Astrocyte-specific knockout of YKL-40/Chi3l1 reduces Aß burden and restores memory functions in 5xFAD mice.

Glial cell-mediated neuroinflammation and neuronal attrition are highly correlated with cognitive impairment in Alzheimer's disease. YKL-40 is a secreted astrocytic glycoprotein that serves as a diagnostic biomarker of Alzheimer's disease. High levels of YKL-40 are associated with either advanced Alzheimer's disease or the normal aging process. However, the functional role of YKL-40 in Alzheimer's disease development has not been firmly established. In a 5xFAD mouse model of Alzheimer's disease, we observed increased YKL-40 expression in the cerebrospinal fluid of 7-month-old mice and was correlated with activated astrocytes. In primary astrocytes, Aß1-42 upregulated YKL-40 in a dose-dependent manner and was correlated with PI3-K signaling pathway activation. Furthermore, primary neurons treated with YKL-40 and/or Aß1-42 resulted in significant synaptic degeneration, reduced dendritic complexity, and impaired electrical parameters. More importantly, astrocyte-specific knockout of YKL-40 over a period of 7 days in symptomatic 5xFAD mice could effectively reduce amyloid plaque deposition in multiple brain regions. This was also associated with attenuated glial activation, reduced neuronal attrition, and restored memory function. These biological phenotypes could be explained by enhanced uptake of Aß1-42 peptides, increased rate of Aß1-42 degradation and acidification of lysosomal compartment in YKL-40 knockout astrocytes. Our results provide new insights into the role of YKL-40 in Alzheimer's disease pathogenesis and demonstrate the potential of targeting this soluble biomarker to alleviate cognitive defects in symptomatic Alzheimer's disease patients.

COVID-19, nausea, and vomiting.

Exclusion of nausea (N) and vomiting (V) from detailed consideration as symptoms of COVID-19 is surprising as N can be an early presenting symptom. We examined the incidence of NV during infection before defining potential mechanisms. We estimate that the overall incidence of nausea (median 10.5%), although variable, is comparable with diarrhea. Poor definition of N, confusion with appetite loss, and reporting of N and/or V as a single entity may contribute to reporting variability and likely underestimation. We propose that emetic mechanisms are activated by mediators released from the intestinal epithelium by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) modulate vagal afferents projecting to the brainstem and after entry into the blood, activate the area postrema (AP) also implicated in anorexia. The receptor for spike protein of SARS-CoV-2, angiotensin 2 converting enzyme (ACE2), and transmembrane protease serine (for viral entry) is expressed in upper gastrointestinal (GI) enterocytes, ACE2 is expressed on enteroendocrine cells (EECs), and SARS-CoV-2 infects enterocytes but not EECs (studies needed with native EECs). The resultant virus-induced release of epithelial mediators due to exocytosis, inflammation, and apoptosis provides the peripheral and central emetic drives. Additionally, data from SARS-CoV-2 show an increase in plasma angiotensin II (consequent on SARS-CoV-2/ACE2 interaction), a centrally (AP) acting emetic, providing a further potential mechanism in COVID-19. Viral invasion of the dorsal brainstem is also a possibility but more likely in delayed onset symptoms. Overall, greater attention must be given to nausea as an early symptom of COVID-19 and for the insights provided into the GI effects of SARS-CoV-2.

Intra-gastrointestinal amyloid-ß1-42 oligomers perturb enteric function and induce Alzheimer's disease pathology.

