GDF15 linked to maternal risk of nausea and vomiting during pregnancy.

GDF15, a hormone acting on the brainstem, has been implicated in the nausea and vomiting of pregnancy, including its most severe form, hyperemesis gravidarum (HG), but a full mechanistic understanding is lacking1-4. Here we report that fetal production of GDF15 and maternal sensitivity to it both contribute substantially to the risk of HG. We confirmed that higher GDF15 levels in maternal blood are associated with vomiting in pregnancy and HG. Using mass spectrometry to detect a naturally labelled GDF15 variant, we demonstrate that the vast majority of GDF15 in the maternal plasma is derived from the feto-placental unit. By studying carriers of rare and common genetic variants, we found that low levels of GDF15 in the non-pregnant state increase the risk of developing HG. Conversely, women with ß-thalassaemia, a condition in which GDF15 levels are chronically high5, report very low levels of nausea and vomiting of pregnancy. In mice, the acute food intake response to a bolus of GDF15 is influenced bi-directionally by prior levels of circulating GDF15 in a manner suggesting that this system is susceptible to desensitization. Our findings support a putative causal role for fetally derived GDF15 in the nausea and vomiting of human pregnancy, with maternal sensitivity, at least partly determined by prepregnancy exposure to the hormone, being a major influence on its severity. They also suggest mechanism-based approaches to the treatment and prevention of HG.

The Management of Nausea and Vomiting Not Related to Anticancer Therapy in Patients with Cancer.

OPINION STATEMENT: In cancer patients, the management of nausea and vomiting that is not directly related to treatment is challenging. Much current practice is based on expert opinion and anecdote. Fortunately, over recent years, a number of quality trials have been undertaken to strengthen the evidence base that guides the care of our patients with these distressing symptoms. Much is still unknown however. In this article, we present the latest literature that addresses some of the outstanding issues.

DGAT1 mutations leading to delayed chronic diarrhoea: a case report.

BACKGROUND: Early-onset chronic diarrhoea often indicates a congenital disorder. Mutation in diacylglycerol o-acyltransferase 1 (DGAT1) has recently been linked to early-onset chronic diarrhoea. To date, only a few cases of DGAT1 deficiency have been reported. Diarrhoea in those cases was severe and developed in the neonatal period or within 2 months after birth. CASE PRESENTATION: Here, we report a female patient with DGAT1 mutations with delayed-onset chronic diarrhoea. The patient had vomiting, hypoalbuminemia, hypertriglyceridemia, and failure to thrive at early infancy. Her intractable chronic diarrhoea occurred until she was 8 months of age. A compound heterozygous DGAT1 mutation was found in the patient, which was first found in the Chinese population. Her symptoms and nutrition status improved after nutritional therapy, including a fat restriction diet. CONCLUSIONS: This case expanded our knowledge of the clinical features of patients with DGAT1 mutations. Intractable diarrhoea with delayed onset could also be a congenital disorder.

Dopamine receptors in emesis: Molecular mechanisms and potential therapeutic function.

Dopamine is a member of the catecholamine family and is associated with multiple physiological functions. Together with its five receptor subtypes, dopamine is closely linked to neurological disorders such as schizophrenia, Parkinson's disease, depression, attention deficit-hyperactivity, and restless leg syndrome. Unfortunately, several dopamine receptor-based agonists used to treat some of these diseases cause nausea and vomiting as impending side-effects. The high degree of cross interactions of dopamine receptor ligands with many other targets including G-protein coupled receptors, transporters, enzymes, and ion-channels, add to the complexity of discovering new targets for the treatment of nausea and vomiting. Using activation status of signaling cascades as mechanism-based biomarkers to foresee drug sensitivity combined with the development of dopamine receptor-based biased agonists may hold great promise and seems as the next step in drug development for the treatment of such multifactorial diseases. In this review, we update the present knowledge on dopamine and dopamine receptors and their potential roles in nausea and vomiting. The pre- and clinical evidence provided in this review supports the implication of both dopamine and dopamine receptor agonists in the incidence of emesis. Besides the conventional dopaminergic antiemetic drugs, potential novel antiemetic targeting emetic protein signaling cascades may offer superior selectivity profile and potency.

The effect of ginger (Zingiber officinale Roscoe) in patients with advanced cancer.

