Neuroprotective Effect And Its Mechanism Of Baicalin On Hippocampal Neurons After Status Epilepticus In Mice

Objective To explore the neuroprotective effect of Baicalin on hippocampal neurons after status epilepticus induced by kainic acid in miceMethods50ICR male mice were randomly divided into five groups:control group, SE group and three baicalin groups, to which baicalin was administered at doses of50,100and200mg/kg, respectively. To establish animal model of status epilepticus,12mg/kg kainic acid was administered to mice by intraperitoneal injection. HE staining was used to observe the pathological changes. Nissl staining was used to assess the necrosis of hippocampal neurons.Western blot was used to detect the expression of the protein level of caspase-3and TUNEL staining was used for determination of neuronal apoptosis.Results①To observe by HE staining:Sham group:the hippocampal CA1, CA3region, the cells were in good arrangement and the form was normal; SE group:the cells arrangement was scattered and cavitation existed in some endochylema, Some neuron swelled and distributed uneveuly, cell nucleus contracted and was stained deeply, nucleoli disappeared, especially in CA3region; Baicalin treatment group:the swelling of neuronal cell bodies or nuclear condensation and deeply stained obviously reduced, but more significantly to100and200mg/kg group.②Nissl staining showed:the Sham group hippocampal CA3region:Nissl granule cells arrangement was neat and dense. SE group:CA3region granule cells arrangement was sparse and a large number of granule cells lost. Baicalin treatment group:Compared with the SE group, Baicalin100and200mg/kg group could obviously increased CA3region granule cells (P<0.05), but it is no significant difference between the100and200mg/kg treatment group.③TUNEL staining showed the hippocampal CA3region of Sham group had a few tan TUNEL positive cells, but the tan TUNEL positive cells significantly increased in hippocampal CA3region of SE group. Compared with the SE group, Baicalin100and200mg/kg treatment group CA3region TUNEL positive cells significantly attenuated (P<0.01), but it is no significant difference between the100and200mg/kg treatment group. For50mg/kg treatment group, TUNEL positive cells decreased, but the difference was not statistically significant.④Western blot showed that the expression of the protein level of caspase-3of Sham group were weak, but its increased significantly after status epilepticus. Compared with the SE group, Baicalin50mg/kg treatment group had a downward trend, but the difference was not statistically significant, while Baicalin100and200mg/kg treatment group could obviously down-regulate the expression of caspase-3protein (P<0.01), but it is no significant difference between the100and200mg/kg treatment group.Conclusion Baicalin could significantly relieve neuronal apoptosis and death to protect hippocampal neurons after status epilepticus in mice; Baicalin100and200mg/kg treatment group could significantly reduce hippocampal neurons apoptosis and death, but the100mg/kg therapeutic dose was the optimal drug concentration.Part Ⅱ The neuroprotective mechanism of Baicalin on hippocampal neurons after status epilepticus in miceObjective To explore the neuroprotective mechanism of Baicalin on hippocampal neurons after status epilepticus induced by kainic acid in mice.Methods45ICR male mice were randomly divided into thre groups (n=15): control group, SE group and baicalin group, to which baicalin was administered at doses of100mg/kg. To establish animal model of status epilepticus,12mg/kg kainic acid was administered to mice by intraperitoneal injection. Immunohistochemistry was used to observe the positive expression of TLR4and MyD88. Western blot was used to detect the expression of the protein level of TLR4> MyD88and NF-KB. Reverse transcription polymerase chain reaction(RT-PCR)was used to detect the expression of the mRNA leveI of IL-1β and TNF-α.Results①Immunohistochemistry showed the Sham group had only a few scattered yellow-brown positive cells of TLR4or MyD88, while the SE group can be seen numerous and densely distributed positive cells. Compared with the SE group, the brown granular positive cells of Baicalin treatment group decreased significantly and their differences was obvious.②Western blot showed that the expression of the protein level of TLR4、MyD88and NF-KB of Sham group were scant, but its increased significantly after status epilepticus(P<0.01). Compared with the SE group, Baicalin could obviously down-regulate the expression of TLR4> MyD88and NF-KB protein (P<0.05).③RT-PCR showed that the expression of the mRNA level of IL-1β and TNF-a of Sham group were scant, but its increased significantly after status epilepticus(P<0.01). Compared with the SE group, Baicalin could obviously down-regulate the expression of IL-1β and TNF-α mRNA (P<0.05).Conclusion TLR4-mediated MyD88-dependent signaling pathway could be activated after status epilepticus and Baicalin could inhibit TLR4-mediated MyD88-dependent signaling pathway to protect the hippocampal neurons after status epilepticus in mice.