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

The efficacy and safety of Xiao-Ban-Xia-Tang in the treatment of chemotherapy-induced nausea and vomiting: A systematic review and meta-analysis

Background

Chemotherapy-induced nausea and vomiting (CINV) is one of the most frequent and critical side effects due to chemotherapeutics. In China, Xiao-Ban-Xia-Tang (XBXT) has already been applied extensively to prevent and treat CINV. However, there is limited testimony on the effectiveness and safety of this purpose, and there was no correlative systematic review. The aim of this review was to systematically evaluate the effectiveness and safety of XBXT in preventing and treating CINV.

Methods

The systematic search was conducted in eight databases to acquire randomized controlled trials (RCTs) that appraised the effect of XBXT in treating CINV. The vomiting and nausea relief efficiency, eating efficiency, quality of life, and adverse reactions were explored for efficacy assessment. Bias risk was rated by manipulating the Cochrane risk of bias tool 2.0 (RoB 2). The retrieved investigations were analyzed by utilizing ReviewManager 5.4 and Stata 17.0. The quality of evidence was evaluated adopting the GRADE tool.

Results

A total of 16 clinical RCTs of XBXT in the treatment of CINV were incorporated into the investigation, with a total of 1246 participants. The meta-analysis showed that compared with conventional antiemetic drugs, XBXT and antiemetics improved the vomiting relief efficiency (RR 1.35, 95% confidence interval: 1.25-1.46, p < 0.00001), nausea relief efficiency (N = 367, RR 1.23, 95% CI: 1.09-1.38, p < 0.00001), and quality of life (RR = 1.37, 95% CI: 1.14-1.65, p = 0.0009) and reduced the adverse events (N = 370, RR 0.53, 95% CI: 0.29-0.96, p = 0.04). XBXT and DARAs raised eating efficiency compared with DARAs (N = 208, RR 1.30, 95% CI: 1.07-1.57, p = 0.007). The data existed as statistically significant, and the publication bias was identified as relatively low from the funnel plot and trim and fill analysis. In addition, sensitivity analysis demonstrated robust outcomes. The quality of evidence for each outcome ranged from moderate to high.

Conclusion

There is some encouraging evidence that XBXT and antiemetics had better therapeutic effects and safety in treating CINV than antiemetic drugs alone. The quality assessment and low publication bias indicated that the overall criterion was scientific. Better research is required to verify the evidence designed with large-scale RCTs and rigorous methods.

Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=281046.

Electrical acupoint stimulation for the treatment of chemotherapy-induced nausea and vomiting: A systematic review and meta-analysis

Background

Chemotherapy-induced nausea and vomiting (CINV) is the most common adverse effect of chemotherapy and affects the continuation of chemotherapy in cancer patients. Electrical acupoint stimulation (EAS), which includes electroacupuncture and transcutaneous electrical stimulation (TES), has been used to treat CINV. This meta-analysis aimed to evaluate the efficacy of EAS in the treatment of CINV.

Methods

Randomized controlled trials (RCTs) of EAS for CINV retrieved form five key databases. Two researchers independently performed article screening, data extraction and data integration. The Cochrane Collaboration's tool for assessing risk of bias was used to assesse the methodological quality according to Cochrane Handbook for Systematic Reviews of Interventions. RevMan 5.4 was used to perform analyses.

Results

10 RCTs with a total of 950 participants were included. The results showed that there was no significant difference between EAS compared to sham EAS in terms of increasing the rate of complete control of CINV and decreasing the overall incidence of CINV [RR = 1.26, 95 % CI (0.96, 1.66), P = 0.95; RR = 1.16, 95 % CI (0.97, 1.40), p = 0.71]. In terms of CINV severity, EAS reduced the occurrence of moderate-to-severe CINV [RR = 0.60, 95 % CI (0.38, 0.94), P = 0.03; RR = 0.50, 95 % CI (0.33, 0.76), P = 0.001].

Conclusion

EAS could improve moderate-to-severe CINV. However, EAS did not show a significant difference in reducing overall incidence and improving complete control rates compared with sham EAS. Due to limitations in the quality of the included articles, the available studies are insufficient to have sufficient evidence to confirm the efficacy of EAS for CINV. Validation with rigorously designed, large-sample, high-quality clinical trial studies may also be needed.

A new experimental rat model of nocebo-related nausea involving double mechanisms of observational learning and conditioning

AIM

The nocebo effect, such as nausea and vomiting, is one of the major reasons patients discontinue therapy. The underlying mechanisms remain unknown due to a lack of reliable experimental models. The goal of this study was to develop a new animal model of nocebo-related nausea by combining observational learning and Pavlovian conditioning paradigms.

METHODS

Male Sprague-Dawley rats with nitroglycerin-induced migraine were given 0.9% saline (a placebo) or LiCl (a nausea inducer) following headache relief, according to different paradigms.

RESULTS

Both strategies provoked nocebo nausea responses, with the conditioning paradigm having a greater induction impact. The superposition of two mechanisms led to a further increase in nausea responses. A preliminary investigation of the underlying mechanism revealed clearly raised peripheral and central cholecystokinin (CCK) levels, as well as specific changes in the 5-hydroxytryptamine and cannabinoid systems. Brain networks related to emotion, cognition, and visceral sense expressed higher c-Fos-positive neurons, including the anterior cingulate cortex (ACC), insula, basolateral amygdala (BLA), thalamic paraventricular nucleus (PVT), hypothalamic paraventricular nucleus (PVN), nucleus tractus solitarius (NTS), periaqueductal gray (PAG), and dorsal raphe nucleus-dorsal part (DRD). We also found that nausea expectances in the model could last for at least 12 days.

