Cisplatin-induced gastric dysrhythmia and emesis in dogs and possible role of gastric electrical stimulation

Mechanisms of Chemotherapy-Induced Neurotoxicity

Since the first clinical trials conducted after World War II, chemotherapeutic drugs have been extensively used in the clinic as the main cancer treatment either alone or as an adjuvant therapy before and after surgery. Although the use of chemotherapeutic drugs improved the survival of cancer patients, these drugs are notorious for causing many severe side effects that significantly reduce the efficacy of anti-cancer treatment and patients’ quality of life. Many widely used chemotherapy drugs including platinum-based agents, taxanes, vinca alkaloids, proteasome inhibitors, and thalidomide analogs may cause direct and indirect neurotoxicity. In this review we discuss the main effects of chemotherapy on the peripheral and central nervous systems, including neuropathic pain, chemobrain, enteric neuropathy, as well as nausea and emesis. Understanding mechanisms involved in chemotherapy-induced neurotoxicity is crucial for the development of drugs that can protect the nervous system, reduce symptoms experienced by millions of patients, and improve the outcome of the treatment and patients’ quality of life.

Insights Into Acute and Delayed Cisplatin-Induced Emesis From a Microelectrode Array, Radiotelemetry and Whole-Body Plethysmography Study of Suncus murinus (House Musk Shrew)

Purpose: Cancer patients receiving cisplatin therapy often experience side-effects such as nausea and emesis, but current anti-emetic regimens are suboptimal. Thus, to enable the development of efficacious anti-emetic treatments, the mechanisms of cisplatin-induced emesis must be determined. We therefore investigated these mechanisms in Suncus murinus, an insectivore that is capable of vomiting.

Methods: We used a microelectrode array system to examine the effect of cisplatin on the spatiotemporal properties of slow waves in stomach antrum, duodenum, ileum and colon tissues isolated from S. murinus. In addition, we used a multi-wire radiotelemetry system to record conscious animals’ gastric myoelectric activity, core body temperature, blood pressure (BP) and heart rate viability over 96-h periods. Furthermore, we used whole-body plethysmography to simultaneously monitor animals’ respiratory activity. At the end of in vivo experiments, the stomach antrum was collected and immunohistochemistry was performed to identify c-Kit and cluster of differentiation 45 (CD45)-positive cells.

Results: Our acute in vitro studies revealed that cisplatin (1–10 μM) treatment had acute region-dependent effects on pacemaking activity along the gastrointestinal tract, such that the stomach and colon responded oppositely to the duodenum and ileum. S. murinus treated with cisplatin for 90 min had a significantly lower dominant frequency (DF) in the ileum and a longer waveform period in the ileum and colon. Our 96-h recordings showed that cisplatin inhibited food and water intake and caused weight loss during the early and delayed phases. Moreover, cisplatin decreased the DF, increased the percentage power of bradygastria, and evoked a hypothermic response during the acute and delayed phases. Reductions in BP and respiratory rate were also observed. Finally, we demonstrated that treatment with cisplatin caused inflammation in the antrum of the stomach and reduced the density of the interstitial cells of Cajal (ICC).

Conclusion: These studies indicate that cisplatin treatment of S. murinus disrupted ICC networking and viability and also affected general homeostatic mechanisms of the cardiovascular system and gastrointestinal tract. The effect on the gastrointestinal tract appeared to be region-specific. Further investigations are required to comprehensively understand these mechanistic effects of cisplatin and their relationship to emesis.

