Histamine H1 Research Articles

Emerging strategies for treating autoimmune disorders in patients with type 1 diabetes and multiple sclerosis

In the world as a whole and in Ukraine in partmicular, the incidence of autoimmune pathologies continues to grow steadily. There is an increase in the number of type 1 diabetes mellitus (T1DM) and multiple sclerosis (MS) cases in the population. Both diseases have an autoimmune nature and several common features in terms of onset, diagnosis, lack of effective treatment and deve­lopment of complications that are potentially life-threatening. In addition, both diseases have genetic risk factors associated with human leukocyte antigen. There are also other genetic risk factors, such as T-cell alleles of interleukin-2 and protein tyrosine phosphatase, non-receptor type 22 in MS and T1DM, respectively. The environment also plays a significant role in the development of both diseases, with smoking and exposure to viruses increasing the risk of MS and T1DM. To date, the proposed methods of therapy for both diseases are not completely effective, and some of them even have serious side effects. The authors consider the possibility of using clemastine fumarate as a histamine H1 antagonist in the management of T1DM and MS. This histamine H1 antagonist penetrates the blood-brain barrier more easily and thus leads to a sedative effect. The efficacy of clemastine fumarate to enhance remyelination in MS was recently demonstrated in a double-blind crossover clinical trial. In addition, this compound was effective in the treatment of T1DM and its complications in a number of experimental studies. The currently available data allow us to recommend clemastine fumarate as the drug of choice in the comprehensive management of patients with MS. Attention is focused on the need for clinical studies to prove the effectiveness of clemastine fumarate in the treatment of patients with T1DM.

Acute Inhibition of the Human Kv1.5 Channel by H1 Receptor Antagonist Dimenhydrinate: Mode of Action.

Dimenhydrinate, an H1 receptor antagonist, is generally used for the prevention and treatment of nausea and vomiting. However, cardiac arrhythmias have been reported to be associated with the overdose of histamine H1 receptor antagonists, indicating the probable effect of antihistamines on ion channels. By using a two-microelectrode voltage clamp, we have herein studied the electrophysiological effects of dimenhydrinate on the human Kv1.5 channel in the Xenopus oocyte expression system. Dimenhydrinate acutely and reversibly suppressed the amplitudes of the peak and the steady-state current, within 6 min. The inhibitory effect of dimenhydrinate on the peak and the steady-state Kv1.5 currents increased progressively from -10 to +50 mV. At each test voltage, the drug suppressed both the peak and the steady-state currents to a similar extent. When the oocytes were stimulated at the rates of 5- and 30-s intervals, dimenhydrinate-induced a use-dependent blockade of the human Kv1.5 channel. Dimenhydrinate expedited the timecourse of the Kv1.5 channel activation more effectively than the timecourse of its inactivation. However, the activation and inactivation curves of the channel were not altered by the H1 receptor antagonist. In conclusion, we found that dimenhydrinate inhibits the human Kv1.5 channel by changing the channel's activation mode, thereby possibly increasing the possibility of triggering cardiac arrhythmias and affecting atrial fibrillation.

Histamine H2 receptor agonist dimaprit dihydrochloride stimulates the hypothalamo-hypophysial-testicular axis in the cichlid fish Oreochromis mossambicus

Histamine is a naturally occurring biogenic monoamine that acts at both central and peripheral levels, serving a crucial role in regulating a range of physiological processes in vertebrates, including immune function and reproduction. This research aims to understand whether the histamine H2 receptor agonist dimaprit dihydrochloride (DIMP) affects the hypothalamo-hypophysial-testis (HPT) axis of the Mozambique tilapia. Treatment with 5 μg DIMP did not alter the numbers of spermatogonia-B and secondary spermatocytes, but caused a significant increase in the numbers of other germ cells. However, treatment with 20 μg DIMP resulted in significantly higher numbers of all germ cells, including spermatogonia-A and B, primary and secondary spermatocytes, and early and late spermatids, compared to those of controls or 5 μg DIMP-treated fish. There was a dose-dependent increase in the diameters of seminiferous lobules and lumens, but the diameter of the interstitium was significantly decreased in DIMP-treated fish. Furthermore, there was also a dose-dependent, significant increase in the density of gonadotropin-releasing hormone-immunoreactive fibres and intensity of androgen receptor immunoreactivity in 5 and 20 μg DIMP-treated fish, concomitant with a significant increase in serum levels of luteinizing hormone in 5 or 20 μg DIMP-treated fish compared to those of controls. Collectively, these results, for the first time, suggest that treatment with DIMP exerts a stimulatory effect on the HPT axis in the teleosts.

