Objective To explore the changes of cognitive ability and thyroid function and mRNA level of thyroid hormone receptor α1 （TRα1） in the brain tissues of rats with nonthyroidal illness syndrome （NTIS）. Methods Nineteen adult male SD rats were randomly divided into normal control （n=9） and NTIS （n=10） groups. The NTIS model, its liver been fiberized was induced by intraperitoneal injecting 0.15 mL carbon tetrachloride （[CCL4], [1：6, diluted by corn oil]） 3 times per week with duration of 8 weeks. The normal control group was injected equal sodium. Morris water-maze task was employed to test the cognitive memory ability of the rats; the concentrations of T3, T4, FT3, FT4, rT3 and TSH in the blood serum and T3, T4 and rT3 in the brain tissue were detected by using radioimmunoassay （RIA）; the mRNA level of TRα1 was detected by fluorescent quantitative RT-PCR. Results Morris water-maze task showed no significant difference in congnitive ability between NTIS and control groups （P〉0.05）. The concentrations ofT4, FT3, FT4 and T3 in blood serum in the NTIS group were significantly lower as compared with those in the normal control group （P〈0.05）. Concentrations of rT3, TSH in the blood serum, the concentrations of T4, T3, rT3 and the mRNA level of TRα1 in the brain tissue had no significant differences between the two groups （P〉0.05）. Conclusion The rats with hepatic fibrosis showed typical NTIS. Thyroid function in central nervous system of these rats is normal, so is their cognitive ability. The mRNA level of TRα1 had no significant change in brain tissue of these rats.
Chinese Journal of Neuromedicine