Navegando por Palavras-chave "novelty"

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    Acute and chronic ethanol differentially modify the emotional significance of a novel environment: implications for addiction
    (Cambridge Univ Press, 2012-09-01) Fukushiro, Daniela Fukue [UNIFESP]; Josino, Fabiana de Souza [UNIFESP]; Saito, Luis Paulo [UNIFESP]; Berro, Laís Fernanda [UNIFESP]; Morgado, Fiorella [UNIFESP]; Frussa-Filho, Roberto [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Using open-field behaviour as an experimental paradigm, we demonstrated a complex interaction between the rewarding/stimulating effects and the anxiogenic/stressful effects of both novelty and acute or chronic amphetamine in mice. As a consequence of this interaction, acute amphetamine-induced hyperlocomotion was inhibited, whereas the expression of its sensitization was facilitated in a novel environment. in the present study, we aimed to investigate the interactions between exposure to a novel environment and the acute and chronic effects of ethanol (Eth), a drug of abuse known to produce anxiolytic-like behaviour in mice. Previously habituated and non-habituated male Swiss mice (3 months old) were tested in an open field after receiving an acute injection of Eth or following repeated treatment with Eth. Acute Eth administration increased locomotion with a greater magnitude in mice exposed to the apparatus for the first time, and this was thought to be related to the attenuation of the stressful effects of novelty produced by the anxiolytic-like effect of acute Eth, leading to a subsequent prevalence of its stimulant effects. However, locomotor sensitization produced by repeated Eth administration was expressed only in the previously explored environment. This result might be related to the well-known tolerance of Eth-induced anxiolytic-like behaviour following repeated treatment, which would restore the anxiogenic effect of novelty. Our data suggest that a complex and plastic interaction between the emotional and motivational properties of novelty and drugs of abuse can critically modify the behavioural expression of addiction-related mechanisms.
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    Amphetamine-induced rapid-onset sensitization: Role of novelty, conditioning and behavioral parameters
    (Elsevier B.V., 2006-04-01) Nascimento Alvarez, J. do; Fukushiro, D. F.; Obara Tatsu, J. A.; Pereira de Carvalho, E.; Castro Gandolfi, A. C. de; Tsuchiya, J. B.; Carrara-Nascimento, P. F.; Lima, M. L.; Gentil Bellot, R.; Frussa-Filho, R.; Universidade Federal de São Paulo (UNIFESP); Univ Metodista São Paulo
    Background: Environmental factors may modulate sensitization to the locomotor-activating effects of psychostimulants. in addition, some parameters of locomotor activity seem to be more sensitive to detect cocaine-induced behavioral sensitization. We examined how novelty and conditioning can modulate a previously described rapid-onset type of behavioral sensitization to amphetamine (AMP) in mice, using total, peripheral and central open-field locomotion frequencies as experimental parameters.Methods: in the first experiment, mice received an ip injection of saline (SAL) or 5.0 mg/kg AMP paired or not with the open-field or in their home-cages. Four hours later, all the animals received an ip SAL challenge injection and, 15 min later, were observed in the open-field for quantification of total, peripheral and central locomotion frequencies. the second experiment had a similar protocol, except that mice received a challenge injection of 1.5 mg/kg AMP.Results: the priming AMP injection significantly increased all the parameters of locomotion of SAL-challenged mice firstly exposed to or previously paired (but not impaired) with the open-field. AMP priming injection enhanced total and peripheral locomotion of all AMP-challenged mice but only increased central locomotion of mice submitted to novelty or environmental conditioning.Conclusion: Our results showed: 1) the development of an AMP-induced rapid-onset sensitization to novelty and rapid-onset environmental conditioning in mice, 2) the potentiation of the AMP-induced rapid-onset sensitization to an AMP challenge injection by novelty and environmental conditioning and 3) the importance of measuring different locomotor activity parameters in behavioral sensitization experiments. (c) 2006 Elsevier Inc. All rights reserved.
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    Chronic amphetamine transforms the emotional significance of a novel but not a familiar environment: implications for addiction
    (Cambridge Univ Press, 2011-08-01) Fukushiro, Daniela Fukue [UNIFESP]; Frussa Filho, Roberto [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Both drug-induced locomotor sensitization and reactivity to novelty in rodents have been related to drug-craving mechanisms in humans. We investigated whether the exposure to a completely novel environment would modulate the expression of locomotor sensitization induced by repeated administration of amphetamine (Amp) in mice. in addition to locomotion, different open-field behavioural parameters were used to evaluate the possible involvement of anxiogenic-like effects induced by Amp, novelty or a combination of the two. in order to avoid misinterpretations due to different locomotor baseline conditions, we used an open-field illumination condition in which previous exposure to the apparatus did not modify locomotion (although it reliably increased grooming behaviour). Acute Amp administration increased locomotion in mice previously habituated to the open field (Hab) but not in mice exposed to the apparatus for the first time (Nov). This absence of Amp-induced locomotor activation in Nov mice may be related to higher anxiety-like levels, because these animals displayed longer freezing duration. However, only Nov mice developed locomotor sensitization. Because Amp challenge in Amp pre-treated Nov mice did not induce an increase in freezing behaviour, the locomotor sensitization in Nov mice might be related to the tolerance of Amp-induced anxiogenic-like behaviour in novel environments. Repeated Amp administration increased motivation to explore the environment in Nov mice in that these animals presented a within-session locomotion-habituation deficit. Our data suggest that a complex and plastic interaction between the anxiogenic and motivational properties of both novelty and Amp can critically modify the behavioural expression of craving-related mechanisms.
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    Naltrexone potentiates the anxiolytic effects of chlordiazepoxide in rats exposed to novel environments
    (Springer, 1999-11-01) Frussa-Filho, R.; Barbosa-Junior, H.; Silva, R. H.; Da Cunha, C.; Mello, C. F.; Universidade Federal de São Paulo (UNIFESP); Univ Fed Parana; Universidade Federal de Sergipe (UFS)
    Rationale: Both novelty and naloxone have been reported to modify the anxiolytic-like effect of benzodiazepines in the elevated plus maze. in addition, it has been largely demonstrated that novelty alters endogenous opioid activity. Objectives: the present study was designed to examine a possible interaction between novelty and naltrexone effects on the behavior of chlordiazepoxide-treated rats in two animal models of anxiety. Methods: Thirty minutes after acute intraperitoneal treatment with saline or naltrexone and saline or chlordiazepoxide, male Wistar rats were exposed for the first time to the elevated plus maze apparatus or the social interaction arena for the quantification of the percentage of time spent in the open arms or the time of active social interaction, respectively. the effects of naltrexone and/or chlordiazepoxide on the plus maze and the social interaction tests were also evaluated after previous exposure to the respective apparatus. Results: Naltrexone dose dependently increased the percentage of time spent in the open arms of the elevated plus maze in chlordiazepoxide-treated (5 mg/kg i.p.) rats exposed for the first time to the apparatus. Similarly, naltrexone (5 mg/kg i.p.) increased the time spent in active social interaction by chlordiazepoxide-treated rats exposed to an unfamiliar arena. in both experiments, naltrexone had no effect when administered alone. When both the plus maze and the social interaction tests were conducted after previous exposure to the respective apparatus, naltrexone did not modify the behavior of chlordiazepoxide- or saline-treated rats. Conclusions: These data suggest that the anxiolytic-like effects of chlordiazepoxide can be modified by opioid mechanisms in navel environments.