BACKGROUND: Anorexia-cachexia syndrome (ACS) is a complex condition in advanced cancer patients, defined by disproportionate loss of skeletal muscle mass, and a lack or loss of appetite. This condition greatly lowers the quality of life and limits the treatment options. ACS is commonly associated with gastrointestinal symptoms such as nausea and vomiting. Ginger has been successful in treating these symptoms but has not yet been tested on patients with advanced cancer. Electrogastrography is a technology that allows the direct recording of the gastric myoelectrical activity (GMA). PURPOSE: The aim of this study is to (1) determine the effects of ginger on the GMA in these patients, (2) evaluate the subjective symptoms using 3 validated scales, and (3) correlate the level of inflammatory factors and ghrelin in this patient population. METHODS: Patients with ACS and advanced cancer were recruited from the Palliative Rehabilitation outpatient program at Elisabeth Bruyère Hospital. Patients were instructed to take a daily capsule of 1650 mg of ginger for 14 days and outcome measures were recorded at pre- and post-intervention, which included a blood test for analysis of CRP, albumin and ghrelin levels, 3 self-administered surveys (DSSI, PG-SGA, ESAS), patient-reported symptoms, and an EGG diagnosis. RESULTS: Fifteen patients with a median age of 58 and varying cancer diagnoses were enrolled. EGG diagnosis showed that 9 of the 15 patients had a direct improvement in their GMA, and all patients showed improvement in reported symptoms, most notably nausea, dysmotility- and reflux-like symptoms. There was no correlation found for ginger administration and inflammatory factors. CONCLUSION: These findings suggest that ginger may improve GMA as measured by EGG and may have a notable effect on symptom improvement.

Effect of paroxetine on intestinal motility in the presence of ondansetron.

Chemotherapy, radiotherapy, surgery and depression are the conditions that run in parallel fashions. All these conditions cause the release of an increased amount of serotonin in the body. Serotonin acts on these 5HT3 receptors and causes nausea and vomiting. Ondansetron acts by blocking serotonin from acting on the receptors and thus is useful in decreasing episodes of nausea and vomiting but when used concomitantly with SSRIs (selective serotonin reuptake inhibitors) as cancer patient also suffered from depression. This combination tends to decrease the efficacy of ondansetron. The present study was carried out to observe the modulatory role of ondansetron on ileal smooth muscle motility in vitro. Experiments were performed in four groups (n=6) and ileal smooth muscle activity was recorded on the power lab (USA). The effects of increasing concentrations of serotonin, ondansetron and paroxetine alone were observed. In the fourth group effects of paroxetine in the presence of fixed concentration (1ml) of ondansetron (10-6M) was observed. The maximum response obtained by serotonin served as a control for our study (100%). Paroxetine response on intestinal motility was completely blocked in the presence of ondansetron. Our findings hence, reinforce the hypothesis that paroxetine decreases the antiemetic activity of serotonin antagonist ondansetron, by super sensitization of serotonergic receptors resulting in an increased incidence of nausea and vomiting in cancer patient despite adequate antiemetic prophylaxis.

Absorption, metabolism, and excretion of the antiemetic rolapitant, a selective neurokinin-1 receptor antagonist, in healthy male subjects.

Rolapitant is a neurokinin-1 receptor antagonist that is approved in combination with other antiemetic agents in adults for the prevention of delayed nausea and vomiting (CINV) associated with initial and repeat courses of emetogenic cancer chemotherapy, including but not limited to highly emetogenic chemotherapy. Here, we assessed the absorption, metabolism, and excretion of 14C-labeled rolapitant in healthy male subjects. Rolapitant was administered as a single 180-mg oral dose containing approximately 100 µCi of total radioactivity, with plasma, urine, and fecal samples collected at defined intervals after dosing. Rolapitant had a large apparent volume of distribution, indicating that it is widely distributed into body tissues. Rolapitant was slowly metabolized and eliminated with a mean half-life of 186 h. Exposure to the major metabolite of rolapitant, C4-pyrrolidinyl hydroxylated rolapitant or M19, was approximately 50% of rolapitant exposure in plasma. Renal clearance was not a significant elimination route for rolapitant-related entities. Total radioactivity recovered in urine accounted for 14.2% of the dose, compared to 72.7% recovery in feces. Adverse events (AEs) were generally mild; there were no serious AEs, and no clinically significant changes in laboratory or electrocardiogram parameters were observed. The combination of rolapitant safety, its long half-life, extensive tissue distribution, and slow elimination via the hepatobiliary route (rather than renal excretion) suggest suitability that a single dose of rolapitant may provide protection against CINV beyond the first 24 h after chemotherapy administration.

