Ondansetron, dexamethasone and an NK1 antagonist block radiation sickness in mice

Further demonstration of running-based food avoidance learning in laboratory mice (Mus musculus)

Voluntary wheel running has hedonically bivalent properties in laboratory rats and mice. While it works as a reward for instrumental performance such as bar pressing, it also functions as an aversive stimulus to establish Pavlovian conditioned avoidance of the paired stimulus. The present study focused on the latter case. Running in closed wheels hampered habituation of a reluctance to eat a target snack in rats (Experiment 1A) and mice (Experiment 1B) trained by pairing access to a target snack with confinement to a wheel attached to the cage. Experiment 2 successfully confirmed and extended this finding with mice running in both open and closed wheels. A differential conditioning procedure employed in Experiment 3 ensured that this phenomenon is specific to the snack paired with running, implying that it reflects Pavlovian conditioned flavor avoidance (CFA). Free exploration in cages without wheels, however, did not results in a CFA.

Strain differences in the development of cisplatin-induced pica behavior in mice

INTRODUCTION

Pica behavior, kaolin ingestion, in rats and mice can be used as an assessment of nausea and vomiting; however, we observed that the incidence of pica behavior in ICR strain mice varied markedly. We investigated the susceptibility of four strains of mice (ICR, BALB/c, C57BL/6, and DBA/2) to the development of pica behavior.

METHODS

Mice received cisplatin (7.5 mg/kg, i.p.) with or without a serotonin 5-HT₃ receptor antagonist (granisetron: 0.1 mg/kg, i.p.) or tachykinin NK₁ receptor antagonist (fosaprepitant: 30 mg/kg, i.p.), and then their daily kaolin intake was measured for 2 days. We examined the expression of preprotachykinin (PPT)-A mRNA in the medulla of cisplatin-treated mice 8 and 32 h after drug administration.

RESULTS

All mice except for ICR strain significantly increased kaolin intake after cisplatin administration. Among the tested strains, DBA/2 mice compared to BALB/c and C57BL/6 mice notably showed pica behavior on both days (P < 0.0001). The expression of PPT-A mRNA was significantly increased 8 h after cisplatin administration in all strains, but the increase remained on the second day only in DBA/2 mice (P < 0.05). Granisetron significantly inhibited pica behavior in DBA/2 mice on the first day (P < 0.0001), but not the second day; however, fosaprepitant completely inhibited the pica behavior on both days (P < 0.001).

DISCUSSION

These results indicate that cisplatin-induced pica behavior in mice is likely to be influenced by the genotype, and that DBA/2 mice are useful to analyze the emetogenic or anti-emetic potential of drugs in preclinical studies.

Effect of sevoflurane anesthesia on the comprehensive mRNA expression profile of the mouse hippocampus

Postoperative nausea and vomiting (PONV) is a common complication after general anesthesia. Recent studies suggested that the hippocampus is involved in PONV. Hypothesising that hippocampal dopaminergic neurons are related to PONV, we examined the comprehensive mRNA profile of the hippocampus, using a sevoflurane-treated mouse model to confirm this. This study was conducted after approval from our institutional animal ethics committee, the Animal Research Center of Sapporo Medical University School of Medicine (project number: 12-033). Eight mice were assigned to two groups: a naïve group and a sevoflurane group (Sev group). In the Sev group, four mice were anesthetised with 3.5% sevoflurane for 1 hour. Subsequently, mRNA was isolated from their hippocampal cells and RNA sequencing was performed on an Illumina HiSeq 2500 platform. Mapping of the quality-controlled, filtered paired-end reads to mouse genomes and quantification of the expression levels of each gene were performed using R software. The Rtn4rl2 gene that encodes the Nogo receptor was the most up-regulated gene in the present study. The expression levels of dopamine receptor genes and the tachykinin gene were increased by sevoflurane exposure, while the genes related to serotonin receptors were not altered by sevoflurane exposure. The expression levels of LIM-homeodomain-related genes were highly down-regulated by sevoflurane. These findings suggest that sevoflurane exposure induces dopaminergic stimulation of hippocampal neurons and triggers PONV, while neuronal inflammation caused by LIM-homeodomain-related genes is down-regulated by sevoflurane.

Involvement of substance P in the development of cisplatin-induced acute and delayed pica in rats

BACKGROUND AND PURPOSE

Although substance P (SP) and neurokinin NK1 receptors have been reported to be involved in cisplatin-induced acute and delayed emesis, their precise roles remain unclear. Pica, the consumption of non-nutrient materials such as kaolin in rats, can be used as a model of nausea in humans. We investigated the time-dependent changes in cisplatin-induced pica and the involvement of SP and NK1 receptors in this behaviour.

EXPERIMENTAL APPROACH

Rats were administered cisplatin with or without a daily injection of a 5-HT3 receptor antagonist (granisetron) or an NK1 receptor antagonist (aprepitant), and kaolin intake was then monitored for 5 days. The effects of granisetron on the cisplatin-induced expression of preprotachykinin-A (PPT-A) mRNA, which encodes mainly for SP, and on SP release in the medulla, measured by in vivo brain microdialysis, were also investigated.

