Vincent Castagné - Academia.edu (original) (raw)

Papers by Vincent Castagné

Research paper thumbnail of Neonatal phencyclidine and social isolation in the rat: effects of clozapine on locomotor activity, social recognition, prepulse inhibition, and executive functions deficits

Research paper thumbnail of Impact of the route of administration in drug discrimination studies in rats

Research paper thumbnail of Comparison of three preclinical models for nausea and vomiting assessment

Journal of pharmacological and toxicological methods

Nausea is a subjective sensation often preceding emesis in humans. Drug-induced nausea remains di... more Nausea is a subjective sensation often preceding emesis in humans. Drug-induced nausea remains difficult to predict in preclinical tests. The aim of this study was to compare the effects of emetic agents in rats (pica behavior), ferrets (acute and delayed phases of emesis) or dogs (emesis and cardiovascular endpoints). Rats and ferrets were administered cisplatin (±aprepitant/ondansetron or aprepitant) or apomorphine (±domperidone). Telemetered dogs were administered apomorphine (±domperidone). Food and kaolin intake was measured in rats whereas the number of emetic events was counted in ferrets and dogs. Cardiovascular changes were also monitored in dogs. In rats, cisplatin (6mg/kg, i.p.) increased kaolin intake (+2257%, p<0.001). The cisplatin effects were not reversed by the combination of aprepitant/ondansetron (2mg/kg, p.o./2mg/kg, i.p.) or by aprepitant (30mg/kg, p.o.). Apomorphine (10mg/kg, i.p.) did not induce pica behavior. In ferrets, cisplatin (8mg/kg, i.p.) induced ac...

Research paper thumbnail of Electrophysiological characteristics and pharmacological sensitivity of two lines of human induced pluripotent stem cell derived cardiomyocytes coming from two different suppliers

Journal of pharmacological and toxicological methods

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are increasingly used as p... more Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are increasingly used as preclinical tool for predicting drug-induced QT prolongation and arrhythmias. This study was conducted to assess the electrophysiological characteristics and the pharmacological sensitivity of two commercialized hiPSC-CMs. The baseline electrophysiological characteristics measured with a multi-electrode array (MEA) technology differ between Cor.4U and iCell: higher beat rate (+32bpm) and shorter field potential duration (FPD, -201ms) for Cor.4U. The FPD lengthening after cisapride (100nM: +65% versus +18%), quinidine (10μM: +65% versus +31%), sotalol (30μM: +90% versus +47%) or flecainide (3μM: +76% versus +22%) application appeared earlier in iCell as compared to Cor.4U. Arrhythmia occurrence also appeared earlier in iCell as compared to Cor.4U for the 3 substances mentioned above. The FPD shortening recorded after verapamil or nifedipine application was similar in both hiPSC-CMs. In con...

Research paper thumbnail of Proarrhythmic risk assessment using conventional and new in vitro assays

Regulatory Toxicology and Pharmacology

Drug-induced QT prolongation is a major safety issue in the drug discovery process. This study wa... more Drug-induced QT prolongation is a major safety issue in the drug discovery process. This study was conducted to assess the electrophysiological responses of four substances using established preclinical assays usually used in regulatory studies (hERG channel or Purkinje fiber action potential) and a new assay (human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs)-field potential). After acute exposure, moxifloxacin and dofetilide concentration-dependently decreased I amplitude (IC values: 102 μM and 40 nM, respectively) and lengthened action potential (100 μM moxifloxacin: +23% and 10 nM dofetilide: +18%) and field potential (300 μM moxifloxacin: +76% and 10 nM dofetilide: +38%) durations. Dofetilide starting from 30 nM induced arrhythmia in hiPSC-CMs. Overnight application of pentamidine (10 and 100 μM) and arsenic (1 and 10 μM) decreased I, whereas they were devoid of effects after acute application. Long-term pentamidine incubation showed a time- and concentration-dependent effect on field potential duration. In conclusion, our data suggest that hiPSC-CMs represent a fully functional cellular electrophysiology model which may significantly improve the predictive validity of in vitro safety studies. Thereafter, lead candidates may be further investigated in patch-clamp assays for mechanistic studies on individual ionic channels or in a multicellular Purkinje fiber preparation for confirmatory studies on cardiac conduction.

Research paper thumbnail of Efficacy of anticonvulsant substances in the 6 Hz seizure test: Comparison of two rodent species

Research paper thumbnail of Complementarity ofin vitroandin vivomodels for the evaluation of gastro-protective effects of pharmacological substances

Fundamental & Clinical Pharmacology, 2016

Gastric mucosa is frequently exposed to various gastric irritants, and there is a continuing requ... more Gastric mucosa is frequently exposed to various gastric irritants, and there is a continuing requirement to develop new gastro-protective agents. This study compares the effects of three such agents, sucralfate, rebamipide, and cimetidine in both in vivo and in vitro indomethacin-induced gastric damage models. For the in vivo approach, rats were orally administered sucralfate, rebamipide, and cimetidine at 300 mg/kg before an acute dose of indomethacin (30 mg/kg). Gastric lesions were then macroscopically examined. For the in vitro approach, gastric mucosal cells were incubated with sucralfate (3 and 5 mg/mL), rebamipide (0.3 and 1 mm), and cimetidine (10 and 50 μg/mL) before exposure to indomethacin (3.8 mm). The release of lactate dehydrogenase (LDH) and mitochondrial function were then measured. Sucralfate, rebamipide, and cimetidine displayed gastro-protective effects in vivo (decreased number of gastric ulcers: -50% P &lt; 0.05, -22% NS, and -69% P &lt; 0.05, respectively, and reduced length of gastric lesions: -62% P &lt; 0.05, -29% NS, and -70% P &lt; 0.001, respectively). Cell damage induced by indomethacin in vitro was inhibited by sucralfate (LDH release) and by rebamipide and cimetidine (mitochondrial function and LDH release). In contrast, sucralfate accentuated the indomethacin-induced decrease in mitochondrial function. Although cultured gastric cells offer a promising tool for evaluating the cytotoxic or protective effects of test compounds, data from in vivo models are still needed to confirm in vitro data. Using both approaches provides more comprehensive insight into the effects of test compounds on the gastric mucosa.

