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Abstract #3295

Detection of GABA C1 Turnover in Rat Brain in Vivo

Jehoon Yang1,2, Jun Shen3

1NIMH, USA; 2Samsung Biomedical Research Institute, Korea; 3NIMH, Bethesda, MD, USA

Previous in vivo MRS studies of GABA turnover have relied on 13C label incorporation into GABA C2. In this study, the [13C]GABA C1 signal at 182.3 ppm in the carboxylic/amide spectral region of localized in vivo 13C spectra was spectrally resolved and detected in the rat brain at 11.7 Tesla using low RF power proton decoupling. GABA-transaminase of rat brain was inhibited by gabaculine after pre-labeling of GABA C1 and its precursors with [2,5-13C2]glucose. A subsequent isotope chase experiment revealed a markedly slow turnover of GABA accompanying the blockade of the GABA shunt.