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See detailShort-term contextual sensitisation and conditioned hyperkinesia produced by cocaine in suckling rats aged 4-10 days and 14-20 days
Tirelli, Ezio ULg

in Psychopharmacology (2001), 156(1), 46-52

RATIONALE: It was hypothesised that the failure to generate sensitisation to the behavioural effects of a motor stimulant in suckling rats was mainly due to not pairing the drug with the test context ... [more ▼]

RATIONALE: It was hypothesised that the failure to generate sensitisation to the behavioural effects of a motor stimulant in suckling rats was mainly due to not pairing the drug with the test context during chronic pretreatment. OBJECTIVE: This study probed the capabilities of neonatal and infant rat pups to show short-term context-specific sensitisation and conditioned drug activity produced by cocaine. METHODS: Two similar experiments were conducted on rat pups aged 4-10 days or 14-20 days, each experiment comprising three phases: a sensitisation phase (days 4-8 and days 14-18 of age), a test session under cocaine for context specificity of sensitisation (day 9 and day 19 of age) and a test session under saline for conditioned drug effects (day 10 and day 20 of age). Over five daily sessions, pups first received an injection of either 16 mg/kg cocaine (paired group) or saline (unpaired group) in test chambers, and 110 min later the converse injections in the vivarium (in a cage that was different from the home cage). A third group received saline in both contexts. Behaviour was scored using videotapes. RESULTS: Sensitisation developed in the paired groups at both ages. In 4- to 10-day-old pups, sensitisation was expressed via locomotion (matrix crosses) and also horizontal and vertical activities (categories comprising several age-specific movements). In 14- to 18-day-old pups, it was displayed by increases in head movements and vertical activity, and by a decline in stationary position. These effects were confirmed to be context specific on the test sessions (day 9 or day 19), the paired groups producing by far the greatest values. On the conditioning test, the paired groups also produced the greatest amounts of the above-mentioned behaviours, revealing a conditioned drug effect. Additionally, the conditioned effect scores were higher than those of two additional groups that had been treated similarly to the others but outside the chamber until the two tests (controlling for a withdrawal effect and possible novelty-induced activity in the test context). There were no differences between these unexposed groups, indicating that no abstinence effect occurred. CONCLUSIONS: The results demonstrate that neonatal rats are capable of showing physiological/non-contextual cocaine-induced behavioural sensitisation as well as its context-specific expression and the conditioned activity following its establishment. [less ▲]

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See detailDose-dependent caffeine-induced conditioned locomotion in mice
Pirona, Alexandre; Ferrara, André Onofrio; Tirelli, Ezio ULg

in Behavioural Pharmacology (2001), 12

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See detailA behavioural analysis of the conditioned drug effects and the context-specific sensitization produced by a low and a high dose of cocaine
Michel, Anne; Tirelli, Ezio ULg

in International Journal of Neuropsychopharmacology (2000), 3(Supplement), 130

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See detailExpectations can influence not only the psychomotor but also the some of the cognitive effects of caffeine
Bernaerts, Pascale; Servais, Christine; Tirelli, Ezio ULg

in International Journal of Neuropsychopharmacology (2000), 3(Supplement), 113

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See detailSelective effects of nicotine on attentional processes
Mancuso, G.; Warburton, D. M.; Melen, Marie-Rose ULg et al

in Psychopharmacology (1999), 146(2), 199-204

RATIONALE: It is now well established from electrophysiological and behavioural evidence that nicotine has effects on information processing. The results are usually explained either by a primary effect ... [more ▼]

RATIONALE: It is now well established from electrophysiological and behavioural evidence that nicotine has effects on information processing. The results are usually explained either by a primary effect of nicotine or by a reversal effect of a nicotine-induced, abstinence deficit. In addition, there is dispute about the cognitive processes underlying the changes in performance. METHODS: This study has approached the first question by using the nicotine patch, in order to administer nicotine chronically. In addition, we examined the effects of nicotine on attention with a selection of tests which assessed the intensity and selectivity features of attention, using the Random Letter Generation test, the Flexibility of Attention test and the Stroop test. RESULTS: Nicotine enhanced the speed of number generation and the speed of processing in both the control and interference conditions of the Stroop test. There were no effects on attentional switching of the Flexibility of Attention test. CONCLUSION: The results are consistent with the hypothesis that nicotine mainly improves the intensity feature of attention, rather than the selectivity feature. [less ▲]

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See detailAnticipatory responding, exclusive drug-context pairing and conditioned effects in sensitization to apomorphine-induced climbing in mice
Tirelli, Ezio ULg; Heidbreder, C.

in Progress in Neuro-Psychopharmacology & Biological Psychiatry (1999), 23(3), 505-518

1. The conditioning aspects of contextual sensitization were examined in the case of apomorphine-induced wall-climbing in mice, measuring onset latencies of the pharmacological response and controlling ... [more ▼]

