Navegando por Palavras-chave "Estresse social"

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    Consequências do estresse de derrota social (episódico e contínuo) sobre os efeitos psicomotores e reforçadores condicionados da nicotina em camundongos
    (Universidade Federal de São Paulo (UNIFESP), 2016-02-29) Domingues, Liz Paola [UNIFESP]; Quadros, Isabel Marian Hartmann de [UNIFESP]; http://lattes.cnpq.br/3982014468609862; http://lattes.cnpq.br/2626872911089070; Universidade Federal de São Paulo (UNIFESP)
    Objective: This study aimed to investigate the consequences of two types of repeated social defeat stress (episodic and continuous) on nicotine-induced psychomotor effects and conditioned reward in mice. Methods: Using the resident-intruder model, experimental mice (intruder) were defeated by an aggressive one (resident). After each daily defeat, intruders returned to their homecage (episodic stress) or cohabitated with the aggressor for 24h (continuous stress), until the next defeat. After the 10-day stress protocol, different batches of mice received nicotine (0.1 mg/kg, s.c.) in locomotor tests (short- and long-term), or for conditioned place preference (CPP). Results: Both defeat protocols induced short-term (within 24h) locomotor suppression, which was potentiated by nicotine only after continuous defeat stress. Ten days after the final defeat, locomotor suppression was no longer observed due to stress or nicotine. Nicotine failed to induce place preference or aversion after either defeat protocol. Only the episodic defeat group showed nicotine-induced locomotor suppression one week after the additional nicotine exposure during the CPP protocol. Conclusion: Our findings indicate that different consequences of episodic and continuous stress on nicotine psychomotor effects were observed shortly after stress. Differential long-term effects on nicotine locomotor response were only observed when stressed mice were further exposed to repeated nicotine administration (during CPP). Also, neither episodic nor continuous defeat stress facilitated the acquisition of conditioned place preference or aversion to nicotine.
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    Efeitos da exposição crônica ao estresse de derrota social sobre os efeitos estimulantes e reforçadores do etanol
    (Universidade Federal de São Paulo (UNIFESP), 2017-03-29) Macedo, Giovana Camila de [UNIFESP]; Quadros, Isabel Marian Hartmann de [UNIFESP]; Suchecki, Deborah [UNIFESP]; http://lattes.cnpq.br/0735654567907174; http://lattes.cnpq.br/3982014468609862; http://lattes.cnpq.br/8280399201081131; Universidade Federal de São Paulo (UNIFESP)
    Repeated exposure to ethanol and other drugs of abuse promotes neuroadaptations on brain reward systems, rendering them hyper responsive (i.e., sensitized) to drugs. The sensitization of brain reward responses to drugs would, in turn, facilitate drug-induced stimulation and reward. Likewise, repeated exposure to episodic stress seems to sensitize brain reward pathways, promoting cross-sensitization with drugs and increased drug intake. In contrast, exposure to continuous stress may induce an anhedonic state associated with the reduction of drug reward. To assess whether repeated exposure to two types of social stress induces cross-sensitization to the stimulant effect of ethanol and promotes increased voluntary ethanol consumption. The association between behavioral sensitization induced by repeated ethanol treatment and voluntary drinking was also tested. Swiss male mice were exposed to two types of social defeat stress (episodic vs. continuous) during 10 days, and 10 days later were challenged with a stimulant dose of ethanol (2.2 g/kg or 1.6 g/kg, ip). Next, we evaluated the voluntary intake of ethanol solutions (6%, 10% and 20% w / v) with two-bottle choice, home cage drinking sessions of 24h, every other day. Another group of animals was exposed to 10 days of repeated treatment with ethanol (2.2 g/kg, i.p.) as a positive control of sensitization, and was evaluated for voluntary ethanol drinking. Repeated exposure to 10 days of continuous social defeat promoted insensitivity to the stimulating effect of ethanol, while episodic defeat had no effects. Pre-exposure to episodic or continuous defeat stress failed to affect voluntary ethanol drinking. On the other hand, a 10-day treatment with ethanol injections induced behavioral sensitization to ethanol-stimulation and increased ethanol intake in concentrations of 10%. These findings indicate that repeated exposure to episodic social stress did not escalate ethanol drinking, nor induced cross-sensitization. Animals exposed to continuous defeat stress showed a blunted stimulant response to ethanol, but no changes in intake. On the other hand, we provided support for a positive association between ethanol-induced behavioral sensitization and ethanol drinking.