Effects of acupuncture at Pericardium-6 and Stomach-36 on nausea, sedation and gastrointestinal motility in healthy dogs administered intravenous lidocaine infusions

The objectives of this study were to assess gastrointestinal transit times, sedation, and signs of nausea associated with intravenous lidocaine infusions in dogs following targeted acupuncture at Pericardium-6 (PC6) and Stomach-36 (ST36). In a randomized, blind crossover design, 6 healthy, adult Beagles were fed thirty 1.5 mm barium-impregnated polyethylene spheres (BIPS), then were subject to 30 minutes of: 1) no acupuncture, 2) bilateral targeted acupuncture at PC6 and ST36, or 3) bilateral non-target acupuncture at Lung-5 (LU5) and Bladder-55 (BL55). Lidocaine was immediately administered at 1 mg/kg intravenously followed by 50 μg/kg/min. BIPS were tracked radiographically; sedation and nausea were scored at baseline (Time 0) and for 11 hours during lidocaine infusions. Transit times and sedation and nausea scores were analyzed with a linear mixed-effects model; the number of BIPS at defined time points was analyzed with a piecewise linear mixed-effects model. All P values were two-sided and P < 0.05 was considered significant. Sedation and nausea scores did not differ between treatments at any time point (all P > 0.05). However, nausea scores in all groups were significantly greater at Times 5 through 7 and at Time 11 compared to Time 0 whereas sedation scores in all groups were significantly greater at Times 2 through 11 compared to Time 0 (all P < 0.05). The number of BIPs found out of the stomach, the number found in the large intestine, gastric emptying and gastrointestinal transit times did not differ between treatments (all P > 0.05). Acupuncture at PC6 and ST36 did not alleviate nausea and sedation associated with lidocaine infusions in clinically normal animals or affect gastric emptying and gastrointestinal transit.

Gastric myoelectric activity during cisplatin-induced acute and delayed emesis reveals a temporal impairment of slow waves in ferrets: effects not reversed by the GLP-1 receptor antagonist, exendin (9-39)

Preclinical studies show that the glucagon-like peptide-1 (GLP-1) receptor antagonist, exendin (9-39), can reduce acute emesis induced by cisplatin. In the present study, we investigate the effect of exendin (9-39) (100 nmol/24 h, i.c.v), on cisplatin (5 mg/kg, i.p.)-induced acute and delayed emesis and changes indicative of ‘nausea’ in ferrets. Cisplatin induced 37.2 ± 2.3 and 59.0 ± 7.7 retches + vomits during the 0-24 (acute) and 24-72 h (delayed) periods, respectively. Cisplatin also increased (P<0.05) the dominant frequency of gastric myoelectric activity from 9.4 ± 0.1 to 10.4 ± 0.41 cpm and decreased the dominant power (DP) during acute emesis; there was a reduction in the % power of normogastria and an increase in the % power of tachygastria; food and water intake was reduced. DP decreased further during delayed emesis, where normogastria predominated. Advanced multifractal detrended fluctuation analysis revealed that the slow wave signal shape became more simplistic during delayed emesis. Cisplatin did not affect blood pressure (BP), but transiently increased heart rate, and decreased heart rate variability (HRV) during acute emesis; HRV spectral analysis indicated a shift to ‘sympathetic dominance’. A hyperthermic response was seen during acute emesis, but hypothermia occurred during delayed emesis and there was also a decrease in HR. Exendin (9-39) did not improve feeding and drinking but reduced cisplatin-induced acute emesis by ~59 % (P<0.05) and antagonised the hypothermic response (P<0.05); systolic, diastolic and mean arterial BP increased during the delayed phase. In conclusion, blocking GLP-1 receptors in the brain reduces cisplatin-induced acute but not delayed emesis. Restoring power and structure to slow waves may represent a novel approach to treat the side effects of chemotherapy.

