Abstract: Objective To investigate distribution of dopamine (DA) receptors in rat pancreatic tissue and β-cells lines (INS-1 and HIT-T15 cells) and further the endocrine function of INS-1 cell. Methods Double-labeled immunofluorescence staining was used to observe the differential distribution of dopamine receptors and immunofluorescence of insulin and glucagon between in rat pancreatic tissue and tumor β-cell lines. The insulin and glucagon content in the supernatant of INS-1 cell line was detected by radioimmunoassay to observe the changes of endocrine function. Results In rat pancreatic tissue, DA receptors D1, D2, and D5 were distributed in the β-cells, δ-cells, and α-cells, PP-cells, respectively, that is, β-cells expressed only D1 receptors. However, not only D1, but also D2 and D5 were distributed in the INS-1 and HIT-T15 β-cell lines. Insulin and glucagon immunoreactivities were simultaneously expressed in the β-cell lines. Furthermore, both the insulin and glucagon were detected in the supernatant of INS-1 β-cell line. Conclusion The present study for the first time demonstrated that the distribution of DA receptors and endocrine function in β-cell lines are different from that in situ.

Key words: dopamine receptors, β cells, INS-1 cells, HIT-T15 cells