In vivo γ-aminobutyric acid measurement in rats with spectral editing at 4.7T

Purpose: To evaluate the feasibility of spectral editing for quantification of c-aminobutyric acid (GABA) in the rat brain and to determine whether altered GABA concentration in the ventral striatum is a neural endophenotype associated with trait-like impulsive behavior. Materials and Methods: Spectra were acquired at 4.7T for 23 male Lister-hooded rats that had been previously screened for extremely low and high impulsivity phenotypes on an automated behavioral task (n511 low-impulsive; n512 high-impulsive). Voxels of 33734mm3 (84 lL) centered bilaterally across the ventral striatum were used to evaluate GABA concentration ratios. Results: Quantifiable GABA signals in the ventral striatum were obtained for all rats. Mean-edited GABA to n-acetyl aspartate (NAA) ratios in the ventral striatum were 0.22 (95% confidence interval [CI] [0.18, 0.25]). Mean GABA/NAA ratios in this region were significantly decreased by 28% in high-impulsive rats compared to low-impulsive rats (P50.02; 95% CI [–53%, –2%]). Conclusion: These findings demonstrate that spectral editing at 4.7T is a feasible method to assess in vivo GABA concentrations in the rat brain. The results show that diminished GABA content in the ventral striatum may be a neural endophenotype associated with impulsivity.