title: Memory-related changes in L-citrulline and agmatine in the rat brain.
abstract: L-citrulline, L-ornithine, and agmatine are the metabolites of L-arginine by nitric oxide synthase (NOS), arginase, and arginine decarboxylase (ADC), respectively. In contrast to the NOS and arginase pathways, the role of the ADC-agmatine pathway in learning and memory has only been paid attention lately. Recent evidence suggests a potential involvement of agmatine in learning and memory processing. The present study further addressed this issue by comparing the levels of agmatine, as well as L-arginine, L-citrulline, and L-ornithine, in the hippocampus, parahippocampal region, prefrontal cortex, vestibular nucleus, and cerebellum in rats that were trained in the delayed nonmatch to position task in the T-maze with their yoked controls. There were significantly increased agmatine levels in the prefrontal, entorhinal, and perirhinal cortices and increased L-citrulline concentrations in the dentate gyrus (DG) and prefrontal cortex in the T-maze training group relative to the control one. L-arginine and L-ornithine levels were not significantly different between groups in the brain regions examined. These results demonstrate T-maze training-induced region-specific increases in L-citrulline and agmatine. Significant positive correlations between prefrontal and perirhinal agmatine levels and animals' performance in the T-maze further suggest the direct involvement of agmatine in learning and memory processing.
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: Yu
authors.initials: Y
authors.lastname: Jing
authors.forename: Nicola D
authors.initials: ND
authors.lastname: Collie
authors.forename: Sree
authors.initials: S
authors.lastname: Chary
authors.forename: Hu
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000376:Agmatine / Q000378:metabolism*; D000818:Animals; D001120:Arginine / Q000378:metabolism; D001921:Brain / Q000502:physiology*; D002956:Citrulline / Q000378:metabolism*; D008297:Male; D018782:Maze Learning / Q000502:physiology; D008568:Memory / Q000502:physiology*; D009952:Ornithine / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002956:Citrulline; D000376:Agmatine; D001120:Arginine; D009952:Ornithine