ABSTRACT
Objective To study the influence of low-iodine diet on the expression of homeobox gene Nkx-6.1 and Nkx-6.2 in rat cerebrum tissue, and to explore the possible molecular mechanism of cerebrum development retardation caused by low-iodine. Methods Twenty female Wistar rats were randomly equally divided into two groups: low-iodine group and control group, both fed with low-iodine diet as low as 13.66 μg/kg determinated by spectrophotometry in Tianjin Institute of Endocrinology and the former with deionized water, the later 200 μg/L potassium iodate. Thyroid hormone level was detected using chemiluminescence immunoassay 3 months later and they were mated with male rats normally fed. Rats of 16-day pregnancy, new-born and 20th days old were detected the content of Nkx-6.1 and Nkx-6.2 mRNA in the cerebrum tissue by real-time fluorescence quantitative PCR 0.61), (3.28±0.80)pmol/L] were lower than the control group[(1.04±0.06), (39.42±14.68)nmol/L, (4.83±0.33), day pregnancy, new-born and 20th days old of control group was (1.90±0.23)×10-3,(1.86±0.40)×10-4, (1.11± 0.27)×10-4(F=827.58, P<0.01), Nkx-6.1 mRNA expression level gradually decreased along with aging(all P<0.05). The intra-group difference was significant (F=297.25, P<0.01) and the Nkxr.1 mRNA expression level during 16 days of pregnancy was the highest(P<0.01). It was higher in the control group than in the low-iodine group during 16 days of pregnancy (t=10.14, P<0.01) as well as in the low-iodine group than in the in 16-day pregnancy, new-born and 20th days old of control group was respectively(1.03±0.19)×10-2, (1.33± 0.10)×10-3, (8.79±0,87)×10-3, and that of low-iodine group was (0.31±0.03)×10-2, (1.53±0.13)×10-3, (7.51±0.86)×10-2. The intra-group difference was significant(F=1293.02,1065.83, all P<0.01). Nkx-6.2 expression level during 20th days old was the highest(P<0.01) and that of newborn was the lowest(P<0.01). The Nkx6.2 mRNA expression level in control group were higher than the low-iodine group during 16-day pregnancy and 20th days old(t=14.35, 4.05, all P<0.01). It was higher in the low-iodine group than in the control group during newboru(t=4.78, P<0.01). Conclusions The difference in the expression of Nkx-6.1 and Nkx-62 is highly related to the brain development retardation caused by low-iodine.
ABSTRACT
Objective To study the influence of low-iodine diet on the expression of homeobox gene nkx2.1 in rat cerebral tissue. Methods Forty female Wistar rats were randomly divided into two groups according to body. quality: low-iodine group and control group,both fed with low-iodine feed at an iodine content of 13.66 μg/kg,respectively given the deionized water and 200 μg/L KIO3 solution. The hormone levels of two group rats were determined with chemiluminescence immunoassay after three months, and then mated with healthy male rats. Cerebral tissues were taken from the fetus of 16-day pregnancy,newborn and 20 days old offspring in low-iodine and control group to detect the content of nkx2.1 mRNA using real-time fluorescence quantitative PCR (FQ-PCR) techniques. Results Serum TT3, TT4, FT3, FT4 level of rats in low-iodine group(0.89±0.20, 0.32±0.16, 3.33± 0.61, 3.28±0.80) was respectively lower than that in the control group(1.04±0.06, 39.42±14.68,4.83±0.33, 26.99±4.48;t = 2.71,6.52,5.70, 12.89, P < 0.05 or < 0.01). The relative nkx2.1 mRNA expression was(5.60± 0.30)×10-3, (1.20 ± 0.29)×10-3, (0.18± 0.06)×10-3 respectively in the fetus of 16-day pregnancy, newborn and 20 days old offspring of control group, while it was (3.00 ± 0.55)×10-3, (1.90 ± 0.21)×10-3,(0.69 ± 0.15)×10-3 in the low-iodine group. The difference of nkx2.1 mRNA expression was significant among fetal and neonatal rats in the control group and low-iodine group(F = 210.07,162.40, both P < 0.01). The nkx2.1 mRNA expression of newborn rats was lower than that of 16-day pregnancy in both groups(P < 0.01), and that of 20 days old rats was lower than that of 16-day pregnant and neonatal rats(P < 0.01). The 16-day pregnant rats of control group had obviously higher level of nkx2.1 expression than those in the low-iodine group(t = 16.073, P< 0.01), while the nkx2.1 of newborn and 20 days old low-iodine rats expressed much higher than healthy rats(t = 7.573,12.221, P < 0.01). Conclusions Brain development retardation caused by low-iodine is closely related to nkx2.1 differential expression in the brain tissue.
ABSTRACT
Objective:To explore the influence of low-iodine diet on the expression of homeobox gene NKX-2.2 in rat cerebrum tissue,and to explain the possible molecular mechanism of cerebrum development retardation caused by low-iodine.Methods:Female Wistar rats were randomly divided into two groups:Low-iodine group and control group,both fed with low-iodine feed,given the deionized water and KIO3 solution respectively,they were drawn from the 16-day pregnancy,new-born and 20th days old low-iodine and normal age offspring after three months,and detect the content of NKX-2.2 mRNA in the cerebrum tissue by Real-time fluorescence quantitative PCR techniques.Results:The thyroid hormone levels of low-iodine group in serum were significantly lower than the control group(P