Murine clock gene expression in the suprachiasmatic nuclei and peripheral blood mononuclear cells during the daily sleep-wake rhythm and after isoflurane anesthesia

Abstract

Clock gene expression is closely associated with the “sleep-wake rhythm”, and can be detected both in central oscillation and in peripheral tissues. In this study, we investigated murine clock gene expression in the SCN (suprachiasmatic nuclei) and PBMCs (peripheral blood mononuclear cells) during the daily sleep-wake rhythm and after isoflurane anesthesia. Seventy-two mice were divided randomly into three groups: a control group, a control reversal group and an isoflurane anesthesia group. The control and isoflurane anesthesia groups were maintained in a regular 12 h light: dark (LD) cycle with lights on at 8:00 am and off at 8:00 pm, while control reversal group was kept in an inverted 12 h LD cycle with lights on at 8:00 pm and off at 8:00 am for 3 weeks. Positive limb (Bmal1, Clock) and negative limb (Per2, Cry1) mRNA expression was examined by reverse transcriptionpolymerase chain reaction. The general anesthetic isoflurane was used for 6 h during the awake period. Clock gene expression in PBMCs was related to SCN in both the regular and inverted 12 h LD cycle. Clock gene mRNA expression significantly changed after anesthesia. Compared to control group, isoflurane anesthesia caused a large phase delay of clock gene expression in PBMCs. In the SCN, Cry1 and Per2 mRNA expression showed a lag after anesthesia, and Bmal1 and Clock mRNA expression showed an advance. A correlation was also shown of clock gene expression in the SCN and in PBMCs after anesthesia. Our work provides a justification for using peripheral blood to do clinical research on the sleep-wake rhythm.