Suppression of excitatory synaptic transmission in the centrolateral amygdala via presynaptic histamine H3 heteroreceptors.

The central histaminergic system has a pivotal role in emotional regulation and psychiatric disorders, including anxiety, depression and schizophrenia. However, the effect of histamine on neuronal activity of the centrolateral amygdala (CeL), an essential node for fear and anxiety processing, remains unknown. Here, using immunostaining and whole-cell patch clamp recording combined with optogenetic manipulation of histaminergic terminals in CeL slices prepared from histidine decarboxylase (HDC)-Cre rats, we show that histamine selectively suppresses excitatory synaptic transmissions, including glutamatergic transmission from the basolateral amygdala, on both PKC-δ- and SOM-positive CeL neurons. The histamine-induced effect is mediated by H3 receptors expressed on VGLUT1-/VGLUT2-positive presynaptic terminals in CeL. Furthermore, optoactivation of histaminergic afferent terminals from the hypothalamic tuberomammillary nucleus (TMN) also significantly suppresses glutamatergic transmissions in CeL via H3 receptors. Histamine neither modulates inhibitory synaptic transmission by presynaptic H3 receptors nor directly excites CeL neurons by postsynaptic H1, H2 or H4 receptors. These results suggest that histaminergic afferent inputs and presynaptic H3 heteroreceptors may hold a critical position in balancing excitatory and inhibitory synaptic transmissions in CeL by selective modulation of glutamatergic drive, which may not only account for the pathophysiology of psychiatric disorders but also provide potential psychotherapeutic targets. KEY POINTS: Histamine selectively suppresses the excitatory, rather than inhibitory, synaptic transmissions on both PKC-δ- and SOM-positive neurons in the centrolateral amygdala (CeL). H3 receptors expressed on VGLUT1- or VGLUT2-positive afferent terminals mediate the suppression of histamine on glutamatergic synaptic transmission in CeL. Optogenetic activation of hypothalamic tuberomammillary nucleus (TMN)-CeL histaminergic projections inhibits glutamatergic transmission in CeL via H3 receptors.

Mast cell activation syndrome: An up-to-date review of literature.

Mast cells are a subtype of white blood cells and are involved in the immune system. These cells contain many chemical substances called mediators, which are involved in the allergic response. The fact that mast cells play a role in many events that require urgent intervention, especially anaphylaxis, has led to a more detailed study of these cells. The diseases also caused by dysfunctions of mast cells have been examined in many circumstances. For instance, mast cell activation syndrome is known as an augmented number of cells due to decreased cell death, resulting in clinical symptoms affecting many systems. The main common symptoms include flushing, hypotension, urticaria, angioedema, headache, vomiting and diarrhea. Although the underlying mechanism is not yet clearly known, we aim to review the literature in a broad perspective and bring together the existing knowledge in the light of the literature due to the diversity of its involvement in the body and the fact that it is a little known syndrome.

The role of histamine and its receptors in breast cancer: from pathology to therapeutic targets.

Breast cancer is the most common malignancy in women, and despite the development of new treatment methods and the decreasing mortality rate in recent years, one of the clinical problems in breast cancer treatment is chronic inflammation in the tumor microenvironment. Histamine, an inflammatory mediator, is produced by tumor cells and can induce chronic inflammation and the growth of some tumors by recruiting inflammatory cells. It can also affect tumor physiopathology, antitumor treatment efficiency, and patient survival. Antihistamines, as histamine receptor antagonists, play a role in modulating the effects of these receptors in tumor cells and can affect some treatment methods for breast cancer therapy; in this review, we investigate the role of histamine, its receptors, and antihistamines in breast cancer pathology and treatment methods.

Occurrence of hemodynamic changes following administration of rocuronium in a dog presenting for an ophthalmic procedure.

A 10-year-old, neutered male, Golden Retriever dog presented for surgical correction of a descemetocele. Acepromazine (0.02 mg/kg) and methadone (0.5 mg/kg) were administered intramuscularly for sedation, propofol (2 mg/kg) and midazolam (0.2 mg/kg) were administered intravenously for anaesthetic induction and isoflurane in oxygen was utilised for anaesthetic maintenance. Rocuronium (0.5 mg/kg), a neuromuscular blocking agent, was administered intravenously to facilitate central positioning of the eye for surgery. Within 10 min of rocuronium administration, the dog became tachycardic and hypotensive. Hemodynamic aberrations did not resolve with initial interventions but were successfully mitigated with the administration of diphenhydramine (0.8 mg/kg) intravenously. The dog remained stable throughout the remainder of the procedure and experienced a smooth and uneventful recovery. While it is difficult to confirm that the hemodynamic changes observed in this clinical case resulted solely from administration of rocuronium, the observance of the cardiovascular changes, timing of events and response to therapy suggest that rocuronium elicited a histamine response that was successfully treated with diphenhydramine.