Research paper thumbnail of CNS safety pharmacology: A focus on cognitive functions

Journal of Pharmacological and Toxicological Methods, 2016

The guidelines from different agencies do not include studies on cognitive functions as part of s... more The guidelines from different agencies do not include studies on cognitive functions as part of safety pharmacology. This is unfortunate as it seems important to verify that drugs entering into the central nervous system (CNS) are devoid of detrimental effects on cognition. Our aim is to show examples on how an evaluation of unwanted effects of drugs on cognitive functions may be included in preclinical studies. Rather than a review of the scientific context, the present text is an appeal for a wider consideration of cognition as a safety pharmacology endpoint. The following procedures provide an index of the ability of substances to induce cognitive deficits in rodents. In the passive avoidance (PA) test, rats receiving an electric shock show on a later occasion an avoidance of the shock-associated environment. In the social recognition (SR) test, rats recognize familiar congeners. In the Morris water maze (MWM) test, rats placed into a tank containing water learn to find an invisible escape platform using extra-maze visual cues. In the delayed alternation (DA) test, rats placed in a Skinner box learn to alternate their pressing behavior between two levers in order to obtain food rewards. In the operant reversal (OR) test, rats adapt their behavior following a change of the reinforcement rule. Standard reference agents were used to confirm that the different assays were able to detect pharmacologically induced cognitive impairments. Diazepam decreased associative memory performances in the PA test. MK-801-induced memory deficits in SR. Haloperidol increased escape latencies in the MWM test. Scopolamine decreased the number of correct responses in the DA test, and nicotine decreased the number of correct responses in the OR test. The relationship between the doses administered and the effects observed was also evaluated. Cognitive assays may provide utility in determining potential undesirable effects or discharging perceived risks with novel CNS drugs under development.

Research paper thumbnail of Effects of baclofen and raclopride on reinstatement of cocaine self-administration in the rat

European journal of pharmacology, Jan 3, 2016

At present there is no satisfactory treatment against relapse of drug-seeking behavior. Relapse c... more At present there is no satisfactory treatment against relapse of drug-seeking behavior. Relapse can be modeled in laboratory animals using reinstatement procedures, whereby previously extinguished self-administration for a drug is reinstated by different factors, such as exposure to cues or drug priming. It is thought that activation of gamma-aminobutyric acid (GABA) B receptor complexes could represent a promising approach to pharmacotherapy for diminishing relapse potential with drugs possessing reinforcing properties. The effects of baclofen (a prototypic GABAB receptor agonist) on cue-induced cocaine reinstatement were evaluated in the rat with or without a priming injection of cocaine. The effects of raclopride (an antagonist of dopamine D2 receptors) were also evaluated. Cue-induced reinstatement under vehicle resulted in a significant increase in the number of presses on the active lever, as compared with extinction lever responding. This effect was accentuated in rats receiv...

Research paper thumbnail of Quantified electroencephalography (QEEG) in safety pharmacology

Journal of Pharmacological and Toxicological Methods, 2014

Research paper thumbnail of Evaluation of pro-convulsant risk in the rat: Spontaneous and provoked convulsions

Journal of pharmacological and toxicological methods

The aim of the present study was to evaluate the utility of different tests performed in the abse... more The aim of the present study was to evaluate the utility of different tests performed in the absence or presence of factors promoting seizures in order to evaluate the pro-convulsant effects of drugs. We studied the effects of theophylline in the rat since this is a well-known pro-convulsant substance in humans. The occurrence of spontaneous convulsions following administration of theophylline was evaluated by observation in the Irwin Test and by measuring brain activity using video-EEG recording in conscious telemetered animals. Theophylline was also tested in the electroconvulsive shock (ECS) threshold and pentylenetetrazole (PTZ)-induced convulsions tests, two commonly used models of provoked convulsions. In the Irwin test, theophylline induced convulsions in 1 out of 6 rats at 128mg/kg. Paroxysmal/seizure activity was also observed by video-EEG recording in 4 out of the 12 animals tested at 128mg/kg, in presence of clonic convulsions in 3 out of the 4 rats. Paroxysmal activity w...

Research paper thumbnail of Effects of diet-induced hyperthreoninemia. I). Amino acid levels in the central nervous system and peripheral tissues

Life sciences, 1993

Rats were fed four levels of threonine (Thr, 0.4, 0.6, 0.8, and 5.8 g/100 g diet). After two week... more Rats were fed four levels of threonine (Thr, 0.4, 0.6, 0.8, and 5.8 g/100 g diet). After two weeks, Thr, serine (Ser), and glycine (Gly) levels were measured in plasma, liver, muscle, and central nervous system. The diet containing 5.8 g/100 g of Thr elevated Thr and Gly concentrations in plasma and nervous tissue in comparison with a standard diet. In muscle and liver, Thr concentrations were also raised but Gly levels did not change. The hepatic Thr dehydratase activity was enhanced. Diets containing moderate Thr quantities (0.6 and 0.8 g/100 g) induced slight elevations of Thr levels in all tissues. Gly concentrations were not modified. The activity of hepatic Thr dehydratase was diminished. Our results show that a high dietary content of Thr (15 times the normal levels) elevates Gly levels in various tissues, including the brain. On the contrary, diets containing 2 to 4 times the normal levels of Thr induce a weak hyperthreoninemia insufficient to modify brain Gly.

