Background and Goal of Study:
Postoperative cognitive dysfunction (POCD) is an important complication after sevoflurane/surgery stress. In human studies, it has been shown that surgery causes systemic inflammation, neuronal inflammation and cognitive dysfunction in elderly patients. We reported that the comprehensive mRNA profile of neurons in the mouse hippocampus were dramatically changed by exposure to sevoflurane1). We hypothesized that sevoflurane/surgery stress regulates the target genes associated with neuronal inflammation and that dexmedetomidine (Dex) has the neuroprotective effect. The goal of this study was to determine the influence mRNA expression in the hippocampus of elderly mice. 
Materials and Methods:
All of the experimental protocols were approved by the Animal Care and Use Committee of Sapporo Medical University School of Medicine, Japan. Twenty-four male mice (53 weeks of age) were divided into four groups: naïve, sevoflurane exposure (Sevo), operation (Ope), and operation with Dex i.p. (Dex). Mice in the sevo group were exposured to 2.5% of sevoflurane for 1h. Mice in the ope group were anaesthetized with 2.5% of sevoflurane and a 10-mm longitudinal incision was made in the lower abdomen. Mice in the Dex group were injected with 10μg/kg of Dex 30 minutes before the surgical procedure. After 1h, the hippocampus of each mouse was punched out, and total RNAs were isolated from the hippocampus. cDNAs were generated by reverse transcription. Taqman probes specific for Rtn4rl2 and Syt1 were used for qRT-PCR. Target gene expression was analyzed using the ΔΔCT method with Gapdh. In qRT-PCR analysis, data were analyzed using one-way ANOVA with post-hoc Bonferroni correction. 
Results and Discussion: 
Rtn4rl2 gene expression was increased in the Ope group and was reduced in the Dex group. In contrast, Syt1 gene expression was not changed significantly in the Ope group but was increased in the Dex group.  
Conclusions: 
The target genes associated with neuroinflammation were influenced by surgery and Dex intervention. These findings may be the key for elucidating the mechanism of POCD. 
 
Reference:
1) Hayase T. et al. Med Gas Res. 2016;6:70-6 

02 / Dexmedetomidine attenuates up-regulation of the Rtn4rl2 gene and restores down-regulation of the Syt1 gene induced by sevoflurane/surgery stress in the hippocampus of elderly mice