[Effects of repeated lower g exposures on high-G induced memory and balance changes in rats].

OBJECTIVE: To study the protective effects of repeated +4 Gz/3 min exposures on memory and balance changes induced by +10 Gz/5 min exposure in rats. METHOD: 32 male SD rats were randomly divided into 4 groups: control group (C) ; +10 Gz/5 min group (10 Gz); 3 d training group (3 d) ; 5 d training (5 d) group (exposed to +4 Gz/3 min per day for 3 or 5 days before +10 Gz/5 min exposure). Changes of memory and balance in rats of all the 4 groups were observed after +10 Gz/5 min exposure. RESULT: In +10 Gz group, the percentage of correct reaction (CR) decreased significantly at all times after +10 Gz exposure (P<0.01), and the reaction time (RT) lengthened significantly at all times after +10 Gz exposure (P<0.01); as compared with control group. In 3 d training group, CR decreased significantly at 1 d, 2 d and 6 d after +10 Gz exposure (P<0.05), RT lengthened significantly at all times after +10 Gz exposure (P<0.05); as compared with control group. CR increased significantly at 2 d, 4 d and 6 d after +10 Gz exposure (P<0.01), RT shortened significantly at 1 d, 2 d, 4 d and 6 d after +10 Gz exposure (P<0.01) as compared with +10 Gz group. In 5 d training group, there were no apparent changes compared to control group; but CR increased significantly and RT shortened significantly at the time of 1 d, 2 d, 4 d and 6 d after +10 Gz exposure (P<0.01) as compared with +10 Gz group. Balancing function (BF) of +10 Gz group decreased significantly immediately and 2 d after +10 Gz exposure (P<0.01) as compared with control group. BF in 3 d and 5 d training group improved significantly immediately and 2 d after +10 Gz exposure as compared with +10 Gz group (P<0.01). CONCLUSION: It is suggested that repeated low +Gz exposures could provide protective effect on memory and balance changes induced by high +Gz exposure in rats.

[Effects of +Gz exposure time on memory and behavior in rats].

OBJECTIVE: To explore the effect of +Gz exposure time on memory and behavior in rats. METHOD: Twenty-four male SD rats were randomly divided into control group (A), +10 Gz/3 min group (B) and +10 Gz/5 min group (C). Rats in group A and B were exposed to +10 Gz for 3 min or 5 min respectively. Changes of memory and behavior in rats were observed after +Gz exposure. RESULT: As compared with control, percentage of right reflex decreased significantly and reaction time lengthened significantly immediately, 1 d, 2 d, 4 d and 6 d after +10 Gz/5 min exposure (P<0.01); reaction time lengthened significantly immediately and 2 d after +10 Gz/3 min exposure (P< 0.01). As compared with +10 Gz/3 min, percentage of right reflex decreased significantly and reaction time lengthened significantly at 1 d, 2 d, 4 d and 6 d after +10 Gz/5 min exposure (P<0.01). As compared with control and +10 Gz/3 min, time stayed in center grille lengthened significantly immediately after +10 Gz/5 min exposure (P<0.01); balancing function decreased significantly immediately and 2 d after +10 Gz/5 min exposure (P< 0.01). CONCLUSION: It is suggested that +10 Gz/ 3 min exposure may induce a provisional disturbance in memory function and a change in behavior in rats, and +10 Gz/5 min exposure may induce a sustained disturbance in memory function and an obvious change in behavior in rats.