References of "Tirelli, Ezio"
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See detailHigher long-lasting ethanol sensitization after adolescent ethanol exposure in mice
Quoilin, Caroline; Didone, Vincent ULg; Tirelli, Ezio ULg et al

in Psychopharmacology (2014), 231

Rationale. Due to their maturing brain, adolescents are suggested to be more vulnerable to the long-term consequences of chronic alcohol use. Increased sensitization to the stimulant effects of ethanol is ... [more ▼]

Rationale. Due to their maturing brain, adolescents are suggested to be more vulnerable to the long-term consequences of chronic alcohol use. Increased sensitization to the stimulant effects of ethanol is a possible consequence of ethanol exposure during adolescence. Objectives. The aim of this study was to characterize the long-term alterations in the stimulant effects of ethanol and in the rate of ethanol sensitization in mice pre-exposed to ethanol during adolescence in comparison to mice pre-exposed to ethanol in adulthood. Methods. Adolescent and adult female SWISS mice were injected with saline or ethanol (2.5 or 4 g/kg) during 14 consecutive days. After a three weeks period of ethanol abstinence, mice were tested as adults before and after a second exposure to daily repeated ethanol injections. Results. All mice pre-exposed to ethanol as adults or adolescents showed higher stimulant effects when re-exposed to ethanol three weeks later. However, this enhanced sensitivity to the stimulant effects of ethanol was of significantly higher magnitude in mice repeatedly injected with high ethanol doses (4g/kg) during adolescence. Furthermore, the increased expression of ethanol stimulant effects in these mice was maintained even after a second procedure of ethanol sensitization. Conclusions. Adolescence is a critical period for the development of a sensitization to ethanol stimulant properties providing that high intermittent ethanol doses are administered. These results might contribute to explain the relationship between age at first alcohol use and risks of later alcohol problems and highlight the dangers of repeated consumption of high alcohol amounts in young adolescents. [less ▲]

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See detailAmphetamine reward in food restricted mice lacking the melanin-concentrating hormone receptor-1
Geuzaine, A; Tyhon, A; Grisar, Thierry ULg et al

in Behavioural Brain Research (2014), 262

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See detailThe histamine H3-receptor inverse agonist Pitolisant improves fear memory in mice
Brabant, Christian ULg; Charlier, Yana ULg; Tirelli, Ezio ULg

in Behavioural Brain Research (2013), 243

Numerous studies have demonstrated that brain histamine plays a crucial role in learning and memory and histamine H3 receptor inverse agonists (H3R inverse agonists) have been proposed to treat cognitive ... [more ▼]

Numerous studies have demonstrated that brain histamine plays a crucial role in learning and memory and histamine H3 receptor inverse agonists (H3R inverse agonists) have been proposed to treat cognitive disorders. Pitolisant (BF2.649, 1-{3-[3-(4-chlorophenyl)propoxy]propyl}piperidine, hydrochloride) was the first H3R inverse agonist that has been tested in human trials and is well tolerated. The present study investigated whether Pitolisant (0.625–20 mg/kg, i.p.) improves consolidation and reconsolidation processes in the fear conditioning task in female C57BL/6J mice. We also tested whether Pitolisant reverses memory deficits induced by the non-competitive N-methyl-d-aspartate (NMDA) antagonist dizocilpine (MK-801). Our results indicate that post-training systemic injections of Pitolisant facilitated consolidation of contextual fear memory and reversed amnesia induced by an i.p. injection of 0.12 mg/kg dizocilpine. In addition, none of the doses of Pitolisant we have tested after reactivation (reexposure to the context in which training took place 48 h earlier) affected reconsolidation, whereas dizocilpine disrupted it. However, Pitolisant was able to reverse the deficit in reconsolidation induced by 0.12 mg/kg dizocilpine. The present results are the first demonstration that Pitolisant is effective in improving consolidation processes in the fear condition task and add further evidence to its potential for treating cognitive disorders. [less ▲]

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See detailChronic tolerance to ethanol-induced sedation: Implication for age-related differences in locomotor sensitization
Quoilin, Caroline; Didone, Vincent ULg; Tirelli, Ezio ULg et al

in Alcohol (2013), 47(4), 317-322

The adolescent brain has been suggested to be particularly sensitive to ethanol-induced neuroadaptations, which in turn could increase the risk of youths for alcohol abuse and dependence. Sensitization to ... [more ▼]

