Effect of pre-infusion of young rat plasma on postoperative cognitive function in aged rats and role of PI3K/Akt signaling pathway / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of pre-infusion of young rat plasma on postoperative cognitive function in aged rats and role of phosphatidylinositol 3 kinase/serine-threonine protein kinase (PI3K/Akt) signaling pathway.Methods:Sixty SPF healthy male Sprague-Dawley rats, aged 18 months, weighing 550-650 g, were divided into 4 groups ( n=15 each) using a random number table method: control group (group C), operation group (group O), young rat plasma group (group P) and PI3K inhibitor LY294002 group (group LY). The young rat plasma 100 μl/time was injected via the caudal vein twice a week for 4 consecutive weeks in group P and group LY, while the equal volume of normal saline was given instead in group C and group O. Rats received internal fixation for unilateral tibial fracture under sevoflurane anesthesia in O, P and LY groups.Rats received no treatment in group C. PI3K inhibitor LY294002 0.3 mg/kg was injected through the caudal vein before anesthesia in group LY.The ability of spontaneous activity was evaluated by open field test at 3 days after surgery, and then the cognitive function was assessed by Morris water maze test.The rats were sacrificed after the end of behavioral testing, and the hippocampal tissues were isolated for determination of the expression of phosphorylated PI3K (p-PI3K), phosphorylated Akt (p-Akt), synapsin, synaptophysin I and synaptic vesicle protein (by Western blot) and for microscopic examination of the ultrastructure of hippocampal neurons (with a transmission electron microscope). The number of synapses was recorded. Results:There was no significant difference in the movement speed and length and time spent in the central zone among the four groups ( P>0.05). Compared with group C, the escape latency was significantly prolonged, the number of crossing the original platform was reduced, the expression of p-PI3K, p-Akt, synapsin, synaptophysin I and synaptic vesicle protein was down-regulated, and the number of synapses was reduced in O and LY groups ( P<0.05), and no significant change was found in the parameters mentioned above in group P ( P>0.05). Compared with group O, the escape latency was significantly shortened, the number of crossing the original platform was increased, the expression of p-PI3K, p-Akt, synapsin, synaptophysin I and synaptic vesicle protein was up-regulated, and the number of synapses was increased in group P ( P<0.05), and no significant change was found in the parameters mentioned above in group LY ( P>0.05). Compared with group P, the escape latency was significantly prolonged, the number of crossing the original platform was reduced, the expression of p-PI3K, p-Akt, synapsin, synaptophysin I and synaptic vesicle protein was down-regulated, and the number of synapses was reduced in group LY ( P<0.05). Conclusion:Pre-infusion of young rat plasma can improve postoperative cognitive function in aged rats, and the mechanism is related to activation of PI3K/Akt pathway and improvement of synaptic plasticity.