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Hypophysiotropic thyrotropin-releasing hormone (TRH) neurons function as metabolic sensors that regulate the thyroid axis and energy homeostasis. Less is known about the role of other hypothalamic TRH neurons. As central administration of TRH decreases food intake and increases histamine in the tuberomammillary nuclei (TMN), and TMN histamine neurons are densely innervated by TRH fibers from an unknown origin, we mapped the location of TRH neurons that project to the TMN. The retrograde tracer, cholera toxin B subunit (CTB), was injected into the TMN E1–E2, E4–E5 subdivisions of adult Sprague–Dawley male rats. TMN projecting neurons were observed in the septum, preoptic area, bed nucleus of the stria terminalis (BNST), perifornical area, anterior paraventricular nucleus, peduncular and tuberal lateral hypothalamus (TuLH), suprachiasmatic nucleus and medial amygdala. However, CTB/pro-TRH178-199 double-labeled cells were only found in the TuLH. The specificity of the retrograde tract-tracing result was confirmed by administering the anterograde tracer, Phaseolus vulgaris leuco-agglutinin (PHAL) into the TuLH. Double-labeled PHAL-pro-TRH boutons were identified in all subdivisions of the TMN. TMN neurons double-labeled for histidine decarboxylase (Hdc)/PHAL, Hdc/Trh receptor (Trhr), and Hdc/Trh. Further confirmation of a TuLH-TRH neuronal projection to the TMN was established in a transgenic mouse that expresses Cre recombinase in TRH-producing cells following microinjection of a Cre recombinase-dependent AAV that expresses mCherry into the TuLH. We conclude that, in rodents, the TRH innervation of TMN originates in part from TRH neurons in the TuLH, and that this TRH population may contribute to regulate energy homeostasis through histamine Trhr-positive neurons of the TMN.

Histamine participates in a variety of physiological functions. The local effects of histamine have a role to provide metabolic energy for the tissues. The objective of this work is to study the mechanism whereby histamine affects serum glucose and liver glycogen fractions. Six groups of 10 male rats received two injections with histamine, H1-agonist (dipyridylethylamine), H2-agonist (dimaprit), H1-agonist plus H1-antagonist (cetirizine), or H2-agonist plus H2-antagonist (famotidine). Serum glucose and liver glycogen fractions were measured. Histamine caused a significant increase in serum glucose (163.7 ± 5.4 vs. 153.2 ± 3.3 mg/dl, p = 0.023). The effect of histamine was mimicked by selective H1-agonist (164.2 ± 3.5 vs. 152.8 ± 2.9 mg/dl, p = 0.005) but not with H2-agonist (159.3 ± 3.7 vs. 156.3 ± 4.8 mg/dl, p = 0.281). The effect of H1-agonist was abolished in the presence of selective H1-antagonist. Treatment by H1- but not H2-agonist decreased total glycogen by about 35% (30.6 ± 0.5 vs. 47.3 ± 2.8 mg/g wet weight of liver, p = 0.003). The decrease happened wholly in ASG fraction (26.8 ± 1.2 vs. 43.7 ± 3.2 mg/g wet weight of liver, p = 0.004), while AIG did not change significantly (4.2 ± 0.5 vs. 4.5 ± 0.4 mg/g wet weight of liver, p = 0.724). Histamine causes to decrease glycogen in the liver and increased serum glucose. The effects of histamine were mediated via H1-receptors. ASG was metabolically active fraction of liver glycogen in this process. The results confirm the role of histamine in providing metabolic energy of the tissues.

Bile ducts are heterogenous in structure and function, and primary sclerosing cholangitis (PSC) damages specific bile ducts leading to ductular reaction (DR), mast cell (MC) infiltration, increased histamine release, inflammation, and fibrosis. Bile duct ligation (BDL) induces large duct damage via cyclic adenosine monophosphate (cAMP)/extracellular signal-related protein kinase (ERK) signaling, and large cholangiocytes express H2 histamine receptor (H2HR). We evaluated how MCs interact with large cholangiocytes during cholestasis. Male wild-type (WT) and MC-deficient (Kit

