Authors: C L Liu Y X Xu Y Zhan H L Hu X M Jia G H Chen D F Zhu
Publish Date: 2010/06/11
Volume: 34, Issue: 4, Pages: 280-286
Abstract
Adultonset hypothyroidism causes cognitive dysfunctions of learning and memory in which many synaptic proteins in hippocampus are involved In our work we studied the effect of adultonset hypothyroidism on the expression of synaptotagmin 1 syt 1 and SNAP25 in dorsal hippocampus as well as its recovery by levothyroxine LT4 replacement therapy Rats were divided into 4 groups control hypothyroidism and hypothyroid rats treated with 5 μg T4/100 g body weight BW and 20 μg LT4/100 g BW respectively Protein levels of syt 1 and SNAP25 in dorsal hippocampus were determined by Western blot and immunohistochemistry The immunoblot analysis indicated that syt 1 was expressed at a significantly lower level in hypothyroid rats while the level of SNAP25 was much higher compared to controls Furthermore using immunostaining we found that on the one hand expression of syt 1 was significantly downregulated in the examined layers of CA1 and CA3 subregions but not dentate gyrus DG however on the other hand expression of SNAP25 was upregulated in the layers of CA1 CA3 and DG Twoweek treatment with 20 μg LT4/100 g BW fully restored the levels of syt 1 and SNAP25 to the normal level which was more effective than 5 μg LT4/100 g BW that partially restored the levels of both proteins These results suggest that adultonset hypothyroidism caused downregulation of syt 1 and upregulation of SNAP25 level in dorsal hippocampus which could be restored by LT4 treatment and the recovery degree is related to the LT4 dosage
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