抄録
The rhythmic oscillation in the suprachiasmatic nucleus (SCN) is feedback controlled by the CLOCK/BMAL1 heterodimer binding to the E-box in target genes (e.g., Arg-vasopressin). The binding affinity is depending on the redox state (i.g., NAD/NADH). To clarify the metabolic function of SCN in relation to the circadian stage, we measured enolase and LDH activities, and their mRNAs were determined, using RT-PCR, under the light/dark cycle and constant dim light in rats. Cyctochrome C oxidase activity was higher during the light period than during the darkness. The LDH and LDHa mRNA contents were higher during the light than in the darkness. The γ-enolase (NSE) activity was higher during the light than in the dark period, while, the peak of γ-enolase mRNA rhythm presented during the dark period. Under the constant dim light, not only the Per2, Bmal1, Rev-Erbα and arg-vasopressin mRNAs, but also the NSE and LDH mRNAs showed free-running rhythm. Beside, after the hypothermia, the enolase mRNA increased, however the Per2 mRNA decreased during the light. In the cortex, no significant rhythmicity in LDH and NSE and their coding mRNA was found. The results indicate the glycolysis levels with energy supply, for the higher metabolic activity during the light than at darkness, are concerning to the rhythm generation in SCN. [Jpn J Physiol 55 Suppl:S198 (2005)]
