Volumetric magnetic resonance imaging of functionally relevant structural alterations in chronic epilepsy after pilocarpine-induced status epilepticus in rats.
OBJECTIVE
After pilocarpine-induced epilepsy in rats, volumetric magnetic resonance imaging (MRI) reveals significant morphologic changes in functionally relevant structures of the brain. To relate structural changes to functional alteration, we studied the correlation of regional brain atrophy (e.g., of the hippocampus) with lesion-induced learning deficits in the Morris water maze.


METHODS
MRI experiments were performed on an MR scanner at 4.7 Tesla. For volumetric analysis, various cerebral structures were segmented in horizontal and coronal T(2)-weighted MR images. Before the MRI investigations, animals were trained for 10 days in a Morris water maze.


RESULTS
Volumetric MRI revealed a significant loss in hippocampal size in both the dorsal and ventral parts, correlated with an increase in ventricular size. Furthermore, significant losses were found in the relative size of thalamus, putamen, cortex, and the combined areas of perirhinal, entorhinal, and piriform cortices adjacent to the hippocampus. A significant correlation of learning performance in the Morris water maze with the relative hippocampal area and not with other areas tested was observed in pilocarpine-treated animals.


CONCLUSIONS
The data provide a quantitative analysis of functionally relevant structural alterations in rats with chronic epilepsy. Water maze performance of pilocarpine-treated animals correlates with the degree of hippocampal but not with the degree of cortical damage, demonstrating the potential of this method for the investigation of cognitive impairments in relation to cerebral changes. In addition, the data point to an important role of even the residual hippocampus in memory formation.
Niessen
Heiko G
HG
Department of Neurology II, Otto-von-Guericke University Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany. heiko.niessen@medizin.uni-magdeburg.de
Angenstein
Frank
F
Vielhaber
Stefan
S
Frisch
Christian
C
Kudin
Alexei
A
Elger
Christian E
CE
Heinze
Hans-Jochen
HJ
Scheich
Henning
H
Kunz
Wolfram S
WS
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001921:Brain / Q000473:pathology* / Q000503:physiopathology; D006624:Hippocampus / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D018782:Maze Learning / Q000502:physiology; D008568:Memory / Q000502:physiology; D010862:Pilocarpine; D051381:Rats; D017208:Rats, Wistar; D013226:Status Epilepticus / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology
D010862:Pilocarpine