Fornari R V, Moreira K M, Oliveira M G
Department of Psychobiology, Universidade Federal de São Paulo (UNIFESP), Rua Napoleão de Barros 925 CEP 04024-002, São Paulo SP, Brazil.
Learn Mem. 2000 Sep-Oct;7(5):287-92. doi: 10.1101/lm.34900.
The nonselective muscarinic antagonist scopolamine is known to impair the acquisition of some learning tasks such as inhibitory avoidance. There has been recent research into the effects of this drug in contextual fear conditioning and tone fear conditioning paradigms. The purpose of the present study was to assess the role of the selective M1 muscarinic antagonist dicyclomine in these paradigms and in the inhibitory avoidance test. Rats were administered different doses of dicyclomine or saline 30 min before acquisition training. The animals were tested 24 hr later, and it was observed that 16 mg/kg of dicyclomine impaired both contextual fear conditioning and inhibitory avoidance. However, dicyclomine (up to 64 mg/kg) did not affect tone fear conditioning. These results suggest that the selective M1 muscarinic antagonist dicyclomine differentially affects aversively motivated tasks known to be dependent on hippocampal integrity (such as contextual fear conditioning and inhibitory avoidance) but does not affect similar hippocampus-independent tasks.
非选择性毒蕈碱拮抗剂东莨菪碱已知会损害某些学习任务的习得，如抑制性回避。最近有关于这种药物在情境恐惧条件反射和音调恐惧条件反射范式中的作用的研究。本研究的目的是评估选择性M1毒蕈碱拮抗剂双环维林在这些范式以及抑制性回避测试中的作用。在习得训练前30分钟，给大鼠施用不同剂量的双环维林或生理盐水。24小时后对动物进行测试，观察到16mg/kg的双环维林损害了情境恐惧条件反射和抑制性回避。然而，双环维林（高达64mg/kg）并不影响音调恐惧条件反射。这些结果表明，选择性M1毒蕈碱拮抗剂双环维林对已知依赖海马完整性的厌恶性动机任务（如情境恐惧条件反射和抑制性回避）有不同影响，但不影响类似的不依赖海马的任务。
