Influence of anesthesia and surgery on the expression of transport receptors and catabolic enzymes of amyloid β-protein in aged rats

Objective　To investigate the expression changes in transport receptor and catabolic enzymes of amyloid β-protein (Aβ) in the brain of aged rats after surgery. Methods　One hundred healthy SD rats were randomly divided into 4 groups according to their ages: aged control group (n=10), aged surgery group (n=40), young control group (n=10), and young surgery group (n=40). Rats in surgery group underwent hepatic lobectomy under anesthesia with 2% sevoflurane, followed by a 2-hour continuous anesthesia after the surgery, and then sacrificed on the 1st, 3rd, 7th and 15th day after surgery to obtain specimens. The expression of low-density lipoprotein receptor-related protein 1 (LRP-1) and receptor for advanced glycation end products (RAGE) in the hippocampus, and the expression of insulin-degrading enzyme (IDE) and neprilysin (NEP) in the cerebral cortex were determined by immunohistochemistry. The mRNA expression of IDE and NEP in the hippocampus was determined with RT-PCR. Results　Compared with aged control group, the expression of LRP-1, NEP and NEP mRNA decreased and the expression of RAGE increased at each time point, the expression of IDE decreased at 1st and 15th day after surgery, and the expression of IDE mRNA decreased at 3rd and 7th day and increased at 15th day after surgery in aged surgery group (P<0.05, P<0.01). Compared with young control group, the expression of IDE mRNA decreased and expressions of RAGE and NEP mRNA increased at each time point, the expression of LRP-1 decreased at 3rd, 7th and 15th day, the expression of IDE decreased at 1st, 3rd day and increased at 15th day, and the expression of NEP increased at 1st day and decreased at 3rd, 7th and 15th day after surgery in young surgery group (P<0.05, P<0.01). Conclusion　The procedure of anesthesia and surgery could significantly inhibit the outward transport and enzymatic degradation of Aβ in the brain of aged rats, and this effect is less evident in young rats. DOI: 10.11855/j.issn.0577-7402.2014.09.09