Orexin-A regulates cell apoptosis in human H295R adrenocortical cells via orexin receptor type 1 through the AKT signaling pathway.

Numerous studies have demonstrated the ability of orexin-A to regulate adrenocortical cells through the mitogen-activated protein kinase signaling pathway. In the present study, human H295R adrenocortical cells were exposed to orexin‑A (10‑10-10‑6 M), with orexin receptor type 1 (OX1 receptor) antagonist SB334867 or AKT antagonist PF‑04691502. It was found that orexin‑A stimulated H295R cell proliferation, reduced the pro‑apoptotic activity of caspase‑3 to protect against apoptotic cell death and increased cortisol secretion. Furthermore, phospho‑AKT protein was increased by orexin‑A. SB334867 (10‑6 M) and PF‑04691502 (10‑6 M) abolished the effects of orexin‑A (10‑6 M). These results suggested that the orexin‑A/OX1 receptor axis has a significant pro-survival function in adrenal cells, which is mediated by AKT activation. Further studies investigating the effects of orexin-A-upregulation may further elucidate the diverse biological effects of orexin-A in adrenal cells.