Effects Of Ginsenoside Rg₂ On Central Monoamine Transmitter In Vascular Dementia Rats Simulated By Cerebral Ischemia Reperfusion

Objective To investigate the learning and memory ability of VD rats which were simulated by the middle cerebral artery occlusion (MCAO)-reperfusion method, and to study the expression of acetylcholinesterase positive neurons, the content of acetylcholinesterase and monoamine transmitter which reflect the activity of cholinergic agents and monoamine transmitter agents. Besides, to explore the effect and mechenism of ginsenoside Rg2 on learning and memory in VD rats simulated by cerebral ischemia reperfusion.Methods Ischemia was induced by occluding middle cerebral artery with infraluminal filament in rats for 0.5 hour, then the circulation was restored after drawing the infraluminal filament a little. Different dosage of ginsenoside Rg2 was given for five days, contrasting with nimodipine. Learning ability was measured by model Y maze in sixth day. Next day memory ability was observed in the same way. Infract area was showed in red tetrazoline staining, cholinergic agents activity by enzymatic cytochemical staining for AchE and spectrophotometry for AchE activity, and the contents of monoamine transmitter in frontal lobe by high pressure liquid chromatography.Results The learning and memory ability of VD rats decreased obviously compared with sham groups(p<0.01), and was improved after using ginsenoside Rg2. Red tetrazoline staining showed that large mass infarct area appeared on left striatum and cortex in model group, and infarct area became smaller in gensenodide Rg2 group. The result of enzymatic histochemical staining for AchE is that the AchE positive neurons have good condition and large number, while in model group the number decreasedsharply. The activity of AchE in model group is higher than that of sham group. Gensenoside Rg2 has the effect of increasing the number of AchE positive neurons and improving the AchE activity, moreover, the trend of changing was positively related to the dosage of gensenoside Rg2. The results of testing monoamine transmitter in frontal lobe indicate the level of NE, DA and 5-HT in model group were decreased in different degree compared with sham group(p<0.01). Fumermore, the level of NE, DA and 5-HT are higher in ginsenoside Rg2 group of median and high dosage.Conclusion The learning and memory ability of vascular dementia rats simulated by cerebral ischemia reperfusion decreased. The number of AchE positive neurons in basal forebrain was decreased obviously and the activity of AchE in rat brain was declined also. The contents of NE, DA, 5-HT in frontal lobe were dropped as well. Ginsenoside Rg2 can improve the learning and memory ability of VD rats, have positive protective effect on neurons by resisting the free radical of oxygen and the influx of calcium. It is supposed that ginsenoside Rg2 can improve the activity of cholinergic agents and monoamine transmitter to further learning and memory ability.