The effect of selenium on learning disability due to maternal hyperthyroidism during lactation

Abstract

Aim: Hyperthyroidism causes adverse changes in hippocampal-dependent learning and memory functions in developmental and adult periods. In the present study, the healing effect of selenium on learning disability in the offspring of mothers given L-thyroxine during lactation was investigated. Material and Methods:12 pregnant rats were used in the study. The pregnant rats were randomly assigned into three groups (n=8 per group): control group (CG), lactational hyperthyroid group (LHG), and lactational hyperthyroid + selenium group (LH+SeG) group. LHG consisted of male rat offspring from these mothers treated with L-thyroxine (0.2 mg kg–1 body mass, 1 mL) during lactation. LH+SeG was induced by selenium supplementation during 39-60 days after lactational hyperthyroid. The offspring of mother rats administered saline during the lactation period formed the control group (CG). Spatial learning and memory function were measured with the Morris water maze (n = 16 for each group). Measurements were made when offspring rats were 60-66 days old. Results: Post-hoc test with one-way ANOVA revealed that LHG group rats found the platform by traveling longer distances and swimming longer than the control group (p 0.005). There was no significant difference between the groups in terms of the time spent in the target quadrant in the probe trial (memory test). Conclusion: The study findings show that high thyroid hormone levels in mother rats during lactation have long-term negative effects on hippocampal-dependent learning function in offspring rats and selenium has a healing effect on these disorders.