Circulating insulin-like growth factor I mediates effects of exercise on the brain.
Physical exercise increases brain activity through mechanisms not yet known. We now report that in rats, running induces uptake of blood insulin-like growth factor I (IGF-I) by specific groups of neurons throughout the brain. Neurons accumulating IGF-I show increased spontaneous firing and a protracted increase in sensitivity to afferent stimulation. Furthermore, systemic injection of IGF-I mimicked the effects of exercise in the brain. Thus, brain uptake of IGF-I after either intracarotid injection or after exercise elicited the same pattern of neuronal accumulation of IGF-I, an identical widespread increase in neuronal c-Fos, and a similar stimulation of hippocampal brain-derived neurotrophic factor. When uptake of IGF-I by brain cells was blocked, the exercise-induced increase on c-Fos expression was also blocked. We conclude that serum IGF-I mediates activational effects of exercise in the brain. Thus, stimulation of the uptake of blood-borne IGF-I by nerve cells may lead to novel neuroprotective strategies.
Carro
E
E
Laboratory of Neuroendocrinology, Cajal Institute, Consejo Superior de Investigaciones Cientificas, 28002 Madrid, Spain.
Nuñez
A
A
Busiguina
S
S
Torres-Aleman
I
I
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002831:Choroid Plexus / Q000378:metabolism*; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000134:cerebrospinal fluid / Q000493:pharmacokinetics*; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D011689:Purkinje Cells / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D016760:Proto-Oncogene Proteins c-fos; D007334:Insulin-Like Growth Factor I