Vasopressin Research Articles

Morphological Signatures of Neurogenesis and Neuronal Migration in Hypothalamic Vasopressinergic Magnocellular Nuclei of the Adult Rat.

The arginine vasopressin (AVP)-magnocellular neurosecretory system (AVPMNS) in the hypothalamus plays a critical role in homeostatic regulation as well as in allostatic motivational behaviors. However, it remains unclear whether adult neurogenesis exists in the AVPMNS. By using immunoreaction against AVP, neurophysin II, glial fibrillar acidic protein (GFAP), cell division marker (Ki67), migrating neuroblast markers (doublecortin, DCX), microglial marker (Ionized calcium binding adaptor molecule 1, Iba1), and 5'-bromo-2'-deoxyuridine (BrdU), we report morphological evidence that low-rate neurogenesis and migration occur in adult AVPMNS in the rat hypothalamus. Tangential AVP/GFAP migration routes and AVP/DCX neuronal chains as well as ascending AVP axonal scaffolds were observed. Chronic water deprivation significantly increased the BrdU+ nuclei within both the supraaoptic (SON) and paraventricular (PVN) nuclei. These findings raise new questions about AVPMNS's potential hormonal role for brain physiological adaptation across the lifespan, with possible involvement in coping with homeostatic adversities.

Ionic mechanisms involved in arginine vasopressin-mediated excitation of auditory cortical and thalamic neurons

The axons containing arginine vasopressin (AVP) from the hypothalamus innervate a variety of structures including the cerebral cortex, thalamus, hippocampus and amygdala. A plethora amount of evidence indicates that activation of the V1a subtype of the vasopressin receptors facilitates anxiety-like and fear responses. As an essential structure involved in fear and anxiety responses, the amygdala, especially the lateral nucleus of amygdala (LA), receives glutamatergic innervations from the auditory cortex and auditory thalamus where high density of V1a receptors have been detected. However, the roles and mechanisms of AVP in these two important areas have not been determined, which prevents the understanding of the mechanisms whereby V1a activation augments anxiety and fear responses. Here, we used coronal brain slices and studied the effects of AVP on neuronal activities of the auditory cortical and thalamic neurons. Our results indicate that activation of V1a receptors excited both auditory cortical and thalamic neurons. In the auditory cortical neurons, AVP increased neuronal excitability by depressing multiple subtypes of inwardly rectifying K+ (Kir) channels including the Kir2 subfamily, the ATP-sensitive K+ channels and the G protein-gated inwardly rectifying K+ (GIRK) channels, whereas activation of V1a receptors excited the auditory thalamic neurons by depressing the Kir2 subfamily of the Kir channels as well as activating the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels and a persistent Na+ channel. Our results may help explain the roles of V1a receptors in facilitating fear and anxiety responses.Categories: Cell Physiology.

Urea transporter UT-A1 as a novel drug target for hyponatremia.

Hyponatremia is the most common disorder of electrolyte imbalances. It is necessary to develop new type of diuretics to treat hyponatremia without losing electrolytes. Urea transporters (UT) play an important role in the urine concentrating process and have been proved as a novel diuretic target. In this study, rat and mouse syndromes of inappropriate antidiuretic hormone secretion (SIADH) models were constructed and analyzed to determine if UTs are a promising drug target for treating hyponatremia. Experimental results showed that 100 mg/kg UT inhibitor 25a significantly increased serum osmolality (from 249.83 ± 5.95 to 294.33 ± 3.90 mOsm/kg) and serum sodium (from 114 ± 2.07 to 136.67 ± 3.82 mmol/L) respectively in hyponatremia rats by diuresis. Serum chemical examination showed that 25a neither caused another electrolyte imbalance nor influenced the lipid metabolism. Using UT-A1 and UT-B knockout mouse SIADH model, it was found that serum osmolality and serum sodium were lowered much less in UT-A1 knockout mice than in UT-B knockout mice, which suggest UT-A1 is a better therapeutic target than UT-B to treat hyponatremia. This study provides a proof of concept that UT-A1 is a diuretic target for SIADH-induced hyponatremia and UT-A1 inhibitors might be developed into new diuretics to treat hyponatremia.