Tingling dermal pain triggered by sweating impairs the lives of patients with cholinergic urticaria and generalized anhidrosis. However, dermal pain evoked by sweating stimuli has been under investigated.To clarify characteristics of tingling dermal pain on sweating, we retrospectively evaluated clinical and histopathological manifestations in 30 patients having the main problem of dermal pain on sweating, and the efficacy of treatments.Dermal pain upon sweating affected mostly young males. It accompanied eruptions upon sweating and/or hypohidrosis in 24 patients, while 6 patients had dermal pain independently of hypohidrosis or eruptions. Dermal pain appeared immediately upon exposure to sweating stimuli, and disappeared within mostly 30 or 10 min. Hypohidrosis was not necessarily generalized but localized or absent. Histological analysis revealed that dermal pain could occur even without morphological changes and inflammation of sweat glands. Hypersensitivity to sweat contents was found only in 26% of patients. Sweat histamine and increase of plasma histamine after thermal induction in patients were significantly higher than those in healthy subjects. Effectiveness of steroid pulse therapy was demonstrated for dermal pain with hypohidrosis. Medications acting on nervous systems and regular sweat-inducing activities for promoting perspiration were also effective.Short-lasting tingling dermal pain appears immediately upon exposure to sweating stimuli, regardless of developing eruptions and/or presence of hypohidrosis, but possibly in association with sweat and plasma histamine.

Western high-fat diets (HFD) are regarded as a major risk factor for prostate cancer (PCa). Using prostate-specific Pten-knockout mice as a PCa model, we previously reported that HFD promoted inflammatory PCa growth. The composition of the gut microbiota changes under the influence of diet exert various effects on the host through immunological mechanisms. Herein, we investigated the etiology of HFD-induced inflammatory cancer growth and the involvement of the gut microbiome. The expression of Hdc, the gene responsible for histamine biosynthesis, and histamine levels were upregulated in large prostate tumors of HFD-fed mice, and the number of mast cells increased around the tumor foci. Administration of fexofenadine, a histamine H1 receptor antagonist, suppressed tumor growth in HFD-fed mice by reducing the number of myeloid-derived suppressor cells and suppressing IL6/STAT3 signaling. HFD intake induced gut dysbiosis, resulting in the elevation of serum lipopolysaccharide (LPS) levels. Intraperitoneal injection of LPS increased Hdc expression in PCa. Inhibition of LPS/Toll-like receptor 4 signaling suppressed HFD-induced tumor growth. The number of mast cells increased around the cancer foci in total prostatectomy specimens of severely obese patients. In conclusion, HFD promotes PCa growth through histamine signaling via mast cells. Dietary high-fat induced gut dysbiosis might be involved in the inflammatory cancer growth.

What is the central question of this study? Is there an interaction between histamine and the GABAergic system in modulation of anxiety in mice? What is the main finding and its importance? There is a synergistic anxiogenic effect between histamine and bicuculline in mice. This effect may be due to a direct or an indirect effect of the histaminergic system on the GABAergic system.It has been documented that both histaminergic and GABAergic systems participate in the neurobiology of anxiety behaviour. In the current research, we investigated the effects of the histaminergic system and GABA

Objectives This study aimed to analyse the potential effect of rupatadine (RUP) on ulcerative colitis (UC) induced by acetic acid (AA). Methods Forty male adult Wistar rats were divided into five groups: Control group: received vehicles for 14 days; AA model group: received AA at the 13th day; Sulfasalazine (SLZ) + AA group: received SLZ (250 mg/kg) for 14 days and AA at the 13th day; RUP-3 + AA group: received RUP (3 mg/kg/day) for 14 days and AA at the 13th day; and RUP-6 + AA group: received RUP (6 mg/kg/day) for 14 days and AA at the 13th day. Evidence of UC was assessed both macroscopically and microscopically. Oxidative stress markers (total antioxidant capacity and malondialdehyde), antioxidant enzyme (superoxide dismutase), histamine and platelet-activating factor (PAF) were determined. Immunohistochemical estimations of vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) were done. Key findings The AA group showed evidence of UC that was associated with a significant increase in oxidative stress, histamine and PAF levels with significant elevation in colonic VEGF and IL-6 immuno-expressions. RUP, in a dose-dependent manner, significantly ameliorated UC. Conclusion RUP protects against UC by reducing oxidative stress and by regulating the PAF/IL-6/VEGF pathway.

Mechanical stimulation of cultured keratinocytes and a living epidermis increases intracellular calcium ion concentrations ([Ca2+]i) in stimulated cells. This action propagates a Ca2+ wave to neighboring keratinocytes via ATP/P2Y2 receptors. Recent behavioral, pharmacological studies revealed that exogenous ATP induces itching via P2X3 receptors in mice. We previously showed that alloknesis occurs when an external stimulus is applied to the skin with increased epidermal histamine in the absence of spontaneous pruritus. Based on these results, we investigated the effects of histamine at a concentration that does not cause itching on ATP-induced itching. The mean number of scratching events induced by the mixture of ATP and histamine increased by 28% over the sum of that induced by histamine alone or ATP alone. A317491, a P2X3 receptor antagonist, suppressed the mixture-induced scratching more often than the ATP-induced scratching. Next, we examined the ATP-induced [Ca2+]i change before and after histamine stimulation using normal human epidermal keratinocytes. Some cells did not respond to ATP before histamine stimulation but responded to ATP afterward, the phenomenon suppressed by chlorpheniramine maleate. These findings suggest that histamine enhances ATP-induced itching and that a potential mechanism could involve increased responsiveness to ATP in keratinocytes.