KEY POINTS: Alzheimer's disease (AD) patients and transgenic mice have beta-amyloid (Aß) aggregation in the gastrointestinal (GI) tract. It is possible that Aß from the periphery contributes to the load of Aß in the brain, as Aß has prion-like properties. The present investigations demonstrate that Aß injected into the GI tract of ICR mice is internalised into enteric cholinergic neurons; at 1 month, administration of Aß into the body of the stomach and the proximal colon was observed to partly redistribute to the fundus and jejunum; at 1 year, vagal and cerebral ß-amyloidosis was present, and mice exhibited GI dysfunction and cognitive deficits. These data reveal a previously undiscovered mechanism that potentially contributes to the development of AD. ABSTRACT: Alzheimer's disease (AD) is the most common age-related cause of dementia, characterised by extracellular beta-amyloid (Aß) plaques and intracellular phosphorylated tau tangles in the brain. Aß deposits have also been observed in the gastrointestinal (GI) tract of AD patients and transgenic mice, with overexpression of amyloid precursor protein. In the present studies, we investigate whether intra-GI administration of Aß can potentially induce amyloidosis in the central nervous system (CNS) and AD-related pathology such as dementia. We micro-injected Aß1-42 oligomers (4 µg per site, five sites) or vehicle (saline, 5 µl) into the gastric wall of ICR mice under general anaesthesia. Immunofluorescence staining and in vivo imaging showed that HiLyte Fluor 555-labelled Aß1-42 had migrated within 3 h via the submucosa to nearby areas and was internalised into cholinergic neurons. At 1 month, HiLyte Fluor 555-labelled Aß1-42 in the body of the stomach and proximal colon had partly re-distributed to the fundus and jejunum. At 1 year, the jejunum showed functional alterations in neuromuscular coupling (P < 0.001), and Aß deposits were present in the vagus and brain, with animals exhibiting cognitive impairments in the Y-maze spontaneous alteration test (P < 0.001) and the novel object recognition test (P < 0.001). We found that enteric Aß oligomers induce an alteration in gastric function, amyloidosis in the CNS, and AD-like dementia via vagal mechanisms. Our results suggest that Aß load is likely to occur initially in the GI tract and may translocate to the brain, opening the possibility of new strategies for the early diagnosis and prevention of AD.

Localization of estrogen receptor ERα, ERß and GPR30 on myenteric neurons of the gastrointestinal tract and their role in motility.

Estrogen is well known to have a modulatory role on gastrointestinal tract, particularly through its interaction with nuclear estrogen receptors (ERs), alpha and beta (ERα/ß). Recent functional studies also indicate that estrogen can activate a G-protein coupled estrogen receptor, GPR30, or GPER1. The present study was designed to identify either the presence or absence of nuclear ERs and GPR30 in the myenteric plexus of the stomach, duodenum, jejunum, ileum and colon of female and male mice. Immunofluorescence staining revealed a high expression of GPR30 in the cytoplasm but not within the nucleus of enteric neurons in female and male mice. ERß localization was similar to GPR30, where it was expressed in cytoplasm of enteric neurons, but was absent from nuclei, opening up the possibility that ERß and GPR30 might work together to manifest estrogenic effects. Comparatively, ERα was mainly located in the nuclei of enteric neurons. ERα, ERß and GPR30 were also expressed in the cytoplasm of glial cells in the stomach and small intestine, but levels were lower in the colon. The expression nuclear:cytoplasm ratio of ERα was higher in male than female mice, which might relate to sex-dependent translocation of ERα from cytoplasm to nucleus in response to known plasma levels of estrogen. A functional study using isolated ileal segments showed that ERα, ERß and GPR30 are involved in the neuronal-mediated contractions in female tissues, but only ERα was involved in male tissues. This may indicate although expression level was similar between males and females, the downstream mechanisms of ERß and GPR30 could be different between sexes. The present study provides a rationale for the action of estrogen to modulate gastrointestinal function in health and disease in different sexes.

Establishment of a radiotelemetric recording technique in mice to investigate gastric slow waves: Modulatory role of putative neurotransmitter systems.