Targeting the Central Histamine H2 Receptor: New Hope for Schizophrenia?

Targeting the Central Histamine H2 Receptor: New Hope for Schizophrenia?

IL-31-Pruritus Interleukin: Serum Values and Clinical Impact in Chronic Spontaneous Urticaria-A Romanian Retrospective Study.

(1) Background: This study aimed to evaluate the implications of interleukin-31 (IL-31) in the pathogenesis of chronic spontaneous urticaria (CSU) and to assess the differences that occur between its serum values compared to controls. Additionally, the serum IL-31 levels were measured alongside other clinical and paraclinical parameters that were identified in the patients to understand its immunological importance in this skin disease and to determine if it could potentially serve as a therapeutic target in CSU in the future. (2) Methods: The serum levels of IL-31 were estimated in 50 patients diagnosed with CSU according to the accepted international guidelines. Additionally, 38 controls who had not experienced any episodes of urticaria during their lifetime were included. (3) Results: Significantly elevated serum IL-31 levels were observed in CSU patients compared to the controls (p < 0.0001). Although no direct correlations were found between IL-31 and inflammatory markers (erythrocyte sedimentation rate (ESR), C-reactive protein (CRP)), eosinophils, or total immunoglobulins E (IgE), significant differences in IL-31 levels were identified based on CSU severity, quality of life impact, itch intensity, and response to histamine H1 receptor antagonists (H1 antihistamines) (p < 0.05 for all). (4) Conclusions: Our findings underscore that IL-31 is not directly associated with general inflammation, eosinophilic response, or atopy in CSU. Nevertheless, its expression is influenced by key disease characteristics: severity, pruritus, and H1 antihistamine response. This investigation provides essential insights into CSU pathogenesis, potentially leading to novel therapeutic interventions. An enhanced understanding of these mechanisms is crucial due to the limitations of current treatment modalities in terms of fully managing CSU symptoms.

Antioxidant and Anti-Glycation Potential of H2 Receptor Antagonists-In Vitro Studies and a Systematic Literature Review.

Background: Histamine H2 receptor antagonists are a group of drugs that inhibit gastric juice secretion in gastrointestinal diseases. However, there is evidence to suggest that H2 blockers have a broader spectrum of activity. The antioxidant properties of H2 blockers have not been fully elucidated, and their anti-glycation potential has not been studied to date. Therefore, this is the first study to compare the antioxidant and antiglycation potentials of the most popular H2 antagonists (ranitidine, cimetidine, and famotidine) on protein glycoxidation in vitro. Methods: Bovine serum albumin (BSA) was glycated using sugars (glucose, fructose, galactose, and ribose) as well as aldehydes (glyoxal and methylglyoxal). Results: In the analyzed group of drugs, ranitidine was the only H2 blocker that significantly inhibited BSA glycation in all tested models. The contents of protein carbonyls, protein glycoxidation products (↓dityrosine, ↓N-formylkynurenine), and early (↓Amadori products) and late-stage (↓AGEs) protein glycation products decreased in samples of glycated BSA with the addition of ranitidine relative to BSA with the addition of the glycating agents. The anti-glycation potential of ranitidine was comparable to those of aminoguanidine and Trolox. In the molecular docking analysis, ranitidine was characterized by the lowest binding energy for BSA sites and could compete with protein amino groups for the addition of carbonyl groups. H2 blockers also scavenge free radicals. The strongest antioxidant properties are found in ranitidine, which additionally has the ability to bind transition metal ions. The systematic literature review also revealed that the anti-glycation effects of ranitidine could be attributed to its antioxidant properties. Conclusions: Ranitidine showed anti-glycation and antioxidant properties. Further research is needed, particularly in patients with diseases that promote protein glycation.

