terminates neurogenic inflammation in the colon.

A sensitive sandwich enzyme immunoassay for calcitonin gene-related peptide (CGRP): characterization and application.

Thirty mouse monoclonal antibodies (mAbs) directed against rat calcitonin gene-related peptide-alpha (CGRP-alpha) have been obtained. These mAbs are classified in 2 groups, one recognizing the peptide N-terminus and the other binding the C-terminus. A two-site immunometric assay was developed using mAb CGRP-83 as capture antibody, whereas mAb CGRP-72 acts as tracer, covalently labeled with enzyme acetylcholinesterase.

Bronchopulmonary inflammation and airway smooth muscle hyperresponsiveness induced by nitrogen dioxide in guinea pigs.

We investigated whether acute exposure to nitrogen dioxide (NO2) causes major inflammatory responses (inflammatory cell recruitment, oedema and smooth muscle hyperresponsiveness) in guinea pig airways. Anaesthetised guinea pigs were exposed to 18 ppm NO2 or air for 4 h through a tracheal cannula. Bronchoalveolar lavage was performed and airway microvascular permeability and in vitro bronchial smooth muscle responsiveness were measured.