TNF and brain infarction: This study demonstrates the following novel findings: One, repression of neonatal endogenous brain GR in a mild HI model sensitizes the neonatal brain to acute HI injury and results in increased brain infarction size in male neonatal rat pups; two, downregulation of brain GR causes greater impairment of short- and long-term neurobehavioral functioning after HI injury; and three, lastly, GR repression significantly increased HI-induced production of inflammatory cytokines TNF-α and IL-10 at six hours after HI injury.