Research paper thumbnail of Comparison of the effects of clonidine, loperamide and metoclopramide in two models of gastric emptying in the rat

Fundamental & clinical pharmacology, 2015

Several methods are used to evaluate gastric emptying (GE) in rats, which is an important endpoin... more Several methods are used to evaluate gastric emptying (GE) in rats, which is an important endpoint in preclinical drug development. Although phenol red model or monitoring of plasma acetaminophen levels are well-established procedures for GE assessment, their capacity to detect the effects of pharmacological agents has rarely been compared. This study was therefore designed to evaluate clonidine with loperamide and metoclopramide in the two test models. Rats were administered phenol red or acetaminophen test meals. The remaining amount of phenol red in the stomach or the time course of plasma acetaminophen levels was then measured. In the phenol red test, loperamide (8 mg/kg, p.o.) and clonidine (100 μg/kg, s.c.) decreased GE (-88 and -42%, P < 0.001 and P < 0.01, respectively). Metoclopramide (10 mg/kg, s.c.) accelerated GE (+42%, P < 0.01). Loperamide reduced acetaminophen plasma levels (-45% at T15 min, P < 0.05), suggesting a delayed GE. Clonidine and metoclopramide ...

Research paper thumbnail of Rodent models of depression: forced swim and tail suspension behavioral despair tests in rats and mice

The development of antidepressants requires simple rodent behavioral tests for initial screening ... more The development of antidepressants requires simple rodent behavioral tests for initial screening before undertaking more complex preclinical tests and clinical evaluation. Presented in the unit are two widely used screening tests used for antidepressants, the forced swim (also termed behavioral despair) test in the rat and mouse, and the tail suspension test in the mouse. These tests have good predictive validity and allow rapid and economical detection of substances with potential antidepressant-like activity. The behavioral despair and the tail suspension tests are based on the same principle: measurement of the duration of immobility when rodents are exposed to an inescapable situation. The majority of clinically used antidepressants decrease the duration of immobility. Antidepressants also increase the latency to immobility, and this additional measure can increase the sensitivity of the behavioral despair test in the mouse for certain classes of antidepressant. Testing of new substances in the behavioral despair and tail suspension tests allows a simple assessment of their potential antidepressant activity by the measurement of their effect on immobility.

Research paper thumbnail of Preclinical Behavioral Models for Predicting Antipsychotic Activity

Advances in Pharmacology, 2009

Schizophrenia is a major psychiatric disease that is characterized by three distinct symptom doma... more Schizophrenia is a major psychiatric disease that is characterized by three distinct symptom domains: positive symptoms, negative symptoms, and cognitive impairment. Additionally, treatment with classical antipsychotic medication can be accompanied by important side effects that involve extrapyramidal symptoms (EPS). The discovery of clozapine in the 1970s, which is efficacious in all three symptom domains and has a reduced propensity to induce EPS, has driven research for new antipsychotic agents with a wider spectrum of activity and a lower propensity to induce EPS. The following chapter reviews existing behavioral procedures in animals for their ability to predict compound efficacy against schizophrenia symptoms and liability to induce EPS. Rodent models of positive symptoms include procedures related to hyperfunction in central dopamine and serotonin (5-hydroxytryptamine) systems and hypofunction of central glutamatergic (N-methyl-d-aspartate) neurotransmission. Procedures for evaluating negative symptoms include rodent models of anhedonia, affective flattening, and diminished social interaction. Cognitive deficits can be assessed in rodent models of attention (prepulse inhibition (PPI), latent inhibition) and of learning and memory (passive avoidance, object and social recognition, Morris water maze, and operant-delayed alternation). The relevance of the conditioned avoidance response (CAR) is also discussed. A final section reviews animal procedures for assessing EPS liability, in particular parkinsonism (catalepsy), acute dystonia (purposeless chewing in rodents, dystonia in monkeys), akathisia (defecation in rodents), and tardive dyskinesia (long-term antipsychotic treatment in rodents and monkeys).

Research paper thumbnail of A rat model with relevance to schizophrenia: Low brain glutathione levels during development induce long-term cognitive deficit

Schizophrenia Research, 2003

We recently reported altered expression of NMDA receptor (NMDAR) subunits and associated intracel... more We recently reported altered expression of NMDA receptor (NMDAR) subunits and associated intracellular molecules in the thalamus of elderly schizophrenic patients,which is consistent with the idea of thalamic and glutamatergic dysfimetion playing a role in this illness. Using in situ hybridization,we examined the expression ofNMDAR subunits and associated PSD proteins (NF-L,PSD95,and SAP102) in tissue from the Stanley Foundation Neuropathology Consortium to replicate our initial findings. We found increased levels of NR2A and decreased expression of NF-L and SAP 102 transcripts in schizophrenia. This pattern of changes differs from our earher findings. However, these data support a hypothesis of glutamatergic dysfunction in the illness,and suggest that it may not only involve aberrant receptor expression, but also a dysregulation of NMDAR-related signaling pathways. Increasing evidence suggests that the etiology of sclfizophrenia may hlvolve a perturbation of brain development. Moore and colleagues have shown that disruption of cortical development by administering the DNAmethylating agent methylazoxymethanol acetate (MAM) on gestational day 17 (GD17) results in rats with neuroanatomical and neurophysiological abnormalities in adulthood suggestive o[ those observed in schizophrenia. In particular, these animals show reductions in crosssectional cortical thickness,increased neuronal density in cortex,and decreased size of the medial thalamus. We hypothesized that these animals would also exhibit thalamic neurochemical abnormahfies similar to those present in schizophrenia, and examined the expression of NMDAR subnnits and related PSD molecules in adult rats exposed to MAM (20-25 mg/kg) on GD17. NRI subunit and NF-L transcript expression was decreased in several thalamic nuclei, including the anterior and mediodorsal nuclei. PSD95 transcript expression did not change in MAM-treated rats,suggesting that the reduction of NRl and NF-L transcripts may be unrelated to thalamic cell loss. Ghitamatergic abnormalities in the thalamus may contribute to the dysregalated cortico-hmbic ch'cuilxy mad subsequent sensory mad cognitive impairment exhibited by MAM-treated animals. Rodent data from this developmental insult model parallel some of the ghitamatergic abnormalities observed in our post-mortem studies in the thalamus in schizophrenia,and provide another example of how MAM administration on GD 17 mimics brain abnormalities associated with schizophrenia.

