Temporal evolution of NMDA-induced excitoxicity in the neonatal rat brain measured with 1H nuclear magnetic resonance imaging

• Published in: Brain research Vol. 618; no. 2; pp. 203 - 212
• Main Authors: Verheul, H.B., Balázs, R., Berkelbach van der Sprenkel, J.W., Tulleken, C.A.F., Nicolay, K., van Lookeren Campagne, M.
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 06.08.1993; Amsterdam Elsevier; New York, NY
• Subjects: Animals; Animals, Newborn - physiology; Biological and medical sciences; Brain damage; Brain Diseases - chemically induced; Brain Diseases - pathology; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Corpus Striatum; Diffusion; Dizocilpine Maleate - pharmacology; Excitotoxicity; Fundamental and applied biological sciences. Psychology; Histocytochemistry; Magnetic resonance imaging; Magnetic Resonance Spectroscopy; Microinjections; N-methyl- d-aspartate (NMDA); N-Methylaspartate - administration & dosage; N-Methylaspartate - toxicity; Necrosis - chemically induced; Necrosis - pathology; Neonatal rat; Rats; Vertebrates: nervous system and sense organs; N-methyl- d-aspartate (NMDA); Brain damage; Magnetic resonance imaging; Diffusion; Excitotoxicity; Neonatal rat; Vertebrata; Mammalia; Rat; Toxicity; Neuromediator; Newborn animal; Rodentia; Central nervous system; Excitatory aminoacid; Nuclear magnetic resonance imaging; Brain (vertebrata)
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/0006-8993(93)91267-V

The aim of this study is to characterize the evolution of excitotoxic damage in neonatal rat brain by diffusion-weighted and T 2-weighted magnetic resonance imaging. Results are compared with histological findings. Magnetic resonance imaging was performed at various times (15 min, 24 h, 3 days and 5 days) after intrastriatal microinjection of N-methyl- d-aspartate (NMDA) at postnatal day 8. The transverse relaxation time (T 2) and apparent diffusion coefficient of water were determined. The results show an acute reduction of the apparent diffusion coefficient, reflected by an ipsilateral hyperintensity in the diffusion-weighted images, within 15 min after intrastriatal NMDA injection. At this time no changes in the T 2-weighted images were apparent. The volume of the hyperintensity was relatively large with a radius of approximately 2 mm and coincided with histological signs of pronounced karyo-dendritic swelling. Subcutaneous administration of MK-801 25 min after the intracerebral NMDA injection readily reversed the hyperintensity and resulted in complete protection as verified by histology. Areas with increased T 2 values were observed 1 day after NMDA microinjection and corresponded to regions with obvious cell necrosis. Five days after NMDA injection the lesion was evident using both diffusion- and T 2-weighted images and coincided with an overt lesion comprising areas of cell loss and dilatation of the ipsilateral ventricle. In conclusion, this study illustrates the possibility of using diffusion-weighted imaging as a tool to monitor efficacy of treatment strategies at an early stage of excitotoxic injury.