Effects of isoflurane anesthesia on plasma cortisol, and brain-derived neurotrophic factor and nerve growth factor in hippocampus in rats

Objective To investigate the effect of isoflurane anesthesia on plasma cortisol,and brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in hippocampus in rots.Methods Thirty-six adult male SD rots,aged 10 weeks,weighing 250-280 g,were randomly assigned into 6 groups:control group (group C,n =6) and O2 group (group O,n =6),isoflurane group (group Ⅰ,n =24).The rats were exposed to 2％ isoflurane for 2 h (FGF 3 L/min) in group Ⅰ.While the rats were only exposed to the pure oxygen in group O.Six rats in each group were chosen to perform Morris water maze test after inhalation of pure oxygen was stopped in group O,and at 2 h,and at 1,7 and 14 days after the end of administration in group Ⅰ.The escape latency and swimming distance in place navigation test,and the number of crossing the platform and swimming distance in spatial probe test were recorded.After water maze test was terminated at each time point,blood samples were taken from the fossa orbitalis to determine the plasma cortisol concentration and the hippocampal tissue was obtained for measurement of the contents of BDNF and NGF.Results Compared with group C,the number of crossing the platform was significantly decreased,the swimming distance was significantly shortened,and the plasma cortisol concentration was significantly decreased in spatial probe test in group O,and the escape latency and swimming distance were significantly prolonged at 1 day after the end of administration in plaee navigation test,and the number of crossing the platform and the content of BDNF in the hippocampal tissue were significantly decreased,and the swimming distance was significantly shortened in spatial probe test in group Ⅰ (P ＜ 0.05 or 0.01 ).Conclusion lsoflurane anesthesia exerts a transient inhibitory effect on cognitive function in the short term,and promotion of the cortisol release and synthesis of BDNF is involved in the mechanism,but not the synthesis of NGF in hippocampus in rats. Key words: Isoflurane; Hydrocortisone; Brain-derived neurotrophic factor; Nerve growth factor; Hippocampus