FIG. 3.

Photomicrographs illustrating the expression of GLP-1r mRNAs in NPY and POMC neurons in rat mid- and caudal ARC as detected by double in situ hybridization histochemistry. Neurons expressing GLP-1 receptor are visualized by a white, dense, silver-grain accumulation, while either NPY (A–C) or POMC (D–F) mRNAs appeared as a black precipitate in cell bodies. In the mid-ARC at low magnification (A and D), many GLP-1 receptor–expressing cells do not express NPY mRNA and are localized more laterally (A). Neurons expressing only GLP-1r are also visualized in the periventricular area posterior to both NPY and POMC neurons (A and D). A high number of POMC-expressing cells are found expressing GLP-1r mRNA characterized by strong silver-grain accumulation over the digoxigenin black precipitate and are clearly seen at higher magnification (F). In the caudal ARC (B and E), many neurons expressing the GLP-1 receptor but not NPY or POMC are found mostly in the posterior and periventricular part (B and E). C and F are photomicrographs at higher magnification of inserts represented by a black square in A and D.