Developmental expression of Pdx1-Cre and adult expression of Rip-CreER. Both Pdx1-Cre and Rip-CreER mice were bred with Ai9 mice. In Pdx1-Cre, Ai9 mice, RFP was looked for in the sections of embryos E10. A specific group of neurons in the brain region of the embryo express intense RFP (a, arrow). (b) The amplified picture of the boxed area in panel a, demonstrating RFP-positive neurons (arrow). Rip-CreER, Ai9 mice were administrated with either vehicle or Tam at eight weeks old. A few neurons were RFP positive with vehicle treatment (c) while abundant neurons were found to express RFP with Tam treatment (d). VMH, ventromedial hypothalamus; Arc, arcuate nucleus; 3, the third ventricle; −Tam, without Tam treatment; +Tam, with Tam treatment. Scale bar = 100 μM.