Effect of exogenous insulin like growth factor 1 on postoperative cognitive function in aged rats

Objective To evaluate the effects of exogenous insulin like growth factor 1(IGF-1)on postoperative cognitive function in aged rats. Methods One hundred and twenty pathogen-free healthy male Sprague-Dawley rats, aged 18-20 months, weighing 500-600 g, were divided into 4 groups(n=30)using a random number table: control group(group C), sham operation group(group S), operation group(group O)and exogenous IGF-1 group(group I). Splenectomy was performed, IGF-1 50 μg/kg was subcutaneously injected at the same time point every day for 7 consecutive day starting from the end of surgery on the day of surgery in group I, and splenectomy was performed, and the equal volume of normal saline was given instead in group O. Morris water maze test was performed on 1, 3 and 7 days after surgery, and the escape latency and swimming distance were recorded.The rats were sacrificed after the end of Morris water maze test, and hippocampi were isolated for determination of the expression of amyloid-β(Aβ), amyloid precusor protein(APP)and β-secretase 1(BACE-1) using immunohistochemistry and Western blot methods. Results Compared with group C, the escape latency and swimming distance were significantly prolonged at 1, 3 and 7 days after surgery, and the expression of Aβ, BACE-1 and APP was up-regulated in O and I groups(P 0.05). Compared with group O, the escape latency and swimming distance were significantly shortened at 1, 3 and 7 days after surgery, and the expression of Aβ, BACE-1 and APP was down-regulated in group I(P<0.05). Conclusion Exogenous IGF-1 can improve postoperative cognitive function in aged rats. Key words: Insulin-like growth factor Ⅰ; Aged; Cognition disorders