Transcriptomic and metabolomic correlates of increased colonic permeability in post-infection irritable bowel syndrome.

BACKGROUND AND AIM: Post-infection irritable bowel syndrome (PI-IBS) is well-known epidemiologically; however, its physiological and molecular characteristics are not well studied. We aimed to determine the physiological phenotypes, colonic transcriptome, fecal microbiome, and metabolome in PI-IBS. METHODS: Fifty-one Rome III Campylobacter PI-IBS patients and 39 healthy volunteers (HV) were enrolled. Participants completed questionnaires, in vivo intestinal permeability, gastrointestinal transit, and rectal sensation. Fecal samples were collected for shotgun metagenomics, untargeted metabolomics, and sigmoid colonic biopsies for bulk RNAseq. Differential gene expression, differences in microbiota composition and metabolite abundance were determined. Gene and metabolite clusters were identified via weighted gene correlation network analysis and correlations with clinical and physiological parameters determined. RESULTS: PI-IBS (59% F, 46±2 yrs.) and HV (64% F, 42±2 yrs.) demographics were comparable. Mean IBS-symptom severity score was 227; 94% were non-constipation. 2-24h lactulose excretion was increased in PI-IBS, suggesting increased colonic permeability (4.4±0.5 mg vs. 2.6±0.3 mg, p=0.01). Colonic transit and sensory thresholds were similar between the two groups. Overall, expression of 2036 mucosal genes and 223 fecal metabolites were different, with changes more prominent in females. Fecal N-acetylputrescine was increased in PI-IBS and associated with colonic permeability, worse diarrhea, and negatively correlated with abundance of Collinsella aerofaciens. Histamine and N-acetyl histamine positively associated with 2-24 hr lactulose excretion. Eight weighted gene coexpression modules significantly correlated with phenotypes (sex, stool frequency, colonic permeability, transit). CONCLUSIONS: Campylobacter PI-IBS patients demonstrate higher colonic permeability which associated with changes in polyamine and histamine metabolites. Female patients demonstrated greater molecular changes.

Correlation between the expression of the iNOS, caspase-3 and α-SMA genes in the parotid glands of albino rats following the administration of two antihistamines from two different generations.

BACKGROUND: Several medications, including antihistamines, can alter salivary gland function, causing dry mouth or xerostomia. Antihistamines are commonly used for treating allergic rhinitis. OBJECTIVES: The aim of the present study was to compare and correlate the effects of first-generation vs. second-generation H1-antihistamines on the parotid glands of rats. MATERIAL AND METHODS: Twelve adult male albino rats were used; 4 rats served as a control group (group I) and the remaining rats were divided into 2 groups: group II received promethazine hydrochloride; and group III received cetirizine dihydrochloride for 3 weeks. The parotid salivary glands were dissected, and examined histologically and analyzed histomorphometrically for the acinar area percentage. In addition, mRNA gene expression of iNOS, caspase-3 and α-SMA was assessed using quantitative realtime polymerase chain reaction (qRT-PCR). Finally, all the obtained data was statistically analyzed. RESULTS: Histologically, group I showed the typical architecture of the gland. In group II, degenerative changes were noticed, including acinar degeneration and shrinkage with widened connective tissue septa, intracellular vacuolization, and increased inflammatory cell infiltration. In group III, similar histological features were detected as in group II, but to a lesser extent. Histomorphometric results revealed significant differences in the acinar area percentage between various groups. In addition, qRT-PCR results showed a significant increase in iNOS expression in both groups II and III as compared to group I, caspase-3 gene expression was significantly increased in group II, while in group III, it increased non-significantly. Finally, α-SMA gene expression non-significantly decreased in both groups II and III. A significant positive correlation was observed between caspase-3 and iNOS gene expression, while an inverse correlation was noticed between caspase-3 and α-SMA gene expression. CONCLUSIONS: The administration of antihistamines resulted in changes in the rat salivary glands, which could be due to the induction of oxidative stress and the resultant apoptotic effect. These changes were suggested to occur mainly through action on muscarinic receptors; yet, action on histamine receptors could not be excluded. However; these effects were less marked with the second-generation antihistamine.