Research paper thumbnail of In vitro safety cardiovascular pharmacology studies: Impact of formulation preparation and analysis

Regulatory Toxicology and Pharmacology, 2013

Collection of formulation samples is required for GLP in vitro studies to check the exposure of t... more Collection of formulation samples is required for GLP in vitro studies to check the exposure of the test system and allow reliable determinations of safety margins. In vitro studies conducted in-house were investigated to evaluate problems of solubility, stability and adsorption of the formulations. Terfenadine was used as reference substance to illustrate the purpose. Lowered target concentrations of test substances in in vitro studies can be attributed to the solubility limitation in the superfusion medium, the low stability under frozen conditions (24% of the final solutions stable at -20 °C) and/or the adsorption on the superfusion tubing (30% of the studies). Terfenadine also showed a limited solubility (measured concentrations ranging from 0.597 μM to 0.833 μM instead of 1 μM) and a loss of substance through the superfusion tubing from -30.2% to -39.2% with dimethylsulfoxide, ethanol or methanol. Terfenadine solubility was improved with 2-hydroxypropyl-β-cyclodextrin, no adsorption was observed, but its capacity to block the hERG channel was decreased. It is recommended to determine the substance solubility in appropriate buffers, to evaluate possible adsorption during method validation (formulation samples collected after superfusion), and to prepare fresh formulation each testing day with immediate analysis in absence of stability data. This strategy clearly favors single-site as opposed to multi-site studies.

Research paper thumbnail of Stress-induced changes of circulating neuropeptide Y in the rat: comparison with catecholamines

Regulatory Peptides, 1987

Circulating concentrations of neuropeptid~ radrenaline (NA) and adrenaline (AD) were m eterized r... more Circulating concentrations of neuropeptid~ radrenaline (NA) and adrenaline (AD) were m eterized rats submitted to various stress proto 52 fmol/ml, 0.90 + 0.11 pm increased by handling (+ 132%, + 76% andduring electric shock treatment. Adrenalecton ance of circulating adrenaline but did not a noradrenaline. In comparison circulating leve ~tide Y-like immunoreactivity ( were measured in conscious, chron ~rotocols. Basal plasma levels of pmol/ml and 0.52 + 0.07 pmc + 629%, respectively) and r Adrenalectomy resulted in the complete alter either control or stres, levels of NPY were reduced, b malectomized animals. Insulin stress induced a large incre ld cold stress induced an increase in plasma NA levels, n NPY concentrations. These results demonstrate that N th catecholamines in the peripheral nervous system, is al ponses and that its release parallels more closely change AD. Furthermore, stress-induced changes in circulating y do not originate from the adrenal gland but mainly frc system, and the release of NPY is dependent upon the na rosine; Noradrenaline; Adrenaline; Adrenal gland; Insul ~'old stress. ¢lorm6de, Laboratoir6 de Psychobiologie des Compartements Adaptatil ~. Saint-Sa6ns, 33077 Bordeaux Cedex, France. © 1987 Elsevier Science Publishers B.V. (Biomedical Division) and AD (194 + nificantly in adrenalecto ma AD levels and parallel change in is colocalized with during stress res lating NA than immunoreactivit, ipheral nervous s3 stimulus. Neuropeptide tyrosme; hypoglycemia; Cold Correspondence: P. Morm6de SERM U.259, Rue C.

Research paper thumbnail of Central and peripheral effects of repeated stress and high NaCl diet on neuropeptide Y

Physiology & Behavior, 1992

This study was performed to investigate the influence of repeated psychological stress alone or c... more This study was performed to investigate the influence of repeated psychological stress alone or combined with high NaCl intake on the function of the sympathetic nervous system. In addition, NPY levels have been measured in brain regions of potential importance in the central regulation of stress responses (ventrolateral and dorsomedial medulla, paraventricular and arcuate nucleus of the hypothalamus, and frontal cortex). Normotensive Wistar rats received a standard diet alone or supplemented with NaCl. To accentuate differences in sodium balance, rats on the high NaCl diet (HNa) were uninephrectomized. Half the animals on each diet were subjected to chronic stress using daily sessions (1 h) of immobilization stress. After 12 days, plasma levels of neuropeptide Y (NPY), norepinephrine (NE), and epinephrine (E) were measured basally and in response to acute footshock stress. HNa intake or chronic stress alone did not significantly alter either basal or stimulated plasma levels of NPY. However, combining the treatments produced a significant interaction, increasing the NPY response to footshock by 31% compared to HNa alone (p = 0.039) and by 98% compared to stress alone (p less than 0.001). Chronic stress increased basal levels of NE and enhanced the response to subsequent acute stress: combining the treatments did not yield further increases. Plasma levels of E were not significantly affected by the treatments. In the brain, stress alone had no effect on the NPY levels in the structures studied. HNa intake induced a significant increase in NPY levels of the arcuate nucleus, and produced a significant interaction with stress in the dorsomedial medulla. In a supplementary experiment, to evaluate the role of the autonomic nervous system in plasma NPY responses, treatment with the ganglion blocker hexamethonium was shown to significantly attenuate stress-induced changes in NPY, NE, and E.

Research paper thumbnail of Neurotoxicology and amino acid intake during development: The case of threonine

Pharmacology Biochemistry and Behavior, 1996

The development of the central nervous system is highly dependent on an adequate supply of nutrie... more The development of the central nervous system is highly dependent on an adequate supply of nutrients. In particular, protein and amino acid availability is of major concern during gestation and in early postnatal life. Numerous data have been published on some amino acids directly involved in brain functions as neurotransmitters or indirectly as precursors of neurotransmitters, but scant information is available on the possible consequences of hyperthreoninemia, a phenomenon repeatedly noted in clinical reports. The results of neurochemical and behavioral studies in the developing rat suggest that despite numerous possible effects of threonine on brain constituents, moderate hyperthreoninemia does not impair markedly the development of the central nervous system.

