Phoenixin (PNX), a newly discovered pleiotropic neuropeptide is produced by proteolytic cleavage of Smim20 protein and exerts its biological effects by Gpr173 receptor [1]. Despite important functions in controlling reproduction system and memory processes, PNX is centrally involved in food intake and its systemic levels positively correlate with BMI [2-4]. Notably, the peptide is also peripherally expressed in adipose tissue [5]. Although recent data suggest that PNX is involved in energy homeostasis, its role in modulating glucose control and metabolism remains unknown. The aim of this study was to investigate the effect of PNX on insulin secretion in INS-1E beta cells and isolated rat pancreatic islets. Furthermore, we studied the mechanism by which PNX modulates insulin exocytosis. Insulin producing INS-1E beta cell line and pancreatic islets isolated from Wistar rats (male, 300-350 g) were used. The presence of PNX peptide in INS-1E cells and pancreas slides was studied by immunofluorescence. The mRNA expression was measured by real-time PCR. Insulin secretion was evaluated by RIA Rat Insulin assay. cAMP synthesis was measured by ELISA kit. Values are means ± S.E.M., compared by ANOVA. We found that Smim20 and Gpr173 mRNA are expressed in INS-1E cells and rat pancreatic islets. PNX peptide is present in INS-1E and rat pancreatic alpha and beta cells. We demonstrated that PNX is secreted in isolated pancreatic islets in a glucose-dependent fashion, more robustly under high (16.7 mmol/l) than under low (2.8 mmol/l) glucose concentrations (0.0615 ± 0.01 vs. 0.1320 ± 0.021 ng/ml; n=6; p<0.05 respectively). Moreover, PNX increased glucose-stimulated insulin secretion in INS-1E cells and isolated pancreatic islets (n=6; p<0.05). In addition, we found that PNX (100 nmol/l) increased cAMP level in INS-1E cells (21.72 ± 0.275 pmol/ml vs. 25.573 ± 1.687 PNX treated; n=6; p<0.05). Pharmacological blockade of cAMP downstream target protein Epac by ESI-09 prevented PNX from stimulating insulin secretion. These results provide strong evidence that PNX modulates insulin secretion via cAMP/Epac pathway.