The adolescent brain has been suggested to be particularly sensitive to ethanol-induced neuroadaptations, which in turn could increase the risk of youths for alcohol abuse and dependence. Sensitization to the locomotor stimulant effects of ethanol has often been used as an animal model of ethanol-induced neuroadaptations. Previously, we showed that young mice were more sensitive than adults to the locomotor sensitization induced by high ethanol doses. However, this effect could be due to age-related differences in chronic tolerance to the sedative effects of ethanol. The aim of the present study is to assess chronic tolerance to the sedative effects of ethanol in weaning 21-day-old (P21), adolescent 35-day-old (P35) and adult 63-day-old (P63) female Swiss mice. After a daily injection of saline or 4 g/kg ethanol during 6 consecutive days, all P21, P35 and P63 mice were injected with 4 g/kg ethanol and submitted to the loss of righting reflex procedure. Our results confirm that the sensitivity to the acute sedative effects of ethanol gradually increases with age. Although this schedule of ethanol injections induces significant age-related differences in ethanol sensitization, it did not reveal significant differences between P21, P35 and P63 mice in the development of a chronic ethanol tolerance to its sedative effects. The present results show that age-related differences in the development of ethanol sensitization cannot be explained by differences in chronic ethanol tolerance to its sedative effects. More broadly, they do not support the idea that ethanol-induced sensitization is a by-product of chronic ethanol tolerance. [less ▲]

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See detailEnvironmental enrichment can accentuate condtioned reward induced by representative cocaine doses in mice
Geuzaine, Annabelle ULg; Tirelli, Ezio ULg

in Journal of Psychopharmacology (2012, August), 26(8), 70

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See detailChronic ethanol exposure during adolescence alters the behavioral responsiveness to ethanol in adult mice
Quoilin, Caroline ULg; Didone, Vincent ULg; Tirelli, Ezio ULg et al

in Behavioural Brain Research (2012), 229

Alcohol exposure during early adolescence is believed to durably alter the behavioral properties of ethanol, increasing the likelihood of later alcohol-related disorders. The aim of the present ... [more ▼]

Alcohol exposure during early adolescence is believed to durably alter the behavioral properties of ethanol, increasing the likelihood of later alcohol-related disorders. The aim of the present experiments was to characterize changes in the behavioral effects of ethanol in adult female Swiss mice after a chronic ethanol exposure during adolescence, extending from postnatal day 28 to postnatal day 42. After a chronic ethanol exposure during adolescence (daily injections of 0, 2.5 or 4 g/kg ethanol for 14 consecutive days), adult mice were tested at postnatal day 63. The locomotor stimulant effects of ethanol, together with ethanol sensitization were tested in experiment 1. In experiment 2, the sedative effects of ethanol were assessed with the loss of righting reflex procedure. Finally, in experiment 3, the anxiolytic effects of ethanol were tested with the light/dark box test. Adult mice chronically exposed to ethanol during adolescence showed a lower basal locomotor activity, but higher locomotor stimulant effects of ethanol than non-exposed mice. Additionally, these adult mice developed higher rates of ethanol sensitization after chronic re-exposure to ethanol in adulthood. Adult mice exposed to ethanol during adolescence also had a stronger tolerance to the sedative effects of high ethanol doses, although they showed no evidence of changes in the anxiolytic effects of ethanol. These results are in agreement with the thesis that chronic alcohol consumption during adolescence, especially in high amounts, increases the risk of later alcohol-related disorders. [less ▲]

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See detailDevelopmental differences in ethanol-induced sensitization using postweanling, adolescent, and adult Swiss mice
Quoilin, Caroline ULg; Didone, Vincent ULg; Tirelli, Ezio ULg et al

in Psychopharmacology (2012), 219

Rationale: The maturing adolescent brain has been suggested to be more sensitive than the adult brain to ethanol-induced neuroadaptations. In animal studies, sensitization to the stimulant effects of ... [more ▼]