CONCLUSION

The present study provides a useful experimental model of nocebo nausea that might be used to develop potential molecular pathways and therapeutic strategies for nocebo.

Analysis of the Efficacy and Safety of Palonosetron Hydrochloride in Preventing Nausea And Vomiting After TACE: A Retrospective Analysis

PURPOSE

To investigate the mechanism of nausea and vomiting after TACE, and analyze the efficacy and safety of palonosetron hydrochloride in the prevention of nausea and vomiting after TACE.

METHODS

The data of 221 patients who underwent TACE in the Department of Intervention Therapy from August 2018 to August 2020 were collected. The patients were divided into two groups: those who did not use palonosetron hydrochloride before TACE (TACE group, N=116); and those who used palonosetron hydrochloride before TACE (TACE+palonosetron group, N=105). Primary study endpoint: The control rate of nausea and vomiting in the two groups at 0-24 h (acute), 24-120 h (delayed), and 0-120 h. Secondary Study Endpoints: Adverse events of palonosetron hydrochloride.

RESULTS

TACE group vs TACE+palonosetron group: 0-24 h, 74 vs. 44 patients with nausea (63.8% vs. 41.9%); 24-120 h, 50 vs. 16 patients with nausea (43.1% vs. 15.2%); 0-120 h after TACE, 81 vs. 50 patients with nausea (69.8% vs. 47.6%). 0-24 h, 52 vs. 26 patients with vomiting (44.8% vs. 24.8%); 24-120 h, 24 vs. 8 patients with vomiting (20.7% vs. 7.6%); 0-120 h after TACE, 64 vs. 26 patients with vomiting (55.2% vs. 24.8%). The incidence of nausea and vomiting after TACE was significantly lower in the TACE+palonosetron group than in the TACE group (p < 0.05).

CONCLUSION

Palonosetron hydrochloride can significantly reduce the incidence of nausea and vomiting in patients after TACE, with exact effect and high safety.

Mechanisms of SSRI Therapy and Discontinuation

SSRIs are one of the most widely used drug therapies in primary care and psychiatry, and central to the management of the most common mental health problems in today's society. Despite this, SSRIs suffer from a slow onset of therapeutic effect and relatively poor efficacy as well as adverse effects, with recent concerns being focused on a disabling SSRI discontinuation syndrome. The mechanism underpinning their therapeutic effect has long shifted away from thinking that SSRIs act simply by increasing 5-HT in the synapse. Rather, a current popular view is that increased 5-HT is just the beginning of a series of complex downstream signalling events, which trigger changes in neural plasticity at the functional and structural level. These changes in plasticity are then thought to interact with neuropsychological processes to enhance re-learning of emotional experiences that ultimately brings about changes in mood. This compelling view of SSRI action is underpinning attempts to understand fast-acting antidepressants, such as ketamine and psychedelic drugs, and aid the development of future therapies. An important gap in the theory is evidence that changes in plasticity are causally linked to relevant behavioural effects. Also, predictions that the SSRI-induced neural plasticity might have applicability in other areas of medicine have not yet been borne out. In contrast to the sophisticated view of the antidepressant action of SSRIs, the mechanism underpinning SSRI discontinuation is little explored. Nevertheless, evidence of rebound increases in 5-HT neuron excitability immediately on cessation of SSRI treatment provide a starting point for future investigation. Indeed, this evidence allows formulation of a mechanistic explanation of SSRI discontinuation which draws on parallels with the withdrawal states of other psychotropic drugs.

Influence of menopause on chemotherapy-induced nausea and vomiting in highly emetogenic chemotherapy for breast cancer: A retrospective observational study

BACKGROUND

Female sex and younger age are reported risk factors for chemotherapy-induced nausea and vomiting (CINV) in highly emetogenic chemotherapy, but the underlying mechanism has not been elucidated. The purpose of this study was to clarify the impact of menopause on CINV.

METHODS

This retrospective observational study analyzed data from consecutive patients who received their first cycle of perioperative anthracycline-based chemotherapy for breast cancer between January 2018 and June 2020. The endpoints were association between CINV (vomiting, ≥Grade 2 nausea, complete response [CR] failure) and menopause as well as the association between CINV and follicle-stimulating hormone [FSH]/estradiol [E2].

RESULTS

Data for 639 patients were analyzed. Among these patients, 109 (17.1%) received olanzapine (four antiemetic combinations) and 530 (82.9%) did not (three antiemetic combinations). Premenopausal state (amenorrhea lasting ≥12 months) was significantly associated with ≥Grade 2 nausea and CR failure in univariate analysis but not in multivariate analysis. The premenopausal FSH/E2 group (defined by serum levels; FSH <40 mIU/mL and E2 ≥20 pg/mL) had a significantly higher rate of ≥Grade 2 nausea than the postmenopausal FSH/E2 group (FSH ≥40 mIU/mL and E2 <20 pg/mL) (48.8% vs. 18.8%, p = 0.023).

CONCLUSIONS

Our results suggest that changes in FSH and E2 due to menopause may affect the severity of nausea and that FSH and E2 (especially FSH) levels might be useful indicators for CINV risk assessment.

