Neuroprotection against hypoxia-ischemia by insulin-like growth factor-I (IGF-I)

Insulin-like growth factor-I (IGF-I) is a polypeptide hormone that has been investigated as a potential neuroprotective drug for the treatment of stroke and other forms of neural damage. Preclinical studies over the last decade have demonstrated that IGF-I and some of its fragments can protect against neuronal and glial cell degeneration in animal models of stroke such as hypoxia-ischemia. Although the results to date are encouraging, the size of the IGF-I molecule has proved problematic and has led researchers to investigate routes of administration that bypass the blood-brain barrier, such as intranasal application, or to focus on fragments of IGF-I, such as the N-terminal peptide Gly-Pro-Glut (GPE). While the results of these studies have also been positive, systematic dose-response comparisons with recognized neuroprotectants have not yet been published, the time window for therapeutic effects is not yet clear and long-term functional studies have not been conducted.