The Influence Of Carboxy-terminus Prokaryotic Expression Protein Fragments Of The TSHR Extracellular Domain On T₄?TRAb Levels In BALB/c Mice

Objective:we use Carboxy-terminus expression protein fragments of the TSHR extracellular domain different does of the fusion protein to immunize BALB/c mice,and to compare the level of T4?TRAb,and use optical microscope to observe the pathological changes of thyroid glands.Methods:to select 6 to 8 weeks of health SPF male BALB/c mice,which were randomly divided into experimental group and control group.The experimental group on the basis of TSHR-c is divided into different concentrations TSHR-c1 group(4ug),TSHR-c2(6ug)TSHR-c3 group(8ug),TSHR-c4 group(lOug).The experimental group use different does TSHR-c protein immune mice,the control group mice immunized with corresponding saline.We use different does of the fusion protein immunized mice,with these combinations respectively 4 times with a interval of 2 wk each time,and the BALB/c in control group were injected with normal saline at the same time.Also the blood was drawn 0 wk before each treatment and 2wk after the fourth immunization.The mice were sacrificed on 60 days to obtain their thyroid glands.In the end,thyroid glands were excised and fixed with 10%paraformaldehyde,the tissues embedded in paraffin to prepare paraffin sections.Then we use hematoxylin and eosin to stain thyroid sections.After that,we compared the level of T4?TRAb,and use optical microscope to observe the pathological changes.Results:In experimental animals,the levels of T4 decreased with the increase of the does of fusion protein,TRAb was positive;in the experimental group and control group,the Pathological Changes of thyroid tissue were that the shape of the thyroid follicular epithelial cells was full,neat rows,rich in pectin content in the follicle.Conclusions:The results show that fusion protein of TSHR-c may have the immunological effect to induce the production of T4?TRAb in the BALB/c mice which was similar to hypothyroidism,it also indicates it is related to TSHR-c contain the epitopes of TSBAb to induce the body to produce TRAb(especially TSBAb).