Effects Of Gastrodin On Learning And Memory Functions Of Depression Model Rats

Objective: The depression model rats were prepared by chronic unpredictable mild stress to observe the effects of gastrodin on learning and memory functions of depression model rats.Methods: Sixty-six male Sprague-Dawley rats were randomly divided into control group(C,n=10,without any treatment)and modeling group(n=56).Rats in modeling group were subject to chronic unpredictable mild stress for 28 days.After the model rats were prepared,all rats were tested by sucrose preference,open field,elevated cross maze,and forced swimming tests for behavioral identification.Forty-nine depression model rats were identified.The model rats were then randomly divided into 5 groups,including CUMS model group(CUMS,n=10),CUMS model and normal saline group(CUMS+NS,n=10),CUMS model and sertraline group(CUMS+SER,n=10),CUMS model and low dose gastrodin group(CUMS+GAS1,n=10),CUMS model and high dose gastrodin group(CUMS+GAS2,n=9).Thereafter,the rats in the C group and the CUMS group undertook no more treatment.The rats in the CUMS+SER group,CUMS+GAS1group and CUMS+GAS2 group were injected sertraline(10mg/kg,ip,qd)and gastrodin(100mg/kg,200mg/kg,ip,qd)for 14 days,while the CUMS+NS group were treated with equal volume normal saline for 14 days(qd),and weighed the rats in each group daily.Finally,after the treatment,the above tests were repeated,and Morris water maze test was performed in all rats to test learning and memory function.Results:1.Comparison of body weightBefore modeling,the weight of rats in the modeling group was similar to that of rats in the C group.After modeling,the weight and weight increase of the rats in the modeling group were lower than those in the C group(P<0.01).The body weight and weight increase of 6 groups during the drug intervention were analyzed by one-way ANOVA showed a statistically significant difference among the groups in the day 7 and day 14(P<0.01).The body weight of CUMS group was lower than C group(P<0.01),and the body weight of CUMS+NS group was similar to that of CUMS group(P>0.05).The weight of CUMS+GAS2 group was higher than that of CUMS+NS group(P<0.01).The weight increase in the first week and the second week was also significantly different among the six groups(P<0.01 or P<0.05).The weight increase of CUMS group was lower than that of C group(P<0.01),the weight increase of CUMS+NS group was similar to that of CUMS group(P>0.05),and the weight increase of CUMS+GAS1 group and CUMS+GAS2 group was higher than CUMS+NS group(P<0.01 or P<0.05).2.Comparisons of sucrose preference test resultsAfter modeling,the sucrose preference percentage in modeling group was lower than that of the C group(P<0.01).After the drug intervention,the sucrose preference percentage in the CUMS group was lower than that of the C group(P<0.01),and the sucrose preference percentage of CUMS+NS group was similar to that of CUMS group(P>0.05).Compared with the CUMS group and the CUMS+NS group,the sucrose preference percentage in the CUMS+SER group,CUMS+GAS1 group and CUMS+GAS2 group all increased significantly(P<0.01).3.Comparisons of open-field test resultsAfter modeling,the number of squares crossed,standing up and self-grooming in the modeling group was less than that in the C group(P<0.05 or P<0.01).After drug intervention,both the number of squares crossed and self-grooming in CUMS group were less than that in C group(P<0.05 or P<0.01),and both the number of squares crossed and self-grooming in CUMS+NS group were similar to that in CUMS group(P>0.05).Compared with CUMS+NS group,the number of squares crossed in CUMS+SER group and CUMS+GAS2 group was significantly increased(P<0.05),and the number of self-grooming in CUMS+GAS1 group and CUMS+GAS2 group were significantly increased(P<0.05 or P<0.01).4.Comparisons of elevated cross maze test resultsAfter modeling,the open arm entry frequency and the open arm retention time in the modeling group were lower than that in the C group(P<0.05 or P<0.01).After drug intervention,the open arm entry frequency in CUMS group was lower than that in C group(P<0.05),the open arm entry frequency in CUMS+NS group was similar to that in CUMS group(P>0.05),and compared with CUMS+NS group,the open arm entry frequency in CUMS+SER group and CUMS+GAS2 group was significantly increased(P<0.05 or P<0.01).5.Comparisons of forced swimming test resultsAfter modeling,the immobility time of rats in the modeling group was longer than that in C group(P<0.01).After drug intervention,immobility time in CUMS group was still longer than that in C group(P<0.05).The immobility time in CUMS+NS group was similar to that in CUMS group(P>0.05),and both CUMS+SER group and CUMS+GAS2 group had shorter immobility time than CUMS+NS group(P<0.05).6.Comparisons of Morris water maze test resultsThe escape latency of rats in 6 groups in the place navigation test during 7 test days showed that,test days(P<0.01)and animal groups(P>0.05),while on the 3rd test day,the main effect among groups were statistically significant(P<0.05),the escape latency of CUMS+SER group,CUMS+GAS1 group and CUMS+GAS2group was shorter than that of CUMS group(P<0.05 or P<0.01),but the difference between CUMS group and C group was not statistically significant(P>0.05).The percentage of active time in the target quadrant of rats in 6 groups in the place navigation test during 7 test days showed that,test days and animal groups were significantly different(P<0.01),and the comparisons of LSD showed that the target quadrant activity time percentage of CUMS group was lower than that of C group(P<0.01),and the target quadrant activity time percentage of CUMS+NS group was similar to that of CUMS group(P>0.05).The target quadrant activity time percentage of CUMS+SER group,CUMS+GAS1 group and CUMS+GAS2 group was higher than that of CUMS group and CUMS+NS group(P<0.05 or P<0.01).And on the 1st,4th,5th,6th,7th test day,the main effect of the target quadrant activity time percentage among groups were significantly different(P<0.05 or P<0.01).In the space exploration experiment,active time in the target quadrant of rats in C group,CUMS+SER group and CUMS+GAS2 group was higher than that of CUMS group(P<0.05 or P<0.01).Conclusions: The depression model rats were successfully prepared by chronic unpredictable mild stress method.The results of body weight,sucrose preference test,open-field test,elevated cross maze test and forced swimming test suggest gastrodin can relieve depressive-like behaviors in depression model rats.Gastrodin may also have an improvement in learning and memory function in depression model rats.