Abstract:

Abstract:Objective
To study the effect of thyroid hormone deficiency on malonaldehyde (MDA) and total antioxidative capacity (TAC) and superoxide dismutase (SOD) levels in different developing stages of rat brain and  further explore the mechanism of impaired brain development caused by thyroid hormone deficiency. Methods Perinatal hypothyroidism was induced by administering propylthiouracil ( PTU) solution to the dams by gavage (2 % PTU 1. 5 mL/d) beginning on embryonic day 15. The blood samples of  pups in different developing stages(7,14,21 d) were collected to measure serum FT3 and FT4 levels. And the brain tissues were collected to measure MDA,TAC and SOD levels in brain homogenate. Age matched controls were pups from normal dams without administering propylthiouracil ( PTU) solution. Results Compared with age matched controls,the MDA and TAC and SOD levels were increased in hypothyroid group of 21 d pups（MDA:14.63 μmol/g/±3.44  μmol/g  vs  10.52 μmol/g ±2.32  μmol/g，P<0.05;TAC:0.051 mmol/g±0.006 mmol/g  vs  0.042 mmol/g±0.003 mmol/g，P<0.05;SOD:79.63 μmol/min/g±10.10  μmol/min/g   vs  63.51 μmol/min/g±8.35 μmol/min/g,P<0.05）,but for the 7 d and 14 d pups,ther
e were no differences between two groups (7 d MDA:11.20 μmol/g±2.39  μmol/g　vs  12.29 μmol/g±1.79  μmol/g,P>0.05;14 d MDA:13.07 μmol/g±3.16  μmol/g  vs  12.98 μmol/±2.93  μmol/g,P>0.05;7 d TAC:0.046 mmol/g  ±0.006 mmol/g vs  0.047 mmol /g  ±0.004 mmol/g,P>0.05;14 d TAC:0.042 mmol/g  ±0.007 mmol/g  vs  0.046 mmol/g ±0.007 mmol/g,P>0.05;7 d SOD:66.34 μmol?min-1/g ±11.20  μmol/min/g  vs  65.49 μmol/min/g±7.52  μmol/min/g,P>0.05;14 d SOD:67.53  μmol/min/g±12.01  μmol/min/g  vs  64.57  μmol/min/g±8.28  μmol/min/g/,P>0.05). Conclusion Thyroid hormone deficiency during rat brain development may cause the changes of MDA,TAC and SOD levels and this may be related to brain damage caused by thyroid hormone deficiency.

Key words: thyroid hormone deficiency;malondialdehyde;total antioxidant capacity;superoxide dismutase;brain development