Lurasidone for the Treatment of Schizophrenia: Design, Development, and Place in Therapy.

Thisreviewaims to provide a comprehensive overview of the current literature on the drug design, development, and therapy of lurasidone for the treatment of schizophrenia. Lurasidone has antagonistic effects on the dopamine D2, 5-hydroxytryptamine (5-HT)2A, and 5-HT7 receptors and a partial agonistic effect on the 5-HT1A receptor with low affinities for muscarinic M1, histamine H1, and a1 adrenergic receptors. The receptor-binding profile of lurasidone is thought to be associated with fewer side effects such as anticholinergic effects, lipid abnormalities, hyperglycemia, and weight gain. Behavioral pharmacological studies have demonstrated that lurasidone exerts anxiolytic and antidepressive effects and improves cognitive function, which are associated with the modulation of 5-HT7 and 5-HT1A receptors. Literature search using PubMed was performed to find published studies of randomized controlled trials and recent meta-analyses regarding efficacy and safety, particularly metabolic side effects of lurasidone in schizophrenia. In short-term studies, the results of randomized placebo-controlled trials and meta-analyses have suggested that lurasidone was superior to placebo in improving total psychopathology, positive symptoms, negative symptoms, and general psychopathology in patients with acute schizophrenia. Regarding safety, lurasidone had minimal metabolic side effects, and was identified as one of the drugs with the most benign profiles for metabolic side effects. Long-term trials revealed that lurasidone had the preventive effects on relapse, with minimal effects on weight gain and other metabolic side effects. Furthermore, lurasidone improves cognitive and functional performance of patients with schizophrenia, especially in long-term treatment. Patients with schizophrenia require long-term treatment with antipsychotics for relapse prevention; thus, minimizing weight gain and other side effects is crucial. Lurasidone is suitable as one of the first-line antipsychotic drugs in the acute phase, and a switching strategy should be considered during the maintenance phase, to balance efficacy and adverse effects and achieve favorable outcomes in the long-term course of schizophrenia.

A mouse model of food allergy permitting skin and nasal symptoms

PurposeDeveloping experimental animal models that show clinical symptoms and methods for quantitative and objective evaluation are important for understanding food allergies. Therefore, this study aimed to develop an ovalbumin (OVA)-induced mouse model of food allergy and a useful method to evaluate the symptoms of food allergy. Material/methodsMice were sensitized via intraperitoneal injection of OVA. Subsequently, local sensitization was performed once weekly by oral administration of OVA. Itching and nasal symptoms were observed after oral administration of the antigen. First, we examined the dose-dependency of the antigen. Symptoms were checked weekly. In order to confirm food allergy symptoms, the effect of histamine H1 receptor antagonist was examined. Finally, we measured antigen-specific IgE antibody levels in the serum. ResultsScratching behavior, sneezing and nasal rubbing were increased. Both itching and rhinitis symptoms increased steadily, after which, the number of symptoms remained almost constant. No difference was observed between the results of 3- and 5-week-old mice. Cetirizine inhibited these symptoms in a dose-dependent manner. In addition, antigen-specific IgE antibodies were produced in both 3- and 5-week-old mice. ConclusionsThis method may be useful for evaluating the symptoms of skin and rhinitis that could not be assessed in the conventional food allergy model and could be induced with a low dose of antigen. In particular, the developed method, which measures the number of itching and nasal symptoms, may enable quantitative, objective, and noninvasive evaluation of food allergy severity.