KEY RESULTS

Cisplatin induced pica within 8 h of its administration that continued for 5 days. Granisetron inhibited the acute phase (day 1), but not the delayed phase (days 2-5), of pica, whereas aprepitant abolished both phases. Within 24 h of the injection of cisplatin, PPT-A mRNA expression and SP release in the medulla were significantly increased; these findings lasted during the observation period and were inhibited by granisetron for up to 24 h.

CONCLUSIONS AND IMPLICATIONS

The profiles of cisplatin-induced pica in rats are similar to clinical findings for cisplatin-induced emesis in humans, and we showed that SP production in the medulla and activation of NK1 receptors are involved in this cisplatin-induced pica.

Radiation induced nausea and vomiting

Radiation induced nausea and vomiting (RINV) is a frequent complication of radiotherapy and still often underestimated by radiation oncologists. Fractionated RT may involve up to 40 fractions over a 6-8 weeks period, and prolonged symptoms of nausea and vomiting affect quality of life. Approximately, 50-80 percent of patients undergoing radiotherapy (RT) will experience these symptoms if no appropriate prophylaxis is applied. The incidence and severity are influenced by the specific RT regimen and by patient-specific factors. Patients should receive antiemetic prophylaxis as suggested by the international antiemetic guidelines based upon a risk assessment, taking especially into account the planned radiotherapy regimen. In this field the guideline from the Multinational Association of Supportive Care in Cancer (MASCC)/European Society of Clinical Oncology (ESMO) and the American Society of Medical Oncology (ASCO) guidelines are wildly endorsed. The emetogenicity of radiotherapy regimens and recommendations for the appropriate use of antiemetics including 5-hydroxytryptamine (5-HT3) receptor antagonists and steroids will be discussed in regard to the applied radiotherapy or radiochemotherapy regimen.

Efficacy and safety of aprepitant in allogeneic hematopoietic stem cell transplantation

Study Objective

To evaluate the efficacy and safety of aprepitant added to standard antiemetic regimens used in high-dose chemotherapy for allogeneic hematopoietic stem cell transplantation (allo-HSCT).

Design

Retrospective medical record review.

Setting

Hematology ward of a university hospital in Japan.

Patients

Of 88 patients treated with high-dose chemotherapy followed by allo-HSCT, 46 received aprepitant and granisetron as antiemetic therapy (between April 1, 2010, and December 31, 2011), and 42 received granisetron alone (between April 1, 2008, and March 31, 2010).

Interventions

Patients in both groups received 3 mg of granisetron intravenously 30 minutes before the administration of anticancer drugs. In the aprepitant group, 125 mg of aprepitant was administered orally 60–90 minutes before the administration of the first moderately to highly emetogenic anticancer drug. On the following days, 80 mg of aprepitant was administered orally every morning. The mean administration duration of aprepitant was 3.3 days (range 3–6 days).

Measurements and Main Results

The primary objective was to evaluate the percentage of patients who achieved complete response (CR; no vomiting and none to mild nausea). The CR rate in the aprepitant group was significantly higher than that in the control group (48% vs 24%, p=0.02). Multivariate analysis showed that nonprophylactic use of aprepitant was associated with failure to achieve CR (odds ratio [OR] 2.92; 95% confidence interval [CI] 1.13–7.99, p=0.03). The frequency of abdominal pain was lower in the aprepitant group (9% vs 25%, p=0.03). Rates of other frequently observed adverse drug events were similar between groups. There was no significant difference in neutrophil engraftment (median 18 vs 17 days), platelet engraftment (median 32 vs 32 days), the incidence of acute graft-versus-host-disease (63% vs 55%, p=0.52), viral infection (74% vs 67%, p=0.49), or 1-year overall survival (63% vs 62%, p=0.90) between the two groups.

Conclusions

The addition of aprepitant to granisetron increases the antiemetic effect without influencing transplantation-related toxicities in allo-HSCT.

Enhanced gastric retention of solid resin beads as a marker for emetic potential of agents in rats

Whereas nausea and emesis are burdensome side effects that lead to poor treatment compliance especially in chemotherapy, it is difficult to predict the emetic potential of agents in rats and mice because rodents do not vomit. We examined the effect of emetics on gastric retention and role of serotonin (5-hydroxytryptamine, 5-HT)<inf>3</inf> receptor in chemotherapeutic-induced enhancement of gastric retention in rats. The gastric retention of solid material was determined using resin beads, which were suitable to beads made with metals or glasses in size, hardness and weight. Each rat was orally given distilled water (0.5 ml/rat) containing 40 resin beads via a plastic feeding tube. The stomach was removed at 1 hr post-dose and cut along the greater curvature under carbon dioxide anesthesia. Beads were given immediately after administration of the drugs except with cisplatin, when there was a 1 hr delay. Cancer chemotherapeutics including cisplatin(0.1-3 mg/kg i.v.) and doxorubicin(0.3-10 mg/kg i.v.) and a nauseant, copper sulfate(1-30 mg/kg p.o.) enhanced gastric retention of beads. Ondansetron, a 5-HT<inf>3</inf> receptor antagonist, dose-dependently antagonized the enhanced gastric retention by cisplatin and doxorubicin. The copper sulfate-induced enhancement was also reversed by ondansetron. Our results suggest that 5-HT<inf>3</inf> receptors mediate the cancer chemotherapeutic-enhanced gastric retention of solid material in rats. This implicates that the gastric retention of solid material is a useful marker to predict the potential of compounds to induce nausea and/or emesis in non-vomiting rodents.

