Abstract：Objective To investigate the protective effects of hyperbaric oxygen (HBO) against hypoxic ischemic brain damage (HIBD) of neonatal rats. Methods Seven-day-old Sprague-Dawley (SD) rat pups were randomly divided into 4 groups (n=10 each): Control group, HIBD group, Hyperbaric air (HBA) group, and Hyperbaric oxygen (HBO) group. The HIBD model was produced by permanent occlusion of left common carotid artery and followed by exposure to a mixture of 8% oxygen and 92% nitrogen for 2 hrs (at 37℃). HBO and HBA treatments [2 atmosphere absolute (ATA) for 1 hr] were administered once daily to rats in the HBO and HBA group respectively after hypoxia for 7 days. Radial arm maze and sensorimotor functional tests were administered from 30 to 35 postnatal days. At the end of the behavior trials, the rats were sacrificed and cerebral histology was analyzed. The CA 1 subfield neurons numbers were counted to evaluate the brain damage. Results In the behavior test, the HIBD group showed different degrees of neurological damage. HBO treatment resulted in significant protection against hypoxia-ischemia induced behavior impairments (all P< 0.01). However, the HBA group did not show any significant improvement. There was a significant reduction of CA 1 neuron density in the left hemisphere of HIBD and HBA groups, compared with that of the Control group and the HBO group (all P< 0.01). Conclusion HBO therapy can attenuate brain damage and improve learning, memory and sensorimotor functions in neonatal rats after HIBD.
