Figure 4.

The EP1 receptor is responsible for the phase shifts by prostaglandin E₂ (PGE₂). (A) Intraperitoneal administration of sulprostone (solid line) or PBS alone (dotted line) was performed at ZT21. mRNA was collected from liver at each time point and the expression levels of mPer1 mRNA were evaluated by real-time quantitative PCR. Each value of mRNA expression levels was normalized to mG3PDH. Data shown are representative of two independent experiments. (B) Intraperitoneal administration of butaprost (solid line) or PBS alone (dotted line) was performed at ZT21. The expression levels of mPer1 mRNA in liver were monitored as in (A). (C) Intraperitoneal administration of PGE₂ together with SC-51322 (solid line), or PBS alone (dotted line) was performed at ZT21. The expression levels of mPer1 mRNA in liver were monitored as in (A).