1. The conditioning aspects of contextual sensitization were examined in the case of apomorphine-induced wall-climbing in mice, measuring onset latencies of the pharmacological response and controlling differential habituation to the test context during drug treatment. 2. Sensitization was generated in male out-bred mice which received intermittent i.p. injections of 0.4 mg/kg apomorphine over 9 daily sessions. On day 10, they were tested for contextual sensitization (all mice under apomorphine). On day 14, after 3 sessions of reinstatement, mice were tested for conditioned climbing (all mice under saline). 3. It was found that simultaneous exposure to both apomorphine and the test context facilitated the expression of a full-blown contextual sensitization (some non-contextual sensitization emerging too); importantly, sensitization was accompanied by a progressive shortening of the latencies to climb (before injections); conditioned climbing appeared only in mice pairing the drug with the test context, that response being absent in mice treated outside the context or never exposed to the context. 4. It is likely that contextual sensitization to apomorphine-induced climbing relies on Pavlovian conditioning processes rather than on habituation-related processes. [less ▲]

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See detailConditioning of and contextual sensitization to apomorphine-induced climbing in mice : evidence against the habitation hypothesis
Tirelli, Ezio ULg; Heidbreder, C.

in Behavioral Neuroscience (1999), 113(2), 368-376

Several predictions of the habituation hypothesis of conditioned drug effects were tested by looking at contextual sensitization to apomorphine-induced climbing in mice (Mus musculus). Mice were first ... [more ▼]

Several predictions of the habituation hypothesis of conditioned drug effects were tested by looking at contextual sensitization to apomorphine-induced climbing in mice (Mus musculus). Mice were first sensitized to that effect after 9 daily injections of 0.4 mg/kg apomorphine in the test context. Other mice received the same treatment outside the test context. On Day 10, all mice were challenged with either saline (conditioned drug effects test) or apomorphine (contextual sensitization test). On both tests, the levels of climbing of mice that received apomorphine paired with the test context during the intermittent treatment were significantly higher than those of mice that were experiencing the test context for the first time (unexposed mice). Also, the rate of extinction in conditioned mice did not parallel the rate of habituation in the unexposed mice. Results contradict the habituation hypothesis of conditioned drug effects and contextual sensitization. ((c) 1999 APA/PsycINFO, all rights reserved)(journal abstract) [less ▲]

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See detailEffects on nicotine administered via a transdermal delivery system on vigilance : a repeated measure study
Mancuso, Giovanna; Andrès Bénito, Pilar; Ansseau, Marc ULg et al

in Psychopharmacology (1999), 142(1), 18-23

Tested 15 male smokers (aged 18-25 yrs) in a within-Ss design to determine the influence of a transdermal patch of 21 mg nicotine on vigilance. Ss were tested on the Rapid Visual Information Processing ... [more ▼]

Tested 15 male smokers (aged 18-25 yrs) in a within-Ss design to determine the influence of a transdermal patch of 21 mg nicotine on vigilance. Ss were tested on the Rapid Visual Information Processing test 1.3, 3 and 6.3 hrs after patch application, to verify the involvement of the dose of nicotine on the performance. The results confirm and extend the knowledge on the increasing effects of nicotine on vigilance previously found with orally and transdermally administered nicotine. Moreover, results show that such performance was independent of the time of nicotine absorption, which suggests that a relatively low dose of nicotine suffices to activate vigilance processing. Regarding motor performance, no convincing effect of nicotine was observed on reaction time. ((c) 1999 APA/PsycINFO, all rights reserved) [less ▲]

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See detailConditioned apomorphine-induced climbing: Influence of cue-exposure and the contribution of "forgetting" to the effects observed
Tirelli, Ezio ULg; Heidbreder, Christian; Terry, Phil

in Behavioural Pharmacology (1999), 10

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See detailLes facteurs biologiques en psychologie
Tirelli, Ezio ULg

in Rondal, Jacques (Ed.) Introduction à la psychologie scientifique (1999)

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See detailContexual sensitization to the behavioral effects of cocaine in neonatal rats
Tirelli, Ezio ULg

in Developmental Psychobiology (1999), 25

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See detailAmphetamine-Induced Conditioned Activity and Sensitization: The Role of Habituation to the Test Context and the Involvement of Pavlovian Processes
Tirelli, Ezio ULg; Terry, P.

in Behavioural Pharmacology (1998, September), 9(5-6), 409

Behaviours associated with drug action can sometimes be elicited, in the absence of drug, by exposure to stimuli that were present during drug administration. Such a finding is usually interpreted as a ... [more ▼]