Solid gastric emptying mediated by the serotonin (5-HT)3 receptor in mice is a simple marker to predict emesis

Nausea and emesis are often observed as side effects with many medicines and may lead to poor treatment compliance. In the present study, we aimed to establish simple methods for predicting nausea and/or emesis in mice, which do not vomit, using drugs and chemicals known to evoke nausea and/or emesis. The gastrointestinal transit test, the liquid gastric emptying by phenol red solution (Phenol red method) and the solid gastric emptying by resin beads (Beads method) were used and the effects of antispasmogenics (atropine, 0.1-3 mg/kg i.p.; salmon calcitonin, 1-30 units/kg i.m.), nauseants (copper sulfate, 1-30 mg/kg p.o.; apomorphine, 0.01-0.3 mg/kg s.c.) and chemotherapeutics (cisplatin, 0.3-10 mg/kg i.v.; doxorubicin, 0.3-10 mg/kg i.v.) were evaluated. In addition, the effects of ondansetron, a serotonin (5-HT)(3) receptor antagonist, on the inhibition of solid gastric emptying induced by salmon calcitonin, copper sulfate, cisplatin and doxorubicin were also assessed. Only the solid gastric emptying method could detect changes of gastric emptying by all drugs and chemicals. We also found that the inhibition of solid gastric emptying induced by cisplatin and doxorubicin was dose-dependently antagonized by ondansetron. However, ondansetron failed to antagonize the salmon calcitonin-induced delay, but exerted only very weak effects with copper sulfate. Solid gastric emptying may be more suitable than gastrointestinal intestinal transit or liquid gastric emptying in mice to predict nausea and/or emesis. Our results also suggest that chemotherapeutic-induced delay of solid gastric emptying mediated via 5-HT(3) receptors in mice could also be useful for prediction purposes.

Homology modelling of the serotoninergic 5-HT2c receptor

Since its discovery, 5-hydroxytryptamine, more usually called serotonin, has been an elusive candidate as a major mood regulator. This capacity gives it a great importance in the treatment of depression. It is within this framework that our work takes place, as it is related more particularly to a new therapeutic class whose leader is agomelatine. This compound binds to the melatoninergic receptors and to the serotoninergic 5-HT2c receptor, giving rise to the MASSA concept (Melatonin Agonist and Selective Serotonin Antagonist). Like the majority of the serotoninergic receptors, the sub-type 5-HT2c is a G-protein coupled receptor (GPCR). The three-dimensional structure of 5-HT2c is not experimentally known, and we thus resorted to comparative homology modelling to build a model allowing us to study its interactions with agomelatine.

Altered feeding behaviour induced by long-term cisplatin in rats

In animals without the emetic reflex, several emetogenic stimuli induce pica, an altered feeding behaviour consisting of the ingestion of non-nutritive substances. The development of pica in response to an emetogenic stimulus has been proposed to be useful as an indirect marker of nausea in the rat. In fact, like nausea and emesis in humans, it is accompanied by serotonin release from the enterochromaffin cells, increased c-fos labelling in the area postrema and the nucleus tractus solitarius, and a delay in gastric emptying. Furthermore, pica, measured as kaolin intake, is reduced by anti-emetic drugs. Pica has been demonstrated after single doses of cisplatin, the most emetogenic chemotherapeutic drug. However, cisplatin, as other antineoplastic drugs, is generally given in cycles, where conventional anti-emetics tend to lose efficiency. The aim of this work was to evaluate the pica induced by long-term treatment with cisplatin. Saline or cisplatin was administered once a week for 5 consecutive weeks, and temperature, body weight, food ingestion and kaolin intake were measured on a daily basis. The influence of isolation (pica is necessarily studied in isolated animals) and exposure to kaolin (basal kaolin intake could modify pica itself and other parameters) on temperature, body weight and daily food ingestion was negligible in saline-treated rats. Cisplatin administered at 3 mg/kg/week was too toxic: it produced hypothermia, weight drop and anorexia in both grouped and isolated rats, and 50% mortality in isolated animals. Toxicity associated with cisplatin administered at 1 mg/kg/week was acceptable, with a slower rate of weight gain being the major effect. In these rats, each cisplatin injection produced both acute anorexia and rebound hyperphagic responses. In addition, each administration induced both acute pica and an increase in basal kaolin intake, resembling the development of nausea in humans. This model could be useful for studying both the mechanisms leading to nausea associated with a long-term antineoplastic treatment and the efficiency of new anti-emetic drugs.