Arginine vasopressin in mood disorders: A potential biomarker of disease pathology and a target for pharmacologic intervention.

Vasopressin or arginine-vasopressin (AVP) is a neuropeptide molecule known for its antidiuretic effects and serves to regulate plasma osmolality and blood pressure. The existing literature suggests that AVP plays a multifaceted-though less well-known-role in the central nervous system (CNS), particularly in relation to the pathophysiology and treatment of mood disorders. Animal models have demonstrated that AVP is implicated in regulating social cognition, affiliative and prosocial behaviors, and aggression, often in conjunction with oxytocin. In humans, AVP is implicated in mood disorders through its effects on the hypothalamic-pituitary-adrenal (HPA) axis as well as on the serotoninergic and glutamatergic systems. Measuring plasma AVP has yielded interesting but mixed results in mood and stress-related disorders. Recent advances have led to the development of copeptin as a stable and reliable surrogate biomarker for AVP. Another interesting but relatively unexplored issue is the interaction between the osmoregulatory system and mood disorder pathophysiology, given that psychotropic medications often cause dysregulation of AVP receptor expression or signaling that can subsequently lead to clinical syndromes like syndrome of inappropriate diuresis and diabetes insipidus. Finally, pharmaceutical trials of agents that act on V1a and V1b receptor antagonists are still underway. This narrative review summarizes: (1) the neurobiology of the vasopressinergic system in the CNS; (2) the interaction between AVP and the monoaminergic and glutamatergic pathways in the pathophysiology and treatment of mood disorders; (3) the iatrogenic AVP dysregulation caused by psychotropic medications; and (4) the pharmaceutical development of AVP receptor antagonists for the treatment of mood disorders.

Urinary hyaluronidase activity is closely related to vasopressinergic system following an oral water load in men: a potential role in blood pressure regulation and early stages of hypertension development.

Blood pressure (BP) regulation is a complex process involving several factors, among which water-sodium balance holds a prominent place. Arginin-vasopressin (AVP), a key player in water metabolism, has been evoked in hypertension development since the 1980s, but, to date, the matter is still controversial. Hyaluronic acid metabolism has been reported to be involved in renal water management, and AVP appears to increase hyaluronidase activity resulting in decreased high-molecular-weight hyaluronan content in the renal interstitium, facilitating water reabsorption in collecting ducts. Hence, our aim was to evaluate urinary hyaluronidase activity in response to an oral water load in hypertensive patients (HT, n=21) compared to normotensive subjects with (NT+, n=36) and without (NT-, n=29) a family history of hypertension, and to study its association with BP and AVP system activation, expressed by serum copeptin levels and urine Aquaporin 2 (AQP2)/creatinine ratio. Eighty-six Caucasian men were studied. Water load test consisted in oral administration of 15-20 ml of water/kg body weight over 40-45 min. BP, heart rate, serum copeptin, urine hyaluronidase activity and AQP2 were monitored for 4 hours. In response to water drinking, BP raised in all groups with a peak at 20-40 min. Baseline levels of serum copeptin, urinary hyaluronidase activity and AQP2/creatinine ratio were similar among groups and all decreased after water load, reaching their nadir at 120min and then gradually recovering to baseline values. Significantly, a blunted reduction in serum copeptin, urinary hyaluronidase activity and AQP2/creatinine ratio was observed in NT+ compared to NT- subjects. A strong positive correlation was also found between urinary hyaluronidase activity and AQP2/creatinine ratio, and, although limited to the NT- group, both parameters were positively associated with systolic BP. Our results demonstrate for the first time the existence in men of a close association between urinary hyaluronidase activity and vasopressinergic system and suggest that NT+ subjects have a reduced ability to respond to water loading possibly contributing to the blood volume expansion involved in early-stage hypertension. Considering these data, AVP could play a central role in BP regulation by affecting water metabolism through both hyaluronidase activity and AQP2 channel expression.

