The Difference Of LTP In The Brain Hippocampus DG Of Middle-aged And Young Mice And The Factors That May Affect The DP Of The Brain Hippocampus DG Of Middle-aged Mice

Because of the synaptic plasticity in hippocampal neurons,long-term potentiation(LTP)and depotentiation(DP)occur by the certain forms of stimulation.Synaptic plasticity is generally considered as the basis of stuying learning and memory,while depotentiation(DP)is believed to be related to the elimination of memory.In this paper,with patch-clamp tech,qPCR and so on,the state of LTP and DP of perforant pathway-dentate gyrus(PP-DG)in hippocampus of mid-aged mice which compared with young mice were studied to explore the differences of LTP in middle age and the factors that may affect DP in middle age.We found the amplitude of LTP generated by hippocampal DG in the mid-aged mice(only about 40%)was smaller than that in young mice(about 60%),and the stimulation induced LTP of the mid-aged mice was stronger than that of young mice,but the failure rate was high.DP can still occur in the DG of hippocampus in young mice even 40 minutes after the induction of LTP,however,this phenomenon didn't occur in mid-aged mice.NMDA receptors play an important role in LTP and DP.There are several subtypes of NMDA receptors,such as NR2A?NR2B.We tested the contents of NR2 A and NR2 B receptors in the hippocampal DG of the different age groups,and found that the content of NR2 A receptors in the hippocampal DG of middle-aged mice were significantly reduced compared with young mice,but there's no significant difference in NR2 B receptors.The contents of NR2 A and NR2 B receptors may be the reason for the differences of LTP in the mid-aged mice and young mice.We used the inhibitors of NR2 A,NR2B and A1 during the induction of DP,and found that the inhibitor PEAQX of NR2 A receptor could inhibit the production of DP,as well as the inhibitor DPCPX of A1 receptor,while the inhibitor ifenprodil of NR2 B receptor could not.These results suggest that NR2 A and A1 receptor were involved in the process of DP.