The suprachiasmatic nucleus (SCN) orchestrates synchrony among many peripheral oscillators and and is required for circadian rhythms of locomotor activity and many physiological processes. However, chronic administration of methamphetamine (MAP) treatment dramatically lengthens circadian period of locomotor activity rhythms and induces rhythms in animals lacking SCN. These unique effects of MAP on circadian behavior suggest methamphetamine-sensitive circadian oscillator (MASCO). At present, the anatomical substrate and the molecular components of the MASCO are unknown.
To understand the mechanism of MASCO in vivo, we developed multiple recording system of Period1(Per1) gene expression rhythm in peripheral tissue and the brain of freely moving mice. Using this technique, we examined the effects of MAP on circadian rhythms of locomotor activity and Per1 expression rhythm in peripheral tissue and the brain.
 MAP was administered by chronic application of MAP in the drinking water or continuous MAP administration into the intraperitoneal cavity using micropump. We found that MAP had different effects on circadian rhythms of locomotor activity and Per1 gene expression rhythm among above administration. In the future, our multiple recording system will be powerful tool to identify and analyze the localization of the MASCO as well as its interaction s with other oscillators in the body, which will be essential to a complete understanding of the organization of the mammalian circadian system.