Introduction: Previous work suggests the existence of a paracrine signaling mechanism in which histamine released from visceral mast cells into the portal circulation contributes to fasting-induced ketogenesis by stimulating biosynthesis of the endogenous high-affinity PPAR-α agonist oleoylethanolamide (OEA). Methods: Male C57Bl/6J mice were rendered obese by exposure to a high-fat diet (HFD; 60% fat). We measured histamine, OEA, and other fatty-acid ethanolamides by liquid-chromatography/mass spectrometry, gene transcription by RT-PCR, protein expression by ELISA, neutral lipid accumulation in the liver using Red Oil O and BODIPY staining, and collagen levels using picrosirius red staining. Results: Long-term exposure to HFD suppressed both fasting-induced histamine release into portal blood and histamine-dependent OEA production in the liver. Additionally, subchronic OEA administration reduced lipid accumulation, inflammatory responses, and fibrosis in the liver of HFD-exposed mice. Discussion: The results suggest that disruption of histamine-dependent OEA signaling in the liver might contribute to pathology in obesity-associated liver steatosis.

Distinct macrophage populations exert highly heterogeneity and perform various functions, among which, a crucial function of lipid metabolism is highlighted. However, the role of histidine metabolism disorder in macrophage lipid metabolism remains elusive. Addressed this question, we sorted and cultured the bone marrow-derived macrophages (BMDMs) of histidine decarboxylase (Hdc) knockout (Hdc

Background Autoantibodies (AAbs) against immunoglobulin E (IgE) antibodies (Abs) and their high-affinity receptor alpha subunits (FceRIα) are key factors in the elicitation of type IIb autoimmune chronic spontaneous urticaria (type IIb aiCSU). In this study, we aimed to develop a new method to detect functional anti-FceRIα and anti-IgE AAbs, which can crosslink the plural FceRІα molecules and IgE Abs on the surface of mast cells and basophils, in sera from aiCSU patients using the amplified luminescence proximity homogeneous assay (Alpha). Methods Sera were obtained from 14 aiCSU patients, as diagnosed by recurrent chronic spontaneous urticaria episodes and positive results for the autologous serum skin test and/or histamine release test (HRT). The AAbs to FceRIα and IgE Abs were determined in sera from aiCSU patients using enzyme-linked immunosorbent assay (ELISA) and Alpha by cross-linking (AlphaCL) of IgE Abs and/or FceRІα. Results Serum anti-FceRIα and anti-IgE AAb levels were not significantly different between aiCSU patients and healthy subjects in ELISA. Anti-FceRIα AAbs were detected in 10 of 14 aiCSU patients who displayed positive (5/5) and negative (5/9) results in the HRT for anti-FceRIα AAbs by AlphaCL, whereas no signals were observed in healthy subjects. Additionally, anti-IgE AAbs were detected in two of four aiCSU patients who displayed positive results in the HRT for anti-IgE AAbs. Conclusions A new assay method using AlphaCL can detect anti-FceRIα and anti-IgE AAbs with FceRIα- and IgE-crosslinking abilities in sera from aiCSU patients. This simple and practical assay method may be available as a diagnostic tool for urticaria patients.

Single intradermal injections of nerve growth factor (NGF) evoke prolonged but temporally distinct sensitization patterns to somatosensory stimuli. Focal administration of the non-histaminergic pruritogen cowhage but not histamine resulted in elevated itch at day 21 after NGF administration. Here, we injected bovine adrenal medulla peptide 8–22 (BAM8–22), β-alanine (β-ALA) and endothelin-1 (ET-1) into NGF-treated skin of 11 healthy volunteers and investigated the corresponding itch/pain and flare reactions. β-ALA was the weakest pruritogen, while BAM8–22 and ET-1 were equally potent as histamine. NGF did not sensitize itch or flare reactions induced by any compound, but injection and evoked pain were increased at day 21 and 49. The involvement of histamine H1 receptors in itch was explored in eight subjects after oral cetirizine. ET-1-induced itch and flare were significantly reduced. BAM8–22 and β-ALA itch were not affected, but flare responses after BAM8–22 reduced by 50%. The results indicate that a single NGF injection does not sensitize for experimentally induced itch but increases pain upon pruritogen injection. In healthy humans, pruritic and algetic processing appear differentially regulated by NGF. However, in patients suffering chronic itch, prolonged elevation of NGF-levels under inflammatory conditions may contribute to elevated itch.

