title: Age-dependent changes in noradrenergic innervations of the frontal cortex in F344 rats.
abstract: Noradrenergic innervations of the frontal cortex with advancing age (9, 13 and 25 months) in male F344 rats were quantified by immunohistochemistry for dopamine-beta-hydroxylase (DBH), which is a marker enzyme for noradrenergic axons. The density of DBH-positive axons, varicosities (swellings along an axon from which noradrenaline is released), and the number of varicosities per unit length of axon were measured in the frontal cortex. We found that the density of axons and varicosities significantly decreased at an earlier stage of aging (9-13 months), but not at a later stage (13-25 months). On the other hand, the number of varicosities per unit length of axon did not change with age. The result shows that the density of varicosities, which represent the synapses of noradrenergic neurons, decrease in the frontal cortex in the early aging process.
authors.affiliation: Department of Basic Gerontology, National Institute for Longevity Sciences, Gengo 36-3, Morioka-cho, 4748522, Obu, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ishida
authors.forename: T
authors.initials: T
authors.lastname: Shirokawa
authors.forename: O
authors.initials: O
authors.lastname: Miyaishi
authors.forename: Y
authors.initials: Y
authors.lastname: Komatsu
authors.forename: K
authors.initials: K
authors.lastname: Isobe
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001923:Brain Chemistry / Q000502:physiology; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D005625:Frontal Lobe / Q000166:cytology* / Q000378:metabolism*; D008125:Locus Coeruleus / Q000166:cytology / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000201:enzymology; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D004299:Dopamine beta-Hydroxylase; D009638:Norepinephrine