Background and purpose: The insulin-like growth factors (IGF) are synthesized in the brain and are involved in fetal brain development. An increased expression of IGF-I and IGF-II occurs in cerebral regions with neuronal damage after experimental hypoxic injury. Furthermore, the expression of mRNAs coding for IGF-I and the binding proteins IGFBP-2 and IGFBP-3 is augmented in response to unilateral ischemia in animal models. The secretory dynamics of IGF-I in human cerebral ischemia have not yet been investigated.
Methods: Plasma IGF-I and IGFBP-3 were measured sequentially in 20 patients with acute ischemic stroke (within 24 hours and 3, 5, and 10 days thereafter). For analysis the patients were assigned to three groups according to the diameter of the infarct area as measured on CT scan: small (< 1.5 cm), moderate (> or = 1.5 cm and < or = 5 cm), and large (> 5 cm). Eight age-matched patients with nonvascular, neurological illnesses served as controls.
Results: Plasma IGF-I and IGFBP-3 plasma concentrations after acute cerebral ischemia were strikingly lower than those in control subjects and healthy individuals reported in the literature. Plasma IGF-I levels in patients with large infarcts were significantly statistically lower than those in control subjects (P < .05), and plasma IGFBP-3 levels were significantly lower than those in control subjects on days 5 and 10.
Conclusions: IGF-I and IGFBP-3 plasma levels are decreased in patients after cerebral ischemia. After acute ischemic stroke, increased demand for growth factors, altered tissue distribution, and accelerated metabolic clearance rate or central inhibition of the somatotrophic axis may contribute to these low plasma concentrations. Growth factors such as IGF-I and IGFBP-3 may play an important role in the pathophysiology of acute cerebral ischemia, and growth factors may have a considerable effect on future therapeutic regimens.