Metoclopramide as a Potential Antipsychotic Against Long-Term Methionine Exposure in Zebrafish

Methionine (MET) contributes to brain function and is required for proper functioning of the central nervous system. However, exceptionally high levels of MET and its metabolites in plasma have been found to be toxic and can lead to cell alterations. Long-term exposure to MET has been shown to mimic psychotic symptoms in schizophrenic patients and rodents. The present study evaluated behavioral and neurochemical effects of long-term exposure to MET in zebrafish. Five groups of zebrafish were exposed to MET at a concentration of 4.5 mM for 7 days, along with acute exposure to 25 μM of clozapine and 750, 1000, and 1250 μM of metoclopramide. In contrast, the normal group was exposed to only water and dimethyl sulfoxide. After the treatment, social interaction, anxiety, memory, and locomotion of zebrafish and serotonin levels in zebrafish brains were evaluated. Our results showed that metoclopramide was not only beneficial in improving MET-induced cognitive impairment but it also prevented social withdrawal in zebrafish exposed to MET. In addition, metoclopramide reversed anxiety-like behavior, as indicated by significant changes in locomotion activity. Despite slight changes in serotonin levels in the zebrafish brain, an in vitro serotonin assay failed to demonstrate significant differences between the disease control, normal, and two treatment groups. Finally, results from the study showed that repeated administration of MET induced schizophrenia-like symptoms, although metoclopramide ameliorated the MET-mediated negative symptoms and cognitive deficits in zebrafish. Overall, our findings suggest a new perspective to further explore the antipsychotic properties of metoclopramide.

Intranasal ondansetron microemulsion counteracting the adverse effects of cisplatin: animal study

BACKGROUND

Cisplatin is considered one of the most effective and commonly used chemotherapeutic drugs, but despite its high therapeutic effectiveness, most patients treated with cisplatin suffer from nausea and vomiting, neurotoxic side effects, and cerebral psychiatric disorders such as depression. Therefore, the aim of the current work was to explore whether a selective 5-HT₃ receptor antagonist (Ondansetron) administered via the oral route or intranasally in microemulsion form would alleviate cisplatin's adverse effects.

METHODS

The selected ondansetron microemulsion was characterized in vitro for particle size, polydispersity, zeta potential, morphology, and nasal permeation, and in vivo in terms of anti-emetic and antidepressant activity, with the assessment of biochemical markers in brain homogenates.

RESULTS

Results revealed that both orally administered ondansetron and intranasally administered microemulsion were able to counteract the pica effect by increasing food consumption, water intake, and decreasing kaolin intake. They were also able to increase BDNF, normalize IL-6, increase serotonin, and normalize NOx, MDA, GSSH/GSH as well as 8OHdG levels in rats' brain homogenates. The intranasal ondansetron microemulsion displayed superiority compared to oral conventional ondansetron in terms of increasing food intake, reduction of stomach content, and normalization of serotonin turnover.

CONCLUSION

Ondansetron microemulsion can be administered by an alternative route of administration (intranasal) rather than oral, for patients on cisplatin chemotherapy.

The Clinical Observation on PONV with the Intervention of Thumbtack Needles Combined with Chinese Medicine Ironing Therapy

Objective

This study aimed to analyze the clinical efficacy of the intervention of thumbtack needles (applicable to subcutaneous embedding) combined with Chinese medicine ironing therapy on postoperation nausea and vomiting (PONV).

Methods

106 patients who scheduled elective surgery were enrolled and randomized into control group and experimental group, with 53 cases in each group. The control group received modern medication, while the experimental group was given thumbtack needles combined with Chinese medicine ironing therapy based on the control group. The PONV score, incidence rate, gastrointestinal hormone level, Functional Living Index-Emesis (FLIE), and General Comfort Questionnaire (GCQ) of the two groups were compared.

Results

After treatment, the incidence of PONV and GCQ in the experimental group was observed to be remarkably lower than that in the control group (P < 0.05), while the levels of gastrointestinal hormones and the level in the FLIE of the experimental group were comparatively higher than those in the control group (P < 0.05).

Conclusion

Thumbtack needles combined with Chinese medicine ironing therapy can be utilized to reduce the incidence of PONV, to improve the level of gastrointestinal hormones, and to improve the comfort and quality of patients' lives.

Male and female rats exhibit comparable gaping behavior but activate brain regions differently during expression of conditioned nausea

Twenty-five to fifty percent of patients undergoing chemotherapy will develop anticipatory nausea and vomiting (ANV), in which symptoms occur in anticipation of treatment. ANV is triggered by environmental cues and shows little response to traditional antiemetic therapy, suggesting that unique neural pathways mediate this response. Understanding the underlying neural mechanisms of this disorder is critical to the development of novel therapeutic interventions. The purpose of the present study was to identify brain areas activated during ANV and characterize sex differences in both the behavior and the brain areas activated during ANV. We used a rat model of ANV by pairing a novel context with the emetic drug lithium chloride (LiCl) to produce conditioned nausea behaviors in the LiCl-paired environment. We quantitated gaping, an analog of human vomiting, after acute or repeated LiCl in a unique environment. To identify brain regions associated with gaping, we measured c-fos activation by immunochemical staining after these same treatments. We found that acute LiCl activated multiple brain regions including the supraoptic nucleus of the hypothalamus, central nucleus of the amygdala, nucleus of the solitary tract and area postrema, none of which were activated during ANV. ANV activated c-fos expression in the frontal cortex, insula and paraventricular nucleus of the hypothalamus of males but not females. These data suggest that therapies such as ondansetron which target the area postrema are not effective in ANV because it is not activated during the ANV response. Further studies aimed at characterizing the neural circuits and cell types that are activated in the conditioned nausea response will help identify novel therapeutic targets for the treatment of this condition, improving both quality of life and outcomes for patients undergoing chemotherapy.

