title: Ultrastructure of aberrant serotonin-immunoreactive fibers in the caudate putamen complex of the aged rat.
abstract: Degeneration of neurons in the central nervous system is associated with morphological changes. Previous observations made at the light microscopical level indicated degeneration of serotonin-immunoreactive (IR) fibers in the aged rat brain. In this study, a comparison at the ultrastructural level was made between serotonin-IR normal thin and aberrant swollen varicose fibers in the caudate-putamen complex of the aged rat. Ultrastructural features such as the size and content of the thin varicose fibers resembled those in the caudate-putamen complex of the young rat as reported by others. The aberrant profiles were swollen, reaching a size of 6 microns. Their vesicles varied in size and were no longer uniformly round. Moreover, distorted mitochondria and membrane-filled vacuolelike structures were a common feature of the aberrant profiles. These changes are indicative of a degenerative process and give further evidence that, whereas many serotonergic fibers are preserved at high age, other serotonergic fibers are degenerating in the caudate-putamen complex of the aged rat.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Free University, Amsterdam, The Netherlands.
authors.forename: M G
authors.initials: MG
authors.lastname: Van Luijtelaar
authors.forename: F G
authors.initials: FG
authors.lastname: Wouterlood
authors.forename: J A
authors.initials: JA
authors.lastname: Tonnaer
authors.forename: H W
authors.initials: HW
authors.lastname: Steinbusch
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D002421:Caudate Nucleus / Q000033:anatomy & histology / Q000276:immunology / Q000648:ultrastructure*; D008297:Male; D008928:Mitochondria / Q000187:drug effects; D009410:Nerve Degeneration; D009474:Neurons / Q000276:immunology / Q000648:ultrastructure*; D011699:Putamen / Q000033:anatomy & histology / Q000276:immunology / Q000648:ultrastructure*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000276:immunology / Q000502:physiology*
chemical_list: D012701:Serotonin