Growth deficits in a postnatal day 3 rat model of hypoxic-ischemic brain injury.

The postnatal day (P) 3 rat model of hypoxic-ischemic (HI) brain injury provides valuable information regarding the cellular response to HI injury in a very immature brain. Our present study is the first to examine growth, metabolic, and behavioral outcomes following a P3 HI brain injury. Rats were injured by cauterizing the right common carotid, and exposure to 8% oxygen for 1.5h. Control rats received sham surgery and exposure to 1.5h of room air. One cohort of rats was examined for growth patterns through P33, evaluated using a battery of tests focused on early postnatal feeding behaviors, and studied using the open field paradigm during the early postnatal and postweaning periods. Another cohort of rats was used to examine metabolic parameters using indirect calorimetry. Significant growth deficits emerged in injured rats during the second postnatal week. No significant differences between groups were noted in the expression of feeding-related behaviors or in metabolic parameters between groups. However, we did observe significant associations between feeding-related behaviors and P14 growth parameters in injured rats. In the open field assessment, HI rats showed increased circling and supination behaviors only during the early postnatal period. Our data reveal that P3 HI brain injury results in generalized growth deficits that persist through postweaning. Analyses suggest that alterations in feeding-related behaviors contribute to growth deficits following a P3 HI brain injury.