A newborn piglet study of moderate hypoxic-ischemic brain injury by 1H-MRS and MRI.

Cerebral hypoxia-ischemia (HI) is an important cause of perinatal brain damage in the term newborn. The areas most affected are the parasagittal regions of the cerebral cortex and, in severe situations, the basal ganglia. The aim of this study was to show that the newborn piglet model can be used to produce neuropathology resulting from moderate HI insult and to monitor damage for 7 days. Two acute cerebral HI were induced in newborn Large White piglets by reducing the inspired oxygen fraction to 4% and occluding the carotid arteries. Newborn piglets were resuscitated, extubated and monitored for 7 days. (31)P magnetic resonance spectroscopy (MRS) offers the ability to monitor the severity of the HI insults. Lactate (Lac) was detected in the HI group at 2 h, 3 days and 5 days after insult by (1)H MRS. Lac/n-acetylaspartate and Lac/choline and Lac/creatine ratios increased significantly (p < 0.01) in the HI group 2 h after HI insults and remained high over 7 days. For the HI group, mean T(2) values increased significantly in the parietal white matter (subcortical) for 5 days after HI insult [117.5 (+/-7.4) to 158.5 (+/-19.2) at T+3 days, 167.7 (+/-15.4) at T+5 days and 160.9 (+/-10.1) at T+7 days (p < 0.01)]. This newborn piglet model of moderate HI brain injury with reproducible cerebral damage could be use as reference for the study of neuroprotective strategy for a period of 7 days.