Objective: To study the depressive behavior induced by simulated weightlessness in rats and the possible mechanism. Method: Simulating weightlessness(SW) 14 days to rats

the open field test

the novel object test

the novelty suppressed feeding test

the forced swimming test and the shuttle box test were applied to evaluate the depressive-behavior in rats. The concentration of serum corticosterone and adrenocorticotropic were measured by enzyme-linked immunosorbent assay (ELISA)

and the changes of the brain-derived neurotrophic factor was measured by western blotting experiment. Result: The results of the open field test were as follows:compared with the control group

the ability of locomotor activity and the number of climbing wall decreased in the SW model rats. The latency of novel object test and the novelty suppressed feeding test in the rats of the model group were longer than those of the control group. The immobility time in the forced swimming test was longer and the number of active avoidance of shuttle box test were lower than the control group. Moreover

the hormone levels of serum corticesterone(CORT) and adrenocorticotropic hormone(ACTH) increased in the rats of the model group than those of the control group. While

the expression of brain-derived neurotrophic factor brain-derived neurotrophic factor(BDNF) in the brain of rats in the model group declined than that of the control group. Conclusion: To simulate weightlessness for 14 days can induce the depressive behavior in rats.