Abstract: Objective To study the effect of selenium supplementation on synaptogenesis in hippocampus of offspring mice during pregnancy and lactation.Methods Sodium selenite was supplemented in drinking water from the first day of conception of the female mice, at the doses of 400 μg/L as the low selenium group and 1600 μg/L as the high selenium group. A control group was set up at the same time. The hippocampus of the offspring was separated in 21 days after birth. The density of dendritic spine in hippocampus was observed through Golgistaining. The mRNA expression of synaptic plasticity related genes, such as PSD95, Drebrin and SYN, were detected using RT-PCR, and the protein expression of Drebrin was detected through Western-blot. Result The mice in the control group and the selenium supplement groups had normal diet, normal hair development, luster, good mental state, and were sensitive to general stimuli such as sound and light, without significant difference between the groups. No abortion, stillbirth, dead fetus, or premature death occurred in all groups. There was no significant difference in the number and weight of the offspring between the groups （P>0.05 for all）. The dendritic spines in the hippocampus were regular and dense in the control group and the selenium-enriched groups. After selenium supplementation during pregnancy and lactation, the Golgi-stained dendritic spine count and Drebrin mRNA expression in the DG and CA1 regions of the low and high selenium groups were higher than those of the control group （all P<0.05）, but no significant differences between the low selenium group and high selenium group （both P>0.05）. There was no significant difference in the expression of Drebrin protein between the 3 groups （P>0.05）. Conclusions Selenium supplementation during pregnancy and lactation can promote the formation of synapses in hippocampus of offspring mice. The specific mechanism needs further study.

Key words: Pregnancy, Mouse, Selenium, Hippocampal synapse