Simultaneous anterior and posterior serosal mapping of gastric slow-wave dysrhythmias induced by vasopressin

NEW FINDINGS

What is the central question of this study? This study aimed to provide the first comparison of simultaneous high-resolution mapping of anterior and posterior gastric serosa over sustained periods. What is the main finding and its importance? Episodes of spontaneous gastric slow-wave dysrhythmias increased significantly following intravenous infusion of vasopressin compared with the baseline state. A number of persistent dysrhythmias were defined, including ectopic activation, conduction block, rotor, retrograde and collision/merger of wavefronts. Slow-wave dysrhythmias could occur either simultaneously or independently on the anterior and posterior gastric serosa, and interacted depending on activation-repolarization and frequency dynamics. High-resolution mapping enables mechanistic insights into gastric slow-wave dysrhythmias and is now achieving clinical translation. However, previous studies have focused mainly on dysrhythmias occurring on the anterior gastric wall. The present study simultaneously mapped the anterior and posterior gastric serosa during episodes of dysrhythmias induced by vasopressin to aid understanding of dysrhythmia initiation, maintenance and termination. High-resolution mapping (8 × 16 electrodes on each serosa; 20-74 cm2 ) was performed in anaesthetized dogs. Baseline recordings (21 ± 8 min) were followed by intravenous infusion of vasopressin (0.1-0.5 IU ml-1 at 60-190 ml h-1 ) and further recordings (22 ± 13 min). Slow-wave activation maps, amplitudes, velocity, interval and frequency were calculated, and differences compared between baseline and postinfusion. All dogs demonstrated an increased prevalence of dysrhythmic events following infusion of vasopressin (17 versus 51%). Both amplitude and velocity demonstrated significant differences (baseline versus postinfusion: 3.6 versus 2.2 mV; 7.7 versus 6.5 mm s-1 ; P < 0.05 for both). Dysrhythmias occurred simultaneously or independently on the anterior and posterior serosa, and then interacted according to frequency dynamics. A number of persistent dysrhythmias were compared, including the following: ectopic activation (n = 2 animals), conduction block (n = 1), rotor (n = 2), retrograde (n = 3) and collision/merger of wavefronts (n = 2). We conclude that infusion of vasopressin induces gastric dysrhythmias, which occur across a heterogeneous range of frequencies and patterns. The results demonstrate that different classes of gastric dysrhythmias may arise simultaneously or independently in one or both surfaces of the serosa, then interact according to their relative frequencies. These results will help to inform interpretation of clinical dysrhythmia.

Impact of electrical stimulation of the stomach on gastric distension-induced emesis in the musk shrew

BACKGROUND

Gastric electrical stimulation (GES) is implicated as a potential therapy for difficult-to-treat nausea and vomiting; however, there is a lack of insight into the mechanisms responsible for these effects. This study tested the relationship between acute GES and emesis in musk shrews, an established emetic model system.

METHODS

Urethane-anesthetized shrews were used to record emetic responses (monitoring intra-tracheal pressure and esophageal contractions), respiration rate, heart rate variability, blood pressure, and gastrointestinal electromyograms. We investigated the effects of acute GES pulse duration (0.3, 1, 5, and 10 ms), current amplitude (0.5, 1, and 2 mA), pulse frequency (8, 15, 30, and 60 Hz), and electrode placement (antrum, body, and fundus) on emesis induced by gastric stretch, using a balloon.

KEY RESULTS

There were four outcomes: (i) GES did not modify the effects of gastric stretch-induced emesis; (ii) GES produced emesis, depending on the stimulation parameters, but was less effective than gastric stretch; (iii) other physiological changes were closely associated with emesis and could be related to a sub-threshold activation of the emetic system, including suppression of breathing and rise in blood pressure; and (iv) a control experiment showed that 8-OH-DPAT, a reported 5-HT1A receptor agonist that acts centrally as an antiemetic, blocked gastric stretch-induced emesis.

CONCLUSIONS AND INFERENCES

These results do not support an antiemetic effect of acute GES on gastric distension-induced emesis within the range of conditions tested, but further evaluation should focus on a broader range of emetic stimuli and GES stimulation parameters.