TRPV1 and mast cell involvement in repeated variate stress (RVS) induced urinary bladder dysfunction in adult female mice.

The etiology of interstitial cystitis/bladder pain syndrome (IC/BPS) is unknown but likely multifactorial. IC/BPS symptoms can be exacerbated by psychological stress, but underlying mechanisms remain to be defined. TRPV1 channels, expressed on nerve fibers, have been implicated in bladder dysfunction and colonic hypersensitivity with stress in rodents. Histamine/H1R activation of TRPV1+ nerves increases bladder afferent fiber sensitivity to distension. TRPV1 channels are also expressed on mast cells, previously implicated in contributing to IC/BPS etiology and symptoms. We have examined the contribution of TRPV1 and mast cells to bladder dysfunction after repeated variate stress (RVS). RVS increased (p ≤ 0.05) serum and fecal corticosterone expression and induced anxiety-like behavior in wild type (WT) mice. Intravesical instillation of the selective TRPV1 antagonist capsazepine (CPZ) rescued RVS-induced bladder dysfunction in WT mice. Trpv1 knockout (KO) mice did not increase voiding frequency with RVS and did not exhibit increased serum corticosterone expression despite exhibiting anxiety-like behavior. Mast cell deficient mice (B6.Cg-Kitw-sh) failed to demonstrate RVS-induced increased voiding frequency or serum corticosterone expression whereas control (no stress) mast cell deficient mice had similar functional bladder capacity to WT mice. TRPV1 protein expression was significantly increased in the rostral lumbar (L1-L2) spinal cord and dorsal root ganglia in WT mice exposed to RVS but no changes were observed in lumbosacral (L6-S1) spinal segments or DRG. These studies demonstrated TRPV1 and mast cell involvement in RVS-induced increased voiding frequency and suggest that TRPV1 and mast cells may be useful targets to mitigate stress-induced urinary bladder dysfunction.

Pathophysiological role of histamine signaling and its implications in glioblastoma.

Glioblastoma (GBM), an extremely aggressive and prevalent malignant brain tumor, remains a challenge to treat. Despite a multimodality treatment approach, GBM recurrence remains inevitable, particularly with the emergence of temozolomide (TMZ) resistance and limited treatment options. Surprisingly, previous studies show that a history of allergies, atopy, or asthma is inversely associated with GBM risk. Further, the electronic medical record at the University Hospital of Lausanne showed that the GBM patients taking antihistamine during treatment had better survival. Histamine is an essential neurotransmitter in the brain and plays a significant role in regulating sleep, hormonal balance, and cognitive functions. Elevated levels of histamine and increased histamine receptor expression have been found in different tumors and their microenvironments, including GBM. High histamine 1 receptor (HRH1) expression is inversely related to overall and progression-free survival in GBM patients, further emphasizing the role of histamine in disease progression. This review aims to provide insights into the challenges of GBM treatment, the role of histamine in GBM progression, and the rationale for considering antihistamines as targeted therapy. The review concludes by encouraging further investigation into antihistamine mechanisms and their impact on the tumor microenvironment.

Sensitive detection of histamine utilizing the SERS platform combined with an azo coupling reaction and a composite hydrophobic layer.

Herein, the surface-enhanced Raman scattering (SERS) platform was combined with an azo coupling reaction and an aluminum alloy covered with a hydrophobic layer of praseodymium oxide and stearic acid complexes for the detection of histamine. The praseodymium oxide on aluminum alloy was successfully synthesized by the rare-earth-salt-solution boiling bath method and modified by stearic acid. Its surface exhibits a water contact angle (WCA) of 125.0°. Through the azo derivatization reaction with 3-amino-5-mercapto-1,2,4-triazole (AMTA) diazonium salts, histamine can be converted into the derivatization product with higher Raman activity. The mixture of the derivatization product and ß-cyclodextrin-modified Ag nanoparticles (ß-CD-AgNPs) were dropped onto the surface of an aluminum alloy covered with a hydrophobic layer of praseodymium oxide and stearic acid complexes, and dried for SERS measurement. The intensity ratio between the SERS peaks at 1246 cm-1 and 1104 cm-1 (I1246/I1104) of the derivatization product was used for the quantification of histamine. Under the selected conditions, the limit of detection (LOD) and the limit of quantification (LOQ) for this method were 7.2 nM (S/N = 3) and 24 nM (S/N = 10), respectively. The relative standard deviation (RSD) of this method for the determination of 1 µM histamine was 6.1 % (n = 20). The method was also successfully used for the determination of histamine in fish samples with recoveries ranging from 92 % to 111 %. The present method is simple, sensitive, reliable, and may provide a new approach for preparing the composite hydrophobic layer that can enhance SERS signals through hydrophobic condensation effect. Meanwhile, it may have a promising future in the determination of small molecular compounds containing an imidazole ring.

