Orexin A Affects INS-1 Rat Insulinoma Cell Proliferation via Orexin Receptor 1 and the AKT Signaling Pathway

Abstract EN

Our aim is to investigate the role of the AKT/PKB (protein kinase B) signaling pathway acting via orexin receptor 1 (OX1R) and the effects of orexin A (OXA) on cell proliferation in the insulin-secreting beta-cell line (INS-1 cells).

Rat INS-1 cells were exposed to different concentrations of OXA in vitro and treated with OX1R antagonist (SB334867), PI3K antagonist (wortmannin), AKT antagonist (PF-04691502), or negative control.

INS-1 amount of cell proliferation, viability and apoptosis, insulin secretion, OX1R protein expression, caspase-3 activity, and AKT protein levels were determined.

We report that OXA (10-10 to 10-6 M) stimulates INS-1 cell proliferation and viability, reduces the proapoptotic activity of caspase-3 to protect against apoptotic cell death, and increases insulin secretion.

Additionally, AKT phosphorylation was stimulated by OXA (10-10 to 10-6 M).

However, the OX1R antagonist SB334867 (10-6 M), the PI3K antagonist wortmannin (10-8 M), the AKT antagonist PF-04691502 (10-6 M), or the combination of both abolished the effects of OXA to a certain extent.

These results suggest that the upregulation of OXA-OX1R mediated by AKT activation may inhibit cell apoptosis and promote cell proliferation in INS-1 cells.

This finding provides functional evidence of the biological actions of OXA in rat insulinoma cells.