The toxic effect of dietary histamine on the intestine of aquatic animals has been demonstrated, but reports on the morphological observation of the intestine are limited. Thus, a feeding trial was conducted to determine the effect of dietary histamine on intestinal histology, inflammatory status and gut microbiota of yellow catfish (Pelteobagrus fulvidraco). Here, we showed that histamine-rich diets caused severe abnormality and damage to the intestine, including a decreased villi length and reduced villi number. In addition, the quantitative real-time PCR (qRT-PCR) demonstrates that histamine-rich diets increased the expression of pro-inflammatory genes (Tnfα, Il1β, and Il8) and decreased the expression of an anti-inflammatory gene (Il10). Furthermore, the alpha-diversity (observed OTUs, Chao1, Shannon and Simpson) and beta-diversity (non-metric multidimensional scaling, with the stress value of 0.17) demonstrated that histamine-rich diets caused alterations in gut microbiota composition and diversity. Co-occurrence networks analysis of the gut microbiota community showed that the histamine influenced the number and the relationship between bacteria species in the phyla of Acidobacteria, Proteobacteria, and Bacteroidetes, which caused the instability of the intestinal microbiota community. Additionally, random forest selected six bacterial species as the biomarkers to separate the three groups, which are Lachnospiraceae Blautia (V520), Bacteroidales S24.7 (V235), Chloroplast Streptophyta (V368), Actinomycetales Streptomycetaceae (V152), Clostridia Clostridiales (V491) and Paraprevotellaceae Prevotella (V245). Finally, Pearson correlation analysis demonstrated that V520, V235, and V491 were negatively correlated with pro-inflammatory factors (Tnfα, Il1β, and Il8) and positively correlated with an anti-inflammatory factor (Il10), which indicated that V520, V235, and V491 might be anti-inflammatory. These findings improved our understanding of the toxic effect of dietary histamine to intestinal histological damage, the induction of mucosa inflammatory status, and the alteration of gut microbiota.

Background We previously reported upregulation of expression of Mas–related G protein–coupled receptor X2 (MRGPRX2) on mast cells (MCs) in the skin of patients with severe chronic spontaneous urticaria (CSU). Serum levels of substance P (SP) were reportedly significantly elevated, in correlation with the severity of CSU. Hemokinin-1 (HK-1) reportedly induced histamine release from LAD2 cells via MRGPRX2. We aimed to investigate HK-1's role in CSU. Methods The concentrations of HK-1 and SP were measured using ELISAs. Skin– and synovium–derived cultured MCs were generated by culturing dispersed skin and synovial cells, respectively, with stem cell factor. MRGPRX2 expression in the MCs was reduced using a lentiviral shRNA silencing technique. Results Anti–SP Ab used in the SP ELISA showed 100% cross–reactivity to HK-1, but anti–HK-1 Ab showed 0% cross–reactivity to SP. The serum level of HK-1 was significantly lower in patients with CSU (n = 151) than in non–atopic healthy control (NC) subjects (n = 114). The EC50 of histamine release from MCs induced by HK-1 (5056 nM) was 12–fold higher than by SP (426 nM). Brief pretreatment of MCs with HK-1 at concentrations of 3.0–10 μM significantly reduced histamine release by 0.1 μM SP. However, brief incubation of MCs with HK-1 did not elicit rapid MRGPRX2 internalization. Conclusions In NC subjects, high HK-1 concentrations may desensitize MGRPRX2–mediated MC activation, thereby preventing MC degranulation by SP.