Validation and Greenness assessment of UPLC Method for bioanalysis of Bilastine in mice PK study

Bilastine, is a second-generation antihistamine drug which is used in the treatment of allergic rhinoconjunctivitis and urticaria. It exerts its effect as a selective histamine H1 receptor antagonist. In this study, an ultra-high-performance liquid chromatography (UPLC) method was developed to measure the concentrations of Bilastine in mouse blood, and the method was applied in measuring the pharmacokinetics of the analyte after oral and intravenous administration. The analyte was extracted by solid phase extraction method. A UPLC BEH C18 column (2.1 mm × 100 mm, 1.8 ?m particle size) was used for chromatographic separation by gradient elution using acetonitrile-water (0.1% formic acid) as the mobile phase at a flow rate of 0.4 mL/min. Bilastine was administered to the mice orally at 2 mg/kg and intravenously at 0.05 mg/kg. Blood was collected at various time intervals, and the blood samples were processed after collection and analyzed by UPLC. The intra-day and inter-day accuracy of Bilastine were 91%-103% and 85%-107%, respectively, and the precision (RSD, %) was less than 15% for both intra-day and inter-day measurements. The matrix effect ranged from 95% to 108%, and the recovery was higher than 70%. The half-life of bilastine in plasma was found to be 7.02 ± 5.21h. Bilastine has a good linear relationship in the range of 10-500 ng/mL, and the lower limit of quantification was 10 ng/mL. The precision, accuracy, extraction recovery, matrix effect, and stability meet the requirements of the guiding principles. A robust and reliable UPLC method was fully optimized and developed to detect the blood concentration of bilastine in mice and the samples were analyzed by Empower software.

Mechanisms for hypothermia during anaphylactic hypotension in awake rats.

Hypothermia develops during systemic anaphylaxis in rodents. The aim of this study was to elucidate the mechanism for the hypothermia by assessing the roles of locomotor activity, tail heat dissipation, heat production in the brown adipose tissue (BAT) activity, and chemical mediators during ovalbumin-induced anaphylactic hypotension in awake rats. We measured the core body temperature (Tcore) and mean blood pressure (MBP), along with the surface temperature of the interscapular region (TiScap), an indirect measure of BAT activity, and the tail (Ttail). During anaphylaxis, MBP decreased to the nadir of 53 ± 2 mmHg at 8 min with recovery toward baseline. Tcore began to decrease at 7.5 min with the nadir of 36.1 ± 0.2°C at 30 min from the baseline of 38.0 ± 0.1°C. TiScap also significantly decreased, but its onset was preceded by that of Tcore. Ttail decreased after antigen, suggesting the absence of increased heat dissipation from the tail. The physical activity, as evaluated by moved distances, did not decrease until 20 min after antigen, followed by a progressive decrease. Reduced movement using a restraint maneuver not only reduced Tcore in nonsensitized rats but also augmented the anaphylactic hypothermia in the early phase (1.5-18 min) in sensitized rats. Combined antagonism against platelet-activating factor (PAF) and histamine H1 receptors abolished antigen-induced hypotension but only attenuated hypothermia. In conclusion, decreased locomotor activity, but not tail heat dissipation or decreased BAT activity, may at least in part contribute to this hypothermia. PAF and histamine are involved mainly in hypotension but only partly in hypothermia during rat anaphylaxis.NEW & NOTEWORTHY Anaphylactic shock is a life-threatening systemic hypotension. Hypothermia is observed during systemic anaphylaxis of rats. We determined the mechanism as follows: decreased locomotor activity, but not tail heat dissipation or decreased BAT activity, may at least in part contribute to this hypothermia. PAF and histamine are involved mainly in hypotension, but only partly in hypothermia during rat anaphylaxis.