Behaviours associated with drug action can sometimes be elicited, in the absence of drug, by exposure to stimuli that were present during drug administration. Such a finding is usually interpreted as a conditioned drug effect. Often, however, the outcome could arise if drug administration in a particular environment retarded behavioural habituation to that environment. To test the 'habituation hypothesis' of conditioned drug effects, mice received 10 daily injections of d-amphetamine ('paired' group) or saline ('unpaired') in test boxes, and the converse injections in the colony room. Another group received saline in both environments. The apparatus and procedures yielded minimal habituation of behaviours (ambulation and rearing) over sessions. Only the paired group demonstrated behavioural sensitization, indicating environment-specific sensitization. The paired group also showed more ambulation and rearing than the others on the critical test of conditioning (saline injection in test box); moreover, their conditioning test scores were higher than those of the other groups on their first exposure to the test boxes, contradicting the habituation hypothesis. Further supporting the involvement of Pavlovian conditioning, levels of ambulation and rearing measured for 10 min before each injection increased in the paired group, relative to the unpaired groups, over successive pairing sessions. Tests controlling for differential handling/injection experience produced results consistent with those previously obtained. Together, the findings are incompatible with the habituation hypothesis, and further support the role of Pavlovian conditioning. [less ▲]

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See detailEvidence for behavioral sensitization to cocaine in preweanling rat pups
Wood, R. D.; Tirelli, Ezio ULg; Snyder, K. J. et al

in Psychopharmacologia (1998), 138(2), 114-123

Sought to determine whether promoting context-dependent sensitization might facilitate expression of sensitization in preweanlings. Sprague-Dawley rats were injected daily from postnatal day 14 to ... [more ▼]

Sought to determine whether promoting context-dependent sensitization might facilitate expression of sensitization in preweanlings. Sprague-Dawley rats were injected daily from postnatal day 14 to postnatal day 20 with 0, 5, 15, or 30 mg/kg cocaine hydrochloride and placed for 30 min in either the experimental chamber or home cage. On postnatal day 21 (test day), Ss were challenged with either 15 mg/kg cocaine or saline prior to placement in the experimental chamber. Significant sensitization of cocaine-induced stereotyped head movements was evident in animals given 15 or 30 mg/kg chronically in the experimental chamber, but not when these same doses were given in the home cage. Less consistent evidence for cocaine-induced sensitization was seen when examining locomotion, although trends for sensitization of this behavior were seen in animals chronically injected in either the test chamber or home cage. Thus, preweanlings can exhibit cocaine sensitization, particularly in terms of stereotypy, when tested shortly after the chronic exposure period, with expression of this sensitization being facilitated by pairing the chronic injections with the test context. ((c) 1998 APA/PsycINFO, all rights reserved) [less ▲]

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See detailConditioned sensitization to the behavioural effects of amphetamine and habituation to the testing context
Tirelli, Ezio ULg; Terry, P.

in Behavioural Pharmacology (1998), 10

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See detailOntogeny of acute sensitization to cocaine in rats
Tirelli, Ezio ULg; Gonzalez, C.

in Behavioural Pharmacology (1998), 9

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See detailApomorphine-induced conditioned sensitization and differential habituation to environmental novelty
Tirelli, Ezio ULg; Heidbreder, C.

in Progress in Neuro-Psychopharmacology & Biological Psychiatry (1998), 23

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See detailGamma-aminobutyric acid-sub(A) agonists differentially gnawing induced by indirect-acting dopamine agonists in C57BL/6J mice
Tirelli, Ezio ULg; Geter-Douglass, B.; Witkin, J. M.

in Journal of Pharmacology and Experimental Therapeutics (The) (1998), 284(1), 116-124

Evaluated the interaction of either gaboxadol HCl (THIP) or muscimol, both gamma-aminobutyric acid (GABA) type A agonists, with indirect-acting dopamine agonists (DAGs) methylphenidate, (+)-amphetamine ... [more ▼]

Evaluated the interaction of either gaboxadol HCl (THIP) or muscimol, both gamma-aminobutyric acid (GABA) type A agonists, with indirect-acting dopamine agonists (DAGs) methylphenidate, (+)-amphetamine, metamphetamine, amfonelic acid, indatraline, nomifensine, diclofensine, mazindol, and GBR 12935 and with direct-acting DAGs WIN 35,428, bupropion, GBR 12909, and cocaine. 1,832 male C57BL/6J mice were given either with saline or 1 of the doses of THIP or muscimol before an injection of a dopamine agonist. Gnawing on corrugated packing paper was measured. Results showed that: (1) indirect- but not direct-acting DAGs induced gnawing, (2) gnawing induced by indirect-acting DAGs GBR 12935, nomifensine and mazindol was potentiated in mice in which GABA type A receptors were stimulated either by THIP or muscimol, and (3) indirect DAGs had a differential sensitivity to the effects of THIP and muscimol. ((c) 1998 APA/PsycINFO, all rights reserved) [less ▲]

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See detailPotentiation of dopamine agonists-induced oral stereotypies by GABA-A agonists in mice : differentiation of dopamine uptake inhibitors
Tirelli, Ezio ULg; Witkin, J. M.

in Journal of Pharmacology and Experimental Therapeutics (The) (1998), 284

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