Purpose Neurotransmitters (NTs) are the key mediators of essential ocular functions, such as processing the visual functions of the retina, maintaining homeostasis of aqueous humor, and regulating ocular blood flow. This study aims to determine variations in the levels of L-glutamate and γ-aminobutyric acid (GABA), histaminergic, adrenergic, cholinergic, and serotonergic NTs in patients with primary glaucoma versus patients with cataract. Methods This case–control study involved three age-matched groups of patients with primary open angle glaucoma (POAG, n = 14), primary angle closure glaucoma (PACG, n = 21), and cataract (control, n = 19). Patients’ aqueous humor and plasma were collected, snap frozen at −80 °C, and subjected to ultrasensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis for quantification of NTs. Results Baseline intraocular pressure and the cup-to-disc ratio were found to be statistically significantly elevated in the POAG and PACG groups compared to the cataract control group. In aqueous humor, histamine was found to be statistically significantly elevated (5-fold, p

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are n-3 polyunsaturated fatty acids (PUFAs), and are abundant in fish oil. These n-3 PUFAs have been reported to improve the lower gastrointestinal (LGI) disorders such as ulcerative colitis and Crohn's disease through their anti-inflammatory effects. However, there are few studies on the effect of n-3 PUFAs on motility of the LGI tract, such as the ileum and colon, the parts frequently affected by these inflammatory disorders. To elucidate the effects of DHA and EPA on the LGI tract motility, we performed comparative evaluation of their effects and linoleic acid (LA), an n-6 PUFA, on contractions in the ileal and colonic longitudinal smooth muscles (LSMs) isolated from guinea pigs. In the ileal and colonic LSMs, DHA and EPA (3 × 10-5 M each) significantly inhibited contractions induced by acetylcholine (ACh), histamine, and prostaglandin (PG) F2α (vs. control), and these effects are stronger than that of LA (3 × 10-5 M). In the colonic LSMs, DHA and EPA also significantly inhibited contractions induced by PGD2 (vs. control). In addition, DHA and EPA significantly inhibited CaCl2-induced ileal and colonic LSM contractions in Ca2+-free 80 mM-KCl solution (vs. control). Any ileal and colonic LSM contractions induced by ACh, histamine, PGF2α, and CaCl2 were completely suppressed by verapamil (10-5 M), a voltage-gated/dependent Ca2+ channel (VGCC/VDCC) inhibitor. These findings suggest that DHA and EPA could improve the abnormal contractile functions of the LGI tract associated with inflammatory diseases, partly through inhibition of VGCC/VDCC-dependent ileal and colonic LSM contractions.

This study investigated the pollution characteristics, exposure levels and health risk assessments of seven kinds of biogenic amines (BAs) in eight varieties of canned sea fish products (n = 131) on the Chinese market. Carbon spheres QuEChERS mixed dispersion solid phase extraction combined with HPLC was used for the classification and analysis of batch samples. The average recovery of single BAs obtained by this method is 92.3~97.7%, and the relative standard deviation is 1.9~4.8%. Different varieties of samples have different degrees of pollution, the mass concentration of single BAs range 0.45~27.74 mg/kg, and the total concentration of ΣBAs range 18.77~368.50 mg/kg, of which the concentration of Σ4BAs range 11.53~368.50 mg/kg. The composition of four BAs is mainly putrescine, cadaverine, histamine and tyramine, which always play an important role in the exposure level and risk assessment of samples. The exposure level of BAs in the human body ranges 67.03~209.52 μg∙kg−1∙d−1. The health risk assessment shows that the gender trend of exposure risk level of BAs is male > female (young age), female > male (middle and old age), the age trend is young age > old age > middle age, and the regional trend is city > countryside. The food safety index of BAs in samples is 0.0062~0.0195, which is far less than 1, so the risk is within the controllable range.

Commonly prescribed selective serotonin reuptake inhibitors (SSRIs) inhibit the serotonin transporter to correct a presumed deficit in extracellular serotonin signaling during depression. These agents bring clinical relief to many who take them; however, a significant and growing number of individuals are resistant to SSRIs. There is emerging evidence that inflammation plays a significant role in the clinical variability of SSRIs, though how SSRIs and inflammation intersect with synaptic serotonin modulation remains unknown. In this work, we use fast in vivo serotonin measurement tools to investigate the nexus between serotonin, inflammation, and SSRIs. Upon acute systemic lipopolysaccharide (LPS) administration in male and female mice, we find robust decreases in extracellular serotonin in the mouse hippocampus. We show that these decreased serotonin levels are supported by increased histamine activity (because of inflammation), acting on inhibitory histamine H3 heteroreceptors on serotonin terminals. Importantly, under LPS-induced histamine increase, the ability of escitalopram to augment extracellular serotonin is impaired because of an off-target action of escitalopram to inhibit histamine reuptake. Finally, we show that a functional decrease in histamine synthesis boosts the ability of escitalopram to increase extracellular serotonin levels following LPS. This work reveals a profound effect of inflammation on brain chemistry, specifically the rapidity of inflammation-induced decreased extracellular serotonin, and points the spotlight at a potentially critical player in the pathology of depression, histamine. The serotonin/histamine homeostasis thus, may be a crucial new avenue in improving serotonin-based treatments for depression. SIGNIFICANCE STATEMENT Acute LPS-induced inflammation (1) increases CNS histamine, (2) decreases CNS serotonin (via inhibitory histamine receptors), and (3) prevents a selective serotonin reuptake inhibitor (SSRI) from effectively increasing extracellular serotonin. A targeted depletion of histamine recovers SSRI-induced increases in extracellular hippocampal serotonin.