Structural, Quantum Chemical, Spectroscopic (UV, FT-IR, FT-Raman and NMR) and Molecular Docking Studies of Diphenylpyraline Hydrochloride as Antihistaminic Drug

Diphenylpyraline hydrochloride, chemically known as 4-benzhydryloxy-1-methypiperidine hydrochloride is a first-generation antihistaminic drug that produces therapeutic antiallergic effects by binding to histamine H1 -receptors. The molecular structural and electronic properties of title compound have been computed at DFT/TD-DFT method with B3LYP/6-311++G(d,p) level. The theoretical spectral data has been compared with experimental ones, showing good agreement. The atomic charges, molecular electrostaitc potential (MEP), the natural bond orbitals (NBOs), the natural hybrid orbital (NHOs), the non-lilear optical (NLO) properties, the vibrational (IR and Raman) frequencies, UV-vis absorption wavelenghts and nuclear magnetic resonance (NMR) chemical shifts of diphenylpyraline hydrochloride have been investigated. The potential energy distribution (PED) of title compound was performed using the VEDA program and these values were compared with the experimental FT-IR and FT-Raman vibrational frequencies. Moreover, molecular docking studies have been performed between the 3RZE and 7DFL target proteins and the title compound. Docking results revealed that the title compound can be designed as potential antihistaminic agent.

Rice bran component γ‐oryzanol promotes sleep in mice by antagonism of histamine H1 receptor

Rice bran component γ‐oryzanol promotes sleep in mice by antagonism of histamine H1 receptor

Effects of the immunoglobulin/histamine complex on panic disorder concurrent with chronic spontaneous urticaria: a case report

BackgroundPanic disorder and panic attacks are two of the most common problems in psychiatry. A psychoimmunological correlation between allergic diseases and panic disorder has been strongly suggested. Histamine H1 receptor antagonists have been suggested as alternative drugs for the treatment of panic disorder. Chronic spontaneous urticaria (CSU) and panic disorder improved simultaneously with selective serotonin reuptake inhibitor antidepressants. Panic disorder has also been treated with the antihistamine chlorpheniramine. The immunoglobulin/histamine complex is a histamine-fixed immunoglobulin preparation that was reported to be effective in treating CSU. This case report describes the successful treatment of a patient with concomitant panic disorder and CSU for 23 years using immunoglobulin/histamine complex therapy.Case presentationThis report describes a 52-year-old female Korean patient who suffered from CSU with panic disorder for 23 years. Basic allergy tests (blood tests and skin prick tests) were conducted before and after treatment for the evaluation of allergic conditions. A multiple allergosorbent test (MAST) for the detection of allergen-specific IgE levels was also performed. The clinical severity of CSU was evaluated using the urticaria severity score system. Diagnostic interviews systematically assessed the diagnostic criteria outlined by the DSM-V, and the patient was evaluated before, during and after treatment using the Beck Depression Inventory (BDI-2) for depression, the State-Trait Anxiety Inventory (STAI) for anxiety and the Beck Hopelessness Score (BHS) for hopelessness. The patient received 2 ml of Histobulin™ (12 mg human immunoglobulin/0.15 µg histamine complex) once a week by subcutaneous injection for the treatment of CSU. Initial improvement of CSU was achieved after the third injection. After the twenty-seventh injection of Histobulin™, she showed no symptoms or signs and ceased allergic medication use. With the remission of CSU, allergic rhinitis was also completely resolved. The frequency of the common cold was significantly decreased during and after treatment. The medication frequency and development of clinical manifestations of panic disorder changed in parallel with the clinical severity of CSU. Moreover, the patient exhibited no clinical manifestations and ceased medication for panic disorder and sleeping pills for insomnia simultaneously with the remission of CSU. In the psychological evaluation, the BDI, STAI and BHS scores improved accordingly.ConclusionsThe immunoglobulin/histamine complex was effective in treating CSU and concomitant panic disorder in this patient and could be effective in treating some types of panic disorder. Considering the mechanisms of action of histamine and the immunoglobulin/histamine complex together with the patient’s clinical progress, histamine seemed to be related to panic disorder in this case. The concept of histamine-mediated syndromes, including allergies and psychiatric disorders, shows that a wider disease identity may be needed. Further studies on the immunopathogenesis of panic disorder and the mechanisms of action of the immunoglobulin/histamine complex are necessary.

