Ghrelin, acting through its receptor growth hormone secretagogue receptor (GHS-R), is an important energy sensor and metabolic regulator. However, the regulatory mechanisms of ghrelin signaling are largely unknown due to limited knowledge in sites of expression of GHS-R. Due to the absence of a specific antibody for GHS-R, the study of GHS-R expression has been limited to RNA level by in situ and transgenic reporter. In this research, GHS-R expression is investigated using GFP-Ghsr reporter mice, where GFP reporter is integrated into endogenous Ghsr gene; thus, GFP expression precisely correlates with endogenous GHS-R expression. Immunohistochemistry and immunofluorescence staining of GFP- Ghsr reporter mouse brain was used to identify expression sites of GHS-R. Images were obtained using light microscopy and confocal microscopy, and detailed image analysis was performed.

These approaches enabled us to map the precise expression patterns of endogenous GHS-R, which can helped shed more light on the sites of action of ghrelin. Understanding the expression pattern of GHS-R can help researchers further expand their research on the role of ghrelin and possible future receptor targeted drug therapy in obesity and insulin resistance.