Rationale: The maturing adolescent brain has been suggested to be more sensitive than the adult brain to ethanol-induced neuroadaptations. In animal studies, sensitization to the stimulant effects of ethanol is used to study the vulnerability to chronic ethanol-induced neurobehavioral alterations. Objectives: The aim of the present study was to systematically characterize age-dependent changes in the development and expression of the sensitization to the stimulant effects of a range of ethanol doses in female Swiss mice. Three ages were studied: 21-day-old mice (postweanlings), 35-day-old mice (adolescents), and 63-day-old mice (adults). Methods: Postweanling, adolescent, and adult mice were daily injected with saline or various ethanol doses (1.5 to 4 g/kg) for 7 days. They were then tested for acute and sensitized locomotor activity. Results: Postweanling and adolescent mice were more sensitive than adult mice to the acute stimulant effects of ethanol. In adult mice, daily injections of ethanol at doses between 2.5 and 4 g/kg led to significant sensitization. Higher ethanol doses (3.5 and 4 g/kg) were required to induce sensitization in postweanling and adolescent mice. However, younger mice showed ethanol sensitization of higher magnitude. Conclusions: Young mice develop very strong ethanol sensitization at doses that mimic binge drinking in humans. These results might explain why early ethanol drinking during adolescence is related to a higher prevalence of subsequent alcohol disorders. [less ▲]

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See detailSpécificité et propriétés interactives des motivations incitatrices : le rôle de la cognition
Anselme, Patrick ULg; Tirelli, Ezio ULg

in Psychologie Française (2012), 57(3), 175-191

La motivation incitatrice est un processus psychologique qui augmente l’attractivité des sources de récompense (nourriture, sexe, drogue, etc.) et qui a pour effet de diriger le comportement vers ces ... [more ▼]

La motivation incitatrice est un processus psychologique qui augmente l’attractivité des sources de récompense (nourriture, sexe, drogue, etc.) et qui a pour effet de diriger le comportement vers ces stimuli – et à l’opposé des événements aversifs. Que se passe-t-il lorsque l’expression d’une motivation est contrecarrée ou que deux motivations antagonistes entrent en conflit ? La plupart des modèles théoriques destinés à expliquer les interactions motivationnelles postulent l’existence d’obscurs mécanismes physiologiques sans investiguer la composante psychologique de ces interactions. Cet article a pour objectif de montrer qu’une théorie motivationnelle peut seulement offrir un cadre interprétatif cohérent des interactions entre motivations incitatrices, et de ces motivations elles-mêmes, à condition d’intégrer certaines variables cognitives – en particulier, l’anticipation et l’attention. Cette approche offre une interprétation des activités de déplacement mieux en accord avec les observations. [less ▲]

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See detail[18F]fallypride binding in the mouse brain: test-retest and effects of registration
Bahri, Mohamed Ali ULg; Geuzaine, Annabelle ULg; Warnock, Geoffrey ULg et al

Conference (2011, January 17)

The quantification of in vivo receptor kinetics with PET tracer experiments is an intricate and challenging problem especially for small animals such as rats and mice. A test-retest scan is usually set up ... [more ▼]

The quantification of in vivo receptor kinetics with PET tracer experiments is an intricate and challenging problem especially for small animals such as rats and mice. A test-retest scan is usually set up in order to confirm an observed experimental effect or to examine the reliability of the experiment design. Inadequate processing of the image data may also mask small effects. The purpose of this study was to investigate the effect of image registration on [18F]fallypride binding potentials calculated from PET mouse test-retest data. Sub-optimal registration affected the quantification of in vivo receptor kinetics with [18F]fallypride. The absence of anatomical information in the [18F]fallypride image and the lack of a homogeneous tracer distribution, even during the earlier minutes of the scan, lead to erroneous automatic registration. A FDG scan after each [18F]fallypride test could improve registration as FDG provides a more homogeneous brain image. Variability in the data could also result from stress induced by anaesthesia or the experimental environment. [less ▲]

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See detailDo excitatory and inhibitory conditioning processes underlie psychomotor sensitization to amphetamine? An analysis using simple and multiple regressions
Brabant, Christian ULg; Tambour, Sophie; Quertemont, Etienne ULg et al

in Behavioural Brain Research (2011), 221

Excitatory or inhibitory conditioning processes have been proposed to account for the context-dependent establishment of amphetamine psychomotor sensitization in rodents. The purpose of this study was to ... [more ▼]