Effect of delayed diagnosis on neuroendocrine function in individuals with suprasellar germ cell tumors.

The impact of delayed diagnosis on tumor-related prognosis appears to be minimal in individuals with intracranial germ cell tumors (iGCTs). However, its effect on neuroendocrine functions remains unclear. We aimed to assess the effects of delayed diagnosis on neuroendocrine function in individuals with suprasellar GCTs. We conducted a retrospective cohort study of 459 individuals with suprasellar GCTs and categorized them into two groups based on disease duration: delayed diagnosis (> 6 months) and non-delayed diagnosis (≤ 6 months). We compared endocrinological symptoms, neuroendocrine dysfunction and its grading (categorized into 0-3 grades based on severity), and recovery from neuroendocrine dysfunction in both groups. Patients with delayed diagnosis exhibited higher incidences of amenorrhea, slow growth, fatigue, and polyuria/polydipsia. Neuroendocrine dysfunction, including central adrenal insufficiency (CAI), central hypothyroidism (CHT), arginine vasopressin deficiency (AVP-D), growth hormone deficiency, hypogonadism, and hyperprolactinemia, was more pronounced in the delayed diagnosis group at diagnosis, the end of treatment, and the last follow-up. Furthermore, individuals with delayed diagnosis showed higher grades of neuroendocrine dysfunction at diagnosis (OR=3.005, 95% CI 1.929-4.845, p<0.001), end of oncologic treatment (OR=4.802, 95% CI 2.878-8.004, p<0.001), and last follow-up(OR=2.335, 95% CI 1.307-4.170, p=0.005) after adjusting for confounders. Finally, less recovery, particularly in CAI, CHT, and AVP-D, was seen among the group with delayed diagnosis after treatment. Among individuals with suprasellar GCTs, delayed diagnosis is associated with increased, more severe, and less recovered neuroendocrine dysfunction, emphasizing the importance of early diagnosis and treatment to reduce neuroendocrine dysfunction.

GCT-02. OPTIC PATHWAY PRIMARY GERMINOMA: DON´T MISS THE DIAGNOSIS

Abstract BACKGROUND Germ Cell tumors usually arise in the midline of brain; location in optic pathway (OP) is extremely rare. This case illustrates an OP primary Germinoma. METHODS A 9 years old female debuted with diminished visual acuity, it was diagnosed and treated as optic neuritis without improvement, a MRI evidenced a gadolinium enhancement with a very subtle thickening on the optic chiasm, along 3 non conclusive vascular like images in the left Virchow space. A differential diagnosis between endophytic Optic pathway glioma and germ cell tumor was made. RESULTS Assessment of AFP and Sub HCG in both blood and CFS was negative, endocrine evaluation confirmed Diabetes insipidus. A stereotaxic biopsy was performed and Pathology confirmed a Pure Germinoma. Non metastatic disease was confirmed as negative Spine MRI and acellular CFS. As a relevant familiar History the father had testicular Germinoma in his teenage. She was treated with 9 weeks of Carboplatin/V16 and radiotherapy as follows: whole ventricular 24 Gy and primary site 16.5 Gy for a total dose of 40.05 Gy. She is free of tumor at 3 follow up years with improvement in visual acuity and arginine vasopressin dependence. CONCLUSIONS This case illustrates a germ cell tumor primary arising in the optic pathway and aware us to consider it as a differential diagnosis with non-exophytic optic pathway Glioma being the biopsy mandatory to establish the correct diagnosis

The effect of liver surgery and fluid strategy on renin activity and aldosterone and anti-diuretic hormone levels: a secondary analysis of the GALILEO trial

