Ultrastructural changes in granule cell somata and mossy fibers of the rat hippocampus during picrotoxin-induced convulsions.
Ultrastructural changes in hippocampal granule cells, mossy fibers and mossy fiber boutons were examined following the administration of picrotoxin in adult rats. Generalized seizures occurred within 5-10 min after the intraperitoneal injection of picrotoxin. The electron-microscopic examination of hippocampal tissues from rats that had been perfused with fixative during the seizure revealed that the large dense-core vesicles increased in number and accumulated on the presynaptic membranes of mossy fiber boutons; some of these vesicles appeared to be fused with the membranes, and omega-shaped exocytotic profiles were frequently seen. Furthermore, greatly increased numbers of coated vesicles (60-90 nm in diameter) were observed on the maturing faces of Golgi fields of granule cells. Thus, our study not only indicates an increased incidence of exocytosis of large dense-core vesicles during picrotoxin-induced seizures, but also suggests that these vesicles are replaced in excess from the perikaryon of the granule cell.
Watanabe
H
H
Department of Anatomy, Okayama University Medical School, Japan.
Mizukawa
K
K
Otsuka
N
N
D000818:Animals; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure*; D002479:Inclusion Bodies / Q000648:ultrastructure*; D008297:Male; D008854:Microscopy, Electron; D010852:Picrotoxin; D051381:Rats; D011919:Rats, Inbred Strains; D012640:Seizures / Q000139:chemically induced* / Q000473:pathology
D010852:Picrotoxin