NEW FINDINGS: What is the central question of this study? Gastric slow waves originating from the interstitial cells of Cajal-smooth muscle syncytium are usually studied in culture or in tissue segments, but nobody has described recordings of slow waves from awake, freely moving mice. Can radiotelemetry be used to record slow waves, and do they respond predictably to drug treatment? What is the main finding and its importance? Radiotelemetry can be used to record slow waves from awake, freely moving mice, permitting an examination of drug actions in vivo, which is crucial to drug discovery projects for characterizing the effects of drugs and metabolites on gastrointestinal function. ABSTRACT: The mouse is the most commonly used species in preclinical research, and isolated tissues are used to study slow waves from the interstitial cells of Cajal-smooth muscle syncytium of the gastrointestinal tract. The aim of this study was to establish a radiotelemetric technique in awake mice to record gastric myoelectric activity from the antrum to gain insight into the effects of endogenous modulatory systems on slow waves. Under general anaesthesia, two biopotential wires from a telemetry transmitter were sutured into the antrum of male ICR (imprinting control region) mice. The animals were allowed 1 week to recover from surgery before the i.p. administration of drugs to stimulate or inhibit slow waves. The basal dominant frequency of slow waves was 6.96 ± 0.43 c.p.m., and the percentages of power in the bradygastric, normogastric and tachygastric ranges were 6.89 ± 0.98, 37.32 ± 1.72 and 34.38 ± 0.77%, respectively (n = 74). Nicotine at 1 mg kg-1 increased normogastric power, but at 3 mg kg-1 it increased bradygastric power (P < 0.05). Metoclopramide at 10 mg kg-1 increased normogastric power; sodium nitroprusside at 10 mg kg-1 had latent effects on tachygastric power (P < 0.05); and l-NAME at 10 mg kg-1 had no effect (P > 0.05). Nicotine and bethanechol also caused varying degrees of hypothermia (>1°C reductions; P < 0.05). In conclusion, radiotelemetry can be used to record slow waves from awake, freely moving mice. In light of our findings, we recommend that studies assessing slow waves should also assess body temperature simultaneously.

Action of Bacopa monnieri to antagonize cisplatin-induced emesis in Suncus murinus (house musk shrew).

Bacopa monnieri (BM, family Scrophulariaceae) is used in several traditional systems of medicine for the management of epilepsy, depression, neuropathic pain, sleep disorders and memory deficits. The present study investigated the potential of BM methanol (BM-MetFr) and BM n-butanol fractions (BM-ButFr) to reduce chemotherapy-induced emesis in Suncus murinus (house musk shrew). Cisplatin (30 mg/kg, i.p.) reliably induced retching and/or vomiting over a 2 day period. BM-MetFr (10-40 mg/kg, s.c.) and BM-ButFr (5-20 mg/kg, s.c.) antagonized the retching and/or vomiting response by ∼59.4% (p < 0.05) and 78.9% (p < 0.05), respectively, while the 5-HT3 receptor antagonist, palonosetron (0.5 mg/kg, s.c.), reduced the response by ∼71% (p < 0.05). The free radical scavenger/antioxidant, N-(2-mercaptopropionyl)-glycine (30-300 mg/kg, s.c.) reduced the retching and/or vomiting response occurring on day one non-significantly by 44% (p > 0.05). In conclusion, the n-butanol fractions of BM have anti-emetic activity comparable with palonosetron and MPG. BM may be useful alone or in combination with other anti-emetic drugs for the treatment of chemotherapy-induced emesis in man.

Resveratrol protects against doxorubicin-induced cardiotoxicity in aged hearts through the SIRT1-USP7 axis.

