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Metallothionein I and II mitigate age‐dependent secondary brain injury
Author(s) -
Natale JoAnne E.,
Knight Jay Brandon,
Cheng Ying,
Rome Justin E.,
Gallo Vittorio
Publication year - 2004
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.20265
Subject(s) - neurodegeneration , apoptosis , context (archaeology) , oxidative stress , central nervous system , metallothionein , thalamus , biology , programmed cell death , reactive oxygen species , medicine , endocrinology , neuroscience , microbiology and biotechnology , gene , biochemistry , paleontology , disease
Both the immediate insult and delayed apoptosis contribute to functional deficits after brain injury. Secondary, delayed apoptotic death is more rapid in immature than in adult CNS neurons, suggesting the presence of age‐dependent protective factors. To understand the molecular pathobiology of secondary injury in the context of brain development, we identified changes in expression of oxidative stress response genes during postnatal development and target deprivation‐induced neurodegeneration. The antioxidants metallothionein I and II (MT I/II) were increased markedly in the thalamus of adult C57BL/6 mice compared to mice <15 days old. Target deprivation generates reactive oxygen species that mediate neuronal apoptosis in the central nervous system; thus the more rapid apoptosis observed in the immature brain might be due to lower levels of MT I/II. We tested this hypothesis by documenting neuronal loss after target‐deprivation injury. MT I/II‐deficient adult mice experienced greater thalamic neuron loss at 96 hr after cortical injury compared to that in controls (80 ± 2% vs. 57 ± 4%, P < 0.01), but not greater overall neuronal loss (84 ± 4% vs. 79 ± 3%, MT I/II‐deficient vs. controls). Ten‐day‐old MT I/II‐deficient mice, however, experienced both faster onset of secondary neuronal death (30 vs. 48 hr) and greater overall neuronal loss (88 ± 2% vs. 69 ± 4%, P = 0.02). MT I/II are thus inhibitors of age‐dependent secondary brain injury, and the low levels of MT I/II in immature brains explains, in part, the enhanced susceptibility of the young brain to neuronal loss after injury. These findings have implications for the development of age‐specific therapeutic strategies to enhance recovery after brain injury. © 2004 Wiley‐Liss, Inc.