Effects of low-iodine diet on the expression of homeobox gene nkx2.1 in rat cerebral tissue / 中国地方病学杂志

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.