목적: Deafness induces many plastic changes in the neural auditory system. Synaptic changes were happened and it was caused by dendritic changes in neural cells. SMI-32 recognizes non-phosphorylated epitopes on medium- and high- molecular weight subunits of neurofilament proteins in dendrites of cortical pyramidal cells. We investigated the SMI-immunoreactive (ir) protein levels after induced unilateral and bilateral deafness in the rat auditory cortex. 방법:Three groups of adult male Sprague-Dawley rats were prepared for control, unilateral deafness and bilateral deafness. Deafness induced using cochlear ablation method. After deafening, 2, 4, 6 and 12 weeks later, auditory cortices were harvested for RT-qPCR and western blot. Immunohistologic staining was performed to evaluate the location of SMI-ir neurons. 결과:In the bilateral deafened group, mRNA expression and western blot showed increasing level of SMI-ir and it was increased at 12 weeks after deafening. However, in the unilaterally deafened group, there were no significant changes in right and left auditory cortex in whole period. 결론:This study showed that unilateral deafness did not affect so much to change the level of neurofilament and suggested that less plastic changes were happened in the auditory cortex of unilaterally deafened rats.