Effects Of Propofol Anesthesia On The Development Of Spatial Cognitive Function In Neonatal Rats

Objective:To observe the effects of propofol anesthesia on the spatial learning and memory function in neonatal rats. Propofol is the latest intravenous anesthetic and has been widely used in clinical anesthesia and ICU sedation. With the development of the mechanism of propofol anesthesia was understood, including the action on y aminobutyric acid receptor (GABA receptor complex) and N-methyl-D-aspartate (NMDA) receptor. But its effect on postoperative cognitive function in the study is still in the exploratory stage. In the study, through the water maze behavioral test and the changes of BDNF and Caspase-3in protein expression, we will investigate the effects of propofol on cognitive function, and discuss the possible mechanism.Methods:Forty-five seven-days-older SD rats were randomly divided into three groups as followings:the control group in which rats were administered intraperitoneally with saline (25mg/kg) initially then maintained with the half dosage every20min for2h; the propofol anesthesia group in which rats were administered intraperitoneally with propofol (25mg/kg) initially then maintained with the half dosage every20min for2h, and the long chain fat emulsion group in which rats were treated with emulsion using the same regiment as propofol group. Four hours after treatment, nine rats in each group were randomly executed and hippocampus were harvested to assay for the expression of Caspase-3by immunohistochemistry and the level of BDNF and Trk-B by western blot. The rest were bred to forty days elder, and then the ability of spatial learning and memory were measured by Morris water maze.Results:1. The Morris water maze test showed a significantly longer escape latency in the propofol group than in the control group and the emulsion group.(P<0.05). Compared with the control group, the propofol group exhibited a lower frequency of passing through the platform (P<0.05).There was also no significant difference between the control group and the emulsion group.2. The control group reflects the level of BDNF and Trk-B in neonatal rats. Compared with the control group, the levels of BDNF and Trk-B decreased significantly. There was no significant difference between the control group and the emulsion group.3.In CA1region of hippocampus of rats in the control group and the emulsion group, the Caspase-3immunocytochemistry staining revealed a sparsely expression. In contrast the expression of Caspase-3increased markedly in the propofol group (P<0.05).Conclusion:Propofol anesthesia in neonatal rats could interfere the development of the spatial cognitive function, which might result from the enhanced apoptosis of neurons and the inhibited activity of BDNF-TrkB pathway in hippocampus during neonatal period.