Clonidine stimulates force of contraction via histamine H2 receptors in the human atrium

Clonidine has various clinical effects mediated by agonism of α1- or α2-adrenoceptors and the blocking of hyperpolarization-activated-nucleotide-gated pacemaker channels (HCN). It is unknown whether clonidine can also stimulate human cardiac histamine H2 receptors (hH2Rs). We used isolated electrically stimulated left and spontaneously beating right atrial preparations from mice overexpressing the hH2R specifically in the heart (H2-TG), and spontaneously beating right atrial preparations of guinea pigs for comparison. Moreover, we studied isolated electrically stimulated muscle strips from the human right atrium. Clonidine (1, 3, and 10 µM) increased force of contraction in isolated left atrial preparations from H2-TG mice. In contrast, clonidine reduced the spontaneous beating rate in right atrial preparations from H2-TG. Clonidine raised the beating rate in guinea pig right atrial preparations. Clonidine failed to increase the force of contraction but reduced beating rate in wild-type litter mate mice (WT). In WT, histamine failed to increase the force of contraction in left atrial preparations and beating rate in right atrial preparations. Clonidine (10 µM) increased the force of contraction in isolated human right atrial preparations. The positive inotropic effect in the human atrium was attenuated by cimetidine (10 µM). Clonidine increased the beating rate of the isolated spontaneously beating guinea pig right atrium and acted as a H2R partial agonist. Furthermore, clonidine showed binding to the guinea pig H2R (100 µM) using HEK cells in a recombinant expression system (pKi < 4.5) but hardly to the human H2R. These data suggest that clonidine can functionally activate cardiac human H2R.

The mRNA expression and secretion of granzyme B are up-regulated via the histamine H2 receptor in human CD4+ T cells

IntroductionGranzyme B (GZMB), a serine protease with cytotoxic and immunomodulatory functions, shows elevated levels in blood plasma of patients with atopic dermatitis (AD). It has been observed that GZMB expression in CD4+ and CD8+ T cells is higher in lesional skin in AD than in healthy skin. Since histamine is present in high concentration in the skin of AD patients, we investigated the regulation of GZMB in human CD4+ T cells by histamine.MethodsNaïve CD4+ T cells polarized into Th2 cells, total CD4+ T cells treated with IL-4 for 72 h and CD4+ T cells isolated from healthy donors and AD patients were investigated. The cells were stimulated with histamine or with different histamine-receptor agonists. Gene expression was evaluated by RNA-Seq. GZMB mRNA expression was detected by quantitative real time PCR, whereas GZMB secretion was measured by ELISpot and ELISA. T cell degranulation was evaluated by flow cytometry using CD107a surface expression as a degranulation marker.ResultsBy RNA-Seq, we identified the up-regulation of various genes of the cytotoxic pathway, in particular of GZMB, by histamine in Th2-polarized CD4+ T cells. In Th2-polarized CD4+ T cells and in CD4+ T cells activated by IL-4 the mRNA expression of GZMB was significantly up-regulated by histamine and by histamine H2 receptor (H2R) agonists. The induction of GZMB secretion by histamine was significantly higher in CD4+ T cells from AD patients than in those from healthy donors. CD107a surface expression was up-regulated by trend in response to histamine in Th2-polarized CD4+ T cells.ConclusionOur findings may help to elucidate novel mechanisms of the H2R and to achieve a better understanding of the role of GZMB in the pathogenesis of AD.

IDENTIFICATION AND QUANTITATION OF FEXOFENADINE HYDROCHLORIDE IN MODEL ORAL DROPS

Relevance. Fexofenadine hydrochloride is a representative of the III generation of histamine H1 receptor blockers, therefore, it is not characterized by the disadvantages of antihistamines, such as: suppression of the central nervous system, cardiotoxic effect, headache, impaired coordination of movements, photosensitivity. Analysis of fexofenadine hydrochloride was performed using UV spectroscopy. The purpose of the study – development of a new analytical method for the qualitative and quantitative identification of fixofenadine in drops for in-ternal use. Material and methods. The study used: fexofenadine, sodium hydroxide, water for injection, UV spectrophotometer type SF-104. Results and conclusions. A method for the qualitative and quantitative determination of fexofenadine hydrochloride in model drops for internal use by the SPS method has been proposed. This method meets the requirements of OFS 1.1.0012.15 Validation of analytical methods, in terms of indica-tors: linearity and analytical area, correctness, precision.