Nausea: current knowledge of mechanisms, measurement and clinical impact

Nausea is a subjective sensation, which often acts as a signal that emesis is imminent. It is a widespread problem that occurs as a clinical sign of disease or as an adverse effect of a drug therapy or surgical procedure. The mechanisms of nausea are complex and the neural pathways are currently poorly understood. This review summarises the current knowledge of nausea mechanisms, the available animal models for nausea research and the anti-nausea properties of commercially available anti-emetic drugs. The review also presents subjective assessment and scoring of nausea. A better understanding of the underlying mechanisms of nausea might reveal potential clinically useful biomarkers for objective measurement of nausea in species of veterinary interest.

Effects and mechanisms of transcutaneous electroacupuncture on chemotherapy-induced nausea and vomiting

Nausea and vomiting are one of the major complications of chemotherapy for cancers. The aim of this study is to investigate the emetic effects and mechanisms involving serotonin and dopamine of needleless transcutaneous electroacupuncture (TEA) at Neiguan (PC6) and Jianshi (PC5) on chemotherapy-induced nausea and vomiting in patients with cancers. Seventy-two patients with chemotherapy were randomly divided into sham-TEA group (sham-TEA, n = 34) and TEA group (n = 38). TEA was performed at PC 6 and PC 5 (1 h, bid) in combination with granisetron. Sham-TEA was delivered at nonacupoints using the same parameters. We found the following. (1) In the acute phase, the conventional antiemetic therapy using Ondansetron effectively reduced nausea and vomiting; the addition of TEA did not show any additive effects. In the delayed phase, however, TEA significantly increased the rate of complete control (P < 0.01) and reduced the nausea score (P < 0.05), compared with sham-TEA. (2) TEA significantly reduced serum levels of 5-HT and dopamine in comparison with sham-TEA. Those results demonstrate that needleless transcutaneous electroacupuncture at PC6 using a watch-size digital stimulator improves emesis and reduces nausea in the delayed phase of chemotherapy in patients with cancers. This antiemetic effect is possibly mediated via mechanisms involving serotonin and dopamine.

Antiemesis effect and brain fMRI response of gastric electrical stimulation with different parameters in dogs

BACKGROUND

The aims of this study were to investigate the effect of gastric electrical stimulation (GES) with different parameters on emesis induced by apomorphine, and possible center mechanisms by brain functional magnetic resonance imaging (fMRI).

METHODS

Six dogs implanted with electrodes on gastric serosa were used in this study. Part 1: Apomorphine was injected in the control session and GES sessions. GESs with different parameters were applied in GES session. Gastric slow waves and emesis and behaviors suggestive of nausea were recorded in each session. Part 2: Each dog was anesthetized and given GESs with different parameters or sham stimulation for 15 min after baseline (5 min), respectively. The location of cerebral activation induced by GES was investigated by fMRI.

KEY RESULTS

Apomorphine induced emesis and behaviors suggestive of nausea, and gastric dysrhythmia. The emesis frequency in control session was 5.5 ± 0.99, and symptoms score was 22.17 ± 1.01. GES with short pulse and long pulse could not improve emesis and symptoms induced by apomorphine. The emesis frequency (4.5 ± 0.76 in short pulse and 6.33 ± 1.05 in long pulse) and symptoms scores had no significant difference compared to control session (each p > 0.05). GES with trains of short pulse reduced emesis time frequency (3.83 ± 0.7, p = 0.042 vs control) and symptoms score (p = 0.037 vs control) obviously. Brain fMRI showed that GES with short pulse and long pulse activated brain stem region, and trains of short pulse made amygdala and occipital lobe activation.

CONCLUSIONS & INFERENCES

Apomorphine induced emesis and gastric dysrhythmia. GES with trains of short pulses relieves emetic responses through activation of amygdala region.

