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

Abstract

Neuropeptide B (NPB) regulates food intake, body weight and energy homeostasis by interacting with NPBW 1 /NPBW 2 in humans and NPBW 1 in rodents. N P B 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 ß-cell functions. Therefore, the aim of the present study was to investigate the effects of NPB on insulin expression and secre¬ tion 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 stimu¬ lated 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.