IGF1 and brain ischemia: It is noteworthy that, in this relationship, significant neuroprotection was found by insulin and insulin-like growth factor 1 during neurodegeneration in models of experimental cerebral ischemia by intranasal treatment, as a safe and effective route of administration, bypassing the blood–brain barrier and maximizing the distribution to the central nervous system (CNS) without systemic side effects and metabolic influence [19].