Effect of bilobalide B on cholinergic hippocampal neurons exposed to cholesterol and apoliprotein E4

Xijuan Jiang; Bin Lu; Yingchang Fan

摘要：BACKGROUND: Extracts of ginkgo biloba leaves have been reported to improve nerve function and activity in Alzheimer's disease, which is associated with reduced secretion of cholinergic neurotransmitter in hippocampal neurons.OBJECTIVE: To validate the protective effect of bilobalide B against in vitro injury of cholinergic neurons of the hippocampus induced by combined cholesterol and apoE4DESIGN, TIME AND SETTING: This randomized, controlled animal experiment was performed in the Pathology Laboratory, Tianjin University of Traditional Chinese Medicine from July 2003 to July 2006.MATERIALS: Neonatal Wistar rats, 1-day-old, both male and female, and mean body mass of 5g were selected for this study. Cholesterol and apolipoprotein E4 (apoE4) were purchased from Sigma Company (USA), bilobalide B was purchased from Tianjin Zhongyi Pharmaceutical Factory, batch number 20050312.METHODS: Hippocampal neurons were divided into three groups; a normal control group (routinely added media), a model group (exposed to media containing 40mg/L cholesterol and 30mg/L apoE4 for 24 hours) and a bilobalide B group (exposed to media containing 160mg/L bilobalide B for 16 hours, and then with addition of 40mg/L cholesterol and 30mg/L apoE4 for an additional 24 hours).MAIN OUTCOME MEASURES: Levels of acetylcholine (ACh) and activity of acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) in hippocampal neurons were determined by microdosage hydroxylamine colorimetry, hydroxylamine colorimetry and radiological chemistry, respectively.RESULTS: The ACh level was significantly lower in the model group than that in the normal control group (P<0.01), while it was markedly higher in the bilobalide B group than in the model group (P<0.05). Activity of AChE was significantly decreased in the model group compared with the normal control group (P<0.05). However, there was no significant difference between the model group and the bilobalide B group (P>0.05). Activity of ChAT was significantly lower in the model group than in the normal control group (P<0.01), while the activity was significantly higher in the bilobalide B group than in the model group (P<0.05).CONCLUSION: Bilobalide B can enhance the ACh level of hippocampal neurons damaged by combined cholesterol and apoE4, by promoting the synthesis, but not the degradation, of ACh.