ABSTRACT
ObjectiveSome studies reported that α7nAChR is closely related to the cognitive function. However, the elderly patients have become a high-risk group of postoperative cognitive dysfunction. The aim of this study was to explore the effect of sevoflurane inhalation on the cognitive function and the quantity of alpha 7nicotinic acetycholine receptors in the hippocampus of elderly model rats.MethodsAdult male Sprague-Dawley rats (N=72) were given subcutaneous injection of D-galactose on the neck for 6 weeks to establish elderly models. The model rats were divided into 4 groups randomly: control group (group Con, n=18) with 6h exposure carrier gas (2L/min Air+2L/min O2); Sevoflurane group (group Sev, n=18) with 6 h exposure to 3.2% sevoflurane through carrier gas. Sev+α7nAChR antagonist group (group Sev+M) injected with methyllycaconitine, after 24 h inhaled of 3.2% sevoflurane and carrier gas for 6 h. Sev+α7nAChR agonist group (group Sev+P, n=18) injected with PNU-282987, after 24 h inhaled of 3.2% sevoflurane and carrier gas for 6 h. Morris water maze experiments were conducted on 6 rats in each group 2 h, 1 week and 4 weeks after treatments, respectively. Every cycle after the behavioral test, the hippocampi were taken out. RT-qPCR method was used to detect α7nAChR mRNA expression. Western blotting was used to detect α7nAChR proteins expression.ResultsBehavioral test: compared with Con group at 2 h after awakening, indicators of working memory and spatial probe test in Sev group and Sev+M group decreased significantly (P0.05). RT-qPCR: compared with Con group at 2 h and 1 w after awakening, the expression of alpha 7nAChR mRNA in the other groups was down-regulated, while at 4 w it was up-regulated (P<0.05).Western blot: protein expression of alpha 7nAChR was down-regulated in the 2 h, 1 w Sev group and the Sev+M group after awakening, and up-regulated in the 4 w group after awakening (P<0.05).ConclusionInhalation of 3.2% sevoflurane for 6 h can cause 7nAChR metabolic disturbance in hippocampus of aging model rats and lead to a short-term (1 w) decline in learning and memory ability of the rats, but this effect is reversible. The PNU-282987 agonist can alleviate the temporary decrease of learning and memory caused by sevoflurane.