BackgroundIt is unknown whether liver surgery leads to increased RAAS activity and anti-diuretic hormone (ADH) levels and subsequent fluid accumulation. Furthermore, it is unknown whether the peri-operative fluid strategy changes this effect. MethodsThis is a pre-planned post hoc analysis of a randomised controlled trial which compared restrictive (n = 20) versus liberal fluid strategy (n = 20) in patients undergoing liver surgery. Primary outcomes for the current study were the difference in hormone levels after anaesthesia induction and after liver resection. Fluid overload was defined as a ≥10% increase in weight. ResultsRenin activity (6 [2.1–15.5] vs. 12 [4.6–33.5]) and ADH levels (6.0 [1.7–16.3] vs. 3.8 [1.6–14.7]) did not differ significantly before and after resection. However, aldosterone levels were significantly higher after resection (0.30 [0.17–0.49] vs. 0.69 [0.31–1.21] ). Renin activity and aldosterone levels did not differ between the groups. ADH was significantly higher in the restrictive strategy group (1.6 [1.1–2.1] vs 5.9 [3.8–16.0]). No differences in hormone levels were found in patients with and without fluid overload. DiscussionAldosterone levels increased after liver surgery but renin activity and ADH levels did not. ADH levels were higher in the restrictive group. Development of post-operative fluid overload was not associated with RAAS activity or ADH levels.

HYDROALCOHOLIC EXTRACT OF Lepidium draba L. AMELIORATES CAPECITABINE -INDUCED ENTEROCOLITIS IN RATS

This study investigated the protective properties of Lepidium draba L. hydroalcoholic extract (LDHE) against enterocolitis induced by Capecitabine (CT), utilizing biochemical, molecular, and histopathological analyses. A study was conducted involving 50 Wistar rats divided into 5 groups of ten rats over 60 days: healthy, 400 mg/kg LDHE, 20 mg/kg CT, and two co-treatment groups receiving both CT and 200 and 400 mg/kg LDHE groups. On the 61st day, serum nitric oxide, antidiuretic hormone (ADH), arginine vasopressin (AVP), tumor necrosis factor-α, interleukin-6, chemokine C-X-C motif ligand 1 (CXCL-1), and interleukin-1β levels were measured, along with the activity of glutathione peroxidase, catalase, and superoxide dismutase enzymes. To evaluate tissue oxidative stress in the intestine, measurements were taken for FRAP, thiol, and TBARS levels. Apoptosis in the intestine was assessed by examining the Bax/Bcl-2, caspase-3, and p53 expression via real-time PCR. Furthermore, real-time PCR was employed to evaluate water homeostasis by examining the AQP3, AQP8, and AQP10 expression, while protein expression was analyzed using western blotting. LDHE extract effectively regulates inflammatory cytokine levels and modulates ADH and AVP levels, thereby preserving serum and intestinal osmotic balance. Furthermore, it attenuated the Bax/Bcl-2, caspase-3, and p53 mitochondrial apoptotic pathways while enhancing the expression of AQP3, AQP8, and AQP10 genes in intestinal tissue. The study suggests that LDHE holds promise in the treatment of enterocolitis in chemotherapy patients. Keywords: Lepidium draba L., Capecitabine, Intestine, Enterocolitis, Apoptosis, Aquaporins

Elevated arginine vasopressin levels surrogate acute lung injury in acute decompensated heart failure

Elevated arginine vasopressin levels surrogate acute lung injury in acute decompensated heart failure

A case of suprasellar mass with arginine vasopressin deficiency: when necessary acute steroid use serendipitously aids differential diagnoses

A case of suprasellar mass with arginine vasopressin deficiency: when necessary acute steroid use serendipitously aids differential diagnoses

Autoimmune hypothalamitis and hypophysitis due to SLE manifesting as arginine vasopressin deficiency and hypothalamic hyperphagia

Autoimmune hypothalamitis and hypophysitis due to SLE manifesting as arginine vasopressin deficiency and hypothalamic hyperphagia

A case of arginine vasopressin deficiency (AVP-D) due to lymphocytic hypophysitis

A case of arginine vasopressin deficiency (AVP-D) due to lymphocytic hypophysitis

The Never-Ending Story of Hyponatremia: A Current Problem to Overcome.