Excitatory or inhibitory conditioning processes have been proposed to account for the context-dependent establishment of amphetamine psychomotor sensitization in rodents. The purpose of this study was to test the predictions of these theories in mice. We first assessed the consequence of the extinction of post-sensitization conditioned activity (CR) on the ulterior expression of sensitization. We also assessed the relations between several measures of sensitization and conditioned hyperactivity revealed on a saline challenge using simple and multiple regression analyses. Context-dependent sensitization was induced via 7 amphetamine injections in the test context given alternately with 7 saline injections in another context in paired mice, unpaired mice receiving the converse pretreatment. Context-dependent sensitization (drug challenge) and the CR (saline challenge) were revealed subsequently. After CR extinction (over 7 every-other-day repetition of the saline challenge), mice were tested again for context-dependent sensitization. Against the excitatory conditioning model, CR extinction spared context-dependent sensitization in paired mice, and regression analyses revealed no significant correlations between the size of the CR and several measures of sensitization. In apparent agreement with the inhibitory conditioning model, unpaired mice expressed higher levels of sensitization in the test context after extinction than before. However, regression analyses did not indicate that activity on the saline challenge was related to measures of sensitization in unpaired mice. Therefore, the present results support neither the excitatory nor the inhibitory conditioning models of context-dependent sensitization, but remain compatible with theories proposing that other inhibitory mechanisms modulate sensitization. [less ▲]

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See detailOntogeny of the stimulant and sedative effects of ethanol in male and female Swiss mice: gradual changes from weaning to adulthood
Quoilin, Caroline ULg; Didone, Vincent ULg; Tirelli, Ezio ULg et al

in Psychopharmacology (2010), 212(4), 501-512

Rationale: The adolescent period is characterized by a specific sensitivity to the effects of alcohol, which is believed to contribute to the enhanced risks of alcohol dependence when drinking is ... [more ▼]

Rationale: The adolescent period is characterized by a specific sensitivity to the effects of alcohol, which is believed to contribute to the enhanced risks of alcohol dependence when drinking is initiated early during adolescence. In adolescent rodents, while the reduced sensitivity to the sedative effects of ethanol has been well characterized, its stimulant effects have not yet been extensively studied. Objectives: The present study characterized the development of the stimulant and sedative effects of acute ethanol in male and female Swiss mice from weaning to early adulthood and tested whether both effects are interrelated. Methods: In a first experiment, mice aged 21, 28, 35, 42 and 60 days were injected with various ethanol doses and tested for ethanol-induced locomotor activity. In an independent experiment, mice of the same groups of age were injected with 4 g/kg ethanol and ethanol-induced sedation was quantified with the loss of righting reflex procedure. Results: In male and female mice, the stimulant effects of ethanol gradually decreased, whereas its sedative effects increased with age. When the sedation was statistically controlled using a covariance analysis, the differences between adult and juvenile mice in the locomotor stimulation were significantly reduced. Conclusions: From weaning to early adulthood, the acute stimulant and sedative effects of ethanol show gradual changes that are similar in male and female mice. Although the initial tolerance to the sedative effects of ethanol contribute to the changes in ethanol-induced locomotor activity, young mice also show a higher sensitivity to the stimulant effects of ethanol. [less ▲]

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See detailAnxiety in adult female mice following perinatal exposure to chlorpyrifos.
Braquenier, Jean-Baptiste; Quertemont, Etienne ULg; Tirelli, Ezio ULg et al

in Neurotoxicology & Teratology (2010), 32

Epidemiologic studies suggested a possible link between prenatal exposure to organophosphate insecticides (OP) and long-term mental delay and some behavioral troubles. Experimental studies in rats and ... [more ▼]

Epidemiologic studies suggested a possible link between prenatal exposure to organophosphate insecticides (OP) and long-term mental delay and some behavioral troubles. Experimental studies in rats and mice have confirmed that a relatively short exposure to low doses of OP such as chlorpyrifos (CPF) during specific perinatal periods decreased anxiety-like behaviors. In the present study, we report that chronic perinatal exposure (GD15-PND14) to low doses of CPF leads to an increase (and not a decrease) in anxiety-like behaviors of female mouse offspring. Pregnant or lactating female mice were exposed to CPF (0.2; 1; or 5 mg/kg day) by oral treatment during 18 consecutive days. Following a recovery period of several weeks, the anxiety of adult female offspring was determined using neurobehavioral tests (elevated plus-maze and light/dark box tests). Our results showed that CPF-exposed female offspring were more anxious than controls. In addition, the magnitude of anxiety profile alterations depended on the level of exposure to CPF during gestation and lactation with a maximal effect observed at the 1 mg/kg day dose. Our results confirm that OP exposure during the perinatal period can induce long-term alterations in mouse anxiety-like behaviors and suggest that the routes of administration and the duration of OP exposure during brain development may be factors to consider when studying the development of anxiety. [less ▲]

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See detailInvolvement of the brain histaminergic system in addiction and addiction-related behaviors: a comprehensive review with emphasis on the potential therapeutic use of histaminergic compounds in drug dependence
Brabant, Christian ULg; Alleva, Livia ULg; Quertemont, Etienne ULg et al

in Progress in Neurobiology (2010), 92

Neurons that produce histamine are exclusively located in the tuberomamillary nucleus of the posterior hypothalamus and send widespread projections to almost all brain areas. Neuronal histamine is ... [more ▼]

