title: Oral glycine administration increases brain glycine/creatine ratios in men: a proton magnetic resonance spectroscopy study.
abstract: Oral high-dose glycine administration has been used as an adjuvant treatment for schizophrenia to enhance glutamate neurotransmission and mitigate glutamate system hypofunction thought to contribute to the disorder. Prior studies in schizophrenia subjects documented clinical improvements after 2 weeks of oral glycine administration, suggesting that brain glycine levels are sufficiently elevated to evoke a clinical response within that time frame. However, no human study has reported on brain glycine changes induced by its administration. We utilized a noninvasive proton magnetic resonance spectroscopy ((1)H-MRS) technique termed echo time-averaged (TEAV) (1)H-MRS, which permits noninvasive quantification of brain glycine in vivo, to determine whether 2 weeks of oral glycine administration (peak dose of 0.8 g/kg/day) increased brain glycine/creatine (Gly/Cr) ratios in 11 healthy adult men. In scans obtained 17 h after the last glycine dose, brain (Gly/Cr) ratios were significantly increased. The data indicate that it is possible to measure brain glycine changes with proton spectroscopy. Developing a more comprehensive understanding of human brain glycine dynamics may lead to optimized use of glycine site agonists and glycine transporter inhibitors to treat schizophrenia, and possibly to treat other disorders associated with glutamate system dysfunction.
authors: Brain Imaging Center, McLean Hospital, Harvard Medical School, Belmont, MA 02478, United States. kaufman@mclean.harvard.edu
authors: Marc J
authors: MJ
authors: Kaufman
authors: Andrew P
authors: AP
authors: Prescot
authors: Dost
authors: D
authors: Ongur
authors: A Eden
authors: AE
authors: Evins
authors: Tanya L
authors: TL
authors: Barros
authors: Carissa L
authors: CL
authors: Medeiros
authors: Julie
authors: J
authors: Covell
authors: Liqun
authors: L
authors: Wang
authors: Maurizio
authors: M
authors: Fava
authors: Perry F
authors: PF
authors: Renshaw
mesh_terms: D000284:Administration, Oral; D000328:Adult; D001921:Brain / Q000378:metabolism*; D003401:Creatine / Q000378:metabolism*; D005998:Glycine / Q000008:administration & dosage* / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D009778:Occipital Lobe / Q000378:metabolism; D011522:Protons
chemical_list: D011522:Protons; D003401:Creatine; D005998:Glycine