Effect of different solvent role, intermolecular forces, allergies and inflammations receptors (H1R & GPCRs) interactions of (2R)-2-{2-[(1R)-1-(4-chlorophenyl)-1-phenylethoxy] ethyl}-1-ethylpyrrolidine

The title compound is (2R)-2-{2-[1-(4-chlorophenyl)-1-phenylethoxy] ethyl}-1-methylpyrrolidine (CLS) and its market name is clemastine. The present molecule is a first-generation antihistamine that treats both colds and allergy-related rhinitis complaints. Antihistamines, which include clemastine, are a class of drugs. It performs by blocking the body's particular histamine from causing allergy symptoms. In this study, the comparison of the spotted geometrical optimization and chemical vibrational spectrum data obtained from the FT-IR and FT-Raman bands with the calculated values obtained from the DFT technique simulation. The structure of the molecule has been determined by the Raman approach using absorbed IR light and scattering radiation, with a focus on the major functional groups (Cl, O, and N). The differences in electro-negative have been addressed, and their effects on biochemistry and medicine were examined. The MEP-map, ELF, and LOL parameters of the molecule were used to describe its chemical reactivity. NHO, NLMO, and NBO's intramolecular relationships were studied. The HOMO-LUMO space of energy in the outer limits of the molecular orbital system was further determined. The primary protease activity of people's histamine H1 cell receptor in complex with the doxepin inhibitor, as well as G-protein-coupled receptors (GPCRs), were the targets of the biological investigation of the title's molecule, which was carried out by employing molecular docking study. GPRs have become important therapeutic targets in recent years. The results of the molecular investigation show that the most effective inhibitory anti-allergic pharmacological molecule for use in contemporary therapeutic targets is clemastine.

Lysergic acid diethylamide stimulates cardiac human H2 histamine and cardiac human 5-HT4-serotonin receptors

Lysergic acid diethylamide (LSD) is an artificial hallucinogenic drug. Thus, we hypothesized that LSD might act 5-HT4 serotonin receptors and/or H2 histamine receptors. We studied isolated electrically stimulated left atrial preparations, spontaneously beating right atrial preparations, and spontaneously beating Langendorff-perfused hearts from transgenic mice with cardiomyocyte-specific overexpression of the human 5-HT4 receptor (5-HT4-TG) or of the H2-histamine receptor (H2-TG). For comparison, we used wild type littermate mice (WT). Finally, we measured isometric force of contraction in isolated electrically stimulated muscle strips from the human right atrium obtained from patients during bypass surgery. LSD (up to 10 µM) concentration dependently increased force of contraction and beating rate in left or right atrial preparations from 5-HT4-TG (n = 6, p < 0.05) in 5-HT4-TG atrial preparations. The inotropic and chronotropic effects of LSD were antagonized by 10 µM tropisetron in 5-HT4-TG. In contrast, LSD (10 µM) increased force of contraction and beating rate in left or right atrial preparations, from H2-TG. After pre-stimulation with cilostamide (1 µM), LSD (10 µM) increased force of contraction in human atrial preparations (n = 6, p < 0.05). The contractile effects of LSD in human atrial preparations could be antagonized by 10 µM cimetidine and 1 µM GR 125487. LSD leads to H2-histamine receptor and 5-HT4-receptor mediated cardiac effects in humans.

