Effect Of TSH Suppression Therapy On Cognitive Function After Total Thyroidectomy In Rats

Objective This study aims to further reveal the possible mechanism of cognitive impairment caused by TSH suppression therapy by establishing an animal model of TSH suppression therapy after total thyroidectomy in rats.Methods A total of 40 healthy female 8-week-old clean Wistar rats were randomly divided into normal control group(NC group),total thyroidectomy group(TD group),TSH replacement therapy group(TR group)after total thyroidectomy,and total thyroid gland.After the resection,the TSH suppression therapy group(TS group),10 rats in each group,after successful model establishment,continued to inject the same amount for 6 weeks and then used the Morris water maze(MWM)for behavioral testing.At the end of the experiment,the levels of thyroid hormones in each group were detected,and the hippocampus was taken.The pathological results were observed by HE staining.The expression of ubiquitin-positive protein in hippocampus CA1 was detected by immunohistochemistry.Results There was no significant difference in serum T3 between the TS group and the NC group(P>0.05).The T4 was increased(P<0.05)and the TSH was significantly decreased(P<0.05).In the water maze experiment,the escape latency of the TS group was significantly longer than that of the NC group(P<0.05);the number of crossing the virtual platform and the target quadrant residence time were significantly reduced(P<0.05).The number of pyramidal cells in hippocampal CA1 area of TS group was significantly reduced,most of the nerve cells shrunk,the structure was loose,the arrangement was disordered,the nucleus was deeply stained,pyknosis,fragmentation,nucleoli disappeared,cytoplasm was lightly stained,and the cells were swollen and round.An air halo was found around the cytoplasm,and the cell spacing was large.There was no significant difference in the expression of ubiquitin-positive protein in the hippocampal CA1 region between the TS group and the NC group(P>0.05).Conclusion 1.TSH suppression therapy after total thyroidectomy in rats can lead to cognitive function impairment caused by decreased learning and memory ability.2.TSH suppression therapy after total thyroidectomy related to cognitive impairment is related to degeneration,necrosis and apoptosis of neuronal cells in hippocampal CA1 area,and has nothing to do with activation or inhibition of ubiquitin proteasome pathway.