Structural and functional MRI following 4-aminopyridine-induced seizures: a comparative imaging and anatomical study.
Structural and functional MRI was used in conjunction with computerized electron microscopy morphometry to study changes 2 h, 24 h and 3 days after 4-aminopyridine-induced seizures lasting 2 h in rats. T2 (relaxation time) values showed changes throughout the cerebral cortex, hippocampus, amygdala and medial thalamus, with a different temporal progression, showing a complete recovery only after 3 days. Two hours after seizures, the apparent diffusion coefficient was decreased throughout the brain compared to control animals, and a further decrease was evident 24 h after seizures. This was followed by a complete recovery at 3 days post-seizures. Functional MRI was performed using regional cerebral blood volume (rCBV) maps. The rCBV was increased shortly after convulsions (2 h) in all structures investigated, with a significant return to baseline values in the parietal cortex and hippocampus, but not in the medial thalamic nuclei, 24 h after seizure onset. No rCBV alterations were detected 3 days after seizures. Electron microscopy of tissue samples of parietal neocortex and hippocampus revealed prominent astrocytic swelling 2 h post-convulsions which decreased thereafter gradually. In conclusion, this experiment reports for the first time structural and functional brain alterations, lasting several hours, in 4-aminopyridine-treated rats after seizure onset. MRI approach combined with histological and ultrastructural analysis provided a clarification of the mechanisms involved in the brain acute response to ictal activity.
Fabene
P F
PF
Section of Anatomy and Histology, Department of Morphological and Biomedical Sciences, Faculty of Medicine, Strada Le Grazie 8, 37134 Verona, Italy. paolo@anatomy.univr.it
Weiczner
R
R
Marzola
P
P
Nicolato
E
E
Calderan
L
L
Andrioli
A
A
Farkas
E
E
Süle
Z
Z
Mihaly
A
A
Sbarbati
A
A
D015761:4-Aminopyridine; D000679:Amygdala / Q000473:pathology / Q000503:physiopathology; D000818:Animals; D001253:Astrocytes / Q000473:pathology / Q000648:ultrastructure; D001921:Brain / Q000473:pathology* / Q000503:physiopathology; D001931:Brain Mapping; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D004827:Epilepsy / Q000139:chemically induced / Q000473:pathology* / Q000503:physiopathology; D006624:Hippocampus / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008854:Microscopy, Electron; D010296:Parietal Lobe / Q000473:pathology / Q000503:physiopathology; D026902:Potassium Channel Blockers; D017966:Pyramidal Cells / Q000473:pathology / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013702:Temporal Lobe / Q000473:pathology / Q000503:physiopathology; D013788:Thalamus / Q000473:pathology / Q000503:physiopathology
D026902:Potassium Channel Blockers; D015761:4-Aminopyridine