Hypoxic ischemic brain injury: animal models reveal new mechanisms of melatonin-mediated neuroprotection.

Oxidative stress (OS) and inflammation play a key role in the development of hypoxic-ischemic (H-I) induced brain damage. Following H-I, rapid neuronal death occurs during the acute phase of inflammation, and activation of the oxidant-antioxidant system contributes to the brain damage by activated microglia. So far, in an animal model of perinatal H-I, it was showed that neuroprostanes are present in all brain damaged areas, including the cerebral cortex, hippocampus and striatum. Based on the interplay between inflammation and OS, it was demonstrated in the same model that inflammation reduced brain sirtuin-1 expression and affected the expression of specific miRNAs. Moreover, through proteomic approach, an increased expression of genes and proteins in cerebral cortex synaptosomes has been revealed after induction of neonatal H-I. Administration of melatonin in the experimental treatment of brain damage and neurodegenerative diseases has produced promising therapeutic results. Melatonin protects against OS, contributes to reduce the generation of pro-inflammatory factors and promotes tissue regeneration and repair. Starting from the above cited aspects, this educational review aims to discuss the inflammatory and OS main pathways in H-I brain injury, focusing on the role of melatonin as neuroprotectant and providing current and emerging evidence.