Research paper thumbnail of Neonatal phencyclidine and social isolation in the rat: effects of clozapine on locomotor activity, social recognition, prepulse inhibition, and executive functions deficits

Research paper thumbnail of Impact of the route of administration in drug discrimination studies in rats

Research paper thumbnail of Comparison of three preclinical models for nausea and vomiting assessment

Journal of pharmacological and toxicological methods

Nausea is a subjective sensation often preceding emesis in humans. Drug-induced nausea remains di... more Nausea is a subjective sensation often preceding emesis in humans. Drug-induced nausea remains difficult to predict in preclinical tests. The aim of this study was to compare the effects of emetic agents in rats (pica behavior), ferrets (acute and delayed phases of emesis) or dogs (emesis and cardiovascular endpoints). Rats and ferrets were administered cisplatin (±aprepitant/ondansetron or aprepitant) or apomorphine (±domperidone). Telemetered dogs were administered apomorphine (±domperidone). Food and kaolin intake was measured in rats whereas the number of emetic events was counted in ferrets and dogs. Cardiovascular changes were also monitored in dogs. In rats, cisplatin (6mg/kg, i.p.) increased kaolin intake (+2257%, p<0.001). The cisplatin effects were not reversed by the combination of aprepitant/ondansetron (2mg/kg, p.o./2mg/kg, i.p.) or by aprepitant (30mg/kg, p.o.). Apomorphine (10mg/kg, i.p.) did not induce pica behavior. In ferrets, cisplatin (8mg/kg, i.p.) induced ac...

Research paper thumbnail of Electrophysiological characteristics and pharmacological sensitivity of two lines of human induced pluripotent stem cell derived cardiomyocytes coming from two different suppliers

Journal of pharmacological and toxicological methods

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are increasingly used as p... more Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are increasingly used as preclinical tool for predicting drug-induced QT prolongation and arrhythmias. This study was conducted to assess the electrophysiological characteristics and the pharmacological sensitivity of two commercialized hiPSC-CMs. The baseline electrophysiological characteristics measured with a multi-electrode array (MEA) technology differ between Cor.4U and iCell: higher beat rate (+32bpm) and shorter field potential duration (FPD, -201ms) for Cor.4U. The FPD lengthening after cisapride (100nM: +65% versus +18%), quinidine (10μM: +65% versus +31%), sotalol (30μM: +90% versus +47%) or flecainide (3μM: +76% versus +22%) application appeared earlier in iCell as compared to Cor.4U. Arrhythmia occurrence also appeared earlier in iCell as compared to Cor.4U for the 3 substances mentioned above. The FPD shortening recorded after verapamil or nifedipine application was similar in both hiPSC-CMs. In con...

Research paper thumbnail of Proarrhythmic risk assessment using conventional and new in vitro assays

Regulatory Toxicology and Pharmacology

Drug-induced QT prolongation is a major safety issue in the drug discovery process. This study wa... more Drug-induced QT prolongation is a major safety issue in the drug discovery process. This study was conducted to assess the electrophysiological responses of four substances using established preclinical assays usually used in regulatory studies (hERG channel or Purkinje fiber action potential) and a new assay (human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs)-field potential). After acute exposure, moxifloxacin and dofetilide concentration-dependently decreased I amplitude (IC values: 102 μM and 40 nM, respectively) and lengthened action potential (100 μM moxifloxacin: +23% and 10 nM dofetilide: +18%) and field potential (300 μM moxifloxacin: +76% and 10 nM dofetilide: +38%) durations. Dofetilide starting from 30 nM induced arrhythmia in hiPSC-CMs. Overnight application of pentamidine (10 and 100 μM) and arsenic (1 and 10 μM) decreased I, whereas they were devoid of effects after acute application. Long-term pentamidine incubation showed a time- and concentration-dependent effect on field potential duration. In conclusion, our data suggest that hiPSC-CMs represent a fully functional cellular electrophysiology model which may significantly improve the predictive validity of in vitro safety studies. Thereafter, lead candidates may be further investigated in patch-clamp assays for mechanistic studies on individual ionic channels or in a multicellular Purkinje fiber preparation for confirmatory studies on cardiac conduction.

Research paper thumbnail of Efficacy of anticonvulsant substances in the 6 Hz seizure test: Comparison of two rodent species

Research paper thumbnail of Complementarity ofin vitroandin vivomodels for the evaluation of gastro-protective effects of pharmacological substances

Fundamental & Clinical Pharmacology, 2016

Gastric mucosa is frequently exposed to various gastric irritants, and there is a continuing requ... more Gastric mucosa is frequently exposed to various gastric irritants, and there is a continuing requirement to develop new gastro-protective agents. This study compares the effects of three such agents, sucralfate, rebamipide, and cimetidine in both in vivo and in vitro indomethacin-induced gastric damage models. For the in vivo approach, rats were orally administered sucralfate, rebamipide, and cimetidine at 300 mg/kg before an acute dose of indomethacin (30 mg/kg). Gastric lesions were then macroscopically examined. For the in vitro approach, gastric mucosal cells were incubated with sucralfate (3 and 5 mg/mL), rebamipide (0.3 and 1 mm), and cimetidine (10 and 50 μg/mL) before exposure to indomethacin (3.8 mm). The release of lactate dehydrogenase (LDH) and mitochondrial function were then measured. Sucralfate, rebamipide, and cimetidine displayed gastro-protective effects in vivo (decreased number of gastric ulcers: -50% P &lt; 0.05, -22% NS, and -69% P &lt; 0.05, respectively, and reduced length of gastric lesions: -62% P &lt; 0.05, -29% NS, and -70% P &lt; 0.001, respectively). Cell damage induced by indomethacin in vitro was inhibited by sucralfate (LDH release) and by rebamipide and cimetidine (mitochondrial function and LDH release). In contrast, sucralfate accentuated the indomethacin-induced decrease in mitochondrial function. Although cultured gastric cells offer a promising tool for evaluating the cytotoxic or protective effects of test compounds, data from in vivo models are still needed to confirm in vitro data. Using both approaches provides more comprehensive insight into the effects of test compounds on the gastric mucosa.

