Serum insulin-like growth factor I regulates brain amyloid-β levels

E. Carro, J. L. Trejo, T. Gomez-Isla, D. LeRoith, I. Torres-Aleman

Research output: Contribution to journalArticlepeer-review

459 Scopus citations


Levels of insulin-like growth factor I (IGF-I), a neuroprotective hormone, decrease in serum during aging, whereas amyloid-β (Aβ), which is involved in the pathogenesis of Alzheimer disease, accumulates in the brain. High brain Aβ levels are found at an early age in mutant mice with low circulating IGF-I, and Aβ burden can be reduced in aging rats by increasing serum IGF-I. This opposing relationship between serum IGF-I and brain Aβ levels reflects the ability of IGF-I to induce clearance of brain Aβ, probably by enhancing transport of Aβ carrier proteins such as albumin and transthyretin into the brain. This effect is antagonized by tumor necrosis factor-α, a proinflammatory cytokine putatively involved in dementia and aging. Because IGF-I treatment of mice overexpressing mutant amyloid markedly reduces their brain Aβ burden, we consider that circulating IGF-I is a physiological regulator of brain amyloid levels with therapeutic potential.

Original languageEnglish
Pages (from-to)1390-1397
Number of pages8
JournalNature Medicine
Issue number12
StatePublished - 1 Dec 2002
Externally publishedYes


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