Alteration Of Synaptic Plasticity And The Change Expression Of Brain-derived Neurotrophic Factor In Hippocampal Of Juvenile Rats Following A Status Convulsion

Objective: To investigate the alteration of synaptic plasticity,such asultrastructure of synaptics and electrophysiology,and the change ofexpression of brain-derived neurotrophic factor (BDNF) in hippocampal ofdeveloping rats following a status convulsion (SC),and explore therelationship between the change.Method:21-day-old Wistar rats were divided into controlgroup(n=80)of normal saline and lithium chloride-pilocarpine induced SCgroup (n=80) randomly. Compare the ultrastructure of synaptics at1day,7days,14,21days after1h SC,analyse the synaptic cleft,the postsynapticdensity,and the length of postsynaptic activity area.The field excitatorypostsynaptic potentials (fEPSP) of hippocampal slices were detected at thesame time points,probe the long-term potentiation (LTP). The location ofBDNF in the hippocampus were observed by immunohistochemistry at12h,1day,3days,7,14,21days after SC.The identification expression of BDNFwere quantitatively analyzed by western blot.Results:(1)7,14days after SC,the postsynaptic density (0.0249±0.008,0.0246±0.006μm)was significantly thinner than the controlgroup(0.036±0.01μ m)(P<0.05);the length of postsynaptic activityarea(0.128±0.063,0.135±0.052μm) was significantly shorter than controlgroup(0.228±0.089μ m)(P<0.05).(2)Compare with the controlgroup(124.01%±26.46%),the slope of fEPSP of7days after SC(162.30%±28.50%) was significantly difference(P<0.05);the slope offEPSP of14days after SC and the control group was83.06%±8.32%,121.64%±23.12%,respectively;and the amplitude was100.54%±16.03%,135.65%±35.85%,respectively;SC group wassignificantly reduced (P<0.05).(3)The positive immunohistochemistry ofBDNF in CA1, CA3of hippocampus had the tendency of enhanced in12h,1day,3days,7days after SC.(4)Quantitatively analyzed the expression ofBDNF by western blot, compare with control group(0.39±0.16,0.37±0.03,0.39±0.02,0.37±0.04),12hours,1,3,7days afterSC(1.08±0.10,1.39±0.08,0.85±0.04,0.53±0.06) were significantly increased(P <0.05).Conclusion:(1) At7,14d after SC,there were morphologicalalteration of the hippocampal synapses.(2) The slope of fEPSP of juvenilerats after1h SC had significance increased compare with control group,1week after SC.There were remarkable reduced at14days after SC.(3)Theexpression of BDNF significantly increased after SC detected byimmunohistochemistry and western blot,it produce evidence that the expression of BDNF can be influence by SC in early stage.(4) BDNF wasable to play a important role in synaptic plasticity.