Effects Of L-655,708on The Cognitive Function Of Rats Anesthetized With Propofol

Objective:To investigate the effects of L-655,708on the cognitive function of rats anesthetized with propofol.Methods:Thirty male two-month-old Wistar rats, weighing180-220g, were randomly divided into6groups:normal saline groups (group C), L-655,708+C group (group LC);1hour after propofol anesthesia group (group PI), L-655,708+P1group (group LP1);24hours after propofol anesthesia group (group P24), L-655,708+P24group (group LP24). Morris water maze tests were used to assess the cognitive function of rats before and1h or24h after anesthesia. The rats were sacrificed at the end of Morris water maze tests and their brains were removed for detection of phospho-Tau and total tau expression (by immuno-histochemistry and western blot) in hippocampus and the morphologic changes with hippocampus nerve cell and the Nissl body (by HE staining and Nissl staining).Results:①Compared with group C, the latency was longer, the time spend in target quadrant was shorter and the phospho-Tau expression was significantly up-regulated in Groups P1and P24(P<0.05). Compared with group P1, the latency was shorter, the time spent in target quadrant was longer and the phospho-Tau expression was down-regulated in Groups LP1and P24(P<0.05). Compared with group P24, the latency was shorter, the time spend in target quadrant was longer and the phospho-Tau expression was down-regulated in Group LP24(P<0.05). While the frequency of passing the original platform and the expression of total tau were equivalent.②In Groups C and LC, the morphology and structure of nerve cells is integrity, the Nissl body is dark staining and widely distributed in the cytoplasm and dendrites. While in Groups P1, LP1, P24and LP24, the cell nuclear karyopyknosis, fragmentation and solution were observed, the Nissl body is light staining or no staining and decreased in the cytoplasm and dendrites; and there is a need for further study to explore whether the differences between Groups P1and LP1, Groups P24and LP24were significant.Conclusion:L-655,708can down-regulate the expression of phospho-tau in hippocampus and improve the cognitive function of rats anesthetized with propofol, but it has little effect on total tau. The high-expression of phospho-Tau and the damage of the nerve cells and Nissl body may be involved in the cognitive impairment.