The factors influencing the concentration of histamine in jarred baby foods containing fish, considering evaluation of daily histamine intake.

Histamine is one of the biogenic amines produced naturally in the human body, but also in foods, especially those rich in protein. Exogenous and endogenous histamine is subject to degradation in vivo, but in the case of sensitive groups, including children, these degradation processes may be less intense, resulting adverse health effects from histamine excess. The aim of the study was to determine the histamine content in jarred baby foods containing fish, taking into account the selected product characteristics and storage conditions. The study included 140 meals with added fish, intended for infants and young children, from 5 leading manufacturers available in Poland. The infant meals were analyzed on the day of opening, after 24 h and 48 h of storage in the refrigerator and at room temperature. Histamine concentration was determined by ELISA. The THQ was calculated from the EDI values for histamine. Histamine was present in all analyzed baby foods. On the day of opening, the products had a lower content of this monoamine (Me=2.59 mg/kg), which increased systematically during storage. Samples taken at 2° C after 48 hours showed an average histamine content of 4.4 mg/kg, while products stored at 22° C at the same time showed a 1.8-fold higher concentration of this monoamine (Me=7.9 mg/kg). Dishes containing tuna and sea fish had higher histamine levels on average than those containing pollock. The storage conditions of the children's food had a significant effect on histamine concentration. The level of histamine in baby foods was related to the amount and type of fish in certain products. The results indicate the need for increased awareness of the risks associated with histamine, especially in a group of people with increased sensitivity to this amine, which may include infants and young children.

Histamine in the neocortex: Towards integrating multiscale effectors.

Histamine is a modulatory neurotransmitter, which has received relatively less attention in the central nervous system than other neurotransmitters. The functional role of histamine in the neocortex, the brain region that controls higher-order cognitive functions such as attention, learning and memory, remains largely unknown. This article focuses on the emerging roles and mechanisms of histamine release in the neocortex. We describe gaps in current knowledge and propose the application of interdisciplinary tools to dissect the detailed multiscale functional logic of histaminergic action in the neocortex ranging from sub-cellular, cellular, dendritic and synaptic levels to microcircuits and mesoscale effects.

Biogenic amines in the testis: sources, receptors and actions.

Biogenic amines are signaling molecules with multiple roles in the central nervous system and in peripheral organs, including the gonads. A series of studies indicated that these molecules, their biosynthetic enzymes and their receptors are present in the testis and that they are involved in the regulation of male reproductive physiology and/or pathology. This mini-review aims to summarize the current knowledge in this field and to pinpoint existing research gaps. We suggest that the widespread clinical use of pharmacological agonists/antagonists of these signaling molecules, calls for new investigations in this area. They are necessary to evaluate the relevance of biogenic amines for human male fertility and infertility, as well as the potential value of at least one of them as an anti-aging compound in the testis.

Histamine deficiency exacerbates cisplatin-induced ferroptosis in cochlea hair cells of HDC knockout mice.

Cisplatin (CDDP) is extensively utilized in the management of diverse types of cancers, but its ototoxicity cannot be ignored, and clinical interventions are not ideal. Histidine decarboxylase (HDC) is the exclusive enzyme for histamine synthesis. Anti-histamine receptor drugs are ubiquitously employed in the therapeutics of allergies and gastrointestinal diseases. Yet, the specific role of histamine and its signaling in the inner ear is not fully understood. This study utilized cisplatin treated mice and HEI-OC1 auditory hair cell line to establish a cisplatin-induced ototoxicity (CIO) model. Histidine decarboxylase knockout (HDC-/-) mice and histamine receptor 1 (H1R) antagonist were utilized to investigate the influence of HDC/histamine/H1R signaling on ototoxicity. The results identified HDC and H1R expression in mouse hair cells. Transcriptomics indicated that the expression levels of oxidative stress-related genes in the cochlea of HDC-/- mice increased. Furthermore, histamine deficiency or suppression of H1R signaling accelerated HC ferroptosis, a pivotal factor underlying the aggravation of CIO in vivo and in vitro, conversely, the supplementation of exogenous histamine reversed these deleterious effects. Mechanistically, this study revealed that the malfunction of HDC/histamine/H1R signaling induced upregulation of NRF2 expression, accompanied by the upregulation of ACSL4 and downregulation of GPX4 expression, which are major regulatory factors of ferroptosis. In summary, histamine deficiency may induce hair cell death by regulating the H1R pathway and exacerbate CIO. Our findings have indicated a potential therapeutic target for CIO.