Research paper thumbnail of CNS safety pharmacology: A focus on cognitive functions

Journal of Pharmacological and Toxicological Methods, 2016

The guidelines from different agencies do not include studies on cognitive functions as part of s... more The guidelines from different agencies do not include studies on cognitive functions as part of safety pharmacology. This is unfortunate as it seems important to verify that drugs entering into the central nervous system (CNS) are devoid of detrimental effects on cognition. Our aim is to show examples on how an evaluation of unwanted effects of drugs on cognitive functions may be included in preclinical studies. Rather than a review of the scientific context, the present text is an appeal for a wider consideration of cognition as a safety pharmacology endpoint. The following procedures provide an index of the ability of substances to induce cognitive deficits in rodents. In the passive avoidance (PA) test, rats receiving an electric shock show on a later occasion an avoidance of the shock-associated environment. In the social recognition (SR) test, rats recognize familiar congeners. In the Morris water maze (MWM) test, rats placed into a tank containing water learn to find an invisible escape platform using extra-maze visual cues. In the delayed alternation (DA) test, rats placed in a Skinner box learn to alternate their pressing behavior between two levers in order to obtain food rewards. In the operant reversal (OR) test, rats adapt their behavior following a change of the reinforcement rule. Standard reference agents were used to confirm that the different assays were able to detect pharmacologically induced cognitive impairments. Diazepam decreased associative memory performances in the PA test. MK-801-induced memory deficits in SR. Haloperidol increased escape latencies in the MWM test. Scopolamine decreased the number of correct responses in the DA test, and nicotine decreased the number of correct responses in the OR test. The relationship between the doses administered and the effects observed was also evaluated. Cognitive assays may provide utility in determining potential undesirable effects or discharging perceived risks with novel CNS drugs under development.

Research paper thumbnail of Effects of baclofen and raclopride on reinstatement of cocaine self-administration in the rat

European journal of pharmacology, Jan 3, 2016

At present there is no satisfactory treatment against relapse of drug-seeking behavior. Relapse c... more At present there is no satisfactory treatment against relapse of drug-seeking behavior. Relapse can be modeled in laboratory animals using reinstatement procedures, whereby previously extinguished self-administration for a drug is reinstated by different factors, such as exposure to cues or drug priming. It is thought that activation of gamma-aminobutyric acid (GABA) B receptor complexes could represent a promising approach to pharmacotherapy for diminishing relapse potential with drugs possessing reinforcing properties. The effects of baclofen (a prototypic GABAB receptor agonist) on cue-induced cocaine reinstatement were evaluated in the rat with or without a priming injection of cocaine. The effects of raclopride (an antagonist of dopamine D2 receptors) were also evaluated. Cue-induced reinstatement under vehicle resulted in a significant increase in the number of presses on the active lever, as compared with extinction lever responding. This effect was accentuated in rats receiv...

Research paper thumbnail of Quantified electroencephalography (QEEG) in safety pharmacology

Journal of Pharmacological and Toxicological Methods, 2014

Research paper thumbnail of Evaluation of pro-convulsant risk in the rat: Spontaneous and provoked convulsions

Journal of pharmacological and toxicological methods

The aim of the present study was to evaluate the utility of different tests performed in the abse... more The aim of the present study was to evaluate the utility of different tests performed in the absence or presence of factors promoting seizures in order to evaluate the pro-convulsant effects of drugs. We studied the effects of theophylline in the rat since this is a well-known pro-convulsant substance in humans. The occurrence of spontaneous convulsions following administration of theophylline was evaluated by observation in the Irwin Test and by measuring brain activity using video-EEG recording in conscious telemetered animals. Theophylline was also tested in the electroconvulsive shock (ECS) threshold and pentylenetetrazole (PTZ)-induced convulsions tests, two commonly used models of provoked convulsions. In the Irwin test, theophylline induced convulsions in 1 out of 6 rats at 128mg/kg. Paroxysmal/seizure activity was also observed by video-EEG recording in 4 out of the 12 animals tested at 128mg/kg, in presence of clonic convulsions in 3 out of the 4 rats. Paroxysmal activity w...

Research paper thumbnail of Effects of diet-induced hyperthreoninemia. I). Amino acid levels in the central nervous system and peripheral tissues

Life sciences, 1993

Rats were fed four levels of threonine (Thr, 0.4, 0.6, 0.8, and 5.8 g/100 g diet). After two week... more Rats were fed four levels of threonine (Thr, 0.4, 0.6, 0.8, and 5.8 g/100 g diet). After two weeks, Thr, serine (Ser), and glycine (Gly) levels were measured in plasma, liver, muscle, and central nervous system. The diet containing 5.8 g/100 g of Thr elevated Thr and Gly concentrations in plasma and nervous tissue in comparison with a standard diet. In muscle and liver, Thr concentrations were also raised but Gly levels did not change. The hepatic Thr dehydratase activity was enhanced. Diets containing moderate Thr quantities (0.6 and 0.8 g/100 g) induced slight elevations of Thr levels in all tissues. Gly concentrations were not modified. The activity of hepatic Thr dehydratase was diminished. Our results show that a high dietary content of Thr (15 times the normal levels) elevates Gly levels in various tissues, including the brain. On the contrary, diets containing 2 to 4 times the normal levels of Thr induce a weak hyperthreoninemia insufficient to modify brain Gly.

