Modulação do sistema colinérgico pelo sistema endocanabinoide em tarefas apreendidas e reapreendidas : efeito do agonista canabinoide WIN-2
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Data
2016-05-11
Autores
Ferreira, Tamara Andrea Alarcón
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Universidade Federal do Espírito Santo
Resumo
The Cannabis sativa plant, commonly known as marijuana, contains compounds named cannabinoids, and the 9-tetrahydrocannabinol (9 - THC) is the most active component. After cloning and characterization of cannabinoid receptors, it was found that they bind to 9 - THC and to endogenous ligands, named endocannabinoids (ECs), capable of modulating multiple neurotransmitter systems, and emerging as important regulators of various physiological brain functions. The effect of endogenous and exogenous cannabinoids in the processes of acquisition, consolidation and recovery of information, both in learning and memory is still controversial. Moreover, there is evidence that the processes of acquisition and consolidation have distinct biological basis with probable involvement of hippocampal and cortical cholinergic system in these differences. In order to understand the molecular basis of cognitive processes that involve the participation of the central cholinergic system by the activation of cannabinoid receptors, we proposed the use of a cannabinoid agonist, WIN 55.212-2 (WIN-2). For this, Swiss mice were treated with WIN-2 at a dose of 2 mg/kg and submitted to testing in the aquatic Morris maze to evaluate aspects of acquisition and consolidation of the task. We observed that the cognitive impairment caused by chronic treatment with WIN-2 is mainly related to short term memory in acquisition of spatial task process, while consolidating remained unchanged. This cognitive impairment in the acquisition may be related to a possible increase in the concentration of 2-AG (2-arachidonylglycerol) and decreased of AEA (anandamide) in the prefrontal cortex. Although the behavioral changes observed in this study are subtle, we verified modulation of cholinergic by endocannabinoid system, since treatment with WIN-2 in the memory consolidation period resulted in a decreased basal release of acetylcholine (ACh) in hippocampus. However, this decrease was not associated with cognitive deficits observed. Therefore, this study confirms the importance of both systems studied in the modulation of cognitive processes and hopefully, in the future, help in developing treatments with pharmacological and non-pharmacological approaches, to seek reduce the cognitive deficits caused by drug abuse, as well as neurodegenerative diseases such as Alzheimer's disease.
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Spatial memory , Endocannabinoid system , Cholinergic system , Memória espacial , Sistema endocanabinoide , Sistema colinérgico