Natural Negative Allosteric Modulators of 5-HT3 Receptors.

Chemotherapy-induced nausea and vomiting (CINV) remain the most common and devastating side-effects associated with cancer chemotherapy. In recent decades, several lines of research emphasize the importance of 5-hydroxytryptamine3 (5-HT3; serotonin) receptors in the pathogenesis and treatment of CINV. 5-HT3 receptors are members of ligand-gated ion channels that mediate the rapid and transient membrane-depolarizing effect of 5-HT in the central and peripheral nervous system. These receptors play important roles in nausea and vomiting, as well as regulation of peristalsis and pain transmission. The development of antagonists for 5-HT3 receptor dramatically improved the treatment of CINV in cancer patients. In fact, the most common use of 5-HT3 receptor antagonists to date is the treatment of nausea and vomiting. In recent years, there has been an increasing tendency to use natural plant products as important therapeutic entities in the treatment of various diseases. In this article, we examined the results of earlier studies on the actions of natural compounds on the functional properties of 5-HT3 receptors. It is likely that these natural modulators of 5-HT3 receptors can be employed as lead structures for the synthesis of therapeutic agents for treating CINV in future clinical studies.

Ginger-Mechanism of action in chemotherapy-induced nausea and vomiting: A review.

Despite advances in antiemetic therapy, chemotherapy-induced nausea and vomiting (CINV) still poses a significant burden to patients undergoing chemotherapy. Nausea, in particular, is still highly prevalent in this population. Ginger has been traditionally used as a folk remedy for gastrointestinal complaints and has been suggested as a viable adjuvant treatment for nausea and vomiting in the cancer context. Substantial research has revealed ginger to possess properties that could exert multiple beneficial effects on chemotherapy patients who experience nausea and vomiting. Bioactive compounds within the rhizome of ginger, particularly the gingerol and shogaol class of compounds, interact with several pathways that are directly implicated in CINV in addition to pathways that could play secondary roles by exacerbating symptoms. These properties include 5-HT3, substance P, and acetylcholine receptor antagonism; antiinflammatory properties; and modulation of cellular redox signaling, vasopressin release, gastrointestinal motility, and gastric emptying rate. This review outlines these proposed mechanisms by discussing the results of clinical, in vitro, and animal studies both within the chemotherapy context and in other relevant fields. The evidence presented in this review indicates that ginger possesses multiple properties that could be beneficial in reducing CINV.

Cannabinoid signaling in health and disease.

Cannabis sativa has long been used for medicinal purposes. To improve safety and efficacy, compounds from C. sativa were purified or synthesized and named under an umbrella group as cannabinoids. Currently, several cannabinoids may be prescribed in Canada for a variety of indications such as nausea and pain. More recently, an increasing number of reports suggest other salutary effects associated with endogenous cannabinoid signaling including cardioprotection. The therapeutic potential of cannabinoids is therefore extended; however, evidence is limited and mechanisms remain unclear. In addition, the use of cannabinoids clinically has been hindered due to pronounced psychoactive side effects. This review provides an overview on the endocannabinoid system, including known physiological roles, and conditions in which cannabinoid receptor signaling has been implicated.

5-HT3 receptors as important mediators of nausea and vomiting due to chemotherapy.

Chemotherapy-induced nausea and vomiting (CINV) is associated with a significant deterioration in quality of life. The emetogenicity of the chemotherapeutic agents, repeated chemotherapy cycles, and patient risk factors significantly influence CINV. The use of a combination of a 5-hydroxytryptamine-3 (5-HT3) receptor antagonist, dexamethasone, and a neurokinin-1 (NK-1) receptor antagonist has significantly improved the control of acute and delayed emesis in single-day chemotherapy. The first generation 5-HT3 receptor antagonists have been very effective in the control of chemotherapy induced emesis in the first 24 h postchemotherapy (acute emesis), but have not been as effective against delayed emesis (24-120 h postchemotherapy). Palonosetron, a second generation 5-HT3 receptor antagonist with a different half-life, a different binding capacity, and a different mechanism of action than the first generation 5-HT3 receptor antagonists appears to be the most effective agent in its class. Despite the control of emesis, nausea has not been well controlled by current agents. Olanzapine, a FDA approved antipsychotic that blocks multiple neurotransmitters: dopamine at D1, D2, D3, D4 brain receptors, serotonin at 5-HT2a, 5-HT2c, 5-HT3, 5-HT6 receptors, catecholamines at alpha1 adrenergic receptors, acetylcholine at muscarinic receptors, and histamine at H1 receptors, has emerged in recent trials as an effective preventative agent for chemotherapy-induced emesis and nausea, as well as a very effective agent for the treatment of breakthrough emesis and nausea. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

