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Degeneration of spinal dorsal root ganglia in adult rats treated with methylmercury: Chronological observations on the cell bodies, centrally directed axons and presynaptic terminals
Author(s) -
Su Mu,
Kakita Akiyoshi,
Wakabayashi Koichi,
Yamada Mitsunori,
Takahashi Hitoshi,
Ikuta Fusahiro
Publication year - 1997
Publication title -
neuropathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.701
H-Index - 61
eISSN - 1440-1789
pISSN - 0919-6544
DOI - 10.1111/j.1440-1789.1997.tb00039.x
Subject(s) - degeneration (medical) , anatomy , cell bodies , spinal cord , axon , ultrastructure , axoplasmic transport , biology , central nervous system , neuroscience , pathology , medicine
In order to elucidate the degenerative process of the central, i.e. ascending, axons and of the spinal dorsal root ganglion (DRG) neurons caused by methylmercury (MeHg) intoxication, we performed chronological ultrastructural observations in rats given 10 mg/kg per day of MeHg on consecutive days and sacrificed on days 5, 6, 7, 9, 11, 12 and 16 (day 1 was the day the first dose was administered; maximum 10 days). On day 5, the distal axons and presynaptic terminals in the gracile nucleus showed dystrophic changes manifested by accumulation of mitochondria, dense bodies and irregularly branching tubular structures, but no abnormalities were detected in the cell bodies in the DRG or the proximal axons in the gracile fascicle. From day 7 onward, cell body degeneration and loss became apparent, followed by anterograde degeneration of the proximal axons. These findings indicate that in MeHg intoxication, the distal portions, including the presynaptic terminals, of the centrally directed axons of the DRG neurons are affected first, but the subsequent pattern of progressive degeneration is not consistent with the dying‐back process. We consider that this initial axonal change reflects the preceding subtle biochemical derangements in the cell bodies.