Effects Of Low-Iodine Diet On The Expression Of Homeobox Gene Nkxs And Cell Apoptosis In Rat Cerebral Tissue

Part one: the Effects of Low-Iodine Diet on the Expression of Homeobox Gene Nkxs in Rat Cerebral TissueTo explore the effects of thyroid hypofunctionon the expression of homeobox gene Nkxs in rat cerebral tissue, we reconstructed the model of iodine-deficient induced thyroid hypofunction rat at embryonic phase and postnatal developmental threshold, we chose 16-day-pregnant, neonatal and 20-day-old mice as the experimental animals(which equals to the early, middle and late fetal development of human) , utilized fluorescence real-time time quantitation PCR to detect the expression of Nkxs of cerebral tissue in normal and low-iodine mice. We discovered that: the expression of Nkx-2.1 was decreased quickly along with age accretion, the expression had statistical significance in each age stage;there was statistical significance in the expression between low-iodine and normal rat at each age group;the expression of Nkx-2.1 of normal pregnant 16 days rat was higher than low-iodine rat, neogenesis and 20 days old low-iodine rat was higher than normal rat. The expression of Nkx-2.2 of normal rat was the lowest in neogenesis; the expression of low-iodine rat increased quickly along with age accretion, there was statistical significance in the expression in each age group. Nkx-6.1 was the highest at the pregnant 16 days ,the expression of low-iodine and normal rat had the statistical significance, there was statistical significance in the expression of neogenesis,20-day-old low-iodine, and normal rat; the expression of normal rat at each age stage had statistical significance;there was statistical significance in the expression of low-iodine rat and neogenesis, 20-day-old, but there was no significance between the expression of neogenesis and 20-day-old. The expression of Nkx-6.2 were low in both pregnant 16 days and neogenesis, 20-day-old was higher than another two groups;There was no significance between neogenesis low-iodine and normal rat. Results: thyroid hormone has confirmative relationship with the homeobox gene Nkx, and the relationship can be revealed in 16-day pregent rat, but the thyroid tissue has not developed, so the mothers' thyroid hormone have effect on the fetal rat, which hinted that iodine-deficient can induce cerebral developmental lag, this may be association with the diversital expression of Nkxs. higher than the control group at 72h; under the stimulation of T₄, the expression of Nkx-2.1 is lower than the control group at12h,24h,48h, and increased correspondingly at 72h. The expression of Nkx-2.2 is lower than the control group 12h after the stimulation of T₃. 24h later was higher than the control group, 48h later decreased slowly, 72h later, it increased correspondingly again, which had significance difference with the control group; the stimulatory function of T₄ on Nkx-2.2 of Neurogliocyte is similar to T₃ at Oh,12h,24h,72h, the down regulation of the expression of Nkx-2.2 is more significantly. The stimulation of T₃,T₄both can down regulate Nkx-6.1 at 12h,24h, the expression were both lower than the control group, the expression were both increased correspondingly at 48h, higher than the control group, the up-regulation of T₃ is stronger than T₄, but the stimulatory function of T₄ was obviously increased at 72h, higher than the control group and T₃ group. The expression of Nkx-6.2 is higher than the control group 12h after the stimulation of T₃,T4, and down regulated slowly after 24,48h,72h after the stimulatory function of T3,T4, both higher than control group. In a word, THs has different stimulatoryfunction on each Nkxs subtype of rat neurogliocyte, but this kind of function tendency is not very obvious possible because the low hormone serum response time excessively is short as well as the cell harvesttime choice is not very appropriate otherwise, T₄ is not a hormonogen, but also the stimulatory function is stronger than T₃ sometimes. Part three: the Effects of Low-Iodine Diet on Cell Apoptosis in Rat Cerebral TissueTo explore the diffenrences of cell apoptosis of in cerebral tissue between the low-iodine rats and the normal ones, we made cytosections using the replicated cerebral tissue of the low-iodine rats and the normal ones, apply In Situ Cell Death Detection Kit(Tunel Kit) to detect the diffenrences of cell apoptosis of cerebral tissue between the low-iodine rats and the normal ones with new-born rats. We find that there was statistical significance of cell apoptosis in cerebral tissue between the low-iodine rats and the normal ones at new-born stage (P＜0.05). which hinted that cerebral developmental lag caused by iodine-deficient is related to its accretion of cell apoptosis, finally causes the brain organization irreversibility damage...