Drug-drug interaction profile of components of a fixed combination of netupitant and palonosetron: Review of clinical data.

Neurokinin-1 (NK1) receptor antagonists (RAs) are commonly coadministered with serotonin (5-HT3) RAs (e.g. palonosetron (PALO)) to prevent chemotherapy-induced nausea/vomiting. Netupitant/palonosetron (NEPA), an oral fixed combination of netupitant (NETU)-a new NK1 RA-and PALO, is currently under development. In vitro data suggest that NETU inhibits CYP3A4 and is a substrate for and weak inhibitor of P-glycoprotein (P-gp). This review evaluates potential drug-drug interactions between NETU or NEPA and CYP3A4 substrates/inducers/inhibitors or P-gp substrates in healthy subjects. Pharmacokinetic (PK) parameters were evaluated for each drug when NETU was coadministered with PALO (single doses) and when single doses of NETU or NEPA were coadministered with CYP3A4 substrates (erythromycin (ERY), midazolam (MID), dexamethasone (DEX), or oral contraceptives), inhibitors (ketoconazole (KETO)), or inducers (rifampicin (RIF)), or a P-gp substrate (digoxin (DIG)). Results showed no relevant PK interactions between NETU and PALO. Coadministration of NETU increased MID and ERY exposure and significantly increased DEX exposure in a dose-dependent manner; NETU exposure was unaffected. NEPA coadministration had no clinically significant effect on oral contraception, although levonorgestrel exposure increased. NETU exposure increased after coadministration of NEPA with KETO and decreased after coadministration with RIF; PALO exposure was unaffected. NETU coadministration did not influence DIG exposure. In conclusion, there were no clinically relevant interactions between NETU and PALO, or NEPA and oral contraceptives (based on levonorgestrel and ethinylestradiol exposure). Coadministration of NETU or NEPA with CYP3A4 inducers/inhibitors/substrates should be done with caution. Dose reduction is recommended for DEX. Dose adjustments are not needed for NETU coadministration with P-gp substrates.

Oxidative damage induced by retching; antiemetic and neuroprotective role of Sambucus ebulus L.

Nausea and vomiting are the most common symptoms in different diseases. Medicinal plants are considered as a reliable source of new drugs to control these symptoms. In this study, we evaluated the antiemetic and neuroprotective effects of the methanolic extract of Sambucus ebulus L. fruit and relationship between emesis (retching) and oxidative stress biomarkers in the mitochondria brain of young chickens. Emesis was induced by ipecac and copper sulphate (60 and 600 mg/kg, orally), respectively, and the methanolic extracts (50, 100, 200 mg/kg) were injected intraperitoneally (i.p.). The extract showed a significant antiemetic activity against ipecac and copper sulphate-induced emesis at all doses (p<0.001; percentages of retching inhibition 46, 96.5 and 83% against ipecac and 73, 79.5 and 69.2% against copper sulphate, respectively). Lipid peroxidation (LPO) was significantly decreased (p<0.001) at all doses of extract in retching induced by copper sulphate, and catalase (CAT) activity significantly increased (p<0.05) in the extract (50 mg/kg) and metoclopromide groups in retching induced by ipecac in the chickens' brain mitochondria. Protein carbonyl (PC) contents significantly (p<0.05) decreased only in extract (100 mg/kg) group in retching induced by ipecac. Mitochondria function (MTT assay) significantly increased by extract (100 mg/kg) as compared to control group in retching induced by ipecac. The results of this study suggests that the extract has protective effects, possibly by central and peripheral mechanisms, and neuroprotective effect by increasing plasma antioxidants or scavenging of free radicals induced by retching. It seems that extract could prevent protein modification and improve oxidative stress in the early stages.

