Characterization of the cuprizone-induced demyelization process in Lewis rat strain

Abstract

The multiple sclerosis is a chronic, demyelinating disease of the central nervous system (CNS), which the relapse-remitting course leads to cognitive and motor impairment. The knowledge about the pathogenesis of the multiple sclerosis has been clarified from studies carried with experimental models, as the experimental autoimmune encephalomyelitis (EAE), which depend on genetically susceptible animals. The Lewis rat strain is highly susceptible to autoimmunity because exhibit a defect in the hypothalamus-ptuitary-adrenal axis leading to reduced plasma corticotrophin release from the pituitary and corticosterone from the adrenal cortex. Although these studies had constituted in a valuable contribution to the knowledge of the inflammatory process, this model has not shown adequate to evaluation of the oligodendrocyte injury. In the EAE model or in virus induced demyelination is characterized by a sporadic, inconsistent and sparse demyelination, becoming the analysis of these injuries difficult due to anatomical reproducibility and by variability between the used animals. In the present project, we propose to characterize through the molecular, morphologic and, biochemist evaluation, the demyelination process induced with cuprizone in Lewis rats strain, which the oligodendrocyte constitute the primordial focus. Since that in this model the animals will not be inoculated with myelin antigens, the oligodendrocyte injury will be evaluated, without the interference of the peripheral immunological response. To evaluate the cuprizone effect the animals will be submitted to the neurotoxicity and behavior test. After the euthanasia, the CNS will be removed and submitted to the Luxol Fast Blue staining to investigate the demyelinization in the corpus callosum, superior cerebellar peduncles and in the cortex, and the myelin quantified. Moreover, the apoptosis occurrence will be demonstrated by the TUNEL, associate to the immunohistochemistry to identify the cellular type. The presence of pro-inflammatory cytokines and peripheral activation will be evaluated by the RT-PCR and ELISA. In this way, the purpose is to clarify if the autoimmunity could to influence the injury process of the oligodendrocyte in the Lewis rats strain. (AU)