A Study On The Expression Of BDNF And BDNFmRNA In The Cerebral Cortex And Hippocampus In The Guinea Pig's Kernicterus Model

Objective To explore the expression of brain derived neurotrophic factor(BDNF) and BDNFmRNA in the region of cerebral cortex and hippocampusand the possible meaning of BDNF in bilirubin encephalopathy model.Methods The guinea pig bilirubin encephalopathy models were made by theway of peritoneal injection of bilirubin. The experimental animals werederided into six groups at random: control groups(C4h and CSh),100μg/ggroups(T₁4h and T₂8b),200μg/g groups(T₂4h and T₂8h).Every group include10 guinea pigs, 2～5 days old. After the injection, the guinea pigs wereexecuted in corresponding time points. Brain tissues were fixed and thencoronal paraffin sections were made and treated with immunohistochemistryand in situ hybridization techniques. The positive-expression neuronswere counted and the average grey level of that were measured in theregions of cerebral cortex and hippocampus.Results (1)The expression of BDNF and BDNFmRNA could be observed in thecerebral cortex and hippocampus region. (2) Comparing with the controlgroups the expression of BDNF of groups T₁4h and T₂4h decreased in theregion of cerebral cortex, and that changed no obviously in hippocampusregion; that of groups T8h increased than that of groups T4h in same doseand that of group T₇8h increased than that of groupsr T₁8h in the bothregions. (3) Comparing with the control groups the expression of BDNFmRNAof groups T4h and groups T8h all increased, and that of groups of T8h increased than that of groups T4h in same dose, and that of group T₂8hincreased than that of groups T, 8h in the both regions. The change of theexpression related with time and dose.Conclusions (1) BDNF and BDNEmRNA exist in the cerebral cortex andhippocampus region of the normal neogenesis guinea pig simultaneously. Thecontent of BDNF and BDNFmRNA and the respond to bilirubin are not identicalin different region of hippocampus. BDNF play important roles inproliferation, differentiation and survival of neurons duringdevelopment, as well as in the synaptic activity and plasticity in manygroups of mature neurons.. (2)The expression of BDNF decreased in theearlier period of injury in the region of cerebral cortex and that changedno obviously in hippocampus. That expression increased with the injurydelayed and aggravated;(3)The expression of BDNFmRNA increased with theinjury delayed and aggravated. (4) BDNFhas double-acting in brain injuredby bilirubin possibly. This experiment indicate that BDNF can protectneurons probably in the earlier period of bilirubin encephalopathy, butin the advanced stage of bilirubin encephalopathy BDNF preventing oraggravating bilirubin-related brain damage is to be further investigated.