Anti-emetic mechanisms of Zingiber officinale against cisplatin induced emesis in the pigeon; behavioral and neurochemical correlates.

BACKGROUND: Zingiber officinale (ZO, family Zingiberaceae) has been reported for its antiemetic activity against cancer chemotherapy induced emesis in animal models and in clinics. Current study was designed to investigate ZO for potential usefulness against cisplatin induced vomiting in pigeon and its effects on central and peripheral neurotransmitters involved in the act of vomiting. METHODS: Zingiber officinale acetone fraction (ZO-ActFr) was investigated for attenuation of emesis induced by cisplatin in healthy pigeons. Neurotransmitters DA, 5HT and their metabolites DOPAC, HVA and 5HIAA were analyzed using High Performance Liquid Chromatography system coupled with electrochemical detector in area postrema, brain stem and intestine. Antiemetic effect of ZO-ActFr was correlated with central and intestinal neurotransmitters levels in pigeon. RESULTS: Cisplatin (7 mg/kg i.v.) induced emesis without lethality upto the observation period. ZO-ActFr (25, 50 & 100 mg/kg) attenuated cisplatin induced emesis ~ 44.18%, 58.13% (P < 0.05) and 27.9%, respectively; the reference drug, metoclopramide (MCP; 30 mg/kg), produced ~ 48.83% reduction (P < 0.05). ZO-ActFr reduced (P < 0.05 - 0.001) 5-hydroxytryptamine (5HT) concentration in the area postrema, brain stem and intestine at 3(rd) hour of cisplatin administration, while at the 18(th) hour ZO treatments attenuated the dopamine upsurge (P < 0.001) caused by cisplatin in the area postrema and 5HT concentration (P < 0.01 - 0.001) in the brain stem and intestine. ZO treatments alone did not altered the basal neurotransmitters and their metabolites in the brain areas and intestine. CONCLUSION: The behavioral study verify the antiemetic profile of ZO against cisplatin induced emesis in the pigeon, where central and peripheral neural evidences advocate the involvement of serotonergic mechanism at initial time point (3(rd) hr), while the later time point (18(th) hr) is associated with serotonergic and dopaminergic component in the mediation of its antiemetic effect.

Theoretical evaluation of antiemetic effects of 5-HT3 receptor antagonists for prevention of vomiting induced by cisplatin.

5-HT(3) receptor antagonists are widely used as antiemetic agents in clinical setting, of which palonosetron, with a long elimination half life (t(1/2)), has recently become available. It is important to evaluate the concentration of serotonin when investigating the antiemetic effects of 5-HT(3) receptor antagonists, as those effects are not based solely on the t(1/2) value. We theoretically evaluated the antiemetic effects of three 5-HT(3) receptor antagonists (granisetron, azasetron, palonosetron) on cisplatin-induced nausea and vomiting by estimating the time course of the 5-HT(3) receptor occupancy of serotonin. We estimated the 5-HT(3) receptor occupancy of serotonin in the small intestine, based on the time course of plasma concentration of each 5-HT(3) receptor antagonist and the time course of concentration of serotonin near the 5-HT(3) receptor in the small intestine after administration of cisplatin. The antiemetic effect of each 5-HT(3) receptor antagonist was evaluated based on the normal level of 5-HT(3) receptor occupancy of serotonin. Our results suggest that an adequate antiemetic effect will be provided when a dose of 75 mg/m(2) of cisplatin is given to patients along with any single administration of granisetron, azasetron, or palonosetron at a usual dose. On the other hand, the 5-HT(3) receptor occupancy of serotonin was found to be significantly lower than normal for several days after administration of palonosetron, as compared to granisetron and azasetron, indicating that constipation may be induced. Our results show that granisetron, azasetron, and palonosetron each have an adequate antiemetic effect after administration of 75 mg/m(2) of cisplatin.

[MODERN APPROACHES TO THE DIAGNOSIS AND TREATMENT OF CHEMOTHERAPY TOXICITY IN PATIENTS WITH BREAST CANCER].

