Neuropeptide B stimulates insulin secretion and expression but not proliferation in rat insulin-producing INS-1E cells

Neuropeptide B (NPB) regulates food intake, body weight and energy homeostasis by interacting with NPBW1/NPBW2 in humans and NPBW1 in rodents. NPB and NPBW1 are widely expressed in the central nervous system and peripheral tissues including pancreatic islets. Although previous studies have demonstrated a prominent role for NPB and NPBW1 in controlling glucose and energy homeostasis, it remains unknown as to whether NPB modulates pancreatic beta-cell functions. Therefore, the aim of the present study was to investigate the effects of NPB on insulin expression and secretion in vitro. Furthermore, the role of NPB in the modulation of INS-1E cell growth, viability and death was examined. Gene expression was assessed by reverse transcription-quantitative PCR. Cell proliferation and viability were determined by BrdU or MTT tests, respectively. Apoptotic cell death was evaluated by relative quantification histone-complexed DNA fragments (mono-and oligonucleosomes). Insulin secretion was studied using an ELISA test. Protein phosphorylation was assessed by western blot analysis. NPB and NPBW1 mRNA was expressed in INS-1E cells and rat pancreatic islets. In INS-1E cells, NPB enhanced insulin 1 mRNA expression via an ERK1/2-dependent mechanism. Furthermore, NPB stimulated insulin secretion from INS-1E cells and rat pancreatic islets. By contrast, NPB failed to affect INS-1E cell growth or death. We conclude that NPB may regulate insulin secretion and expression in INS-1E cells and insulin secretion in rat pancreatic islets.