Serum insulin-like growth factor I and ischemic brain injury.
Serum insulin-like growth factor I (IGF-I), which is mostly produced by the liver, has recently been shown to have the unexpected ability to modulate normal brain function as well as brain response to injury. Moreover, serum IGF-I levels are modified in many brain diseases, including stroke. However, whether these modifications are related to the disease process remains uncertain. We now examined a potential relationship between serum IGF-I and ischemic brain injury after middle cerebral artery occlusion (MCAo) and reperfusion in mice with either high or low serum IGF-I levels prior to insult. Surprisingly, we found that chronic high serum IGF-I correlates with increased brain infarct size following MCAo, while low levels correlate with reduced lesion size. Immunocytochemistry and immunoblot analyses revealed that levels of phosphorylated (i.e., activated) MAPK, known to be associated with the severity of ischemic brain injury, were increased in IGF-I treated mice. No overall effect of IGF-I treatment on IGF family mRNA expression in the brain was observed. Altogether, these results indicate that serum IGF-I levels negatively correlate with stroke outcome. Therefore, lowering serum IGF-I levels in aging mammals, including humans, may be beneficial against the increased risk of stroke associated to old age.
Endres
Matthias
M
Klinik und Poliklinik für Neurologie, Charité-Universitätsmedizin Berlin, Campus Mitte, Charitéplatz 1, 10117 Berlin, Germany. matthias.endres@charite.de
Piriz
Joaquin
J
Gertz
Karen
K
Harms
Christoph
C
Meisel
Andreas
A
Kronenberg
Golo
G
Torres-Aleman
Ignacio
I
D000704:Analysis of Variance; D000818:Animals; D001930:Brain Injuries / Q000209:etiology* / Q000378:metabolism*; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000502:physiology*; D020244:Infarction, Middle Cerebral Artery / Q000150:complications*; D007334:Insulin-Like Growth Factor I / Q000172:deficiency / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism
D007334:Insulin-Like Growth Factor I; D020929:Mitogen-Activated Protein Kinase Kinases