KEY POINTS: Doxorubicin induced functional deteriorations and elevations of USP7-related apoptotic/catabolic signalling in the senescent heart Resveratrol protects against doxorubicin-induced alterations through the restoration of SIRT1 deacetylase activity ABSTRACT: A compromised cardiac function is often seen in elderly cancer patients receiving doxorubicin therapy. The present study tested the hypothesis that acute intervention with resveratrol, a natural anti-oxidant found in grapes and red wine, reduces the cardiotoxicity of doxorubicin through restoration of sirtuin 1 (SIRT1) deacetylase activity, and attenuation of the catabolic/apoptotic pathways orchestrated by USP7, a p53 deubiquitinating protein, using young (aged 2 months) and old (aged 10 months) senescence-accelerated mice prone 8 (SAMP8). Animals were randomised to receive saline, doxorubicin, and doxorubicin in combination with resveratrol, in the presence or absence of SIRT1 inhibitors, sirtinol or EX527. Resveratrol alone, but not in combination with either of the SIRT1 inhibitors, suppressed the doxorubicin-induced impairment of cardiac systolic function in aged animals. Doxorubicin reduced SIRT1 deacetylase activity, and elevated proteasomal activity and USP7; it also increased the protein level of p300 and ubiquitinated proteins in hearts from aged SAMP8. These doxorubicin-induced alterations were prevented by resveratrol, whereas the protective action of resveratrol was antagonised by sirtinol and EX527. In young SAMP8 hearts, resveratrol attenuated the doxorubicin-induced increases in acetylation of Foxo1 and transactivation of MuRF-1, whereas these mitigations were not found after treatment with SIRT1 inhibitors. However, the protein contents of acetylated Foxo1 and MuRF-1 were not affected by any of the drugs studied in aged SAMP8 hearts. Resveratrol also ameliorated the augmentation of pro-apoptotic markers including p53, Bax, caspase 3 activity and apoptotic DNA fragmentation induced by doxorubicin in hearts from aged animals, whereas these reductions were diminished by combined treatment with SIRT1 inhibitors. These data demonstrate that resveratrol ameliorates doxorubicin-induced cardiotoxicity in aged hearts through the restoration of SIRT1 activity to attenuate USP7-related catabolic/pro-apoptotic signalling.

Autophagy upregulation and apoptosis downregulation in DAHP and triptolide treated cerebral ischemia.

It has previously been demonstrated that ischemic stroke activates autophagy pathways; however, the mechanism remains unclear. The aim of this study is to further investigate the role that autophagy plays in cerebral ischemia. 2, 4-diamino-6-hydroxy-pyrimidine (DAHP), for its nitric oxide synthase (NOS) inhibiting neuroprotective effect, and triptolide (TP), for its anti-inflammatory property, were selected to administer pre middle cerebral artery occlusion (MCAO). The drugs were administered 12 hours prior to MCAO. Both magnetic resonance imaging (MRI) and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining showed that the drugs reduce the area of infarction. Immunoblotting analysis revealed increases in Beclin-1 and myeloid cell leukelia-1(Mcl-1) in treated rats. This could be a contributing factor to the reduction in autophagy induced damage. Immunochemistry and western blot showed that mTOR expression in treated rats was marginally different 24 h after injury, and this could also be significant in the mechanism. Furthermore, terminal deoxynucleotidyl transferase- (TdT-) mediated dUTP nick end labeling (TUNEL) staining proved that the drugs are effective in reducing apoptosis. The upregulation of Beclin-1 and Mcl-1 and downregulation of Bcl-2, caspase-3, and the Bcl-2/Beclin-1 ratio infer that the neuroprotective effect of DAHP and TP act via the mediation of autophagy and apoptosis pathways.

Modulating effect of SIRT1 activation induced by resveratrol on Foxo1-associated apoptotic signalling in senescent heart.

Elevations of cardiomyocyte apoptosis and fibrotic deposition are major characteristics of the ageing heart. Resveratrol, a polyphenol in grapes and red wine, is known to improve insulin resistance and increase mitochondrial biogenesis through the SIRT1-PGC-1α signalling axis. Recent studies attempted to relate SIRT1 activation by resveratrol to the regulation of apoptosis in various disease models of cardiac muscle. In the present study, we tested the hypothesis that long-term (8-month) treatment of resveratrol would activate SIRT1 and improve the cardiac function of senescent mice through suppression of Foxo1-associated pro-apoptotic signalling. Our echocardiographic measurements indicated that the cardiac systolic function measured as fractional shortening and ejection fraction was significantly reduced in aged mice when compared with the young mice. These reductions, however, were not observed in resveratrol-treated hearts. Ageing significantly reduced the deacetylase activity, but not the protein abundance of SIRT1 in the heart. This reduction was accompanied by increased acetylation of the Foxo1 transcription factor and transactivation of its target, pro-apoptotic Bim. Subsequent analyses indicated that pro-apoptotic signalling measured as p53, Bax and apoptotic DNA fragmentation was up-regulated in the heart of aged mice. In contrast, resveratrol restored SIRT1 activity and suppressed elevations of Foxo1 acetylation, Bim and pro-apoptotic signalling in the aged heart. In parallel, resveratrol also attenuated the ageing-induced elevations of fibrotic collagen deposition and markers of oxidative damage including 4HNE and nitrotyrosine. In conclusion, these novel data demonstrate that resveratrol mitigates pro-apoptotic signalling in senescent heart through a deacetylation mechanism of SIRT1 that represses the Foxo1-Bim-associated pro-apoptotic signalling axis.

