Abstract: OBJECTIVE：To evaluate effects of sub-chronic (90 d) exposure to cerium nitrate [Ce(NO₃)₃] on neurobehavioral functions in SD rats and to provide scientific basis for risk assessment of rare earth element cerium. METHODS：SD rats (PND21) were randomly divided into 4 groups (12 males and 12 females in each group) by body mass，which were control group (exposure to ddH₂O) and 20，100，500 mg/(kg·d) Ce(NO₃)₃ exposure groups. The rats were administrated orally with Ce(NO₃)₃ for 90 days. Neurobehavioral functions were then evaluated by experiments such as elevated plus maze， open field， rotarod and Morris water maze. Histopathological structure of hippocampus was analyzed with HE staining. RESULTS： Compared with the control group，the exposures did not cause significant changes in time on the rotarod test. From the Open field and elevated plus maze tests， there was no statistically significant differences between groups of rats in the time spent in the center of the arena，the number of entrances into the center of the arena，the percentage of entrances into the open arms and the time spent on the open arms. In the Morris water test，the difference in the escape latencies among the three cerium nitrate exposed groups and the control group was not statistically significant， nor were the differences in various metrics of the space exploration test including the times crossing platform，swimming speed and the times required for swimming in target quadrant. Histopathological analysis showed that no pathological changes were observed in the dosing groups. CONCLUSION： Sub-chronic oral exposure to cerium nitrate did not cause anxiety， deficient motor functions， and abnormal learning and memory in SD rats.

Key words: cerium nitrate, neurobehavior, rats, sub-chronic exposure