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Epilepsy induced collateral sprouting of hippocampal mossy fibers: Does it induce the development of ectopic synapses with granule cell dendrites?
Author(s) -
Represa Alfonso,
Jorquera Isabel,
le gal la Salle Gildas,
BenAri Yehezkel
Publication year - 1993
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.450030303
Subject(s) - neuroscience , granule cell , mossy fiber (hippocampus) , schaffer collateral , hippocampal formation , chemistry , dendritic spine , anatomy , biology , excitatory postsynaptic potential , dentate gyrus , inhibitory postsynaptic potential
In the present study, using Golgi and electron microscopy techniques, experimentally induced epilepsy (kindling and kainate treatment) elicited collateral sprouting of mossy fibers in rat hippocampus. Collateral branches invade the hilus, cross the granule cell layer, and distribute throughout the inner third of the molecular layer. These newly developed collaterals may acquire the typical features of mossy fibers including giant fiber varicosities (mousses), although the mean surface of these mousses was thinner in these collaterals than in terminal branches. Granule cell dendrites may develop giant thorny excrescences, suggesting that the targets of these collaterals are granule cells. Giant synaptic boutons appear in the inner third of molecular layer of epileptic rats. These boutons acquire the morphological features of mossy fiber boutons and made multiple synaptic contacts with dendritic spines. The analysis of the profile types suggests that some of the newly developed collateral mossy fibers made hypotrophic synaptic contacts.