Neuroprotective effects of Sonic hedgehog agonist SAG in a rat model of neonatal stroke

Objective: Neonatal stroke affects 1 in 2800 live births and is a major cause of neurological injury. The Sonic Hedgehog (Shh) signaling pathway is critical for central nervous system (CNS) development and has neuroprotective and reparative effects in different CNS injury models. Previous studies have demonstrated beneficial effects of small molecule Shh-Smoothened-agonist (SAG) against neonatal cerebellar injury and it improves Down syndrome-related brain structural deficits in mice. Here, we investigated SAG neuroprotection in rat models of neonatal ischemia-reperfusion (stroke) and adult focal white matter injury. Methods: We used transient middle cerebral artery occlusion at P10 and ethidium bromide injection in adult rats to induce damage. Following surgery and SAG or vehicle treatment we analyzed tissue loss, cell proliferation and fate, and behavioral outcome. Results: We report that a single dose of SAG administered following neonatal stroke preserved brain volume, reduced inflammation, enhanced oligodendrocyte progenitor cell (OPC) and EC proliferation, and resulted in long-term cognitive improvement. Single-dose SAG also promoted proliferation of OPCs following focal demyelination in the adult rat. Conclusion: These findings indicate benefit of one-time SAG treatment post-insult in reducing brain injury and improving behavioral outcome after experimental neonatal stroke