Effects of isoflurane on c-fos expression induced by ketamine in cingulated gyrus of brain in rats

Aim: Ketamine can induce c-fos expression in cingulated gyrus, and the mental ill effect is produced.To investigate the effects of isoflurane on ketamine-induced c-fos expression in cingulated gyrus of rats. Methods: The experiment was conducted at the Animal Laboratory, Tangdu Hospital,Fourth Military Medical University during June 2001. Fifteen SD rats were randomly divided into: control group, isoflurane group, ketamine group, isoflurane+ketamine I, II group with 3 rats in each group. Rats in isoflurane group inhaled 2% isoflurane for 1 hour. The rats in isoflurane + ketamine I and II group inhaled 1% or 2% isoflurane for 5 minutes,followed by 100 mg/kg ketamine with intraperitoneal injection. The rats inhaled isoflurane for 1 hour continuously.The rats were administered saline,or 100 mg/kg ketamine with intraperitoneal injection in control group and ketamine group. The brain of rats were separated and sliced under frozen condition to perform immunohistochemical staining for Fos-protein. Results: Totally 15 experimental rats were involved in the result analysis. (1) There was few Fos-like immunoreactivity neurons (FLIN) in cingulated gyrus of sections in the control group and the isoflurane groups and there was no significant difference between two groups (P > 0.05). (2) The number of FLIN in ketamine group was 126 ±23 and was more significantly than that in the control group and isoflurane group (P < 0.01). (3) The number of FUN in isoflurane + ketamine I and II group were 54 ±8,11 ±4 respectively and less significantly than that in the ketamine group (P < 0.01). Furthermore, the number of FLIN in II group were less obviously than that in I group (P < 0.01). (4) Compared with the control group, the number of FLIN in the isoflurane+ ketamine II group had no significant difference (P > 0.05). Conclusion: Isoflurane can inhibit the expression of c-fos induced by ketamine in cingulated gyrus of rats in a dose-dependent manner, and relieve or eliminate the mental ill effect of ketamine.