Differential hypoglycaemic, anorectic, autonomic and emetic effects of the glucagon-like peptide receptor agonist, exendin-4, in the conscious telemetered ferret.

BACKGROUND: Rodents are incapable of emesis and consequently the emetic potential of glucagon-like peptide-1 receptor (GLP-1R) agonists in studies designed to assess a potential blood glucose lowering action of the compound was missed. Therefore, we investigated if the ferret, a carnivore with demonstrated translation capability in emesis research, would identify the emetic potential of the GLP-1R agonist, exendin-4, and any associated effects on gastric motor function, appetite and cardiovascular homeostasis. METHODS: The biological activity of the GLP-1R ligands was investigated in vivo using a glucose tolerance test in pentobarbitone-anesthetised ferrets and in vitro using organ bath studies. Radiotelemetry was used to investigate the effect of exendin-4 on gastric myoelectric activity (GMA) and cardiovascular function in conscious ferrets; behaviour was also simultaneously assessed. Western blot was used to characterize GLP-1R distribution in the gastrointestinal and brain tissues. RESULTS: In anesthetised ferrets, exendin-4 (30 nmol/kg, s.c.) reduced experimentally elevated blood glucose levels by 36.3%, whereas the GLP-1R antagonist, exendin (9-39) (300 nmol/kg, s.c.) antagonised the effect and increased AUC0-120 by 31.0% when injected alone (P < 0.05). In animals with radiotelemetry devices, exendin-4 (100 nmol/kg, s.c.) induced emesis in 1/9 ferrets, but inhibited food intake and decreased heart rate variability (HRV) in all animals (P < 0.05). In the animals not exhibiting emesis, there was no effect on GMA, mean arterial blood pressure, heart rate, or core body temperature. In the ferret exhibiting emesis, there was a shift in the GMA towards bradygastria with a decrease in power, and a concomitant decrease in HRV. Western blot revealed GLP-1R throughout the gastrointestinal tract but exendin-4 (up to 300 nM) and exendin (9-39), failed to contract or relax isolated ferret gut tissues. GLP-1R were found in all major brain regions and the levels were comparable those in the vagus nerve. CONCLUSIONS: Peripherally administered exendin-4 reduced blood glucose and inhibited feeding with a low emetic potential similar to that in humans (11% vs 12.8%). A disrupted GMA only occurred in the animal exhibiting emesis raising the possibility that disruption of the GMA may influence the probability of emesis occurring in response to treatment with GLP-1R agonists.

Attenuation of cisplatin-induced emetogenesis by standardized Bacopa monnieri extracts in the pigeon: behavioral and neurochemical correlations.

Nausea and vomiting are the most distressing and common side effects of cancer chemotherapy which often result in patient noncompliance. In the present study, standardized methanolic and n-butanolic fractions of Bacopa monnieri were evaluated against cisplatin-induced emesis in the pigeon in relation to their activity on central and intestinal neurotransmitters levels. Cisplatin (7.0 mg/kg, i. v.) induced reproducible emesis without lethality in healthy pigeons. The methanolic (10-40 mg/kg) and the bacoside-rich n-butanolic fractions of B. monnieri (5-20 mg/kg), as well as the antioxidant N-(2-mercaptopropionyl) glycine (10 mg/kg), attenuated cisplatin-induced emesis by 66.3% (p < 0.05), 71.6% (p < 0.001), and 76.5% (p < 0.001), respectively, where the standard antiemetic metoclopramide (30 mg/kg) produced a 48.9% reduction (p < 0.01). The methanolic and n-butanolic fractions of B. monnieri at all of the doses tested significantly reduced the serotonin concentration (p < 0.001) in the brain stem and intestine 3 h after cisplatin administration, while at the 18th h, B. monnieri treatments attenuated not only the dopamine upsurge in the area postrema and brain stem (p < 0.05-0.001), but also the intestinal 5-HT concentration (p < 0.01-0.001). B. monnieri treatments alone did not alter the basal neurotransmitters or their metabolites in the brain areas and intestine. The prolonged suppressive effect of B. monnieri treatments on the behavioral signs of cisplatin-induced emesis, the subsequent supportive neural evidence, and the safety and tolerability profile suggest that B. monnieri methanolic and bacoside-rich n-butanolic fractions might be a valuable adjunct in the treatment of emetogenic chemotherapy, and this warrants further study in other models of emesis.