Although respiratory symptoms in children are often attributed to gastroesophageal reflux disease, establishing a clear diagnosis of extraesophageal reflux disease (EERD) can be challenging, as there are no sensitive or specific EERD biomarkers. The aim of this study was to evaluate the metabolite profile in bronchoalveolar (BAL) fluid from children with suspected EERD and assess the impact of reflux treatment on these metabolites. In this prospective pilot study, we performed nontargeted global metabolomic profiling on BAL fluid from 43 children undergoing testing with bronchoscopy, upper endoscopy, and multichannel intraluminal impedance with pH (pH‐MII) for evaluation of chronic respiratory symptoms. Twenty‐three (54%) patients had an abnormal pH‐MII study. Seventeen (40%) patients were on proton pump inhibitors (PPIs) for testing. Levels of histamine, malate, adenosine 5′‐monophosphate, and ascorbate were significantly lower in subjects with abnormal pH‐MII studies compared to those normal studies. Furthermore, in children off PPI therapy, those with abnormal pH‐MII studies had robust increases in a number of glycerophospholipids within phospholipid metabolic pathways, including derivatives of glycerophosphorylcholine, glycerophosphoglycerol, and glycerophosphoinositol, compared to those with normal pH‐MII studies. These findings offer insight into the impact of reflux and PPIs on the lungs and provide a foundation for future studies using targeted metabolomic analysis to identify potential biomarkers of EERD.

Goals and background Stress ulcer prophylaxis has been shown to lower gastrointestinal bleeding (GIB) rates. Various agents have been studied, and the optimal strategy continues to be contested. This study evaluates the efficacy between proton pump inhibitors (PPIs) and histamine-2-receptor antagonists. Small sample sizes and methodology flaws limited prior studies. Study A systematic search of MEDLINE, EMBASE, CENTRAL, Web of Science, and ClinicalTrials.gov for randomized controlled trials reporting the use of PPI and histamine-2-receptor antagonist reporting rates of GIB and standardized intensive care outcomes. Risk ratios (RR) and standardized mean difference (SMD) with 95% confidence intervals (CIs). A trial sequential analysis was performed to guard against errors. Results A total of 14 randomized controlled trials of 28,526 patients with a mean age of 57.83±17.35 years and 30.82% females. In our pooled analysis, PPI outperformed its comparator (RR: 0.68; 95% CI: 0.57-0.82) in clinically significant GIB. PPI re-demonstrated significant reduction in overt GIB (RR: 0.61; 95% CI: 0.39-0.97). No differences between groups was noted toward all-cause mortality (RR: 1.05; 95% CI: 1.00-1.10) or incidence of pneumonia (RR: 1.11; 95% CI: 0.82-1.51). Duration of stay (SMD: 0.07; 95% CI: -0.04-0.17) and ventilator days (SMD: 0.01; 95% CI: -0.01-0.04) were indifferent between the groups. Conclusions Among critically ill patients, PPI was associated with reduced clinically significant or overt GIB. No differences in pneumonia were seen with the use of either agent. Trial sequential analysis for clinically significant GIB ruled out the risk for false-positive results, and thereby it is unlikely that future trials will affect our conclusions.

RATIONALE: Women meet criteria for substance use disorder after fewer years of drug use than men; this accelerated time-course, or telescoping effect, has been observed for multiple drugs, including cocaine. Preclinical findings similarly indicate an enhanced vulnerability in females to developing an addiction-like phenotype; however, it is not yet known if this phenotype develops faster in females versus males. OBJECTIVES: The goal of this study was to determine using a rat model whether two key features of addiction in humans, an enhanced motivation for cocaine and compulsive use, emerge sooner during withdrawal from extended-access cocaine self-administration in females versus males. METHODS: Motivation for cocaine, as assessed under a progressive-ratio reinforcement schedule, was determined prior to and following extended-access cocaine self-administration (24 h/day, 96 infusions/day, 10 days) and after 7, 14, or 60 days of withdrawal. Compulsive use, or use despite punishment, was evaluated once progressive-ratio responding stabilized by adding histamine, an aversive stimulus, to the cocaine solutions. RESULTS: Motivation for cocaine increased from baseline sooner during withdrawal in females than males (at 7 versus 14 days); motivation was also highest in the 60-day group. Histamine decreased progressive-ratio responding for cocaine in both sexes although effects were greatest in males in the 7-day withdrawal group; males reached the female-level of resistance to histamine-punishment by 14 days of withdrawal. CONCLUSIONS: Female rats developed addition-like features sooner during withdrawal than male rats indicating that the telescoping effect observed in humans is biologically-based. Additionally, like drug-seeking/craving, motivation for cocaine and measures of compulsive use incubate over withdrawal.

