Measurement of GABA following GABA-transaminase inhibition by gabaculine: A 1H and 31P NMR spectroscopic study of rat brain in vivo

A selective ¹H NMR spin-echo editing method was used to detect the CCH, of GABA in rat brain in vivo before and after intravenous administration of the highly selective GABA transaminase inhibitor, gabaculine (3-amino-2,3-dihydrobenzoic acid-HCl; 100 mg/kg, intravenously). The effects of the inhibitor on high energy phosphates and pH, were determined by ³¹P NMR. GABA levels increased approximately linearly (r = 0.81 to 0.94; P < 0.0005) from 1.9 ± 0.4 μmol/g (pre-gabaculine; mean ± SD) to between 6 and 8 μmollg after 4 hr at rates of accumulation of 1.1 to 2.9 μmol/hr/g. ¹H NMR spectroscopic measurements of cerebral GABA and its rate of turnover offers a new approach in the study of GABA-mediated processes in vivo.