Exploring the role of ghrelin and des-acyl ghrelin in chemotherapy-induced nausea and vomiting.

Ghrelin and its mimetics have been shown to reduce cisplatin-induced emesis in preclinical studies using ferrets and shrews. This study investigated the effectiveness of ghrelin and des-acyl ghrelin (DAG) in antagonizing cisplatin-induced emesis and physiological changes indicative of nausea in Suncus murinus. Animals implanted with radiotelemetry devices were administered ghrelin (0.2, 1.0, and 5.0 µg/day), DAG (0.2, 1.0, and 5.0 µg/day), or saline (14 µL/day) intracerebroventricularly 4 days before and 3 days after treatment with cisplatin (30 mg/kg). At the end, the anti-apoptotic potentials of ghrelin and DAG were assessed by measuring Bax expression and cytochrome C activity. Neurotransmitter changes in the brain were evaluated using liquid chromatography-mass spectrometry analysis. Ghrelin and DAG reduced cisplatin-induced emesis in the delayed (24-72 h) but not the acute phase (0-24 h) of emesis. Ghrelin also partially reversed the inhibitory effects of cisplatin on food intake without affecting gastrointestinal myoelectrical activity or causing hypothermia; however, ghrelin or DAG did not prevent these effects. Ghrelin and DAG could attenuate the cisplatin-induced upregulation of Bax and cytochrome C in the ileum. Cisplatin dysregulated neurotransmitter levels in the frontal cortex, amygdala, thalamus, hypothalamus, and brainstem, and this was partially restored by low doses of ghrelin and DAG. Our findings suggest that ghrelin and DAG exhibit protective effects against cisplatin-induced delayed emesis. The underlying antiemetic mechanism may involve GHSR and/or unspecified pathways that modulate the neurotransmitters involved in emesis control in the brain and an action to attenuate apoptosis in the gastrointestinal tract.

Predicting drug adverse effects using a new Gastro-Intestinal Pacemaker Activity Drug Database (GIPADD).

Electrical data could be a new source of big-data for training artificial intelligence (AI) for drug discovery. A Gastro-Intestinal Pacemaker Activity Drug Database (GIPADD) was built using a standardized methodology to test drug effects on electrical gastrointestinal (GI) pacemaker activity. The current report used data obtained from 89 drugs with 4867 datasets to evaluate the potential use of the GIPADD for predicting drug adverse effects (AEs) using a machine-learning (ML) approach and to explore correlations between AEs and GI pacemaker activity. Twenty-four "electrical" features (EFs) were extracted using an automated analytical pipeline from the electrical signals recorded before and after acute drug treatment at three concentrations (or more) on four-types of GI tissues (stomach, duodenum, ileum and colon). Extracted features were normalized and merged with an online side-effect resource (SIDER) database. Sixty-six common AEs were selected. Different algorithms of classification ML models, including Naïve Bayes, discriminant analysis, classification tree, k-nearest neighbors, support vector machine and an ensemble model were tested. Separated tissue models were also tested. Averaging experimental repeats and dose adjustment were performed to refine the prediction results. Random datasets were created for model validation. After model validation, nine AEs classification ML model were constructed with accuracy ranging from 67 to 80%. EF can be further grouped into 'excitatory' and 'inhibitory' types of AEs. This is the first time drugs are being clustered based on EF. Drugs acting on similar receptors share similar EF profile, indicating potential use of the database to predict drug targets too. GIPADD is a growing database, where prediction accuracy is expected to improve. The current approach provides novel insights on how EF may be used as new source of big-data in health and disease.

