title: A multivariate analysis of the effects of aging on glutamate, GABA and arginine metabolites in the rat vestibular nucleus.
abstract: Aging is associated with neurochemical changes in the brain that result in impaired vestibular reflex function. We analysed the concentrations of 9 related neurochemicals (l-arginine, l-citrulline, l-ornithine, agmatine, putrescine, spermidine, spermine, glutamate and gamma-aminobutyric acid (GABA)) in the vestibular nucleus of aged (24 months old) and young (4 month old) rats; the cerebellum was analysed for comparison. The effects of the housing conditions of the rats were also investigated. Age significantly affected the concentrations of the 9 neurochemicals in both the vestibular nucleus and cerebellum (P = 0.000). Housing did not have a significant effect and the interaction between age and housing was significant only for the vestibular nucleus (P = 0.03). For both the vestibular nucleus and cerebellum, linear discriminant functions were identified that significantly predicted whether the animals were 4 or 24 months old (P = 0.000). Using multiple regression analysis, only vestibular nucleus spermidine, spermine and l-arginine could be predicted from the other neurochemical variables with an adjusted R(2) of >80%. Cluster analyses were performed to determine if the neurochemical variables formed distinct groups and whether this changed as a function of age. For the vestibular nucleus but not the cerebellum, the clusters were substantially different for the 24 month old and 4 month old animals.
authors.affiliation: Department of Anatomy and Structural Biology, University of Otago, Dunedin, New Zealand.
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.forename: Hu
authors.initials: H
authors.lastname: Zhang
authors.forename: Renuka
authors.initials: R
authors.lastname: Devaraj
authors.forename: Ganes S
authors.initials: GS
authors.lastname: Ganesalingam
authors.forename: Paul F
authors.initials: PF
authors.lastname: Smith
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001120:Arginine / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism; D016000:Cluster Analysis; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D023421:Models, Animal; D015999:Multivariate Analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013095:Spermidine / Q000378:metabolism; D013096:Spermine / Q000378:metabolism; D014726:Vestibular Nuclei / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D013096:Spermine; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D001120:Arginine; D013095:Spermidine