| Objective:Nkxs gene family is closely related to the development of brain tissue[1,2].In this paper,we want to study whether low iodine pregnant rats supplied thyroid hormones can supply the thyroid hormones of future generations brain development or not,and to know the best time and dose of treatment.Methods:We copied the low thyroid hormone rat model caused by the deficiency of Iodine.And we give different doses of thyroid hormone in the early and late period of brain development.According to the period and the dose of thyroid hormone,we set different groups of the treatment,and we set the normal and low iodine groups,we Arrangement 17 days of pregnancy,newborn and 20-day-old rats as experimental animals.According to each gene in the process of brain development during the crucial role,we focus on the critical period in the expression level.Results:1.We use fluorescence real-time quantitative PCR detection the expression level of nkxs in normal,low iodine group and treatment group:(1) In normal group nkx2.1 expression level gradually decreased with age (P<0.05),Low-iodine group were lower than the expression level of normal group during the same period(P<0.05),and the expression level of 17th day of pregnant is near to the normal group at the same time(P>0.05);(2) The average trend of nkx2.2 gene expression level in the normal group:To increase gradually with age,the expression level in low-iodine group were higher than normal group during the same period,and it increased gradually with age. Within the late period middle dose group,the neonatal period,20 days after birth have the same level with the normal group at the same time period(P>0.05);(3) In normal group nkx6.1 expression level gradually decreased with age (P<0.05),in low-iodine group,the expression level 17th day pregnant at the same time period is less than of normal group(P<0.05),and the expression level of 17th day of pregnant is near to the normal group at the same time(P>0.05); (4) The average trend of nkx6.2 gene expression level in the normal group:To increase gradually with age(P>0.05 ).The differences between treatment groups is not significant(P>0.05),and it is close to normal expression level(P> 0.05).2.We use immunohistochemical staining to detect the protein expression level of Nkx2.1 in rat brain:Trend from an average point of view,in normal group the expression level gradually decreased with age(P<0.05),Low-iodine group were lower than the expression level of normal group during the same period(P<0.05), the level in 17th days of the pregnant group is similar to the normal level.Conclusions:1.Normal and Low-iodine group:Nkx2.1,Nkx2.1:Trend from an average point of view,in normal group the expression level gradually decreased with age, Low-iodine group were lower than the expression level of normal group during the same period;Nkx2.2:To increase gradually with age,the expression level in low-iodine group were higher than normal group during the same period; Nkx6.1:Expression level gradually decreased with age.2.Treatment groups:Low iodine pregnant rats continue to be gived the middle-dose(2μg/100g·d) of the thyroid hormone therapy from early to late pregnancy during the brain development,and offspring can reach the normal NKXs expression levels.3.To sum up,the differences of NKXs expression in low-iodine rats and normal rats group exist significance differences,low-iodine resulted in retardation of the brain is associated with NKXs differential expression in brain tissue.The results of This is the guidance of early pregnancy screening for thyroid hormone levels,and it has a certain significance of theoretical guidance.
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