IGF1 (insulin-like growth factor 1) protein is cleaved into des-N-(1-3)-IGF-1 and an N-terminal Gly-Pro-Glu (GPE tripeptide). It is thought to be an outcome of specific neural processing.

Gly-Pro-Glu (GPE) is a neuroactive peptide and prevents the binding of glutamate to N-methyl-D-aspartate (NMDA) receptor. It positively regulates the potassium-mediated release of acetylcholine from rat cortical slices. Thus, it is involved in the control of brain function. In vitro studies show that this peptide confers neuroprotection to CA1-2 hippocampal neurons against excitotoxic insult.

Gly-Pro-Glu is a neuroprotective compound and the N-terminal tripeptide of IGF-1.

Gly-Pro-Glu is a neuroprotective compound and the N-terminal tripeptide of IGF-1. Gly-Pro-Glu is neuroprotective after central administration in animal models of neurodegenerative processes, such as Huntington′s, Parkinson′s, Alzheimer′s diseases, and varies acute brain injury animal models. The neuroprotective activity is not related to its affinity to glutamate receptor. Findings indicate that GPE mimics insulin-like growth factor I effects on the somatostatin system through a mechanism independent of β-amyloid clearance that involves modulation of calcium and glycogen synthase kinase 3β signaling.