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and cerebral salt-wasting syndrome (CSWS) are in general associated to refractory hyponatremia especially in patients with neurologic disorders.Extracellular fluid (ECF) assessment is the key to distinguish between SIADH and CSWS.Nevertheless, measurement of the ECF volume is not sufficient to determine the correct etiology and more established diagnostic algorithms are required.

Discovery and evaluation of a novel 18F-labeled vasopressin 1a receptor PET ligand with peripheral binding specificity

The arginine-vasopressin (AVP) hormone plays a pivotal role in regulating various physiological processes, such as hormone secretion, cardiovascular modulation, and social behavior. Recent studies have highlighted the V1a receptor as a promising therapeutic target. In-depth insights into V1a receptor-related pathologies, attained through in vivo imaging and quantification in both peripheral organs and the central nervous system (CNS), could significantly advance the development of effective V1a inhibitors. To address this need, we develop a novel V1a-targeted positron emission tomography (PET) ligand, [18F]V1A-2303 ([18F]8), which demonstrates favorable in vitro binding affinity and selectivity for the V1a receptor. Specific tracer binding in peripheral tissues was also confirmed through rigorous cell uptake studies, autoradiography, biodistribution assessments. Furthermore, [18F]8 was employed in PET imaging and arterial blood sampling studies in healthy rhesus monkeys to assess its brain permeability and specificity, whole-body distribution, and kinetic properties. Our research indicated [18F]8 as a valuable tool for noninvasively studying V1a receptors in peripheral organs, and as a foundational element for the development of next-generation, brain-penetrant ligands specifically designed for the CNS.

Repurposing hemostatic drug desmopressin in AVPR2-expressing triple-negative breast cancer: Target expression analysis and preclinical antineoplastic effects on tumor growth and metastatic progression.

e15087 Background: Desmopressin (dDAVP) is a hemostatic drug that acts as an agonist of the arginine vasopressin receptor 2 (AVPR2) that is present in vascular and malignant cells. Preclinical data show that dDAVP triggers cytostatic mechanisms, blocking angiogenesis and reducing metastases by limiting the survival of circulating tumor cells. Triple-negative breast cancer (TNBC) is associated with poor prognosis due to limited response to therapy and frequent early metastatic recurrence. Considering the unsatisfied clinical need for novel therapeutic options in TNBC, we evaluated the antitumoral activity of dDAVP on experimental models of TNBC, alone or in addition to chemotherapy. We also assessed the expression and clinical impact of AVPR2 in breast cancer samples. Methods: Human and murine TNBC cell lines were used for in vitro experiments. Target expression was assessed by qPCR and immunohistochemistry (IHC), in experimental or clinical tumors (NCT01606072). Effects of dDAVP were evaluated by proliferation, clonogenic, 3D growth and chemotaxis assays, qPCR arrays, and confocal microscopy. Local and distant tumor progression were assessed in vivo in nude or BALB/c mice. TIMER2.0 and UCSC Xena platforms (BRCA TCGA /n = 1260) were used for bioinformatic studies. Results: dDAVP significantly reduced growth and chemotaxis of AVPR2-expressing TNBC cells. Cytostatic effects of dDAVP were associated with altered actin cytoskeleton dynamics and differential expression of angiogenesis and metastasis-related genes. Cooperative effects were observed in vitro and in vivo after combining dDAVP with taxane or alkylating therapy. Tumor-bearing mice were treated with intravenous injections of dDAVP (0.3 µg/kg, thrice weekly) in combination with weekly cycles of paclitaxel (10 mg/kg i.p.) or carmustine (25 mg/kg i.p.). Combination regimens resulted in greater survival and tumor growth and metastasis inhibition. Bioinformatic analysis of the TCGA database showed that AVPR2 had a positive prognostic impact on overall survival in breast cancer patients, especially in the basal-like molecular subtype. AVPR2 also correlated with different immune cell infiltrates such as NK and dendritic cells, and CD4+ and CD8+ T cells. Moreover, AVPR2 expression was detected by IHC in 6/18 breast cancer clinical samples using a small cohort of surgical specimens. Conclusions: AVPR2 expression is associated with improved outcomes in patients with TNBC. Agonist activation of AVPR2 using dDAVP leads to cancer cell growth inhibition in TNBC cell lines and mouse models. We propose dDAVP as a potential novel therapeutic option for treating TNBC either as monotherapy or in combination with chemotherapy. The therapeutic impact of its addition to immune checkpoint inhibitors remains to be explored.

