A Ferret Model of Inflammation-sensitized Late Preterm Hypoxic-ischemic Brain Injury.

Abstract

There is an ongoing need for clinically relevant models of perinatal infection and hypoxia-ischemia (HI) in which to test therapeutic interventions for infants with the neurological sequela of prematurity. Ferrets are ideal candidates for modeling the preterm human brain, as they are born lissencephalic and develop gyrencephalic brains postnatally. At birth, ferret brain development is similar to a 13 week human fetus, with postnatal-day (P) 17 kits considered to be equivalent to an infant at 32-36 weeks' gestation. We describe an injury model in the P17 ferret, where lipopolysaccharide administration is followed by bilateral cerebral ischemia, hypoxia, and hyperoxia. This simulates the complex interaction of prolonged inflammation, ischemia, hypoxia, and oxidative stress experienced in a number of neonates who develop brain injury. Injured animals display a range of gross injury severity, with morphological changes in the brain including narrowing of multiple cortical gyri and associated sulci. Injured animals also show slowed reflex development, slower and more variable speed of locomotion in an automated catwalk, and decreased exploration in an open field. This model provides a platform in which to test putative therapies for infants with neonatal encephalopathy associated with inflammation and HI, study mechanisms of injury that affect cortical development, and investigate pathways that provide resilience in unaffected animals.