Tapping into 5-HT3 Receptors to Modify Metabolic and Immune Responses

5-hydroxytryptamine type 3 (5-HT₃) receptors are ligand gated ion channels, which clearly distinguish their mode of action from the other G-protein coupled 5-HT or serotonin receptors. 5-HT₃ receptors are well established targets for emesis and gastrointestinal mobility and are used as adjunct targets in treating schizophrenia. However, the distribution of these receptors is wider than the nervous system and there is potential that these additional sites can be targeted to modulate inflammatory and/or metabolic conditions. Recent progress in structural biology and pharmacology of 5-HT₃ receptors have provided profound insights into mechanisms of their action. These advances, combined with insights into clinical relevance of mutations in genes encoding 5-HT₃ subunits and increasing understanding of their implications in patient's predisposition to diseases and response to the treatment, open new avenues for personalized precision medicine. In this review, we recap on the current status of 5-HT₃ receptor-based therapies using a biochemical and physiological perspective. We assess the potential for targeting 5-HT₃ receptors in conditions involving metabolic or inflammatory disorders based on recent findings, underscoring the challenges and limitations of this approach.

A novel CT contrast agent for intestinal-targeted imaging through rectal administration

In this study, a novel CT contrast agent used by rectal administration is developed for targeting intestinal imaging. Iopamidol, an iodinated contrast agent, is loaded in chitosan (CS) nanospheres modified by Anti-5-HT3R (AH) antibody. The obtained AH-CS-I nanospheres (AH-CS-I Ns) would combine to 5-HT3 receptors highly expressed on the gastrointestinal mucosal, enhancing the intestinal-targeting ability of the contrast agent. The AH-CS-I Ns were administered by the rectal route for intestinal CT imaging, and FITC-labeled AH-CS-I Ns were prepared for investigating the in vivo distribution of the contrast agent. As a result, obvious contrast enhancement could still be observed at 6 h post administration because of the poorly absorption of enteral AH-CS-I Ns. Unlike the intravascularly administered agents, AH-CS-I Ns would not accumulate in the kidney and induce adverse reactions. Therefore, this technology has potential applications in the examination of intestinal diseases and could reduce the side effect of commercial iopamidol.

Therapeutic Potential of Cannabidiol, Cannabidiolic Acid, and Cannabidiolic Acid Methyl Ester as Treatments for Nausea and Vomiting

Introduction: Nausea and vomiting are the most distressing symptoms reported by oncology patients undergoing anticancer treatment. With the currently available treatments, vomiting and especially nausea remain problematic, highlighting the need for alternative treatments. Discussion: Here we review in vitro and in vivo evidence for the effectiveness of the nonpsychoactive cannabinoid cannabidiol (CBD) in managing nausea and vomiting. In addition, we also review the evidence for CBD's acidic precursor, cannabidiolic acid (CBDA), and a methylated version of CBDA (CBDA-ME) in these phenomena. Finally, we explore the potential role of CBD in the treatment of cannabinoid hyperemesis syndrome. Conclusions: CBD has demonstrated efficacy in reducing nausea and vomiting, with CBDA and CBDA-ME being more potent. The data suggest a need for these compounds to be evaluated in clinical trials for their ability to reduce nausea and/or vomiting.

Single daily dosing versus divided dosing intravenous ondansetron to prevent chemotherapy-induced nausea and vomiting among children: A comparative randomized double-blind controlled trial

BACKGROUND

Chemotherapy-induced nausea and vomiting (CINV) is a common complication in cancer treatment. Ondansetron is an effective antiemetic drug widely used to prevent CINV; however, the effective administrative dosing strategies among pediatrics remain unclear. The study aimed to investigate clinical effectiveness of single daily dosing versus divided dosing ondansetron.

METHODS

In all, 194 children undergoing chemotherapy were randomized to receive either single daily dosing (0.3 mg/kg/dose) or divided dosing (0.15 mg/kg/dose every 8 hours) intravenous ondansetron for 24 hours. Clinical parameters including number of emesis episodes, nausea scores, appetite levels, parent's satisfaction, and adverse effects within 24 hours were analyzed.

RESULTS

No significant differences were found between the two dosing strategies concerning number of emesis episodes and parent's satisfaction. However, nonleukemic hematologic malignancies and concurrent administration of intrathecal methotrexate-hydrocortisone-cytarabine (IT-MHA) were associated with increased risk of acute-phase vomiting. Interestingly, none of the patients aged under 7 years, receiving divided dosing ondansetron, presented nausea symptoms compared with those receiving single daily dosing (p-value .034). No significant differences regarding headache were observed between the two dosing strategies and none of the patients experienced QTc prolongation.

CONCLUSION

Ondansetron administered as divided dosing should be considered among children aged under 7 years to prevent chemotherapy-induced nausea and among patients receiving low emetogenic chemotherapy to maintain their appetite. Both administrative dosing strategies were well tolerated with no significant adverse effects.

Colonic 5-HT4 receptors are targets for novel prokinetic drugs

5-HT₄ receptors are G protein-coupled receptors that link to the stimulatory protein Gs which activates adenylate cyclase to increase intracellular cyclic AMP which then activates protein kinase A (PKA). 5-HT₄ receptors are expressed by neurons in the central and peripheral nervous systems especially the enteric nervous system (ENS). In general, 5-HT₄ receptors are stimulatory and their activation in the ENS enhances neurotransmitter release and propulsive motility patterns. 5-HT₄ receptors are expressed by enterochromaffin (EC) cells, Goblet cells, and most enteric neurons. The study by Konen and colleagues in this issue of Neurogastroenterology and Motility features two novel 5-HT₄ receptor agonists (5-HT₄ -LA1 and 5-HT₄ -LA-2) that are not absorbed from the gastrointestinal tract of mice and act locally in the colonic mucosa to stimulate propulsive motility. The authors show that 5-HT₄ -LA1 and 5-HT₄ -LA2 were not absorbed from the colon and that both drugs stimulated colonic transit when administered by gavage. Both agonists stimulated colonic glass bead expulsion, and 5-HT₄ LA1 activation stimulated fecal output and increased fecal water content. These effects were detected in young and aged mice. 5-HT₄ receptors were also localized to the epithelium of the human duodenum, ileum, and colon. These studies highlight novel 5-HT₄ receptor agonists that have prokinetic actions on the GI tract. These drugs are not absorbed and act locally in the gut mucosa to stimulate propulsive motility while minimizing access to systemic 5-HT₄ receptors and avoiding potential unwanted side effects.