Regional differences of tachykinin effects on smooth muscle and pacemaker potentials of the stomach, duodenum, ileum and colon of an emetic model, the house musk shrews.

BACKGROUND AND AIMS: The contractile effects of tachykinins on the gastrointestinal tract are well-known, but how they modulate slow-waves, particularly in species capable of emesis, remains largely unknown. We aimed to elucidate the effects of tachykinins on myoelectric and contractile activity of isolated gastrointestinal tissues of the Suncus murinus. METHODS: The effects of substance P (SP), neurokinin (NK)A, NKB and selective NK1 (CP122,721, CP99,994), NK2 (SR48,968, GR159,897) and NK3 (SB218,795, SB222,200) receptor antagonists on isolated stomach, duodenum, ileum and colon segments were studied. Mechanical contractile activity was recorded using isometric force displacement transducers. Electrical pacemaker activity was recorded using a microelectrode array. RESULTS: Compared with NKA, SP induced larger contractions in stomach tissue and smaller contractions in intestinal segments, where oscillation magnitudes increased in intestinal segments, but not the stomach. CP122,721 and GR159,897 inhibited electrical field stimulation-induced contractions of the stomach, ileum and colon. NKB and NK3 had minor effects on contractile activity. The inhibitory potencies of SP and NKA on the peristaltic frequency of the colon and ileum, respectively, were correlated with those on electrical pacemaker frequency. SP, NKA and NKB inhibited pacemaker activity of the duodenum and ileum, but increased that of the stomach and colon. SP elicited a dose-dependent contradictive pacemaker frequency response in the colon. CONCLUSION: This study revealed distinct effects of tachykinins on the mechanical and electrical properties of the stomach and colon vs. the proximal intestine, providing a unique aspect on neuromuscular correlation in terms of the effects of tachykinin on peristaltic and pacemaker activity in gastrointestinal-related symptoms.

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.

The Actions of Centrally Administered Nesfatin-1 on Emesis, Feeding, and Locomotor Activity in Suncus murinus (House Musk Shrew).

Nesfatin-1 is an anorectic peptide expressed in both peripheral tissues and brain areas involved in the regulation of feeding, emotion and emesis. The aim of the present study is to characterize the distribution of NUCB2/nesfatin-1 in Suncus murinus and to investigate the actions of nesfatin-1 to affect gastrointestinal contractility, emesis, food and water intake, and locomotor activity. The deduced amino acid sequence of S. murinus nesfatin-1 using in silico cloning showed high homology with humans and rodents. NUCB2 mRNA was detected throughout the entire brain and in the gastrointestinal tract, including the stomach and gut. Western blot analysis and immunohistochemistry confirmed the expression of nesfatin-1 protein in these regions. The NUCB2 mRNA levels in the hypothalamus, hippocampus and brainstem were significantly decreased, whereas that in the striatum were increased after 24 h starvation compared to ad libitum-fed animals (p < 0.05). In in vitro studies, nesfatin-1 (0.3-1,000 pM) failed to contract or relax the isolated gastric antrum and intestinal segments. In conscious, freely moving animals, intracerebroventricular administration of nesfatin-1 (1-50 pmol) induced emesis (p < 0.05) and suppressed 6-h cumulative food intake (p < 0.05), without affecting the latency to feeding. Nesfatin-1 (25 pmol, i.c.v.) decreased 24-h cumulative food and water intake by 28.3 and 35.4%, respectively (p < 0.01). No significant differences in locomotor activity were observed. In conclusion, NUCB2/nesfatin-1 might be a potent regulator of feeding and emesis in S. murinus. Further studies are required to elucidate the mechanism of actions of this peptide as a mediator linking the brainstem NUCB2/nesfatin-1 to forebrain system.

Anti-neuroinflammatory and neurotrophic effects of combined therapy with annexin II and Reg-2 on injured spinal cord.

