title: Effects of aging on agmatine levels in memory-associated brain structures.
abstract: Agmatine is a metabolite of L-arginine by arginine decarboxylase. Recent evidence suggests that it exists in mammalian brain and is a novel neurotransmitter. The present study measured agmatine levels in several memory-associated brain structures in aged (24-month-old), middle-aged (12-month-old), and young (4-month-old) male Sprague Dawley rats using liquid chromatography/mass spectrometry. Agmatine levels were significantly decreased in the CA1, but increased in the CA2/3 and dentate gyrus, subregions of the hippocampus in aged and middle-aged rats relative to the young adults. In the prefrontal cortex, a dramatic decrease in agmatine level was found in aged rats as compared with middle-aged and young rats. There were significantly increased levels of agmatine in the entorhinal and perirhinal cortices in aged relative to middle-aged and young rats. In the postrhinal and temporal cortices, agmatine levels were significantly increased in aged and middle-aged rats as compared with young adults. The present findings, for the first time, demonstrate age-related changes in agmatine levels in memory-associated brain structures and raise a novel issue of the potential involvement of agmatine in the aging process.
authors.affiliation: Department of Anatomy and Structural Biology, University of Otago, Dunedin, New Zealand. ping.liu@stonebow.otago.ac.nz
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.forename: Sree
authors.initials: S
authors.lastname: Chary
authors.forename: Renuka
authors.initials: R
authors.lastname: Devaraj
authors.forename: Yu
authors.initials: Y
authors.lastname: Jing
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Darlington
authors.forename: Paul F
authors.initials: PF
authors.lastname: Smith
authors.forename: Ian G
authors.initials: IG
authors.lastname: Tucker
authors.forename: Hu
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000375:Aging / Q000378:metabolism* / Q000502:physiology / Q000523:psychology; D000376:Agmatine / Q000032:analysis / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000502:physiology; D006624:Hippocampus / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D008297:Male; D008568:Memory / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013702:Temporal Lobe / Q000737:chemistry / Q000378:metabolism / Q000502:physiology
chemical_list: D000376:Agmatine