Recent advances with 5-HT3 modulators for neuropsychiatric and gastrointestinal disorders

Serotonin (5-hydroxytryptophan [5-HT]) is a biologically active amine expressed in platelets, in gastrointestinal (GI) cells and, to a lesser extent, in the central nervous system (CNS). This biogenic compound acts through the activation of seven 5-HT receptors (5-HT_1-7 Rs). The 5-HT₃ R is a ligand-gated ion channel belonging to the Cys-loop receptor family. There is a wide variety of 5-HT₃ R modulators, but only receptor antagonists (known as setrons) have been used clinically for chemotherapy-induced nausea and vomiting and irritable bowel syndrome treatment. However, since the discovery of the setrons in the mid-1980s, a large number of studies have been published exploring new potential applications due their potency in the CNS and mild side effects. The results of these studies have revealed new potential applications, including the treatment of neuropsychiatric disorders such as schizophrenia, depression, anxiety, and drug abuse. In this review, we provide information related to therapeutic potential of 5-HT₃ R antagonists on GI and neuropsychiatric disorders. The major attention is paid to the structure, function, and pharmacology of novel 5-HT₃ R modulators developed over the past 10 years.

Supportive care during pediatric hematopoietic stem cell transplantation: beyond infectious diseases. A report from workshops on supportive care of the Pediatric Diseases Working Party (PDWP) of the European Society for Blood and Marrow Transplantation (EBMT)

Hematopoietic stem cell transplantation (HSCT) is currently the standard of care for many malignant and nonmalignant blood diseases. As several treatment-emerging acute toxicities are expected, optimal supportive measurements critically affect HSCT outcomes. The paucity of good clinical studies in supportive practices gives rise to the establishment of heterogeneous guidelines across the different centers, which hampers direct clinical comparison in multicentric studies. Aiming to harmonize the supportive care provided during the pediatric HSCT in Europe, the Pediatric Diseases Working Party (PDWP) of the European Society for Blood and Marrow Transplantation (EBMT) promoted dedicated workshops during the years 2017 and 2018. The present paper describes the resulting consensus on the management of sinusoidal obstructive syndrome, mucositis, enteral and parenteral nutrition, iron overload, and emesis during HSCT.

Gingerol inhibits cisplatin-induced acute and delayed emesis in rats and minks by regulating the central and peripheral 5-HT, SP, and DA systems

Abstract

Gingerol, a biologically active component in ginger, has shown antiemetic properties. Our study aimed to explore the underlying mechanisms of gingerol on protecting rats and minks from chemotherapy-induced nausea and vomiting. The preventive impact of gingerol was evaluated in the pica model of rats and the vomiting model of minks induced by cisplatin at every 6 h continuously for a duration of 72 h. Animals were arbitrarily separated into blank control group, simple gingerol control group, cisplatin control group, cisplatin + metoclopramide group, cisplatin + three different doses gingerol group (low-dose; middle-dose; high-dose). The area postrema as well as ileum damage were assessed using H&E stain. The levels of 5-TH, 5-HT₃ receptor, TPH, SERT, SP, NK₁ receptor, PPT, NEP, DA, D2R, TH, and DAT were determined using immunohistochemistry or qRT-PCR in rats and minks. All indicators were measured in the area postrema along with ileum. The kaolin intake by rats and the incidence of CINV of minks were significantly decreased after pretreatment with gingerol in a dosage-dependent way for the duration of 0–24-h and 24–72-h. Gingerol markedly decreased the levels of 5-TH, 5-HT₃ receptor, TPH, SP, NK₁ receptor, PPT, DA, D2R, TH, alleviated area postrema as well as ileum damage, and increased the accumulation of SERT, NEP, DAT in the area postrema along with ileum of rats and minks. Gingerol alleviates cisplatin-induced kaolin intake of rats and emesis of minks possibly by regulating central and peripheral 5-HT system, SP system and DA system.

Graphic abstract

Selective serotonin reuptake inhibitor escitalopram inhibits 5-HT3 receptor currents in NCB-20 cells

Escitalopram is one of selective serotonin reuptake inhibitor antidepressants. As an S-enantiomer of citalopram, it shows better therapeutic outcome in depression and anxiety disorder treatment because it has higher selectivity for serotonin reuptake transporter than citalopram. The objective of this study was to determine the direct inhibitory effect of escitalopram on 5-hydroxytryptamine type 3 (5-HT₃) receptor currents and study its blocking mechanism to explore additional pharmacological effects of escitalopram through 5-HT₃ receptors. Using a whole-cell voltage clamp method, we recorded currents of 5-HT₃ receptors when 5-HT was applied alone or co-applied with escitalopram in cultured NCB-20 neuroblastoma cells known to express 5-HT₃ receptors. 5-HT induced currents were inhibited by escitalopram in a concentration-dependent manner. EC₅₀ of 5-HT on 5-HT₃ receptor currents was increased by escitalopram while the maximal peak amplitude was reduced by escitalopram. The inhibitory effect of escitalopram was voltage independent. Escitalopram worked more effectively when it was co-applied with 5-HT than pre-application of escitalopram. Moreover, escitalopram showed fast association and dissociation to the open state of 5-HT₃ receptor channel with accelerating receptor desensitization. Although escitalopram accelerated 5-HT₃ receptor desensitization, it did not change the time course of desensitization recovery. These results suggest that escitalopram can inhibit 5-HT₃ receptor currents in a non-competitive manner with the mechanism of open channel blocking.

