Effects Of Hashimoto's Thyroiditis On Serotonin In Hippocampus Of Pregnant Mice

Objective Hashimoto's thyroiditis is an autoimmune thyroiditis.In recent years,the incidence of mood disorders in pregnancy with hashimoto thyroiditis has been found to be increasing.Serotonin(5-HT)is an important neurotransmitter involved in mood regulation.In this study,we established a pregnant mouse model of hashimoto's thyroiditis with normal thyroid function and observed the effect of hashimoto's thyroiditis on the open field behavior and expression levels of 5-ht and receptors in the hippocampus of pregnant mice Methods70 female and 16 male NOD mice aged 5-6 weeks were adaptively fed for one week.Female mice were randomly divided into normal pregnancy group(CON group)and HT pregnancy group(HT group).The HT mouse model was established through two times of immunological induction by pig thyroglobulin(pTg)combined with freund's adjuvant.Steps: Take 25?g of porcine thyroglobulin(pTg)and dissolve it in100?l physiological saline solution.Then mix the syringe with complete freshener adjuvant(CFA)in a 1:1 ratio with pTg solution in the mortar.Grind it in the ice bath until it was fully emulsified.0.1 ml emulsifying agent was injected subcutaneously at 1cm at the tail root of the HT group of mice.The CON group was injected with CFA emulsifier containing an equal amount of normal saline.After 14 days,the CFA wasreplaced with incomplete Freund's adjuvant(IFA),mixed with pTg to prepare an emulsion,and 0.1 ml was injected subcutaneously at 1 cm from the tail root of mice in the HT group.In the CON group,an equal amount of pTg-free IFA emulsifier was injected.After 7 weeks,the two groups of mice were randomly caged with male rats in a ratio of 2: 1 and mated for 10-12 h.Female rats formed vaginal plugs at the vaginal opening,which was considered a successful mating.16 pregnant rats were randomly selected from each group.The spontaneous behavior,behavior and emotional response of mice in new and different environments were observed through open field experiment.After the experiment,the serum thyroid hormone and antibody levels were measured by electrochemical luminescence immunoassay and enzyme-linked immunosorbent assay;thyroid HE staining;enzyme-linked The content of 5-HT in hippocampus of mice in each group was detected by immunosorbent method;the content and distribution of 5-HT2 CR in hippocampus of mice in each group were observed by Western blot and immunohistochemistry.Statistical analysis was performed using SPSS 17.0 software,using two independent sample t tests.The difference was statistically significant with P <0.05.Result1.Open field experiment: Compared with the CON group,the HT group of mice stayed significantly shorter in the central area of the open field,and the difference was statistically significant(P <0.01).The total exercise distance and the number of feces occurred in the HT group were increased compared with the CON group,but there was no significant trend(P> 0.05).Compared with the control group,the observation indexes of the average speed,the number of times in the central zone,the number of times of standing,and the number of times of modification showed a decreasing trend,but there was no statistical significance(P> 0.05).2.Thyroid hormone and antibody levels: Compared with the CON group,serum thyroidperoxidase antibody(TPOAb)and anti-thyroglobulin antibody(TGAb)levels were increased(P <0.05),and free triiodothyronine Acid(FT3),free tetraiodothyronine(FT4),thyroid stimulating hormone(TSH)have no significant difference3.HE staining of the thyroid showed that the thyroid tissues of the mice in the CON group were evenly distributed,and the thyroid follicular epithelial cells were almost the same in size and shape.The follicular cavity has a complete structure and a pink jelly-like substance.Lymphocytic infiltration and disruption in the visual field are rare.In the HT group,the thyroid follicular epithelial cells had irregular morphology,and the morphology of the follicular cavity was destroyed,with obvious lymphocyte infiltration.4.5-HT expression in hippocampus: Compared with the CON group,5-HT expression in the hippocampus of the HT group was reduced(P <0.01)5.5-HT2 C receptor expression in hippocampus: Compared with the CON group,the expression level of 5-HT2 CR in the hippocampus of the HT group increased(P <0.001)6.5-HT2 C receptor distribution in the hippocampus: 5-HT2 CR immune response products are brown particles,mainly in the hippocampal CA1,CA3 region pyramidal cell layer and DG region granular cells.Compared with the CON group,the positive particles in the pyramidal cell layer of the hippocampal CA3 area increased in the HT group,and the difference was statistically significant(P <0.01);the CA1 and DG areas had an increasing trend,but no statistical significance(P> 0.05).Conclusion1.Hashimoto's thyroiditis can affect mood-related behavior changes in pregnant mice.2.Hashimoto's thyroiditis significantly reduced the expression of 5-HT and increased the expression of 5-HT2 CR in the hippocampus of pregnant mice.Emotional changes in Hashimoto thyroiditis mice during pregnancy may be related to 5-HT changes.