title: Metabolite changes in neonatal rat brain during and after cerebral hypoxia-ischemia: a magnetic resonance spectroscopic imaging study.
abstract: Cerebral metabolite concentrations were measured in infant rats using proton magnetic resonance spectroscopic imaging. Measurements were made prior to, during and after exposure of rats (6- and 7-day-old) to unilateral cerebral hypoxia-ischemia (right carotid artery occlusion +2h 8% oxygen). Data clustered according to age and outcome-6-day-old animals with no infarct and 7-day-old animals with infarct. In 6-day-old animals, cerebral lactate concentration increased during hypoxia-ischemia, particularly ipsilateral to the occlusion, and returned to normal soon after the end of hypoxia. There were no major changes in N-acetyl-aspartate levels (NAA) in this group and no regions of hyperintensity on T2 or DW weighted images at 24 h. In the 7-day-old animals, lactate increased during hypoxia-ischemia and remained elevated in the first hour after reperfusion. Furthermore, lactate remained at 258+/-117% and 233+/-56% of pre-hypoxic levels, 24 and 48 h post-hypoxia, respectively. NAA concentrations ipsilateral to the occlusion decreased to 55+/-14% during hypoxia, recovered early post-hypoxia and again decreased to 61+/-25% and 41+/-28% at 24 and 48 h post-hypoxia-ischemia, respectively. The infarct volumes measured by diffusion weighted and T2 weighted MRI at 48 h post-hypoxia were 152+/-40 mm3 and 172+/-35 mm3, respectively. Thus, irreversible damage correlated well with measured in vivo lactate and NAA changes. Those animals in which NAA was unaltered and lactate recovered soon after hypoxia did not show long-term damage (6-day-old animals), whereas those animals in which NAA decreased and lactate remained elevated went on to infarction (7-day-old animals).
authors: Institute for Biodiagnostics, NRCC, Winnipeg, Manitoba, Canada.
authors: K L
authors: KL
authors: Malisza
authors: P
authors: P
authors: Kozlowski
authors: G
authors: G
authors: Ning
authors: S
authors: S
authors: Bascaramurty
authors: U I
authors: UI
authors: Tuor
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002545:Brain Ischemia / Q000150:complications / Q000378:metabolism*; D002544:Cerebral Infarction / Q000209:etiology / Q000378:metabolism; D005260:Female; D002534:Hypoxia, Brain / Q000150:complications / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods; D011247:Pregnancy; D011522:Protons; D051381:Rats; D017208:Rats, Wistar
chemical_list: D011522:Protons; D001224:Aspartic Acid; D019344:Lactic Acid; C000179:N-acetylaspartate