IGF1 and ischemic stroke: Glycoprolines may be derived from collagen or IGF-I; a study in rats has shown that oral administration of cyclic glycine-proline, a glycoproline derived from IGF-I, promoted neural plasticity and remodelling in animals with focal ischaemic lesions, suggesting a neuroprotective effect of cyclic glycine-proline against ischaemic stroke or its recovery [35].