Research paper thumbnail of Comparison of the effects of clonidine, loperamide and metoclopramide in two models of gastric emptying in the rat

Fundamental & clinical pharmacology, 2015

Several methods are used to evaluate gastric emptying (GE) in rats, which is an important endpoin... more Several methods are used to evaluate gastric emptying (GE) in rats, which is an important endpoint in preclinical drug development. Although phenol red model or monitoring of plasma acetaminophen levels are well-established procedures for GE assessment, their capacity to detect the effects of pharmacological agents has rarely been compared. This study was therefore designed to evaluate clonidine with loperamide and metoclopramide in the two test models. Rats were administered phenol red or acetaminophen test meals. The remaining amount of phenol red in the stomach or the time course of plasma acetaminophen levels was then measured. In the phenol red test, loperamide (8 mg/kg, p.o.) and clonidine (100 μg/kg, s.c.) decreased GE (-88 and -42%, P < 0.001 and P < 0.01, respectively). Metoclopramide (10 mg/kg, s.c.) accelerated GE (+42%, P < 0.01). Loperamide reduced acetaminophen plasma levels (-45% at T15 min, P < 0.05), suggesting a delayed GE. Clonidine and metoclopramide ...

Research paper thumbnail of Rodent models of depression: forced swim and tail suspension behavioral despair tests in rats and mice

The development of antidepressants requires simple rodent behavioral tests for initial screening ... more The development of antidepressants requires simple rodent behavioral tests for initial screening before undertaking more complex preclinical tests and clinical evaluation. Presented in the unit are two widely used screening tests used for antidepressants, the forced swim (also termed behavioral despair) test in the rat and mouse, and the tail suspension test in the mouse. These tests have good predictive validity and allow rapid and economical detection of substances with potential antidepressant-like activity. The behavioral despair and the tail suspension tests are based on the same principle: measurement of the duration of immobility when rodents are exposed to an inescapable situation. The majority of clinically used antidepressants decrease the duration of immobility. Antidepressants also increase the latency to immobility, and this additional measure can increase the sensitivity of the behavioral despair test in the mouse for certain classes of antidepressant. Testing of new substances in the behavioral despair and tail suspension tests allows a simple assessment of their potential antidepressant activity by the measurement of their effect on immobility.

Research paper thumbnail of Preclinical Behavioral Models for Predicting Antipsychotic Activity

Advances in Pharmacology, 2009

Schizophrenia is a major psychiatric disease that is characterized by three distinct symptom doma... more Schizophrenia is a major psychiatric disease that is characterized by three distinct symptom domains: positive symptoms, negative symptoms, and cognitive impairment. Additionally, treatment with classical antipsychotic medication can be accompanied by important side effects that involve extrapyramidal symptoms (EPS). The discovery of clozapine in the 1970s, which is efficacious in all three symptom domains and has a reduced propensity to induce EPS, has driven research for new antipsychotic agents with a wider spectrum of activity and a lower propensity to induce EPS. The following chapter reviews existing behavioral procedures in animals for their ability to predict compound efficacy against schizophrenia symptoms and liability to induce EPS. Rodent models of positive symptoms include procedures related to hyperfunction in central dopamine and serotonin (5-hydroxytryptamine) systems and hypofunction of central glutamatergic (N-methyl-d-aspartate) neurotransmission. Procedures for evaluating negative symptoms include rodent models of anhedonia, affective flattening, and diminished social interaction. Cognitive deficits can be assessed in rodent models of attention (prepulse inhibition (PPI), latent inhibition) and of learning and memory (passive avoidance, object and social recognition, Morris water maze, and operant-delayed alternation). The relevance of the conditioned avoidance response (CAR) is also discussed. A final section reviews animal procedures for assessing EPS liability, in particular parkinsonism (catalepsy), acute dystonia (purposeless chewing in rodents, dystonia in monkeys), akathisia (defecation in rodents), and tardive dyskinesia (long-term antipsychotic treatment in rodents and monkeys).

Research paper thumbnail of A rat model with relevance to schizophrenia: Low brain glutathione levels during development induce long-term cognitive deficit

Schizophrenia Research, 2003

We recently reported altered expression of NMDA receptor (NMDAR) subunits and associated intracel... more We recently reported altered expression of NMDA receptor (NMDAR) subunits and associated intracellular molecules in the thalamus of elderly schizophrenic patients,which is consistent with the idea of thalamic and glutamatergic dysfimetion playing a role in this illness. Using in situ hybridization,we examined the expression ofNMDAR subunits and associated PSD proteins (NF-L,PSD95,and SAP102) in tissue from the Stanley Foundation Neuropathology Consortium to replicate our initial findings. We found increased levels of NR2A and decreased expression of NF-L and SAP 102 transcripts in schizophrenia. This pattern of changes differs from our earher findings. However, these data support a hypothesis of glutamatergic dysfunction in the illness,and suggest that it may not only involve aberrant receptor expression, but also a dysregulation of NMDAR-related signaling pathways. Increasing evidence suggests that the etiology of sclfizophrenia may hlvolve a perturbation of brain development. Moore and colleagues have shown that disruption of cortical development by administering the DNAmethylating agent methylazoxymethanol acetate (MAM) on gestational day 17 (GD17) results in rats with neuroanatomical and neurophysiological abnormalities in adulthood suggestive o[ those observed in schizophrenia. In particular, these animals show reductions in crosssectional cortical thickness,increased neuronal density in cortex,and decreased size of the medial thalamus. We hypothesized that these animals would also exhibit thalamic neurochemical abnormahfies similar to those present in schizophrenia, and examined the expression of NMDAR subnnits and related PSD molecules in adult rats exposed to MAM (20-25 mg/kg) on GD17. NRI subunit and NF-L transcript expression was decreased in several thalamic nuclei, including the anterior and mediodorsal nuclei. PSD95 transcript expression did not change in MAM-treated rats,suggesting that the reduction of NRl and NF-L transcripts may be unrelated to thalamic cell loss. Ghitamatergic abnormalities in the thalamus may contribute to the dysregalated cortico-hmbic ch'cuilxy mad subsequent sensory mad cognitive impairment exhibited by MAM-treated animals. Rodent data from this developmental insult model parallel some of the ghitamatergic abnormalities observed in our post-mortem studies in the thalamus in schizophrenia,and provide another example of how MAM administration on GD 17 mimics brain abnormalities associated with schizophrenia.

