Effect of maternal excessive iodine intake on neurodevelopment and cognitive function in rat offspring

BMC Neuroscience

Zhongyan Shan¹  Hongmei Zhang¹  Hong Wang¹  Chenling Fan¹  Jinyuan Mao¹  Jing Li¹  Yuhui Liu¹  Weiping Teng¹  Le Zhang¹ 

[1] Endocrinology Institute of China Medical University, Liaoning Provincial Key Laboratory of Endocrine Diseases, Shenyang 110001, People’s Republic of China

关键词: Neurodevelopment;    Hippocampus;    Thyroid hormone;    Iodine excess;    Iodine deficiency;   

Others  :  1140928
DOI  :  10.1186/1471-2202-13-121

 received in 2012-05-21, accepted in 2012-10-04,  发布年份 2012

【 摘 要 】

Background

Iodine deficiency and iodine excess are both associated with adverse health consequences. Iodine deficiency during pregnancy leads to insufficient maternal thyroid hormone, subsequently causing irreversible adverse effects on the neurological and cognitive functions of the offspring. The results of our previous epidemiological study suggested that mild iodine excess might increase the prevalence of subclinical hypothyroidism. In the present study, female Wistar rats maintained on low-iodine grain were randomly assigned to three groups based on iodated water concentration: low iodine (LI, 1.2 μg/d), normal iodine (NI, 5–6 μg/d), and 3-fold high iodine (3HI, 15–16 μg/d). The present study investigated whether higher-than-normal iodine intake (3HI) by rats from before pregnancy until breastfeeding affects the postnatal (PN) neurodevelopment (PN7 and PN45) of their offspring during particularly sensitive periods in brain development.

Results

After 12 weeks of treatment (before pregnancy), iodine concentrations in urine and thyroid tissue and circulating thyroxine of adult females correlated with iodine intake. Brain-derived neurotrophic factor (BDNF) expression in the hippocampi of pups on PN7 and PN45 was decreased in 3HI group compared to the NI controls (P < 0.05, all) On PN7 and PN45, the BDNF levels of the 3HI pups were 83.5% and 88.8%, respectively, that of the NI pups. In addition, the 3HI group had a higher neuroendocrine-specific protein A (NSP-A) level than the NI controls on PN7 (P < 0.05). NSP-A levels of the 3HI pups were 117.0% that of the NI pups. No significant difference was observed in the expressions of c-Fos or c-Jun in the hippocampal CA1 region of the 3HI group compared to the controls (P > 0.05). Results from the Morris water maze test revealed that pups of the 3HI group had mild learning and spatial memory deficits.

Conclusions

The neurodevelopmental and cognitive deficits of the 3HI pups were mild and temporary, likely related to the changes in hippocampal protein expressions of BDNF and NSP-A.

【 授权许可】

   
2012 Zhang et al.; licensee BioMed Central Ltd.

【 图 表 】

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