ABSTRACT
OBJECTIVE: To observe the effects of maternal low-level decabromodiphenyl( BDE209) exposure on nervous system and secretion of thyroid hormones in offspring mice. METHODS: Sixty-four specific pathogen free female,aged 4 weeks Kunming mice were used. These mice were randomly divided into control group and low,medium and high exposure groups after successful mating was confirmed. The rats of control group were fed with 0. 01 L/kg body mass of peanut oil.The maternal mice in the experimental groups were given BDE209 at doses of 50,100 and 300 μg/kg body mass by oral gavage once per day. Continuous exposure was given until 21 days after birth of offspring,the exposure model from gestation to lactation was established. At the end of the exposure,10 mice of each group including half female and half male were randomly selected and the body mass and growth development status were observed. Morris water maze was used to examine the learning and memory ability in offspring mice. The serum levels of total triiodothyronine( TT3),free triiodothyronine( FT3), total tetraiodothyronine( TT4) and free tetraiodothyronine( FT4) were measured by chemiluminescence immunoassay. The levels of glutathione transferase( GST), superoxide dismutase( SOD) and malondialdehyde( MDA) level in hippocampus were measured by colorimetry. RESULTS: The escape latency of the medium exposure group was longer than that of the control group( P < 0. 05). The escape latency of high exposure group was longer than that of control group,low exposure group and medium exposure group( P < 0. 05). The time of quadrant movement and number of crossing the platform in offspring rats in high exposure group were less than that of the control group and the low and medium exposure groups( P < 0. 05). The serum levels of TT3,FT3,TT4 and FT4 increased,the activities of GST and SOD in hippocampus tissue decreased,the MDA level increased with the increasing exposure dose( P < 0. 05).CONCLUSION: Maternal low-level BDE209 exposure can result in decrease the learning and memory ability of offspring mice. It also can increase the serum thyroid hormone level and induce oxidative stress injury in hippocampus in a dose dependent manner in offspring mice.
ABSTRACT
Objective To investigate the effect of low dose of BDE209 on thyroid hormone and thyroid hormone metabolism enzyme-iodothyroninedeiodinases Ⅱ(D2) in off spring mice after pregnancy exposure .Methods Total 64 adult SPF female Kun-ming mice were randomly divided into 4 groups ,which treated with oral gavage of 0 ,50 ,100 ,300 μg · kg -1 · d-1 dose of BDE209 after successful pregnancy ,the exposure continue to 21 days after delivery .10 mice was randomly selected in each offspring group and get the peripheral blood and brain sample ,the serum thyroid hormones level ,oxidative damage and the expression of D2 mRNA in brain were detected .Results Compared with the control group(0μg · kg -1 · d-1 dose of BDE209) ,the TT4 ,TT3 ,FT4 and FT3 levels of offspring mice increased significantly in every exposure group (P< 0 .05);antioxidant enzyme glutathione-S transferees (GST) ,superoxide dismutase (SOD) activity decreased with the BDE209 dose increase (P<0 .05) ,and malondialdehyde (MDA) level increased (P<0 .05);the D2 mRNA relative expression of brain in middle(100μg · kg -1 · d-1 dose of BDE209) and high(300μg · kg -1 · d-1 dose of BDE209) dose group decreased when compared with control group (P< 0 .05) .Conclusion Low level of BDE209 exposure in pregnancy resulted in the increasing of thyroid hormone levels in offspring mice ,which may cause oxidative damage and decrease expression of D2 mRNA in the brain .