Alterations of colonic sensitivity and gastric dysmotility after acute cisplatin and granisetron

BACKGROUND

Cisplatin is a highly emetogenic antineoplastic drug and induces peripheral neuropathy when given in cycles. Granisetron, a 5-HT₃ antagonist, is clinically used to prevent chemotherapy-induced nausea/emesis and abdominal pain in irritable bowel syndrome. The effects of cisplatin on visceral sensitivity and those of granisetron in the context of cancer chemotherapy are not well known.

METHODS

Adult male Wistar rats received two intraperitoneal injections 30 minutes apart: granisetron (1 mg kg^-1 )/vehicle and cisplatin (6 mg kg^-1 )/vehicle. Thereafter, nausea-like behavior was measured as bedding intake for 4 hours, and gastric dysmotility was measured radiographically for 8 hours. Gastric weight and size were determined ex vivo and samples of the forestomach, corpus, ileum, and colon were obtained for histological analysis at 4 and 30 hours after cisplatin/vehicle. Visceral sensitivity was measured as abdominal contractions in response to mechanical intracolonic stimulation 2 hours after cisplatin/vehicle.

KEY RESULTS

Cisplatin-induced bedding intake and gastric dysmotility, and granisetron blocked these effects, which occurred in the absence of frank mucositis. Visceral sensitivity was reduced to a similar extent by both drugs alone or in combination.

CONCLUSIONS AND INFERENCES

Cisplatin-induced bedding intake and gastric dysmotility were blocked by granisetron, confirming the involvement of serotonin acting on 5-HT₃ receptors. Unexpectedly, visceral sensitivity to colonic distension was reduced, to the same extent, by cisplatin, granisetron, and their combination, suggesting important mechanistic differences with nausea and gastric dysmotility that warrant further investigation.

Potential roles of 5-HT3 receptor (5-HT3R) antagonists in modulating the effects of nicotine

5-HT₃R antagonists such as ondansetron, granisetron and tropisetron have been clinically used to treat nausea and vomiting in chemotherapy patients. However, current study and research revealed novel potentials of these ligands in other diseases like inflammation, Alzheimer's, and drug abuse. Towards utilising these drugs as anti-smoking agents to treat nicotine dependence problem, there are conflicting reports regarding the potential of these ligands in modulating the effects of nicotine in both human and animal behavioural studies. This is complicated by the heterogeneity of 5-HT₃R itself, cross regulation between nicotinic acetylcholinergic receptor (nAChR) and distinct pharmacological profiles of 5-HT₃R antagonists. This review gathered existing studies conducted investigating the potential of "-setron" class of 5-HT₃R antagonists in modulating nicotine effects. We proposed that the mechanism where 5-HT₃R antagonists mediate the effects of nicotine could be attributed by both direct at 5-HT₃R and indirect mechanism in nicotine addiction downstream regulation. The indirect mechanism mediated by the 5-HT₃R antagonist could be through α7 nAChR, 5-HT_1B receptor (5-HT_1BR), 5-HT_1C receptor (5-HT_1CR), calcineurin activity, p38 MAPK level, PPAR-γ and NF-κβ. Our review suggested that future studies should focus on newer 5-HT₃R antagonist with superior pharmacological profile or the one with multitarget action rather than high selectivity at single receptor.

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.

Evolving role of neurokinin 1-receptor antagonists for chemotherapy-induced nausea and vomiting

To examine pharmacologic and clinical characteristics of neurokinin 1 (NK₁)-receptor antagonists (RAs) for preventing chemotherapy-induced nausea and vomiting (CINV) following highly or moderately emetogenic chemotherapy, a literature search was performed for clinical studies in patients at risk of CINV with any approved NK₁ RAs in the title or abstract: aprepitant (capsules or oral suspension), HTX019 (intravenous [IV] aprepitant), fosaprepitant (IV aprepitant prodrug), rolapitant (tablets or IV), and fixed-dose tablets combining netupitant or fosnetupi-tant (IV netupitant prodrug) with the 5-hydroxytryptamine type 3 (5HT₃) RA palonosetron (oral or IV). All NK₁ RAs are effective, but exhibit important differences in efficacy against acute and delayed CINV. The magnitude of benefit of NK₁-RA-containing three-drug vs two-drug regimens is greater for delayed vs acute CINV. Oral rolapitant has the longest half-life of available NK₁ RAs, but as a consequence should not be administered more frequently than every 2 weeks. In general, NK₁ RAs are well tolerated; however, IV rolapitant was recently removed from US distribution, due to hypersensitivity and anaphylaxis, and IV fosaprepitant is associated with infusion-site reactions and hypersensitivity presumed related to its polysorbate 80 excipient. Also, available NK₁ RAs have potential drug–drug interactions. Adding an NK₁ RA to 5HT₃ RA and dexamethasone significantly improves CINV control vs the two-drug regimen. Newer NK₁ RAs offer more formulation options, higher acute-phase plasma levels, or improved tolerability, and increase clinicians’ opportunities to maximize benefits of this important class of antiemetics.

