Um estudo sobre as possíveis interações entre o Chronic Mild Stress e o desempenho operante

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Chronic Mild Stress-induced anhedonia is an animal experimental model that exposes rats to a mild stressors regime for a long period of time. This model was proposed in 1987 Willner, Towell, Sampson, Sophokleus e Muscat. The purpose of the present study was to verify whether the exposure of rats to an operate procedure when a concurrent schedule with equal FR component, each one producing a different reinforcer (water or sucrose) would alter: a) the body weight; b) the water and sucrose intake, measured on weekly consumption and preference tests; c) the number of lever pressing responses on operant sessions, before, during and after the stress regime. The experimental design had three experimental conditions: total fluid intake and preference of sucrose over water tests, operant sessions of concurrent and the chronic mild stress regime. The subjects were differently exposed to these conditions. Group 1 subjects were exposed to six weeks of stress regime. Group 2 subjects were first submitted to the concurrent sessions (FR water FR sucrose), then they were exposed to the stress regime for six weeks and finally were put back in the concurrent schedule sessions. Group 3 subjects were submitted to concurrent sessions during the stress regime. All subjects of the three groups were submitted weekly to fluid intake and sucrose preference tests before, during and after the stress regime. A control subject was submitted to the consumption and preference tests without exposure either to stress regime or the operant sessions. Results showed five major points: 1) a change of body weight for all subjects exposed to the stress regime; 2) reduction in sucrose intake and in the preference for sucrose over water during the stress regime, measured by consumption and preference tests; 3) subjects submitted to the concurrent sessions before the stress regime recovered sucrose intake and preference for sucrose in the consumption and preference tests after the stress regime; 4) subjects submitted to the operant sessions presented more responses in the sucrose correspondent lever than in the water correspondent lever before and after the stress regime; 5) subjects submitted to operant sessions during the stress regime decreased response in sucrose correspondent lever during the stress regime, however two out of these three subjects recovered to the level of responding prior to stress regime before the stress regime was terminated

ASSUNTO(S)

valor reforçador psicologia experimental preferência regime de estressores crônicos e moderados reinforcing value, preference, depression esquema concorrente concurrent schedule of reinforcement avaliacao do comportamento chronic mild stress depressão

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