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Direct in vivo measurement of glycine and the neurochemical profile in the rat medulla oblongata
Author(s) -
Xin Lijing,
Gambarota Giulio,
Duarte João M. N.,
Mlynárik Vladimír,
Gruetter Rolf
Publication year - 2010
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1537
Subject(s) - glycine , neurochemical , taurine , glutamine , in vivo , chemistry , glutamate receptor , biochemistry , sarcosine , biology , endocrinology , amino acid , receptor , microbiology and biotechnology
The medulla oblongata (MO) contains a high density of glycinergic synapses and a particularly high concentration of glycine. The aims of this study were to measure directly in vivo the neurochemical profile, including glycine, in MO using a spin‐echo‐based 1 H MRS sequence at TE = 2.8 ms and to compare it with three other brain regions (cortex, striatum and hippocampus) in the rat. Glycine was quantified in MO at TE = 2.8 ms with a Cramér–Rao lower bound (CRLB) of approximately 5%. As a result of the relatively low level of glycine in the other three regions, the measurement of glycine was performed at TE = 20 ms, which provides a favorable J‐modulation of overlapping myo‐inositol resonance. The other 14 metabolites composing the neurochemical profile were quantified in vivo in MO with CRLBs below 25%. Absolute concentrations of metabolites in MO, such as glutamate, glutamine, γ‐aminobutyrate, taurine and glycine, were in the range of previous in vitro quantifications in tissue extracts. Compared with the other regions, MO had a three‐fold higher glycine concentration, and was characterised by reduced ( p < 0.001) concentrations of glutamate (−50 ± 4%), glutamine (–54 ± 3%) and taurine (−78 ± 3%). This study suggests that the functional specialisation of distinct brain regions is reflected in the neurochemical profile. Copyright © 2010 John Wiley & Sons, Ltd.