Update meta-analysis on the efficacy and safety issues of fexofenadine

BackgroundFexofenadine emerged as one of the most representative second generation histamine H1 antagonist drugs since the 1990s, with an outstanding efficacy and appreciable safety for the treatment of allergic patients. While allergic rhino-conjunctivitis represents the most frequent atopic disease globally, an update of fexofenadine efficacy and safety on this entity was proposed as a surrogate of allergic condition. MethodsDouble blind, placebo controlled, randomized clinical trials investigating the efficacy and safety of fexofenadine for the treatment of Allergic Rhinitis were searched in 5 major global databases. Eligibility criteria and characteristics, risk of bias, and validity assessment, data extraction and heterogeneity evaluation are described. Primary outcome selected corresponded to 12-reflective and instantaneous total symptom scores (TSS), besides morning instantaneous TSS and the frequency of reported adverse events (AEs); analysis was planned on the intention-to-treat population.Standardized mean differences of scoring systems were analyzed, and Cochran's Q statistic test and the I2 test were assessed for heterogeneity. ResultsFrom the initial 83 identified records, 12 eligible studies were selected. In the evaluated patients, individuals receiving fexofenadine (1910) showed a significant reduction of TSS compared with those who received placebo (1777), change from baseline: standardized mean difference (SMD) –0.33; 95% CI–0.47 to −0.18, p < 0.0001. Morning instantaneous TSS also demonstrated lower symptoms (change from baseline: SMS -1.42; 95% CI -2.22 to −0.62, p = 0.0005). Heterogeneity was found across selected studies.Frequency of AEs was similar compared to placebo (OR = 1.04; 0.88–1.21), with no detection of heterogeneity across these 12 studies. ConclusionsAccording to this new evidence, fexofenadine maintains its beneficial profile on signs and symptoms of patients with allergic conditions, as well as its attributes as one of the major candidates for an ideal antihistamine medication (including special conditions such as pregnancy and pre-school age), providing support to its over-the-counter condition in several countries.

Ergometrine stimulates histamine H2 receptors in the isolated human atrium

Ergometrine (6aR,9R)-N-((S)-1-hydroxypropan-2-yl)-7-methyl-4,6,6a,7,8,9-hexa-hydro-indolo-[4,3-fg]chinolin-9-carboxamide or lysergide acid β-ethanolamide or ergonovine) activates several types of serotonin and histamine receptors in the animal heart. We thus examined whether ergometrine can activate human serotonin 5-HT4 receptors (h5-HT4R) and/or human histamine H2 receptors (hH2R) in the heart of transgenic mice and/or in the human isolated atrium. Force of contraction or beating rates were studied in electrically stimulated left atrial or spontaneously beating right atrial preparations or spontaneously beating isolated retrogradely perfused hearts (Langendorff setup) of mice with cardiac specific overexpression of the h5-HT4R (5-HT4-TG) or of mice with cardiac specific overexpression of the hH2R (H2-TG) or in electrically stimulated human right atrial preparations obtained during cardiac surgery. Western blots to assess phospholamban (PLB) phosphorylation on serine 16 were performed. Ergometrine exerted concentration- and time-dependent positive inotropic effects and positive chronotropic effects in atrial preparations starting at 0.3 µM and reaching a plateau at 10 µM in H2-TGs (n = 7). This was accompanied by an increase in PLB phosphorylation at serine 16. Ergometrine up 10 µM failed to increase force of contraction in left atrial preparations from 5-HT4-TGs (n = 5). Ten micrometer ergometrine increased the force of contraction in isolated retrogradely perfused spontaneously beating heart preparations (Langendorff setup) from H2-TG but not 5-HT4-TG. In the presence of the phosphodiesterase inhibitor cilostamide (1 µM), ergometrine at 10 µM exerted positive inotropic effects in isolated electrically stimulated human right atrial preparations, obtained during cardiac surgery, and these effects were eliminated by 10 µM of the H2R antagonist cimetidine but not by 10 µM of the 5-HT4R antagonist tropisetron. Furthermore, ergometrine showed binding to human histamine H2 receptors (at 100 µM and 1 mM) using HEK cells in a recombinant expression system (pKi < 4.5, n = 3). In conclusion, we suggest that ergometrine is an agonist at cardiac human H2Rs.