Abstract: AIM: To investigate the effects of propo-fol on ketamine-induced c-fos mRNA and protein expres-sion in the rat posterior cingulate cortex, and to explore the possible mechanisms of using propofol to prevent or treat ketamine-induced psychotomimetic effects and neuro-nal damage.METHODS: Thirty male Wistar rats weigh-ing 250 -300 g were randomly divided into five groups with six animals in each :saline group which received nor-mal saline 5 ml intraperitoneally ip (NS), ketamine 100 group which received ketamine 100 mg°kg^-1 ip (K); propofol 100 group which received propofol 100 mg°kg^-1 ip (P);propofol 50 +ketmaine 100 group which received propofol 50 mg°kg^-1 +ketmaine 100 mg°kg^-1 ip (P 1 K) and propofol 100 +Ketamine 100 group which received propofol 100 mg°kg^-1+Ketamine 100 mg°kg^-1 ip (P 2 K). In group P 1 K and P 2 K, the interval between propofol and ketamine administration was 15 min.Two hours later, the animals were decapitated and brain was removed.c-fos mRNA expression in the posterion cingu-late cortex was detected by semi-quantitative RT-PCR technique, c-fos protein expression in posterior cingulated cortex was determined by immuno-histochemical method. RESULTS: The levels of c-fos mRNA and c-fos protein expression were significantly different among 5 groups. Ketamine induced marked c-fos mRNA and c-fos protein expression in the posterior cingulate cortex.Propofol did not induce c-fos gene expression in this brain region. Propofol significantly inhibited ketamine-induced c-fos mRNA and c-fos protein expression in the posterior cingu-lated cortex in a dose-dependent manner.CONCLUSION: Propofol pretreatment can significantly inhibit ket-amine-induced c-fos mRNA and protein expression in the posterior cingulate cortex. It may be one of mechanisms of inhibition of ketamine-induced psychotomimetic effect and neuronal damage by propofol.

Key words: propofol, ketamine, c-fos gene, posterior cingulate cortex