Role of hepcidin and its downstream proteins in early brain injury after experimental subarachnoid hemorrhage in rats.

Early brain injury (EBI) is a major cause of mortality from subarachnoid hemorrhage (SAH). We aimed to study the pathophysiology of EBI and explore the role of hepcidin, a protein involved in iron homeostatic regulation, and its downstream proteins. One hundred and thirty-two male Sprague-Dawley rats were assigned into groups (n = 24/group): sham, SAH, SAH + hepcidin, SAH + hepcidin-targeting small interfering ribonucleic acid (siRNA), and SAH + scramble siRNA. Three hepcidin-targeting siRNAs and one scramble siRNA for hepcidin were injected 24 h before hemorrhage induction, and hepcidin protein was injected 30 min before induction. The rats were neurologically evaluated at 24 h and euthanized at 72 h. Hepcidin, ferroportin-1, and ceruloplasmin protein expression were measured by immunohistochemistry and Western blotting. Brain water content, blood-brain barrier (BBB) leakage, non-heme tissue iron and Garcia scale were evaluated. Hepcidin expression increased in the cerebral cortex and hippocampus after experimental SAH (P < 0.05 compared to sham), while ferroportin-1 and ceruloplasmin decreased (P < 0.05). Hepcidin injection lowered the expression of ferroportin-1 and ceruloplasmin further but siRNA reduced the levels of hepcidin (P < 0.05 compared to SAH) resulting in recovery of ferroportin-1 and ceruloplasmin levels. Apoptosis was increased in SAH rats compared to sham (P < 0.05) and increased slightly more by hepcidin, but decreased by siRNA (P < 0.05 compared to SAH). SAH rats had lower neurological scores, high brain water content, BBB permeability, and non-heme tissue iron (P < 0.05). In conclusion, downregulation of ferroportin-1 and ceruloplasmin caused by hepcidin enhanced iron-dependent oxidative damage and may be the potential mechanism of SAH.