Longitudinal 1H MRS of rat forebrain from infancy to adulthood reveals adolescence as a distinctive phase of neurometabolite development

This study represents the first longitudinal, within-subject (1) H MRS investigation of the developing rat brain spanning infancy, adolescence and early adulthood. We obtained neurometabolite profiles from a voxel located in a central location of the forebrain, centered on the striatum, with smaller contributions for the cortex, thalamus and hypothalamus, on postnatal days 7, 35 and 60. Water-scaled metabolite signals were corrected for T1 effects and quantified using the automated processing software LCModel, yielding molal concentrations. Our findings indicate age-related concentration changes in N-acetylaspartate + N-acetylaspartylglutamate, myo-inositol, glutamate + glutamine, taurine, creatine + phosphocreatine and glycerophosphocholine + phosphocholine. Using a repeated measures design and analysis, we identified significant neurodevelopment changes across all three developmental ages and identified adolescence as a distinctive phase in normative neurometabolic brain development. Between postnatal days 35 and 60, changes were observed in the concentrations of N-acetylaspartate + N-acetylaspartylglutamate, glutamate + glutamine and glycerophosphocholine + phosphocholine. Our data replicate past studies of early neurometabolite development and, for the first time, link maturational profiles in the same subjects across infancy, adolescence and adulthood.