Histamine promotes mouse decidualization through stimulating epithelial amphiregulin release.

Accumulating evidence shows that inflammation is essential for embryo implantation and decidualization. Histamine, a proinflammatory factor that is present in almost all mammalian tissues, is synthesized through decarboxylating histidine by histidine decarboxylase (HDC). Although histamine is known to be essential for decidualization, the underlying mechanism remains undefined. In the present study, histamine had no obvious direct effects on in vitro decidualization in mice. However, the obvious differences in HDC protein levels between day 4 of pregnancy and day 4 of pseudopregnancy, as well as between delayed and activated implantation, suggested that the blastocyst may be involved in regulating HDC expression. Furthermore, blastocyst-derived tumor necrosis factor α (TNFα) significantly increased HDC levels in the luminal epithelium. Histamine increased the levels of amphiregulin (AREG) and disintegrin and metalloproteinase domain-containing protein 17 (ADAM17) proteins, which was abrogated by treatment with famotidine, a specific histamine type 2 receptor (H2R) inhibitor, or by TPAI-1 (a specific inhibitor of ADAM17). Intraluminal injection of urocanic acid (HDC inhibitor) on day 4 of pregnancy significantly reduced the number of implantation sites on day 5 of pregnancy. TNFα-stimulated increases in HDC, AREG and ADAM17 protein levels was abrogated by urocanic acid, a specific inhibitor of HDC. Additionally, AREG treatment significantly promoted in vitro decidualization. Collectively, our data suggests that blastocyst-derived TNFα induces luminal epithelial histamine secretion, and histamine increases mouse decidualization through ADAM17-mediated AREG release.

Spinal histamine H4 receptor mediates chronic pruritus via p-ERK in acetone-ether-water (AEW)-induced dry skin mice.

Dry skin is common to many pruritic diseases and is difficult to improve with oral traditional antihistamines. Recently, increasing evidence indicated that histamine H4 receptor (H4R) plays an important role in the occurrence and development of pruritus. Extracellular signal-regulated kinase (ERK) phosphorylation activation in the spinal cord mediates histamine-induced acute and choric itch. However, whether the histamine H4 receptor regulates ERK activation in the dry skin itch remains unclear. In the study, we explore the role of the histamine H4 receptor and p-ERK in the spinal cord in a dry skin mouse model induced by acetone-ether-water (AEW). q-PCR, Western blot, pharmacology and immunofluorescence  were applied in the study. We established a dry skin itch model by repeated application of AEW on the nape of neck in mice. The AEW mice showed typically dry skin histological change and persistent spontaneous scratching behaviour. Histamine H4 receptor, instead of histamine H1 receptor, mediated spontaneous scratching behaviour in AEW mice. Moreover, c-Fos and p-ERK expression in the spinal cord neurons were increased and co-labelled with GRPR-positive neurons in AEW mice. Furthermore, H4R agonist 4-methyhistamine dihydrochloride (4-MH)induced itch. Both 4-MH-induced itch and the spontaneous itch in AEW mice were blocked by p-ERK inhibitor U0126. Finally, intrathecal H4R receptor antagonist JNJ7777120 inhibited spinal p-ERK expression in AEW mice. Our results indicated that spinal H4R mediates itch via ERK activation in the AEW-induced dry skin mice.

Phylogenetically diverse bacterial species produce histamine.