The use of modern chemotherapy (CT) allowed to achieve significant progress in the treatment of many malignant tumors that were previously considered fatal. Improving the efficiency of the treatment was achieved by the intensification of chemotherapy. However, intensification of chemotherapy regimes provoked increase in the number of side effects of anticancer therapy,which often lead to a decrease in the intensity of the selected mode, the additional financial costs of treating the complications and the formation of the negative attitude of the patient to treatment. Thus, the side effects of chemotherapy are the actual problem of modern oncology. The purpose of this literature review was to investigate the frequency, symptoms and ways to prevent and treat various types of toxicity of chemotherapy.

Involvement of substance P and the NK-1 receptor in human pathology.

The peptide substance P (SP) shows a widespread distribution in both the central and peripheral nervous systems, but it is also present in cells not belonging to the nervous system (immune cells, liver, lung, placenta, etc.). SP is located in all body fluids, such as blood, cerebrospinal fluid, breast milk, etc. i.e. it is ubiquitous in human body. After binding to the neurokinin-1 (NK-1) receptor, SP regulates many pathophysiological functions in the central nervous system, such as emotional behavior, stress, depression, anxiety, emesis, vomiting, migraine, alcohol addiction, seizures and neurodegeneration. SP has been also implicated in pain, inflammation, hepatitis, hepatotoxicity, cholestasis, pruritus, myocarditis, bronchiolitis, abortus, bacteria and viral infection (e.g., HIV infection) and it plays an important role in cancer (e.g., tumor cell proliferation, antiapoptotic effects in tumor cells, angiogenesis, migration of tumor cells for invasion, infiltration and metastasis). This means that the SP/NK-1 receptor system is involved in the molecular bases of many human pathologies. Thus, knowledge of this system is the key for a better understanding and hence a better management of many human diseases. In this review, we update the involvement of the SP/NK-1 receptor system in the physiopathology of the above-mentioned pathologies and we suggest valuable future therapeutic interventions involving the use of NK-1 receptor antagonists, particularly in the treatment of emesis, depression, cancer, neural degeneration, inflammatory bowel disease, viral infection and pruritus, in which that system is upregulated.

Safety and pharmacokinetic evaluation of repeated intravenous administration of palonosetron 0.75 mg in patients receiving highly or moderately emetogenic chemotherapy.

PURPOSE: The aims of this study were to evaluate the safety, efficacy, and pharmacokinetics of repeated doses of palonosetron 0.75 mg on days 1 and 3 in Japanese patients who received highly or moderately emetogenic chemotherapy. METHODS: Twenty- six patients received palonosetron 0.75 mg intravenously before chemotherapy on days 1 and 3 plus dexamethasone (12-16 mg before chemotherapy on day 1 and 4-8 mg on days 2 and 3). The primary endpoints were safety and pharmacokinetics. Pharmacokinetics were evaluated in a subset of patients (n=6). Complete response and complete protection were evaluated as secondary endpoints. RESULTS: The accumulation ratios for C max and AUClast after the second dose on day 3 were 1.42 and 1.37, respectively. These values were consistent with the theoretical values expected from the half-life of palonosetron on day 1. Almost all of the patients had no nausea or vomiting in the acute phase (complete response (CR) rate, 96.2% [25/26]; CP rate, 92.3% [24/26]). In the delayed phase (24-192 h post-chemotherapy), the complete response and complete protection rates were 76.9% (20/26) and 61.5% (16/26), respectively. Treatment was well tolerated. CONCLUSIONS: This is the first study to report the pharmacokinetics of multiple doses of palonosetron 0.75 mg, given on days 1 and 3, in Japanese patients. Repeated treatment with palonosetron was safe and well tolerated by patients who received highly or moderately emetogenic anticancer chemotherapy.

Characterizing a new tool to manipulate area postrema GLP1R+ neurons across species.

Nausea is an uncomfortable sensation that accompanies many therapeutics, especially diabetes treatments involving glucagon-like peptide-1 receptor (GLP1R) agonists. Recent studies in mice have revealed that GLP1R-expressing neurons in the area postrema play critical roles in nausea. Here, we characterized a ligand-conjugated saporin that can efficiently ablate GLP1R+ cells from humans, mice, and the Suncus murinus, a small animal model capable of emesis. This new tool provides a strategy to manipulate specific neural pathways in the area postrema in the Suncus murinus and may help elucidate roles of area postrema GLP1R+ neurons in emesis during therapeutics involving GLP1R agonists.