Identification of the mPOA as a downstream target of AGRP neurons. Identification of the mPOA as a downstream target of AGRP neurons. A, Illustration of the genetic strategy to fluorescently label synapses of AGRP neurons. In AGRPcre::Ai34 animals, Cre induces excision of the stop codon to allow expression of synaptophysin, a synaptic protein, fused with tdTomato in AGRP neurons. B, Representative coronal sections of AGRPcre::Ai34 females showing fluorescent tdTomato signals detected in the ARC and in the mPOA, which was costained with antibodies against Esr1. The plane of the sections is indicated by the dashed line in the sagittal section on the left. Scale bar, 100 μm. C, Representative images showing patterns of AGRP immunostaining in wild-type females (top row) and Synaptophysin-tdTomato signals (bottom row) in AGRPCre::Ai34 females along the anterior–posterior axis from bregma 0.14 mm to bregma −0.34 mm with key landmarks outlined. aca, Anterior commissure, anterior part; acp, anterior commissure, posterior; ic, internal capsule; f, fornix; 3V, third ventricle. Rectangular boxes in the top row show reference atlas position for images at the bottom. Scale bar, 500 μm. D, Mean fluorescence density of the synaptophysin-tdTomato signals in brain regions targeted by AGRP neurons. N = 4. AU, Arbitrary unit. Each black circle represents an animal. Data are presented as mean ± SEM. Xing-Yu Li et al. J. Neurosci. 2019;39:456-471 ©2019 by Society for Neuroscience