Paraneoplastic neurological syndromes of small cell lung cancer.

This article reviews the relevant literature on paraneoplastic neurological syndromes of small cell lung cancer and discusses the clinical presentation, pathophysiology, and diagnosis of these syndromes. It also includes a summary of the current treatment options for the management of them. Paraneoplastic syndromes are a group of signs and symptoms that develop due to cancer in a remote site, mainly triggered by an autoantibody produced by the tissues involved or lymphocytes during anti-cancer defense. Among the cancers associated with paraneoplastic syndromes, lung cancers are the most common type, with small cell lung cancer being the most common subtype. The most common antibody associated with paraneoplastic syndromes is anti-Hu. Neurological and neuroendocrine syndromes comprise the majority of small cell lung cancer-related paraneoplastic syndromes. Classical paraneoplastic neurological syndromes include inappropriate antidiuretic hormone secretion, Cushing's syndrome, myasthenia gravis, Lambert-Eaton myasthenic syndrome, limbic encephalitis, paraneoplastic cerebellar degeneration, opsoclonus myoclonus ataxia, sensory neuropathy, and chorea. Antibodies mediate paraneoplastic syndromes, and antibody detection is a crucial part of diagnosing these entities. Managing the underlying tumor is the best treatment approach for most paraneoplastic syndromes. Therefore, early diagnosis of small cell lung cancer may significantly improve the prognosis of paraneoplastic syndromes associated with it.

Hypoalbuminemia contributes to ascites formation via sodium and water retention: Evidence from clinical date and albumin deficient mice

Albumin infusions improve circulatory and renal function in patients with decompensated cirrhosis. However, there is no convincing evidence that hypoalbuminemia contributes to ascites formation in liver cirrhosis. The aim of our study is to determine the exact role of hypoalbuminemia in the formation of ascites caused by liver cirrhosis and its underlying mechanism. Clinical profiles of patients with liver cirrhosis retrospectively analyzed. The details of albumin involved in ascites formation were investigated in rat model and murine model. Statistical analysis demonstrated hypoalbuminemia was an independent risk factor for ascites formation in patients with liver cirrhosis (OR = 0.722, P < 0.001). In carbon tetrachloride (CCl4)-induced rat model of liver cirrhosis, a significant reduction in serum albumin was observed in rats with ascites (13.37 g/L) compared with rats without ascites (21.43 g/L, P < 0.001). In thioacetamide (TAA)-treated mice, ascites amount of heterozygous albumin (Alb+/−) mice (112.0 mg) was larger than that of wild-type (Alb+/+) mice (58.46 mg, P < 0.001). In CCl4-induced chronic liver injury, ascites amounts of Alb+/− or Alb+/+ mice were 80.00 mg or 48.46 mg (P = 0.001). Further study demonstrated 24-h urinary sodium excretion in Alb+/− mice was lower than that of Alb+/+ mice in TAA/CCl4-induce murine models of liver cirrhosis. Additionally, serum sodium concentration of Alb+/− mice was lower than that of Alb+/+ mice. In cirrhotic mice, higher level of antidiuretic hormone was observed in Alb+/− mice compared with the control; and renal aquaporin (AQP2) expression in Alb+/− mice was significantly higher than that of WT mice. These revealed hypoalbuminemia contributed to the occurrence of ascites in liver cirrhosis through sodium and water retention.

