Modulação contexto-específica dos efeitos comportamentais e neuroquímicos decorrentes da cafeína
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Data
2010-07-30
Autores
Zancheta, Roberta [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A cafeína é a substância psicoativa mais consumida no mundo. A administração repetida de psicostimulantes pode aumentar ou diminuir o efeito da substância, induzindo sensibilização ou tolerância, respectivamente, dependendo do procedimento de administração. Além da dose e do regime de administração, o ambiente onde a substância é administrada parece modular as mudanças comportamentais que ocorrem após administração repetida. O objetivo do presente estudo foi analisar a influência do contexto ambiental nas respostas comportamentais induzidas pela cafeína após administração repetida dessa substância. Também foi investigado se as alterações comportamentais estavam relacionadas a mudanças nas concentrações teciduais de dopamina e seus metabólitos no córtex pré-frontal medial, núcleo accumbens e caudado putamen. Para tanto, administramos cafeína (15mg/kg) ou salina (1mL/kg) a ratos adultos em dias alternados durante 13 dias (uma injeção a cada 48 horas; 7 administrações no total), o tratamento repetido com cafeína foi realizado de duas formas: 1) pareado ao ambiente onde foi realizado o teste locomotor; 2) não pareado ao ambiente onde foi realizado o teste locomotor. Três dias após a última injeção de cafeína ou salina foi realizado o teste comportamental dos animais. Imediatamente após o registro do comportamento os animais foram decapitados e seus encéfalos foram removidos para determinação das concentrações de dopamina e seus metabólitos por cromatografia líquida de alta resolução. Nossos resultados mostraram que a administração repetida de cafeína induziu sensibilização psicomotora quando as injeções foram pareadas ao ambiente onde foi realizado o teste locomotor dos animais, enquanto tolerância foi observada quando os animais receberam cafeína repetidamente em um ambiente distinto daquele onde o teste locomotor dos animais...
Caffeine is the psychostimulant drug most consumed in the world. Repeated administration of psychostimulants can either decrease or increase the drug effect, inducing tolerance or sensitization, respectively; depending on the administration procedure. Besides dose and regime of drug administrations, the environment where drug is administered seems to modulate the changes in locomotor activity following repeated psychostimulant administration. The purpose of the present study was to examine the influence of the environmental context on caffeine-induced psychomotor stimulation following repeated administration of this drug. We also investigated whether the behavioral alterations were related to changes on dopamine or its metabolites tissue levels in the medial prefrontal cortex, nucleus accumbens and caudate putamen. For this purpose adult rats received caffeine (15mg/kg) or saline (1ml/kg) on alternate days for 13 days (one injection every 48 hours, seven administrations in total), the repeated treatment with caffeine was performed in two ways: 1) paired with the environment where the behavioral test was performed, 2) non-paired with the environment where the the behavioral test was performed. Three days after the last injection of caffeine or saline the behavioral test was performed. Immediately after the behavioral test the animals were killed by decapitation and their brains were removed for determination of dopamine and its metabolites by HPLC. Our results showed that repeated caffeine induces psychomotor sensitization when injections were paired with the environment where the animals were subsequently tested; while tolerance was observed when the animals received caffeine in an environment different from that where tests were performed. Dopaminergic alterations were detected in the medial prefrontal cortex, caudate putamen and nucleus accumbens in response to repeated treatment with... (Complete abstract click electronic access below)
Caffeine is the psychostimulant drug most consumed in the world. Repeated administration of psychostimulants can either decrease or increase the drug effect, inducing tolerance or sensitization, respectively; depending on the administration procedure. Besides dose and regime of drug administrations, the environment where drug is administered seems to modulate the changes in locomotor activity following repeated psychostimulant administration. The purpose of the present study was to examine the influence of the environmental context on caffeine-induced psychomotor stimulation following repeated administration of this drug. We also investigated whether the behavioral alterations were related to changes on dopamine or its metabolites tissue levels in the medial prefrontal cortex, nucleus accumbens and caudate putamen. For this purpose adult rats received caffeine (15mg/kg) or saline (1ml/kg) on alternate days for 13 days (one injection every 48 hours, seven administrations in total), the repeated treatment with caffeine was performed in two ways: 1) paired with the environment where the behavioral test was performed, 2) non-paired with the environment where the the behavioral test was performed. Three days after the last injection of caffeine or saline the behavioral test was performed. Immediately after the behavioral test the animals were killed by decapitation and their brains were removed for determination of dopamine and its metabolites by HPLC. Our results showed that repeated caffeine induces psychomotor sensitization when injections were paired with the environment where the animals were subsequently tested; while tolerance was observed when the animals received caffeine in an environment different from that where tests were performed. Dopaminergic alterations were detected in the medial prefrontal cortex, caudate putamen and nucleus accumbens in response to repeated treatment with... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Cafeína - Efeito fisiológico, Tolerancia, Contexto ambiental, Sensibilização, Caffeine, Sensitization, Tolerance, Environmental context, Dopamine
Como citar
ZANCHETA, Roberta. Modulação contexto-específica dos efeitos comportamentais e neuroquímicos decorrentes da cafeína. 2010. 62 f. Dissertação (mestrado) - UNESP/UFSCar, Programa Interinstitucional de Pós-Graduação em Ciências Fisiológicas, 2010.