The Effect of Hyperthermic Pretreatment in a Neonatal Rat Model of Hypoxic-ischemic Brain Injury

ABSTRACT

PURPOSE: Perinatal asphyxia is an important cause of neonatal mortality and subsequent lifelong neurodevelopmental handicaps. Although many treatment strategies have been tested, there is currently no clinically effective treatment to prevent or reduce the harmful effects of hypoxia and ischemia in humans. In the clinical setting, maternal hyperthermia induces adverse effects on the neonatal brain, but recent studies have shown that hyperthermic pretreatment (PT) plays some role in hypoxic-ischemic (HI) injuries of the developing brain. The present study investigated the effect of hyperthermic PT on HI brain injuries in newborn rats. METHODS: HI was produced in 7-day-old neonatal rats by unilateral common carotid artery ligation, followed by hypoxia with 8% oxygen at 38degrees C for 2 hours. Twenty-four hours before HI, one-half of the pups were exposed to a 40degrees C environment for 2 hours. The severity of the brain injury was assessed 7 days after the HI. RESULTS: Hyperthermic PT reduced the gross and histopathologic findings of brain injury from 64.7 to 31.2% (P<0.05). There were no differences in location and severity of injury between the pretreated and control brains. CONCLUSION: These findings indicate that hyperthermic PT provides neuroprotective benefits on HI in the developing brain. Also, these findings suggest maternal hyperthermia may have protective effect on perinatal HI brain injuries.