Effects of inhalation of different concentrations of isoflurane on hippocampal cytochrome c expression in aged rats

Objective To investigate the effects of inhalation of different concentrations of isoflurane on the expression of cytochrome c （ Cyt c） in hippocampus in aged rats. Methods Sixty-three aged male SD rats （20 months） weighing 500-600 g were randomly divided into 3 groups （ n = 21 each） ： control group inhaling 30% 02 for 2 h （group C） and 2 isoflurane groups anesthetized with 0.75% and 1.5% isoflurane in 30% Oz for 2 h respectively （group I1 and I2 ）. Arterial blood samples were obtained from 5 rats at 30 min, 1 and 2 h of anesthesia for blood gas analysis. Eight animals were killed at 24 h after anesthesia in each group. Their hippocampi were immediately removed for determination of Cyt c expression by immuno-histochcmistry and Western blot analysis. Cognitive function was assessed by Morris water maze test the day before experiment and once a day for 6 consecutive days starting from the 1st postoperative day. Results The Cyt c expression in hippocampus was significantly increased in I1 and I2 groups in a concentration-dependent manner as compared with group C. The escape latency was significantly prolonged and the frequency of crossing the original platform and the duration of staying at the original platform quadrant were decreased in group I1 and I2 compared with group C. Conclusion Inhalation of isoflurane anesthesia can decrease cognitive function through up-regulating the Cyt c expression in hippocampus in aged rats. Key words: Isoflurance ;  Cytochromes c ;  Hippocampus