Expression of hepcidin at the choroid plexus in normal aging rats is associated with IL-6/Stat3 signaling pathway

Accumulating evidence has revealed that brain iron concentrations increase with aging, and the choroid plexus (CP) may be at the basis of iron-mediated toxicity and the increase in inflammation and oxidative stress that occurs with aging. The mechanism involves not only hepcidin, the key hormone in iron metabolism, but also iron-related proteins and signaling-transduction molecules, such as IL-6 and signal transducer and activator of transcription 3 (Stat3). The aim of the present study was to investigate the correlation between the IL-6/Stat3 signaling pathway and hepcidin at the CP in normal aging. Quantitative real time PCR and Western blot were used to determine the alterations in specific mRNA and corresponding protein changes at the CP at ages of 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33 and 36 months in Brown-Norway/Fischer (B-N/F) rats. The results demonstrated that hepcidin mRNA level at the CP kept stable in young rats (from 3 to 18 months), and increased with aging (from 21 to 36 months). The alterations of IL-6/p-Stat3 mRNA and protein expressions in normal aging were in accordance with that of hepcidin mRNA. Our data suggest that IL-6 may regulate hepcidin expression at the CP, upon interaction with the cognate cellular receptor, and through the Stat3 signaling transduction pathway.