Anaphylactoid reactions are potentially fatal allergic diseases caused by mast cells (MCs), which release histamine and lipid mediators under certain stimuli. Therefore, there is an urgent need to develop new drug candidates to treat anaphylactoid reactions. The MrgX2 receptor mediates anaphylactoid reactions that cause inflammatory diseases. Cortex dictamni is a Chinese herb used for treating allergy-related diseases; however, its active compound is still unknown and its mechanism of action has not yet been reported. The aim of this study was to screen the anti-anaphylactoid compound from C. dictamni extracts. An MrgX2/CMC-HPLC method was established for screening MrgX2-specific compounds retained from the alcohol extract of C. dictamni. A mouse model of hindpaw extravasation was used to evaluate the anti-anaphylactoid effect of this ingredient. Intracellular Ca2+ mobilization was assessed using a calcium imaging assay. Enzyme immunoassays were performed to measure cytokine and chemokine release levels. The molecular signaling pathways were explored by western blotting. As a result, dictamnine was identified as an effective compound using the MrgX2/CMC method, which remarkably suppressed MC intracellular Ca2+ mobilization and the release of de novo degranulated substances, and inhibited PKC-PLCγ-IP3R-associated protein signaling molecules. Hence, dictamnine is a novel therapeutic candidate for anaphylactoid reactions via MrgX2.

The common bed bug (Cimex lectularius L.) is a hematophagous pest species that lives in close proximity to humans. Following a blood meal, bed bugs deposit fecal material indoors. The feces contain a variety of compounds, including histamine, which serves as a component of their aggregation pheromone. Histamine is a pivotal mammalian immune modulator, and recently it was shown to be present in high concentrations in household dust from homes infested with bed bugs. To better understand the dynamics of histamine excretion, we analyzed bed bug fecal material from different life stages and populations, along with fecal material collected at different post-feeding times and from bed bugs fed on different diets. Our analysis showed significant variation in histamine excretion among life stages, with mated females excreting the most histamine and first instar nymphs excreting the least histamine. However, when histamine excretion was normalized for blood consumption, males were found to excrete more histamine than the other life stages. There was no difference in histamine excretion among laboratory and recently home-collected bed bug populations. Further, we found histamine excretion continued for at least 14 d post-feeding, with the highest amount of histamine excreted 3–4 d after a bloodmeal. Overall, this work demonstrates that bed bugs excrete histamine across all feeding life stages, populations, and at various times after feeding, and that histamine excretion is directly related to blood feeding. These results will be used to better understand the health risks associated with histamine excretion and potential mitigation strategies of environmental histamine.

Background Stress-induced mental illnesses (mediated by neuroinflammation) pose one of the world’s most urgent public health challenges. A reliable in vivo chemical biomarker of stress would significantly improve the clinical communities’ diagnostic and therapeutic approaches to illnesses, such as depression. Methods Male and female C57BL/6J mice underwent a chronic stress paradigm. We paired innovative in vivo serotonin and histamine voltammetric measurement technologies, behavioral testing, and cutting-edge mathematical methods to correlate chemistry to stress and behavior. Results Inflammation-induced increases in hypothalamic histamine were co-measured with decreased in vivo extracellular hippocampal serotonin in mice that underwent a chronic stress paradigm, regardless of behavioral phenotype. In animals with depression phenotypes, correlations were found between serotonin and the extent of behavioral indices of depression. We created a high accuracy algorithm that could predict whether animals had been exposed to stress or not based solely on the serotonin measurement. We next developed a model of serotonin and histamine modulation, which predicted that stress-induced neuroinflammation increases histaminergic activity, serving to inhibit serotonin. Finally, we created a mathematical index of stress, Si and predicted that during chronic stress, where Si is high, simultaneously increasing serotonin and decreasing histamine is the most effective chemical strategy to restoring serotonin to pre-stress levels. When we pursued this idea pharmacologically, our experiments were nearly identical to the model’s predictions. Conclusions This work shines the light on two biomarkers of chronic stress, histamine and serotonin, and implies that both may be important in our future investigations of the pathology and treatment of inflammation-induced depression.

