Effect Of Ketamine Administration On Memory Consolidation, P-CREB And C-fos Expression In Hippocampal Slices Of Infant Rats

Objective To investigate the effect of ketamine administration on the ability of memory consolidation of infant rats and the possible mechanism .Methods Ninety-six SD rats of 21 days old were divided into passive control group(The rats were killed after 5 minutes staying in the Y-maze) , normal saline group(The rats were given equal volume of 0.9% saline and were traind firstly one day after the injection ),pseudotraining group(The rats were trained according to the average traning time and times of normal saline group and were killed at one hour after the training) , ketamine group(Be divided into four subsets according to the time and the ketamine dose :k1agroup and k1bgroup were anesthetized with 75 mg/kg ketamine ip and were trained firstly respectively one day and three days after ketamine administration ; k7a group and k7b group were anesthetized with 50 mg/kg ketamine ip respectively qd for 7 times and were trained firstly respectively one day and three days after ketamine administration). Some of the group rats which were trained for two times were killed at 1h after the first train,and the others were trained again at three days after the first train.Y-maze was used to test the ability of memory consolidation of rats. p-CREB and c-fos protein was tested by using immunhistochemistry .Results (1) The p-CREB and c-fos protein expressing cells of normal saline group [(72.00±9.89),(90.63±7.44)] were higher than those in passive control group [(7.25±1.16),(9.25±1.04)], pseudotraining group[(7.63±2.45),(44.75±3.62)], k1a group([20.88±3.18),(27.13±3.04)] and k7a group[(23.38±2.62),(27.00±3.63)](P<0.05). However ,there was not significant difference between normal saline group and k1b group[(72.75±9.04),(90.50±7.96)] or k7b group([74.88±9.61),(91.63±10.10)]. The c-fos protein expressing cells of pseudotraining group was higher than those in passive control group,however, the p-CREB protein expressing cells was not significant difference.(2) The memory consolidation rate in normal saline group mice was higher than that in k1a group [(46.25±10.61)%]and k7a group[(61.25±6.41)%](P<0.05). However, normal saline group between k1b group[(86.25±15.06)%]or k7b group[(87.50±10.35)%]was not significant difference.Conclusion Administration of ketamine may temporally affect the ability of memory consolidation of infant rats through suppressing expression of p-CREB and c-fos protein in hippocampus.