Alteration of electrophysiology and expression of brain-derived neurotrophic factor in hippocampus of juvenile rats following a status convulsion

Abstract:

Objective：To investigate the alteration of electrophysiology and the change of expression of brain-derived neurotrophic factor（BDNF） in hippocampus of juvenile rats following a status convulsion（SC） and to explore the relationship between the two. Methods：Totally 21-day-old Wistar rats were divided into control group（n=80） and experiment group（n=80）. Rats in control group were injected with normal saline. Intraperitoneal injection of lithium chloride-pilocarpine was conducted to establish SC model. Changes in slope and amplitude of field excitatory postsynaptic potentials（fEPSP） on 1，7，14，21 d after model establishment were detected by patch clamp technique and long-term potentiation（LTP was compared. Location of BDNF in the hippocampus was observed by immunohistochemistry at 12 h and on 1，3，7，14，21 d after SC. Expression of BDNF was quantitatively analyzed by Western blot. Results：（1）Slope of fEPSP on 7 d after SC was significantly higher in experiment group（162.30±28.50）% than in control group（124.01±26.46）%（P<0.05）. Slopes of fEPSP on 14 d after SC in experiment group and control group were （83.06±8.32）% and（121.64±23.12）%，respectively；amplitudes in experiment group and control group were （100.54±16.03）% and （135.65±35.85）%，respectively；slope and amplitude were decreased in experiment group than in control group with statistical differences（P<0.05）. （2）Im－munohistochemistry showed that positive staining of BDNF in CA1 and CA3 region of hippocampus was enhanced after SC；enhance－ment of positive staining of BDNF in CA1 and CA3 region of hippocampus was higher in experiment group than in control group at 12 h and on 1，3，7 d after SC and there was no differences between two group on 14，21 d after SC. （3）According to the results of Western blot，expression of BDNF in experiment group and control group at 12 h and on 1，3，7 d after SC was 1.08±0.10，1.39±0.08，0.85±0.04，0.53±0.06 and 0.39±0.16，0.37±0.03，0.39±0.02，0.37±0.04 respectively，with statistical differences between the two groups（P<0.05）. Conclusions：（1）Slope of fEPSP of juvenile rats on 7 d after SC is significantly increased in experiment group than in con－trol group and slope and amplitude of juvenile rats on 14 d after SC are significantly decreased in experiment group and control group，which indicates that LTP can be increased at acute stage after SC and be decreased at latency stage. （2）Expression of BDNF can be influenced by SC based on results of immunohistochemistry and Western blot and expression of BDNF can be increased at a－cute stage after SC. （3）BDNF plays an important role in the formation of LTP.