Assessment of low-dose cisplatin as a model of nausea and emesis in beagle dogs, potential for repeated administration

Cisplatin is a highly emetogenic cancer chemotherapy agent, which is often used to induce nausea and emesis in animal models. The cytotoxic properties of cisplatin also cause adverse events that negatively impact on animal welfare preventing repeated administration of cisplatin. In this study, we assessed whether a low (subclinical) dose of cisplatin could be utilized as a model of nausea and emesis in the dog while decreasing the severity of adverse events to allow repeated administration. The emetic, nausea-like behavior and potential biomarker response to both the clinical dose (70 mg/m²) and low dose (15 mg/m²) of cisplatin was assessed. Plasma creatinine concentrations and granulocyte counts were used to assess adverse effects on the kidneys and bone marrow, respectively. Nausea-like behavior and emesis was induced by both doses of cisplatin, but the latency to onset was greater in the low-dose group. No significant change in plasma creatinine was detected for either dose groups. Granulocytes were significantly reduced compared with baseline (P = 0.000) following the clinical, but not the low-dose cisplatin group. Tolerability of repeated administration was assessed with 4 administrations of an 18 mg/m² dose cisplatin. Plasma creatinine did not change significantly. Cumulative effects on the granulocytes occurred, they were significantly decreased (P = 0.03) from baseline at 3 weeks following cisplatin for the 4th administration only. Our results suggest that subclinical doses (15 and 18 mg/m²) of cisplatin induce nausea-like behavior and emesis but have reduced adverse effects compared with the clinical dose allowing for repeated administration in crossover studies.

Short pulse gastric electrical stimulation for cisplatin-induced emesis in dogs

BACKGROUND

In a previous study, we investigated the ameliorating effect of gastric electrical stimulation (GES) with a single set of parameters on emesis and behaviors suggestive of nausea induced by cisplatin in dogs. The aim of this study was to investigate the effects of GES with different parameters on cisplatin-induced emesis in dogs.

METHODS

Seven dogs implanted with gastric serosal electrodes were studied in six randomized sessions: one control session with cisplatin (2 mg kg(-1)) and five sessions with cisplatin plus GES of different parameters: GES-A: 14 Hz, 5 mA, 0.3 ms, 0.1 s on and 5 s off; GES-B: increased frequency and on-time; GES-C: increased frequency; GES-D: increased frequency and pulse width; and GES-E: increased frequency and amplitude. Gastric slow waves and emetic responses were recorded in each session.

KEY RESULTS

(i) Cisplatin induced emetic responses and gastric dysrhythmia. The peak time of the emetic response was during the fourth hour after cisplatin. (ii) GES with appropriate parameters reduced cisplatin-induced emesis. The number of vomiting times during the 6 h after cisplatin was 7.0 ± 1.4 in the control, 4.7 ± 1.2 with GES-A (P = 0.179), 4.2 ± 1.2 with GES-B (P = 0.109), 7.0 ± 0.8 with GES-C (P = 0.928), 2.1 ± 0.3 with GES-D (P = 0.005) and 4.7 ± 1.5 with GES-E (P = 0.129). However, none of the GES parameters could improve gastric dysrhythmia.

CONCLUSIONS & INFERENCES

Gastric electrical stimulation with appropriate parameters reduces cisplatin-induced emetic responses and behaviors suggestive of nausea in dogs. Among the tested parameters, GES with increased pulse width seems to produce better relief of cisplatin-induced emesis.

Involvement of 5-hydroxytryptamine in the preventive effect of Armillariella tabescens against cisplatin-induced changes in gastric electromyographic activity in rats

AIM: To investigate the preventive effect of Armillariella tabescens against cisplatin-induced changes in gastric electromyographic activity in rats and to explore the role of 5-hydroxytryptamine (5-HT) in this process.

METHODS: Ninety male Sprague-Dawley rats were randomized into control group, model group, ondansetron group, low-, medium-, and high-dose Armillariella tabescens groups. Rats were injected intraperitoneally with cisplatin (6 mg/kg) to induce pica. The electrical activity of gastric antral smooth muscle was recorded and analyzed using the Biopac MP100-CE acquisition system. The concentration of 5-HT in gastric antrum tissue was assayed by ELISA. The effect of Armillariella tabescens on gastric electromyographic activity and its relationship with 5-HT were then examined.