Histamine is a major neurotransmitter and alleviates neuronal damage after ischemic injury via H

Opioid use disorder (OUD) and opioid-related deaths remain a significant public health crisis having reached epidemic status globally. OUDs are defined as chronic, relapsing conditions often characterized by compulsive drug seeking despite the deleterious consequences of drug taking. The use of nicotine-containing products has been linked to increased likelihood of prescription opioid misuse, and there exists a significant comorbidity between habitual nicotine use and opioid dependence. In rodent models, nicotine administration nearly doubles the amount of opioids taken in intravenous self-administration paradigms. Here, we examined the effect of acute systemic nicotine administration in male rats on responding for the synthetic opioid remifentanil (RMF) in a contextual punishment paradigm using either an exteroceptive punisher (foot-shock) or an interoceptive punisher (histamine). Nicotine administration, relative to saline, increased RMF intake in both unpunished and punished contexts, regardless of form of punishment, and resulted in significantly higher motivation to obtain RMF in the previously punished context, as measured by progressive ratio breakpoint. Additionally, regardless of context, nicotine-treated rats were slower to extinguish RMF responding following drug removal and displayed higher levels of cue-induced reinstatement than saline-treated controls. Furthermore, these data support that, compared with histamine adulteration, contingent foot-shock is a more potent form of punishment, as histamine punishment failed to support contextual discrimination between the unpunished and punished contexts. In contrast to RMF administration, augmentation of responding for an audiovisual cue by nicotine pretreatment was lost following contextual punishment. In conclusion, acute nicotine administration in adult male rats significantly enhances compulsive-like responding for RMF that persists despite contingent punishment of drug-directed responding.

Photobiomodulation therapy (PBMT) is a non-thermal therapeutic procedure widely used in clinical practice. It is considered an effective modality of treatment for the control of various inflammatory conditions with fewer adverse effects as compared to conventional therapy. However, despite the clinical effects, the mechanisms of action and dosimetric parameters of PBMT are not fully understood. This study was performed to describe the effects of two different doses of PBMT on experimental models of inflammation. Male Swiss mice were administered with 0.9% of saline or phlogistic agents (carrageenan, dextran, serotonin, histamine, or bradykinin) by intra-plantar injection and were treated with PBMT at a dose of 1 or 5 J/cm2; right after, the variation of the paw volume was made, and histopathological analysis and myeloperoxidase assay of the carrageenan-induced edematous paw tissues were performed. The action of PBMT on carrageenan-induced vascular permeability was further evaluated. Our results showed that PBMT (1 J/cm2) led to an improvement in paw edema induced by the phlogistic agents and further reduced the histological scores. Inhibition of neutrophil migration was observed following the administration of 1 and 5 J/cm2 of PBMT. However, only 1 J/cm2 of PBMT showed beneficial effects on carrageenan-induced edema. Laser at a dose of 1 J/cm2 showed cellular and vascular effects since it was able to reverse all the inflammatory parameters, and laser at a dose of 5 J/cm2 probably has only cellular effects in the presence of acute inflammation.

Background: Central histamine H3 receptors are a family of presynaptic auto and heteroreceptors. Blockade of the presynaptic H3 receptors activates the downstream pathway(s) involved in the processes of learning and memory, making it a potential therapeutic option for ameliorating cognitive dysfunction. Samelisant (SUVN-G3031) is a potent and selective inverse agonist at the H3 receptors. Aim: The aim of this research is to study the effects of Samelisant in diverse animal models of cognitive functions. Methods: The effects of Samelisant on cognitive functions were studied using social recognition, object recognition and Morris water maze tasks. Neurochemical and electrophysiological effects of Samelisant were monitored using microdialysis and electroencephalography techniques. Results: Samelisant showed procognitive effects in diverse animal models of cognition at doses ranging from 0.3 to 3 mg/kg, per os ( p.o.) (social recognition and object recognition task). Samelisant significantly increased the brain acetylcholine levels in the cortex at doses of 10 and 20 mg/kg, p.o. In the Morris water maze task, combined administration of suboptimal doses of Samelisant and donepezil resulted in procognitive effects significantly larger than the either treatment. Similarly, Samelisant significantly potentiated the effects of donepezil on pharmacodynamic biomarkers of cognition i.e. acetylcholine levels in brain and neuronal theta oscillations. Conclusion: Samelisant may have potential utility in the treatment of cognitive deficits associated with hypocholinergic state.