Tricyclic antidepressant amitriptyline inhibits 5-hydroxytryptamine 3 receptor currents in NCB-20 cells

Amitriptyline, a tricyclic antidepressant, is commonly used to treat depression and neuropathic pain, but its mechanism is still unclear. We tested the effect of amitriptyline on 5-hydroxytryptamine 3 (5-HT₃) receptor currents and studied its blocking mechanism because the clinical applications of amitriptyline overlapped with 5-HT₃ receptor therapeutic potentials. Using a whole-cell voltage clamp method, we recorded the currents of the 5-HT₃ receptor when 5-HT was applied alone or co-applied with amitriptyline in cultured NCB-20 neuroblastoma cells known to express 5-HT₃ receptors. To elucidate the mechanism of amitriptyline, we simulated the 5-HT₃ receptor currents using Berkeley Madonna® software and calculated the rate constants of the agonist binding and receptor transition steps. The 5-HT₃ receptor currents were inhibited by amitriptyline in a concentration-dependent, voltage-independent manner, and a competitive mode. Amitriptyline accelerated the desensitization of the 5-HT₃ receptor. When amitriptyline was applied before 5-HT treatment, the currents rose slowly until the end of 5-HT treatment. When amitriptyline was co-applied with 5-HT, currents rose and decayed rapidly. Peak current amplitudes were decreased in both applications. All macroscopic currents recorded in whole cell voltage clamping experiments were reproduced by simulation and the changes of rate constants by amitriptyline were correlated with macroscopic current recording data. These results suggest that amitriptyline blocks the 5-HT₃ receptor by close and open state blocking mechanisms, in a competitive manner. We could expand an understanding of pharmacological mechanisms of amitriptyline related to the modulation of a 5-HT₃ receptor, a potential target of neurologic and psychiatric diseases through this study.

Recent advances in antiemetics: new formulations of 5HT3-receptor antagonists

Purpose

To discuss new therapeutic strategies for chemotherapy-induced nausea and vomiting (CINV) involving 5-hydroxytryptamine type 3 (5HT₃)-receptor antagonists (RAs).

Summary

CINV remains poorly controlled in patients receiving moderately emetogenic chemotherapy (MEC) or highly emetogenic chemotherapy (HEC); nausea and delayed-phase CINV (24-120 hours after chemotherapy) are the most difficult to control. National Comprehensive Cancer Network (NCCN) and American Society of Clinical Oncology (ASCO) antiemesis-guideline recommendations for HEC include a four-drug regimen (5HT₃ RA, neurokinin 1 [NK₁] RA, dexamethasone, and olanzapine). For some MEC regimens, a three-drug regimen (5HT₃ RA, NK₁ RA, and dexamethasone) is recommended. While 5HT₃ RAs have dramatically improved CINV in the acute phase (0-24 hours after chemotherapy), their efficacy declines in the delayed phase. Newer formulations have been developed to extend 5HT₃-RA efficacy into the delayed phase. Granisetron extended-release subcutaneous (GERSC), the most recently approved 5HT₃ RA, provides slow, controlled release of therapeutic granisetron concentrations for ≥5 days. GERSC is included in the NCCN and ASCO guidelines for MEC and HEC, with NCCN-preferred status for MEC in the absence of an NK₁ RA. Efficacy and safety of 5HT₃ RAs in the context of guideline-recommended antiemetic therapy are reviewed.

Conclusion

Recent updates in antiemetic guidelines and the development of newer antiemet-ics should help mitigate CINV, this dreaded side effect of chemotherapy. GERSC, the most recently approved 5HT₃-RA formulation, is indicated for use with other antiemetics to prevent acute and delayed nausea and vomiting associated with initial and repeat courses of MEC and anthracycline-cyclophosphamide combination-chemotherapy regimens.

Acute chemotherapy-induced nausea and vomiting in children with cancer: Still waiting for a common consensus on treatment

Chemotherapy-induced nausea and vomiting (CINV) is one of the most common treatment side-effects, and remains a significant concern, in children undergoing chemotherapy. Although adult patients receive chemotherapy regimens combined with appropriate standardized antiemetic treatment, children can receive markedly varying antiemetic treatments. A narrative review of CINV was performed regarding CINV definition, scoring system, prevention and treatment, specifically focussing on studies conducted with paediatric oncology patients. The review highlighted a lack of rigorously developed CINV scoring systems and standardized CINV pharmacological treatment for paediatric oncology patients. Different scoring systems were found to identify potential risk factors for CINV associated with the use of several different antiemetic drugs, however, few studies have been performed in children undergoing chemotherapy. Thus, CINV remains a distressing and partially controlled side-effect in the paediatric patient population. To reduce emesis and improve quality of life in paediatric oncology patients, standardized antiemetic treatment may be preferred, using a unique CINV scoring system that accounts for the emetogenic level of the chemotherapy regimen adopted and the children's clinical characteristics.

Investigation of 5-HT3 receptor-triggered serotonin release from guinea-pig isolated colonic mucosa: a role of PYY-containing endocrine cell

The effect of a 5-HT₃ receptor-selective agonist SR57227A was investigated on the outflow of 5-hydroxytryptamine (5-HT) from isolated muscle layer-free mucosal preparations of guinea-pig colon. The mucosal preparations were incubated in vitro and the outflow of 5-HT from these preparations was determined by high-performance liquid chromatography with electrochemical detection. SR57227A (100μM) produced a tetrodotoxin-resistant and sustained increase in the outflow of 5-HT from the mucosal preparations. The SR57227A-evoked sustained 5-HT outflow was completely inhibited by the 5-HT₃ receptor antagonist ramosetron (1μM). The neuropeptide Y₁ receptor antagonist BIBO3304 (100nM) partially inhibited the SR57227A-evoked sustained 5-HT outflow, but the Y₂ receptor antagonist BIIE0246 (1μM) or the glucagon-like peptide-1 (GLP-1) receptor antagonist exendin-(9-39) (1μM), showed a minimal effect on the SR57227A-evoked sustained 5-HT outflow. In the presence of BIBO3304 (100nM) and exendin-(9-39) (1μM), SR57227A (100μM) failed to produce a sustained increase in the outflow of 5-HT. The Y₁ receptor agonist [Leu³¹, Pro³⁴]-neuropeptide Y (10nM), but not GLP-1-(7-36) amide (100nM), produced a sustained increase in the outflow of 5-HT. We found that 5-HT₃ receptor-triggered 5-HT release from guinea-pig colonic mucosa is mediated by the activation of 5-HT₃ receptors located at endocrine cells (enterochromaffin cells and peptide YY (PYY)-containing endocrine cells). The activation of both Y₁ and GLP-1 receptors appears to be required for the maintenance of 5-HT₃ receptor-triggered 5-HT release. It is therefore considered that 5-HT₃ receptors located at colonic mucosa play a crucial role in paracrine signaling between enterochromaffin cells and PYY-containing endocrine cells.