RESULTS: During 24-72 h after cisplatin administration, the cycles per minute (CPM) and amplitude of vibration (AV) of slow-wave in the gastric antrum were significantly higher in the model group than in the control group (all P < 0.05), medium-, and high-dose Armillariella tabescens groups (all P < 0.01), and the differences were most significant between the model group (CPM: 7.33 ± 2.92, AV: 249.75 ± 79.09) and the control group (CPM: 3.00 ± 1.55, AV: 148.04 ± 63.51) and high-dose Armillariella tabescens group (CPM: 4.13 ± 1.14, AV: 163.46 ± 26.14) at 24 h after cisplatin administration. Compared with the control group, the concentrations of 5-HT (μg/L) in the other groups were dramatically increased (24 h: 389.7 ± 25.5, 354.5 ± 34.9, 314.5 ± 31.5, 282.2 ± 19.6, 271.0 ± 21.1 vs 244.6 ± 27.3, all P < 0.05 or 0.01). CMP and AV increased with the increase in the concentrations of 5-HT.

CONCLUSION: Armillariella tabescens could effectively inhibit cisplatin-induced changes in gastric electromyographic activity in rats possibly via mechanisms involving 5-HT.

Reduced normogastric electrical activity associated with emesis: A telemetric study in ferrets

AIM: To characterize the gastric myoelectric activity (GMA) and intra-abdominal pressure changes induced by emetic stimuli (apomorphine and cisplatin) in the ferret.

METHODS: GMA and intra-abdominal pressure were recorded in conscious, unrestrained ferrets surgically implanted with radiotelemetry transmitters. Animals were challenged with apomorphine (0.25 mg/kg sc) and cisplatin (10 mg/kg ip), and the emetic response was quantified via direct observation and intra-abdominal pressure recording for 1 and 4 h, respectively. The GMA was analyzed by spectral analysis; the parameters used to characterize the GMA were the dominant frequency (DF) and the repartition of spectral power in the bradygastric, normogastric and tachygastric frequency ranges.

RESULTS: Retches were identified on the intra-abdominal pressure trace as peaks 0.30 ± 1.01 s in duration and 59.57 ± 2.74 mmHg in amplitude, vomit peaks were longer (0.82 ± 0.06 s, P < 0.01) and reached a higher pressure (87.73 ± 8.12 mmHg, P < 0.001). The number of retches and vomits quantified via direct observation [apomorphine: 65.5 ± 11.8 retches + vomits (R+V), cisplatin: 202.6 ± 64.1 R+V] and intra-abdominal pressure (apomorphine: 68.3 ± 13.7 R+V, n = 8; cisplatin: 219.0 ± 69.2 R+V, n = 8) were correlated (r = 0.97, P < 0.0001) and the timing of emesis was consistent between the 2 methods. Apomorphine induced a decrease in normogastria from 45.48% ± 4.35% to 36.70 ± 4.34% (n = 8, P < 0.05) but the DF of the slow waves was not changed [8.95 ± 0.25 counts/min (cpm) vs 8.68 ± 0.35 cpm, n = 8, P > 0.05]. Cisplatin induced a decrease in normogastria from 55.83% ± 4.30% to 29.22% ± 5.16% and an increase in bradygastria from 14.28% ± 2.32% to 31.19% ± 8.33% (n = 8, P < 0.001) but the DF (9.14 ± 0.13 cpm) remained unchanged (P > 0.05). The GMA changes induced by cisplatin preceded the emetic response as normogastria was reduced for 1 h before the onset of emesis (57.61% ± 5.66% to 39.91% ± 5.74%, n = 6, P < 0.05). Peri-emesis analysis revealed that the GMA was significantly disturbed during and immediately after, but not immediately before, the emetic episodes.

CONCLUSION: The induction of emesis is reliably associated with a disrupted GMA, but changes may also occur prior to and following the emetic response.