Research paper thumbnail of In vitro safety cardiovascular pharmacology studies: Impact of formulation preparation and analysis

Regulatory Toxicology and Pharmacology, 2013

Collection of formulation samples is required for GLP in vitro studies to check the exposure of t... more Collection of formulation samples is required for GLP in vitro studies to check the exposure of the test system and allow reliable determinations of safety margins. In vitro studies conducted in-house were investigated to evaluate problems of solubility, stability and adsorption of the formulations. Terfenadine was used as reference substance to illustrate the purpose. Lowered target concentrations of test substances in in vitro studies can be attributed to the solubility limitation in the superfusion medium, the low stability under frozen conditions (24% of the final solutions stable at -20 °C) and/or the adsorption on the superfusion tubing (30% of the studies). Terfenadine also showed a limited solubility (measured concentrations ranging from 0.597 μM to 0.833 μM instead of 1 μM) and a loss of substance through the superfusion tubing from -30.2% to -39.2% with dimethylsulfoxide, ethanol or methanol. Terfenadine solubility was improved with 2-hydroxypropyl-β-cyclodextrin, no adsorption was observed, but its capacity to block the hERG channel was decreased. It is recommended to determine the substance solubility in appropriate buffers, to evaluate possible adsorption during method validation (formulation samples collected after superfusion), and to prepare fresh formulation each testing day with immediate analysis in absence of stability data. This strategy clearly favors single-site as opposed to multi-site studies.

Research paper thumbnail of Stress-induced changes of circulating neuropeptide Y in the rat: comparison with catecholamines

Regulatory Peptides, 1987

Circulating concentrations of neuropeptid~ radrenaline (NA) and adrenaline (AD) were m eterized r... more Circulating concentrations of neuropeptid~ radrenaline (NA) and adrenaline (AD) were m eterized rats submitted to various stress proto 52 fmol/ml, 0.90 + 0.11 pm increased by handling (+ 132%, + 76% andduring electric shock treatment. Adrenalecton ance of circulating adrenaline but did not a noradrenaline. In comparison circulating leve ~tide Y-like immunoreactivity ( were measured in conscious, chron ~rotocols. Basal plasma levels of pmol/ml and 0.52 + 0.07 pmc + 629%, respectively) and r Adrenalectomy resulted in the complete alter either control or stres, levels of NPY were reduced, b malectomized animals. Insulin stress induced a large incre ld cold stress induced an increase in plasma NA levels, n NPY concentrations. These results demonstrate that N th catecholamines in the peripheral nervous system, is al ponses and that its release parallels more closely change AD. Furthermore, stress-induced changes in circulating y do not originate from the adrenal gland but mainly frc system, and the release of NPY is dependent upon the na rosine; Noradrenaline; Adrenaline; Adrenal gland; Insul ~'old stress. ¢lorm6de, Laboratoir6 de Psychobiologie des Compartements Adaptatil ~. Saint-Sa6ns, 33077 Bordeaux Cedex, France. © 1987 Elsevier Science Publishers B.V. (Biomedical Division) and AD (194 + nificantly in adrenalecto ma AD levels and parallel change in is colocalized with during stress res lating NA than immunoreactivit, ipheral nervous s3 stimulus. Neuropeptide tyrosme; hypoglycemia; Cold Correspondence: P. Morm6de SERM U.259, Rue C.

Research paper thumbnail of Central and peripheral effects of repeated stress and high NaCl diet on neuropeptide Y

Physiology & Behavior, 1992

This study was performed to investigate the influence of repeated psychological stress alone or c... more This study was performed to investigate the influence of repeated psychological stress alone or combined with high NaCl intake on the function of the sympathetic nervous system. In addition, NPY levels have been measured in brain regions of potential importance in the central regulation of stress responses (ventrolateral and dorsomedial medulla, paraventricular and arcuate nucleus of the hypothalamus, and frontal cortex). Normotensive Wistar rats received a standard diet alone or supplemented with NaCl. To accentuate differences in sodium balance, rats on the high NaCl diet (HNa) were uninephrectomized. Half the animals on each diet were subjected to chronic stress using daily sessions (1 h) of immobilization stress. After 12 days, plasma levels of neuropeptide Y (NPY), norepinephrine (NE), and epinephrine (E) were measured basally and in response to acute footshock stress. HNa intake or chronic stress alone did not significantly alter either basal or stimulated plasma levels of NPY. However, combining the treatments produced a significant interaction, increasing the NPY response to footshock by 31% compared to HNa alone (p = 0.039) and by 98% compared to stress alone (p less than 0.001). Chronic stress increased basal levels of NE and enhanced the response to subsequent acute stress: combining the treatments did not yield further increases. Plasma levels of E were not significantly affected by the treatments. In the brain, stress alone had no effect on the NPY levels in the structures studied. HNa intake induced a significant increase in NPY levels of the arcuate nucleus, and produced a significant interaction with stress in the dorsomedial medulla. In a supplementary experiment, to evaluate the role of the autonomic nervous system in plasma NPY responses, treatment with the ganglion blocker hexamethonium was shown to significantly attenuate stress-induced changes in NPY, NE, and E.

Research paper thumbnail of Neurotoxicology and amino acid intake during development: The case of threonine

Pharmacology Biochemistry and Behavior, 1996

The development of the central nervous system is highly dependent on an adequate supply of nutrie... more The development of the central nervous system is highly dependent on an adequate supply of nutrients. In particular, protein and amino acid availability is of major concern during gestation and in early postnatal life. Numerous data have been published on some amino acids directly involved in brain functions as neurotransmitters or indirectly as precursors of neurotransmitters, but scant information is available on the possible consequences of hyperthreoninemia, a phenomenon repeatedly noted in clinical reports. The results of neurochemical and behavioral studies in the developing rat suggest that despite numerous possible effects of threonine on brain constituents, moderate hyperthreoninemia does not impair markedly the development of the central nervous system.