The Experimental Research About Effect Of Intravenous Infusion Of Propofol On Spatial Learning And Memory Function In Rats

The experimental research about effect of intravenous infusion of propofol on spatial learning and memory function in rats Objective Propofol is the latest intravenous anesthetics and has been widely used in clinical anesthesia and ICU sedation. With the development of molecular biology, electrophysiological techniques and the application of PET in recent years, the mechanism of propofol anesthesia was understood, including the action on y aminobutyric acid receptor (GABA receptor complex) and N-methyl-D-aspartate (NMDA) receptors.Except that,there are other non-anaesthesia action such as reducing the brain uptake and cerebral metabolism, cerebral ischemia protective effect and regulating three platelet inflammatory mediators, etc.But its effect on postoperative cognitive function in the study is still in the exploratory stage. In this study, through the water maze behavioral test and in vivo multi-channel neural recording technology,we will investigate the effects of different doses propofol on spatial learning and memory function in healthy rats,how LFPs of prefrontal cortex neurons reflect the effect of propfol on cognitive function,and disccus the possible mechanism.Methods Thirty healthy male SD rats were randomly equally divided into 3 groups according to propofol infusion dose:small dose group(P1) 0.1mg·kg-1·min-1,large dose group(P2) 0.5mg·kg-1·min-1, and control group(C group)10%intralipid 0.01ml·kg-1·min-1.Rats in control group and other two propofol groups were administrated intravenously through the tail vein. The infusion time of drugs was 2 hours. All of the rats were underwent improved Morris water maze test two times a day for 4 training days and 1 test day.The latency period,swimming speed,percentage of platform quadrant swim distance on total swim distance, first central point and total score of Morris water maze test were recorded. After two weeks,rats in propfol groups underwent in vivo multi-channel neural recording technique in prefrontal cortex neurons which were anesthetized intravenously with propofol in the same concentration.Neuron's LFPs during anesthesia and 5 days after anesthesia were recorded which were analysized with MATLAB software,and then caculated their complexity under and after anesthesia,analyzed the LFPs's phase correlation synchronism.Results 1.Morris water maze test results:①Localization navigation experiment: group P1 and group C did not existed statistics difference with slowly decline trend totally(P>0.05). Compared with group C and group P1, the latency period in the first two days of group P2 were longer in training period.And there was statistics difference in test period(P<0.05).②Space exploration experiments:There was not statistics difference between group P1 and group C(P>0.05). Compared with group C and group P1, the results of P2 group of the fourth quadrant into the water were significantly different(P<0.05).2. Neuron's LFPs results:①Complexity:The values of group P1 were bigger than group P2,and there existed statistics differenceunder anesthesia(P<0.05). Under anesthesia of two dosage,the values of LFPs complexity were smaller than awakely(P<0.05).Compared with the complexity values under totally awakening, there did not exist statistics difference of group P1 of first 5 days after anesthesia(P>0.05). Compared with the complexity values under totally awakening,there was statistics difference about of group P2 of first 2 days after anesthesia(P<0.05).And it did not exist difference in other days(P>0.05).②LFPs phase correlation synchronism:The LFPs phase correlation synchronism of group P2 was higher than group P1's(P<0.05),and under anesthesia of two dosage,LFPs phase correlation synchronism were higher than awakely(P<0.05). LFPs phase correlation synchronism of group P1 and group P2 existed statistic difference from the first day to the second day after anesthesia(P<0.05). Compared with the values under totally awakening,there were not statistics difference about phase correlation synchronism of group P1 of first 5 days after anesthesia(P>0.05).There were statistics difference about phase correlation synchronism of group P2 of first 2 days after anesthesia (P<0.05).And it did not exist difference in other days from totally awakening(P>0.05).Conclusion 1.Propofol 0.1 mg·kg-1·min-1 continuous intravenous infusion may not cause spatial cognitive dysfunction.Propofol 0.5mg·kg-1·min-1 may affect spatial cognitive function transiently,but not for a long term.2.The inhibition degree of cerebral cortex neurons electric discharge activity of propofol 0.5mg·kg-1·min-1 is bigger than propofol 0.1mg·kg-1·min-1.3. The effects on spatial learn and memory may be related to the inhibition of propofol on prefrontal cortex neuronal discharge activity.Innovation 1. Propofol 0.1 mg·kg-1·min-1 and 0.5mg·kg-1·min-1 continuous intravenous infusion 2h affects recovery process of spatial learning and memory ability in rats.2. From the view of electrophysiology, means through a multi-channel recording techniques to observe the electrical activity of cortical neurons and neuronal synchronization of the cluster effect, and combining with behavior detection indicator can reflect the effect of intravenous anesthetic propofol on spatial learning and memory ability in normal rats.