Histamine is an important biogenic amine known to impact a variety of patho-physiological processes ranging from allergic reactions, gut-mediated anti-inflammatory responses, and neurotransmitter activity. Histamine is found both endogenously within specialized host cells and exogenously in microbes. Exogenous histamine is produced through the decarboxylation of the amino acid L-histidine by bacterial-derived histidine decarboxylase enzymes. To investigate how widespread histamine production is across bacterial species, we examined 102,018 annotated genomes in the Integrated Microbial Genomes Database and identified 3,679 bacterial genomes (3.6 %) which possess the enzymatic machinery to generate histamine. These bacteria belonged to 10 phyla: Bacillota, Bacteroidota, Actinomycetota, Pseudomonadota, Lentisphaerota, Fusobacteriota, Armatimonadota, Cyanobacteriota, Thermodesulfobacteriota, and Verrucomicrobiota. The majority of the identified bacteria were terrestrial or aquatic in origin, although several bacteria originated in the human gut microbiota. We used liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based targeted metabolomics to confirm our genome discoveries correlated with L-histidine-to-histamine conversion in a chemically defined bacterial growth medium by a cohort of select environmental and human gut bacteria. We found that environmental microbes Vibrio harveyi, Pseudomonas fluorescens and Streptomyces griseus generated considerable levels of histamine (788 - 8,730 ng/mL). Interestingly, we found higher concentrations of histamine produced by gut-associated Fusobacterium varium, Clostridium perfringens, Limosilactobacillus reuteri and Morganella morganii (8,510--82,400 ng/mL). This work expands our knowledge of histamine production by diverse microbes.

Detection of Steroids in Topical Fairness Preparations Using Histamine Wheal Test.

Topical corticosteroid (TC) abuse is a common, worldwide, problem. One of the recent emerging concerns is the adulteration of TC in fairness cream. The presence of TC in skin-whitening cosmetic creams can be detected by high-performance liquid chromatography (HPLC). Since HPLC is expensive, time-taking and not easily available, we suggest the use of histamine wheal test as a simple and inexpensive test to detect the presence of topical steroids in fairness cream.

Exploring factors influencing the levels of biogenic amines in wine and microbiological strategies for controlling their occurrence in winemaking.

Fermented beverages, including wine, can accumulate high concentrations of biogenic amines (BAs), which can pose potential health risks. BAs are produced by various yeasts and lactic acid bacteria (LAB) during winemaking. LAB are the main contributors to the formation of histamine and tyramine, the most toxic and food safety relevant biogenic amines. Numerous factors, ranging from agricultural and oenological practices to sanitation conditions, can contribute to the formation of BAs in wines. Moreover, organic and biodynamic wines impose limitations on the use of common food additives employed to control the proliferation of native and spoilage microorganisms during vinification and storage. To mitigate histamine production, commercial starter cultures incapable of synthesising histamine have been effectively utilised to reduce wine histamine content. Alternative fermentative microorganisms are currently under investigation to enhance the safety, quality, and typicity of wines, including indigenous LAB, non-Saccharomyces yeasts, and BAs degrading strains. Furthermore, exploration of extracts from BAs-degrading microorganisms and their purified enzymes has been undertaken to reduce BAs levels in wines. This review highlights microbial contributors to BAs in wines, factors affecting their growth and BA production, and alternative microorganisms that can degrade or avoid BAs. The aim is to lessen reliance on additives, providing consumers with safer wine choices.

TRPC3 signalling contributes to the biogenesis of extracellular vesicles.

Extracellular vesicles (EVs) contribute to a wide range of pathological processes including cancer progression, yet the molecular mechanisms underlying their biogenesis remain incompletely characterized. The development of tetraspanin-based pHluorin reporters has enabled the real-time analysis of EV release at the plasma membrane. Here, we employed CD81-pHluorin to investigate mechanisms of EV release in ovarian cancer (OC) cells and report a novel role for the Ca2+-permeable transient receptor potential (TRP) channel TRPC3 in EV-mediated communication. We found that specific activation of TRPC3 increased Ca2+ signalling in SKOV3 cells and stimulated an immediate increase in EV release. Ca2+-stimulants histamine and ionomycin likewise induced EV release, and imaging analysis revealed distinct stimulation-dependent temporal and spatial release dynamics. Interestingly, inhibition of TRPC3 attenuated histamine-stimulated Ca2+-entry and EV release, indicating that TRPC3 is likely to act downstream of histamine signalling in EV biogenesis. Furthermore, we found that direct activation of TRPC3 as well as the application of EVs derived from TRPC3-activated cells increased SKOV3 proliferation. Our data provides insights into the molecular mechanisms and dynamics underlying EV release in OC cells, proposing a key role for TRPC3 in EV biogenesis.