Insulin-like growth factor-1 in plasma and brain: regulation in health and disease.

IGF-1 was first described as a growth mediating factor regulated in the context of the somatotrophic axis. During the last decade, it has gained much attention for its role in the regulation of lifespan, brain function, cell growth, and metabolism. Associations of plasma IGF-1 levels in physiological and pathological conditions such as aging, cardiovascular disease, metabolic disorders, dementia, and neurodegenerative disorders, and its potential as a neurotrophic agent, have been intensively studied. Acromegaly due to jGH and IGF-1 excess and growth hormone deficiency with decreased GH and IGF-1 might serve as models to study IGF-1 function, but the effects of GH and IGF-1 in these conditions are often indistinguishable. Due to this overlap, this article will only briefly mention pathophysiological implications in acromegaly and growth hormone deficiency. It will focus on IGF-1 and give an overview of the vast literature on the role and regulation of IGF-1 in plasma and brain, its alteration in health and disease and its possible therapeutical applications.