title: Manganese-enhanced magnetic resonance imaging of mossy fiber plasticity in vivo.
abstract: Mn(2+)-enhanced magnetic resonance imaging (MEMRI) was used to characterize activity-dependent plasticity in the mossy fiber pathway after intraperitoneal kainic acid (KA) injection. Enhancement of the MEMRI signal in the dentate gyrus and the CA3 subregion of the hippocampus was evident 3 to 5 days after injection of MnCl(2) into the entorhinal cortex both in control and KA-injected rats. In volume-rendered three-dimensional reconstructions, Mn(2+)-induced signal enhancement revealed the extent of the mossy fiber pathway throughout the septotemporal axis of the dentate gyrus. An increase in the number of Mn(2+)-enhanced pixels in the dentate gyrus and CA3 subfield of rats with KA injection correlated (P < 0.05) with histologically verified mossy fiber sprouting. These data demonstrate that MEMRI can be used to detect specific changes at the cellular level during activity-dependent plasticity in vivo. The present findings also suggest that MEMRI signal changes can serve as an imaging marker of epileptogenesis.
authors.affiliation: Department of Biomedical NMR and National Bio-NMR Facility, Virtanen Institute for Molecular Sciences, University of Kuopio, PO Box 1627, FIN-70 211 Kuopio, Finland.
authors.forename: Jaak
authors.initials: J
authors.lastname: Nairismägi
authors.forename: Asla
authors.initials: A
authors.lastname: Pitkänen
authors.forename: Susanna
authors.initials: S
authors.lastname: Narkilahti
authors.forename: Joanna
authors.initials: J
authors.lastname: Huttunen
authors.forename: Risto A
authors.initials: RA
authors.lastname: Kauppinen
authors.forename: Olli H J
authors.initials: OH
authors.lastname: Gröhn
mesh_terms: D000818:Animals; D001369:Axons / Q000000981:diagnostic imaging; D001921:Brain / Q000033:anatomy & histology*; D001931:Brain Mapping; D002712:Chlorides; D018891:Dentate Gyrus / Q000033:anatomy & histology; D004292:Dominance, Cerebral / Q000502:physiology; D018728:Entorhinal Cortex / Q000033:anatomy & histology; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007608:Kainic Acid; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D017895:Manganese Compounds; D019599:Mossy Fibers, Hippocampal / Q000648:ultrastructure; D009412:Nerve Fibers / Q000648:ultrastructure*; D009415:Nerve Net / Q000033:anatomy & histology; D009416:Nerve Regeneration / Q000502:physiology; D009434:Neural Pathways / Q000033:anatomy & histology*; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000000981:diagnostic imaging; D051381:Rats; D013788:Thalamus / Q000033:anatomy & histology; D014463:Ultrasonography
chemical_list: D002712:Chlorides; D017895:Manganese Compounds; C025340:manganese chloride; D007608:Kainic Acid