Factors Which Influence Owners When Deciding to Use Chemotherapy in Terminally Ill Pets

Chemotherapy is a commonly integrated treatment option within human and animal oncology regimes. Limited research has investigated pet owners' treatment decision-making in animals diagnosed with malignant neoplasia. Dog and cat owners were asked to complete an online questionnaire to elucidate factors which are key to the decision making process. Seventy-eight respondents completed the questionnaire in full. Fifty-eight percent of pet owners would not elect to treat pets with chemotherapy due to the negative impact of the associated side effects. Seventytwo percent of respondents over estimated pet survival time post chemotherapy, indicating a general perception that it would lead to remission or a cure. Vomiting was considered an acceptable side effect but inappetence, weight loss and depression were considered unacceptable. Owners did expect animals' to be less active, sleep more and play less, but common side effects were not rated as acceptable despite the potential benefits of chemotherapy. Based on the results, veterinary teams involved with oncology consultations should establish if clients have prior experience of cancer treatments and their expectations of survival time. Quality of life assessments should also be implemented during initial oncology consultations and conducted regularly during chemotherapy courses to inform client decision making and to safe guard animal welfare.

Palonosetron-5-HT3 Receptor Interactions As Shown by a Binding Protein Cocrystal Structure

Palonosetron is a potent 5-HT₃ receptor antagonist and an effective therapeutic agent against emesis. Here we identify the molecular determinants of compound recognition in the receptor binding site by obtaining a high resolution structure of palonosetron bound to an engineered acetylcholine binding protein that mimics the 5-HT₃ receptor binding site, termed 5-HTBP, and by examining the potency of palonosetron in a range of 5-HT₃ receptors with mutated binding site residues. The structural data indicate that palonosetron forms a tight and effective wedge in the binding pocket, made possible by its rigid tricyclic ring structure and its interactions with binding site residues; it adopts a binding pose that is distinct from the related antiemetics granisetron and tropisetron. The functional data show many residues previously shown to interact with agonists and antagonists in the binding site are important for palonosetron binding, and indicate those of particular importance are W183 (a cation-π interaction and a hydrogen bond) and Y153 (a hydrogen bond). This information, and the availability of the structure of palonosetron bound to 5-HTBP, should aid the development of novel and more efficacious drugs that act via 5-HT₃ receptors.

A Screen of FDA-Approved Drugs for Inhibitors of Zika Virus Infection

Currently there are no approved vaccines or specific therapies to prevent or treat Zika virus (ZIKV) infection. We interrogated a library of FDA-approved drugs for their ability to block infection of human HuH-7 cells by a newly isolated ZIKV strain (ZIKV MEX_I_7). More than 20 out of 774 tested compounds decreased ZIKV infection in our in vitro screening assay. Selected compounds were further validated for inhibition of ZIKV infection in human cervical, placental, and neural stem cell lines, as well as primary human amnion cells. Established anti-flaviviral drugs (e.g., bortezomib and mycophenolic acid) and others that had no previously known antiviral activity (e.g., daptomycin) were identified as inhibitors of ZIKV infection. Several drugs reduced ZIKV infection across multiple cell types. This study identifies drugs that could be tested in clinical studies of ZIKV infection and provides a resource of small molecules to study ZIKV pathogenesis.

Management of chemotherapy-induced nausea and vomiting by risk profile: role of netupitant/palonosetron

As recommended by most recent antiemetic guidelines, the optimal prophylaxis of chemotherapy-induced nausea and vomiting (CINV) requires the combination of 5-HT3 receptor antagonist (RA) with an NK1-RA. Moreover, the major predictors of acute and delayed CINV include: young age, female sex, platinum- or anthracycline-based chemotherapy, nondrinker status, emesis in the earlier cycles of chemotherapy, and previous history of motion/morning sickness. Despite improved knowledge of the pathophysiology of CINV and advances in the availability of active antiemetics, an inconsistent compliance with their use has been reported, thereby resulting in suboptimal control of CINV in several cases. In this scenario, a new anti-emetic drug is now available, which seems to be able to guarantee better prophylaxis of CINV and improvement of adherence to guidelines. In fact, netupitant/palonosetron (NEPA) is a ready-to-use single oral capsule, combining an NK1-RA (netupitant) and a 5-HT3-RA (palonosetron), which is to be taken 1 hour before the administration of chemotherapy, ensuring the coverage from CINV for 5 days. We reviewed the role of NEPA in patients at high risk of CINV receiving highly emetogenic chemotherapy. In these patients, NEPA plus dexamethasone, as compared to standard treatments, achieved superior efficacy in all primary and secondary end points during the acute, delayed, and overall phases, including nausea assessment. Moreover, these results were also achieved in female patients receiving anthracycline plus cyclophosphamide-based chemotherapy. NEPA represents a real step forward in the prophylaxis of CINV.