GPR39 is region-specifically expressed in mouse oviduct correlating with the Zn²⁺ distribution

G-protein-coupled receptor 39 (GPR39) plays a role in cellular and physiological processes, including insulin secretion, cell death inhibition, wound healing, and obesity. Increasing evidence suggests that GPR39 is potently stimulated by zinc ions (Zn²⁺) and is therefore considered a putative Zn²⁺ receptor. Given the importance of Zn²⁺ in the reproductive system, we proposed that GPR39 might have a functional role in the reproductive system. However, the localization of GPR39 in the reproductive system remains unknown. Here, we used mice expressing a Gpr39 promoter-driven LacZ reporter system to detect Gpr39 expression in the reproductive system at different phases of the estrous cycle and found an interesting region-specific distribution of Gpr39 in the mouse oviduct epithelium, with strong expression at the ampulla and weak expression at the isthmus, which was consistent with the results using reverse transcription polymerase chain reaction and immunofluorescence. Moreover, using ZnSe^AMG staining, we found that Zn²⁺, the putative ligand of GPR39, also found a distribution similar to GPR39 expression, suggesting that their potential interaction mediates fertilization and embryo transportation.