Neurons that produce histamine are exclusively located in the tuberomamillary nucleus of the posterior hypothalamus and send widespread projections to almost all brain areas. Neuronal histamine is involved in many physiological and behavioral functions such as arousal, feeding behavior and learning. Although conflicting data have been published, several studies have also demonstrated a role of histamine in the psychomotor and rewarding effects of addictive drugs. Pharmacological and brain lesion experiments initially led to the proposition that the histaminergic system exerts an inhibitory influence on drug reward processes, opposed to that of the dopaminergic system. The purpose of this review is to summarize the relevant literature on this topic and to discuss whether the inhibitory function of histamine on drug reward is supported by current evidence from published results. Research conducted during the past decade demonstrated that the ability of many antihistaminic drugs to potentiate addictionrelated behaviors essentially results from non-specific effects and does not constitute a valid argument in support of an inhibitory function of histamine on reward processes. The reviewed findings also indicate that histamine can either stimulate or inhibit the dopamine mesolimbic system through distinct neuronal mechanisms involving different histamine receptors. Finally, the hypothesis that the histaminergic system plays an inhibitory role on drug reward appears to be essentially supported by place conditioning studies that focused on morphine reward. The present review suggests that the development of drugs capable of activating the histaminergic system may offer promising therapeutic tools for the treatment of opioid dependence. [less ▲]

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See detailEthanol-induced behaviors in mice genetically deficient in MCH1 receptors
Didone, Vincent ULg; Tirelli, Ezio ULg; Quertemont, Etienne ULg et al

in Alcoholism, Clinical & Experimental Research (2010), 34(8), 93-93

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See detailLa dépendance au cannabis : propriétés addictives, tolérance et sevrage
Quertemont, Etienne ULg; Tirelli, Ezio ULg

in Seutin, Vincent; Scuvée, Jacqueline; Quertemont, Etienne (Eds.) Regards croisés sur le cannabis (2010)

En dépit de controverses récurrentes, les données expérimentales récoltées dans de nombreuses études animales et humaines indiquent que le cannabis présente toutes les caractéristiques associées aux ... [more ▼]

En dépit de controverses récurrentes, les données expérimentales récoltées dans de nombreuses études animales et humaines indiquent que le cannabis présente toutes les caractéristiques associées aux autres drogues toxicomanogènes. Le cannabis induit manifestement une dépendance psychologique primaire chez l’homme et les modèles animaux ont démontré qu’il possède des propriétés renforçantes, quoique de moindre intensité que celles d’autres drogues comme la cocaïne ou les opiacés. La consommation chronique de cannabis produit une tolérance envers certains de ses effets, ce qui est susceptible d’entraîner un accroissement des doses utilisées par un utilisateur régulier. On reconnaît aussi au cannabis la capacité d’induire une véritable dépendance physiologique chez les plus gros consommateurs. Cette dépendance physiologique se manifeste par un syndrome de sevrage typique lors de l’arrêt de la consommation. Toutefois, il est clair que la dépendance au cannabis (aussi bien psychologique que physiologique) est moins sévère que celle induite par d’autres drogues majeures comme l’alcool, la cocaïne ou les opiacés. De plus, elle ne concerne qu’une petite fraction des consommateurs de cannabis. Depuis de nombreuses années, on s’interroge sur le risque d’escalade vers la consommation de drogues « plus dures » que produirait la consommation de cannabis. Les études scientifiques ont clairement démontré qu’il existe un lien statistique significatif entre usage de cannabis et consommation d’autres drogues illicites. Toutefois, la nature de cette relation statistique reste controversée. Selon les tenants de « la théorie de la porte d’entrée », le cannabis conduit directement, par des mécanismes biologiques, psychologiques ou sociaux, à une augmentation du risque de consommer des drogues telles que la cocaïne ou l’héroïne. Au contraire, les adeptes de « la théorie du facteur commun » soutiennent que les consommations de cannabis, d’héroïne ou de cocaïne sont expliqués par des facteurs généraux identiques, conduisant ainsi à une relation statistique qui ne serait qu’apparente et en aucun cas de nature causale. A l’heure actuelle, les données expérimentales disponibles ne permettent pas de trancher définitivement entre ces deux théories explicatives. [less ▲]

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