Scopolamine On Different Phases Of Object Recognition Memory In Mice

The object recognition test(ORT),is a new one-trial test for measuring the non-spatial working memory in free moving animals.This model inclued three phases.In habituation phase,there is no recognize objects in the behavioer box,on the fast three days allow animals explore the environment freely.Then on the forth day,there are the sample and the choice phases.In the sample phase,there are two same objects,and record the exploreing time.After some time,came in the choice phase,now change a familiar object by a new one,record the exploreing time.The fast aim of this study is to set up experimental mice model of object recognition and study the mice's object recognition memory decline with time characteristics.The results showed that:there was a significant difference in 1 h and 3h intervals(P＜0.05),mice can distinguish the objects from the familiar and the novel one.After training 1 h and 3h animals can maintain a good memory,object recognition can be carried out; and the delay time for 4h and 24h,the animals did not discriminate between the novel and the familiar object (discrimination index was equal to zero).So,mice forget the novel and the familiar objects between 3-4 hours after the sample phase.The second purpose of this study is to evaluate the scopolamine on object recognition memory's acquisition,retention,retrieval and the impact of naltrexone on scopolamine-induced object recognition memory impairment.The results showed that 20 minutes before the sample phase given scopolamine(1mg/kg,ip) can impair the object recognition memory's encoding(P＜0.05),but injected scopolamine immediately after learning and 20 minutes before testing period did not damage the object recognition memory in mice.So,scopolamine can't impair the object recognition memory's retention and retrieval stage.Finally,give scopolamine and naltrexone(1mg/kg,ip) at the same time on object recognition memory's three stages.It's showed that,in memory's acquisition stage,naltrexone can partly ameliorate the mice to recognize the familiar and the novel objects,but it is't showed a significant differences.As separate injection of scopolamine group had no significant differences on the object recognition memory's retention and retrieval,1mg/kg naltrexone had no adverse effects on scopolamine.So,the role of naltrexone improving memory is also required further study.