Abstract:

Abstract:Objective
To detect the levels of the oxidation products and hormones related to the thyroid,and to discuss the effect of high dose of  vitamin E(VE) on the  level of the oxidative stress and thyroid function of the rats,and to provide the experimental reference for the  questions might be caused by overdose usage of VE in population.Methods 30 Wistar rats were randomly divided into control group(n=6),vehicle group(n=6),low dose of VE group(n=6), medium dose of  VE group(n=6),and high dose of VE group(n=6).The solvent for VE was peanut oil,and the doses of VE for the  rats in low,medium,and high doses of VE  groups  were 400,800,and 1 600 mg/kg, respectively.The  rats were killed 30 d after administration,and  the serum levels of free thyroxine (FT3),free triiodothyronine (FT4),the concertration of malondialdehyde (MDA),and the activities of superoxide dismutase (SOD) and  glutathione peroxidase (GSH-Px) of the  rats in various groups were determined.Results In medium and high doses of VE  groups,the rats’ hair turned yellow and messy and no luster,and they showed sleepiness,mental apathetic state.The concentration  of serum MDA of the rats  in  high dose of VE group  was higher than those in  control,vehicle,low and medium doses of VE  groups (P<0.05);the activity of SOD was significantly increased(P<0.05) and the activity of  GSH-Px was  significantly decreased(P<0.05).Compared with control and vehicle groups,the levels of FT3 and FT4 in low,medium and high doses of  VE groups were significantly decreased (P<0.05).The thyroid follicular epithelial cells of the  rats in medium and high doses of  VE groups  had a higher level of hyperplasia compared with  control and vehicle groups,and  the nucleus became larger and irregular. Conclusion Ingestion of high dose of VE can cause oxidative stress and produce effects on the structure and function of thyroid in the rats.

Key words: vitamin E, oxidative stress, thyroid function