1992 Fiscal Year Final Research Report Summary
Morphology and function of mossy fiber sprouting associated with limbic seizures
| Project/Area Number |
03670569
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Psychiatric science
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| Research Institution | Fukushima Medical College |
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Principal Investigator |
MORI Norio Fukushima Medical College Assistant Prof., 医学部, 講師 (00174376)
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| Project Period (FY) |
1991 – 1992
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| Keywords | epileptic seizures / hippocampus / mossy fiber / granule cell / sprouting |
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| Research Abstract |
The possible roles played by mossy fiber sprouting in the generalization and expression of limbic seizures were examined. In this study, amygdaloid-kindled rat was used as a chronic model of epilepsy. Limbic status epileptics induced by intra-amygdaloid injection of dibutyryl-cAMP (ab-cAMP) was used an acute model of epilepsy. El mouse was used as a hereditary model of epilepsy.
1. In kindled rats, morphological examination showed evidence of mossy fiber sprouting in the inner molecular layer of the dentate gyrus and in the CA3/CA4 subfield of bilateral hippocampi. Limbic status epileptics caused a similar sprouting, especially in the bilateral dentate gyri. However, no evidence of mossy fiber sprouting was obtained in El mice. Thus, kindling and status epilepticus, but not El mouse, are suitable models for examination of seizure-related mossy fiber sprouting.
2. When rats which experienced limbic status epilepticus were subjected to MAP2 immunohistochemistry, a marked increase in MAP2 immunoreactivity was observed in the bilateral dentate gyri. This suggest that mossy fiber synaptic reorganization occurs in the dentate gyri after limbic seizures.
3. Sprague-Dawley (SD) rats have infrapyramidal bundle of mossy fibers in CA3/CA4 subfield of the hippocampus. This distribution of mossy fibers is not seen in Wistar rats, but becomes to be evident after completion of kindling. Destruction of granule cells decreased the rate of kindling in SD rats, but had no effect in Wistar rats. The same treatment after completion of kindling suppressed generalized kindled seizures in Wistar rats, but had no effect in SD rats. It is suggested that mossy fibers in the infrapyramidal region have an important role in the development of limbic motor seizures.
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