Abstract: Obective To observe the expression of OBR and NPY in mouse hypothalamus. Methods In mouse hypothalamus, the location and coexpression of OBR and NPY were observed with immunohistochemistry and double immunohistochemistry. Results OBR positive cells distributed as clump in hypothalamus ME, ARC and VMN, having obscure boundary. OBR positive cells were also present in choroid plexus, brain ependymal layer cell and vascular endothelial cell. In hypothalamus ARC, NPY positive neurons were present with bright red color in cell plasma. The NPY positive neurons were found as round or ellipse, having many neurites. NPY positive fibers were present in ME. In double immunohistochemitry result, the coexpression of OBR and NPY showed black color, because that OBR positive cells showed brown purple or dark purple granula near the NPY positive neurons. Conclusions OBR distributed in ME, ARC, VMN of mouse hypothalamus, choroid plexus, brain ependymal layer cells and vascular endothelial cells. Meanwhile NPY also distributed in ME, ARC, cerebral cortex and hippocampus and so on. Moreover the coexpression of OBR and NPY was present in mouse hypothalamus ARC.

Key words: obR, NPY