Influência da aprendizagem e da manipulação do sistema colinérgico muscarínico na sensibilização ao efeito estimulante do etanol

• Ano de defesa: 2011
• Autor(a) principal: Takahashi, Shirley [UNIFESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo (UNIFESP)
• Palavras-chave em Português: Antagonistas colinérgicos; Atividade motora; Neurotransmissão; Etanol; Receptores muscarínicos; Hidrobrometo de escopolamina; Camundongos; Animais; Transmissão sináptica; Cholinergic antagonists; Motor activity; Synaptic transmission; Ethanol; Receptors, muscarinic; Scopolamine hydrobromide; Mice; Animals
• Link de acesso: http://repositorio.unifesp.br/handle/11600/9745

Several authors suggest that behavioral sensitization, characterized as psychomotor activity increase in response to psychoactive drugs repeated administration, seems to play a fundamental role in the development of abuse and dependence, increasing the reinforcement property of these substances. Animals that develop sensitization to ethanol differ regarding the binding to some neurotransmitter receptors and also differ regarding the response to the administration of agonists and antagonists of these receptors. Behavioral sensitization is a complex phenomenon that involves different factors, being affected by environment and learning. To evaluate the influence of learning capacity in the sensitization process, in the present study we compared the performance of two groups of mice that presented different levels of sensitization (high and low) in two different learning tasks (appetitive and aversive). We also evaluated the influence of an amnestic drug (scopolamine) in the development and expression of sensitization. It was observed that mice with different levels of sensitization did not differ regarding their learning capacity after chronic treatment with ethanol, in both tasks. Scopolamine, when administered in the dorsal hippocampus simultaneously with ethanol treatment, did not alter the sensitization development. However, when administered subcutaneously it induced higher levels of locomotor activity in those animals that had already developed high sensitization than in low sensitized mice or in the control group. This phenomenon was not observed when scopolamine was administered directly in the nucleus accumbens. When administered in combination with ethanol, it blocked the sensitization. These data suggest that the cholinergic system acts as a neuromodulator in the sensitization process. However, the cholinergic system seems to act in different ways depending on the level of sensitization developed by the animal.