Long-term perturbation of muscle iron homeostasis following hindlimb suspension in old rats is associated with high levels of oxidative stress and impaired recovery from atrophy.

TitleLong-term perturbation of muscle iron homeostasis following hindlimb suspension in old rats is associated with high levels of oxidative stress and impaired recovery from atrophy.
Publication TypeJournal Article
Year of Publication2012
AuthorsXu J, C Y Hwang J, Lees HA, Wohlgemuth SE, Knutson MD, Judge AR, Dupont-Versteegden EE, Marzetti E, Leeuwenburgh C
JournalExp Gerontol
Volume47
Issue1
Pagination100-8
Date Published2012 Jan
ISSN1873-6815
KeywordsAnimals, Body Weight, Cation Transport Proteins, DNA, GPI-Linked Proteins, Hemochromatosis Protein, Hindlimb Suspension, Homeostasis, Iron, Lipid Peroxidation, Male, Membrane Proteins, Muscle, Skeletal, Muscular Atrophy, Oxidation-Reduction, Oxidative Stress, Rats, Rats, Inbred F344, Receptors, Transferrin, Recovery of Function, RNA, Tyrosine
Abstract

In the present study, we investigated the effects of 7 and 14 days of re-loading following 14-day muscle unweighting (hindlimb suspension, HS) on iron transport, non-heme iron levels and oxidative damage in the gastrocnemius muscle of young (6 months) and old (32 months) male Fischer 344×Brown Norway rats. Our results demonstrated that old rats had lower muscle mass, higher levels of total non-heme iron and oxidative damage in skeletal muscle in comparison with young rats. Non-heme iron concentrations and total non-heme iron amounts were 3.4- and 2.3-fold higher in aged rats as compared with their young counterparts, respectively. Seven and 14 days of re-loading was associated with higher muscle weights in young animals as compared with age-matched HS rats, but there was no difference in muscle weights among aged HS, 7 and 14 days of re-loading rats, indicating that aged rats may have a lower adaptability to muscle disuse and a lower capacity to recover from muscle atrophy. Protein levels of cellular iron transporters, such as divalent metal transport-1 (DMT1), transferrin receptor-1 (TfR1), Zip14, and ferroportin (FPN), and their mRNA abundance were determined. TfR1 protein and mRNA levels were significantly lower in aged muscle. Seven and 14 days of re-loading were associated with higher TfR1 mRNA and protein levels in young animals in comparison with their age-matched HS counterparts, but there was no difference between cohorts in aged animals, suggesting adaptive responses in the old to cope with iron deregulation. The extremely low expression of FPN in skeletal muscle might lead to inefficient iron export in the presence of iron overload and play a critical role in age-related iron accumulation in skeletal muscle. Moreover, oxidative stress was much greater in the muscles of the older animals measured as 4-hydroxy-2-nonhenal (HNE)-modified proteins and 8-oxo-7,8-dihydroguanosine levels. These markers remained fairly constant with either HS or re-loading in young rats. In old rats, HNE-modified proteins and 8-oxo-7,8-dihydroguanosine levels were markedly higher in HS and were lower after 7 days of recovery. However, no difference was observed following 14 days of recovery between control and re-loading animals. In conclusion, advanced age is associated with disruption of muscle iron metabolism which is further perturbed by disuse and persists over a longer time period.

DOI10.1016/j.exger.2011.10.011
Alternate JournalExp. Gerontol.
PubMed ID22085543
PubMed Central IDPMC4545509
Grant ListR01 AG017994 / AG / NIA NIH HHS / United States
AG17994 / AG / NIA NIH HHS / United States
P30 AG028740 / AG / NIA NIH HHS / United States
R01 DK080706 / DK / NIDDK NIH HHS / United States
R01 AG028925 / AG / NIA NIH HHS / United States
AG028925 / AG / NIA NIH HHS / United States
DK080706 / DK / NIDDK NIH HHS / United States
1 P30AG028740 / AG / NIA NIH HHS / United States