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

Abstract

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 24h before hemorrhage induction, and hepcidin protein was injected 30min before induction. The rats were neurologically evaluated at 24h and euthanized at 72h. 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.