title: Preferential Accumulation of 14C-N-Glycolylneuraminic Acid over 14C-N-Acetylneuraminic Acid in the Rat Brain after Tail Vein Injection.
abstract: The two main molecular species of sialic acid existing in nature are N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc). Neu5Ac is abundant in mammalian brains and plays crucial roles in many neural functions. In contrast, Neu5Gc is present only at a trace level in vertebrate brains. The brain-specific suppression of Neu5Gc synthesis, which is a common feature in mammals, suggests that Neu5Gc has toxicity against brain functions. However, in vivo kinetics of Neu5Gc in the whole body, especially in the brain, has not been studied in sufficient detail. To determine the in vivo kinetics of Neu5Gc, 14C-Neu5Gc was enzymatically synthesized and injected into rat tail veins. Although most of 14C-Neu5Gc was excreted in urine, a small amount of 14C-Neu5Gc was detected in the brain. Brain autoradiography indicated that 14C-Neu5Gc was accumulated predominantly in the hippocampus. 14C-Neu5Gc transferred into the brain was incorporated into gangliosides including GM1, GD1a, GD1b, GT1b and GQ1b. Reduction of 14C-Neu5Gc after intracerebroventricular infusion was slower than that of 14C-Neu5Ac in the brain and hippocampus. The results suggest that Neu5Gc is transferred from blood into the brain across the blood brain barrier and accumulates in the brain more preferentially than does Neu5Ac.
authors.affiliation: Department of Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Risa
authors.initials: R
authors.lastname: Taguchi
authors.affiliation: Department of Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Minami
authors.affiliation: Department of Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Yukino
authors.initials: Y
authors.lastname: Matsuda
authors.affiliation: Department of Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Tadanobu
authors.initials: T
authors.lastname: Takahashi
authors.affiliation: Department of Organic Chemistry, School of Pharmaceutical Sciences, Hiroshima International University, Hiroshima, Japan.
authors.forename: Tadamune
authors.initials: T
authors.lastname: Otsubo
authors.affiliation: Department of Organic Chemistry, School of Pharmaceutical Sciences, Hiroshima International University, Hiroshima, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ikeda
authors.affiliation: Department of Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D001345:Autoradiography; D001812:Blood-Brain Barrier; D001921:Brain / Q000378:metabolism*; D002250:Carbon Radioisotopes; D006624:Hippocampus / Q000378:metabolism; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D008297:Male; D019158:N-Acetylneuraminic Acid / Q000008:administration & dosage / Q000493:pharmacokinetics*; D009438:Neuraminic Acids / Q000008:administration & dosage / Q000493:pharmacokinetics*; D051381:Rats; D017208:Rats, Wistar; D013623:Tail / Q000098:blood supply; D014018:Tissue Distribution
chemical_list: D002250:Carbon Radioisotopes; D009438:Neuraminic Acids; C032592:N-glycolylneuraminic acid; D019158:N-Acetylneuraminic Acid