The present study was designed to investigate the neuroprotective effects of Ca(2+)-dependent phospholipid-binding protein annexin II and a secreted protein Reg-2 (regeneration gene protein 2) in spinal cord injury (SCI) model produced by contusion SCI at T(9) using the weight drop method. The agents were delivered intrathecally with Alzet miniosmotic pumps. We found that annexin II and Reg-2 remarkably reduced neuronal death, attenuated tissue damage and alleviated detrimental inflammation in vivo; meanwhile, a significant increase in white matter sparing and myelination area was observed. The propriospinal axons and long-distance supraspinal pathways were protected by the treatments as revealed by retrograde tracing. Basso Beattie Bresnahan locomotor rating scores also revealed a measurable behavioral improvement. However, no evident behavioral improvements in locomotor performance were achieved by the combined treatment with annexin II and Reg-2, compared with the separate treatment with annexin II and Reg-2.

A pipeline for phase-based analysis of in vitro micro-electrode array recordings of gastrointestinal slow waves.

Motility of the gastrointestinal tract (GI) is governed by an bioelectrical event termed slow waves. Accurately measuring the characteristics of GI slow waves is critical to understanding its role in clinical applications. High-resolution (HR) bioelectrical mapping involves placing a spatially dense array of electrodes directly over the surface of the GI wall to record the spatiotemporal changes in slow waves. A micro-electrode array (MEA) with spatial resolution of 200 µm in an 8x8 configuration was employed to record intestinal slow waves using isolated tissues from small animals including rodents, shrews and ferrets. A filtering, processing, and analytic pipeline was developed to extract useful metrics from the recordings. The pipeline relied on CWT and Hilbert Transform to identify the frequency and phase of the signals, from which the individual activation times of slow waves were identified and clustered using k-means. A structural similarity index was applied to group the major activation patterns. Overall, the pipeline identified 91 cycles of slow waves from 300 s of recordings in mice, with an average frequency of 20.68 ± 0.71 cpm, amplitude of 7.94 ± 2.15 µV, and velocity of 3.64 ± 1.75 mm s-1. Three major propagation patterns were identified during this period. The findings of this study will inform the development of a high throughput software platform for future in vitro pharmacological studies using the MEA.

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.

Involvement of TRPV1 and TRPA1 in the modulation of pacemaker potentials in the mouse ileum.

BACKGROUND: The roles of transient receptor potential cation channel, subfamily V, member 1 (TRPV1) and subfamily A, member 1 (TRPA1) in mechanisms of gastrointestinal motility are complex. This study aimed to clarify the effects of several TRPV1 and TRPA1 ligands on the electrical potentials generated by pacemaker cells in the mouse-isolated ileum. METHOD: The pacemaker potentials of ileal segments of mice were recorded extracellularly using a 60-channel microelectrode array. The dominant frequencies, average waveform periods and propagation velocities were quantified. The effects of TRPV1 and TRPA1 agonist and antagonist were compared with the baseline recordings. RESULTS: The electrophysiological recordings showed that capsaicin (30 µM to 3 mM), resiniferatoxin (300 µM), capsazepine (100-300 µM), allyl isothiocyanate (300 µM), isovelleral (300 µM), icilin (300 µM), A-967,079 (10 µM), AP18 (20 µM) and HC-030,031 (50 µM) significantly reduced the pacemaker frequency and increased the waveform period relative to the baseline. Conversely, ruthenium red (300 µM) significantly increased the pacemaker frequency and reduced the waveform period. Capsaicin (3 mM) and AP18 (20 µM) also significantly reduced the propagation velocity. However, all tested antagonists failed to inhibit the effects of agonists. AMG9810 (300 µM), but not A-967,079 (300 µM), significantly inhibited the increases in pacemaker frequency caused by increased temperatures. CONCLUSION: Our findings suggest that TRPV1 and TRPA1 play a minor role in regulating pacemaker potentials and that at non-specific actions at other TRP and ion channels most likely contributed to the overall effects on the electrophysiological recordings that we observed.