Atrial Natriuretic Peptide Alleviates Motion Sickness Potentially through Regulating Endolymph Volume in the Inner Ear Increased by Arginine Vasopressin

Introduction: Dimenhydrinate and scopolamine are frequently used drugs, but they cause drowsiness and performance decrement. Therefore, it is crucial to find peripheral targets and develop new drugs without central side effects. This study aimed to investigate the anti-motion sickness action and inner ear-related mechanisms of atrial natriuretic peptide (ANP). Methods: Endolymph volume in the inner ear was measured with magnetic resonance imaging and expression of AQP2 and p-AQP2 was detected with Western blot analysis and immunofluorescence method. Results: Both rotational stimulus and intraperitoneal arginine vasopressin (AVP) injection induced conditioned taste aversion (CTA) to 0.15% sodium saccharin solution and an increase in the endolymph volume of the inner ear. However, intraperitoneal injection of ANP effectively alleviated the CTA behaviour and reduced the increase in the endolymph volume after rotational stimulus. Intratympanic injection of ANP also inhibited rotational stimulus-induced CTA behaviour, but anantin peptide, an inhibitor of ANP receptor A (NPR-A), blocked this inhibitory effect of ANP. Both rotational stimulus and intraperitoneal AVP injection increased the expression of AQP2 and p-AQP2 in the inner ear of rats, but these increases were blunted by ANP injection. In in vitro experiments, ANP addition decreased AVP-induced increases in the expression and phosphorylation of AQP2 in cultured endolymphatic sac epithelial cells. Conclusion: Therefore, the present study suggests that ANP could alleviate motion sickness through regulating endolymph volume of the inner ear increased by AVP, and this action of ANP is potentially mediated by activating NPR-A and antagonising the increasing effect of AVP on AQP2 expression and phosphorylation.

N-Ethylhexedrone: A very long and bad trip! A case series.

N-ethylhexedrone (NEH) is a new cathinone derivative with, currently, low toxicokinetic and toxicodynamic knowledge. We present three documented clinical cases of NEH intoxication with plasma and urine concentrations. A thorough search for metabolites was performed. The three patients were admitted to the emergency department, and two out of the three were hospitalized for an extended period. While recovering from the drug effects, 12-24 h after nasal intake of New Psychoactive Substance (NPS), the patients described the following disorders: anxiety, feelings of persecution, asthenia, anhedonia, abulia, psychomotor slowing and loss of consciousness. NEH was identified in all samples by liquid chromatography-high resolution mass spectrometry (LC-HRMS), and quantified by liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS). Quantitative analysis showed decreasing concentrations over time: for Case 1, from 97.2 (Day 1, D1) to 0.7 (Day 7, D7) µg/L for plasma, and from 724 (D1) to 0.5 (D7) µg/L for urine. NEH concentration of 7.9 µg/L was found in the plasma collected at admission for Case 2. For Case 3, concentrations ranging from 49 (D1) to 1.8 (D7) µg/L in plasma, and from 327.3 (Day 6, D6) to 116.8 (D7) µg/L in urine were found. NEH was no longer detected in the urine sample at Day 10. Elimination half-life was estimated at 19, and 28 hours in Patients 1 and 3, respectively. Four metabolites were identified in blood and urine: reduced NEH, dealkyl-NEH, reduced dealkyl-NEH and hydroxy-NEH. The cases presented highlight the long detectable lifetime of NEH. Characterization of the metabolites will allow better identification of the consumption of this drug. Serious adverse events can be observed after NEH consumption, as two out of the three patients required intubation and ventilation. A syndrome of inappropriate antidiuretic hormone secretion (SIADH) was also diagnosed. Two out of the three cases are notable because of the number of samples collected and because NEH was the only drug of abuse detected.