Efeitos do protocolo de estressores sobre a preferência de água adocicada e sobre o consumo de ração em ratos submetidos a diferentes regimes de privação e sobre a aquisição de uma discriminação simples

• Autor(a) principal: Silva, Paulo Eduardo da
• Data de Publicação: 2020
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da PUC_SP
• Texto Completo: https://tede2.pucsp.br/handle/handle/23071
• topic: Análise do Comportamento; Privação; Sacarose; Behavior Analysis; Deprivation; Sucrose; CNPQ::CIENCIAS HUMANAS::PSICOLOGIA::PSICOLOGIA EXPERIMENTAL

Anhedonia is a main symptom for the diagnosis of depression in humans, described in the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) as a deficit in the capacity of feeling pleasure and interest for things. The Chronic Mild Stress (CMS) was proposed as an animal model of anhedonia by Willner, Towell, Sampson, Sophokleous and Muscat (1987) when they verified that, after being exposed to a set of moderated stressful and uncontrollable stimuli, individuals presented a decrease on sweetened water consumption. However, some studies have found difficulties to replicate the results reported by Willner et al. (1987). Methodological differences related to deprivation, baseline and sensibility of each organism to water with sucrose can be some of the variables responsible for the discrepancy on the results. The present work aimed to: (1) evaluate the effects of the exposition to a Stressors Protocol (SP) on the consumption of water and water with sucrose under different deprivation schemes and (2) evaluate the effects of SP on the weekly consumption of ration in the cage. Sixteen experimentally naive male Wistar rats were used. When the subjects have reached 90 days old, the first water with sucrose consumption test was performed putting a bottle with two grams of sucrose diluted in 98 ml of water (100 ml of water-sucrose solution) for one hour in the cage. Seven days after the first test, a second test was accomplished following the same routine. All the tests were performed at the same time and day of the week. Seven days after the second test with one bottle, the first test with two bottles was performed, one of which containing 100 ml of water and the other 100 ml of water-sucrose solution aiming to assess the preference of the subjects. The two bottles tests were performed weekly until the end of the experiment totalizing 13 tests (4 before, 6 during SP exposition and 3 after). The consumption of liquids was calculated considerating the amount available and the leftover after 1 hour. The subjects were distributed randomly among 4 groups with the same size. The subjects of Group 1 were not submitted to SP and were divided into two subgroups: Group 1 23h – two subjects were submitted to a 23 hours water and food deprivation before the weekly consumption tests – and Group 1 85% – two subjects were submitted to continuous water deprivation to maintain their weights at 85% ad lib. (computed from the 90° day from birth), remaining under this deprivation for the whole study. The subjects of Group 2 were submitted to water and food deprivation before consumption tests + deprivation as a component of SP. The subjects of Group 3 were submitted to 23 hours deprivation of water and food before the consumption tests + deprivation as a component of SP + 85% ad lib. The subjects of Group 4 were submitted to continuous water deprivation at 85% ad lib. The results showed that the subjects weights varied depending on the kind of deprivation. Regardless of the sort of deprivation, the water-sucrose solution consumption was greater than the water consumption on the tests performed before, during and after the exposition to SP. Unlike what CMS model proposed by Willner et al. (1987) predicts the submission to SP was followed by an increase in water-sucrose solution consumption. On the other hand, the weekly food consumption in the cage before, during and after SP was significantly different for Group 4´ subjects (p=0.018) with lower values when the rats were submitted to SP, replicating data found by Silva and Malerbi (2018) and strengthening the proposal that this measure can be an alternative to the preference of liquids in the consumption tests to assess the effects of SP, at least in rats deprived of water in a scheme which keeps them at 85% of their weights ad lib. and not submitted to water and food deprivation as a component of stressors protocol