Stable isotope approaches for CNS lipid metabolism: From precision quantification to metabolic tracing

Lipids are central to membrane organization, signaling, myelination, and metabolic homeostasis in the central nervous system (CNS), where their abundance, turnover, and spatial distribution are tightly regulated. Stable isotope approaches provide complementary ways to interrogate this complexity. Here, we integrate evidence from cellular, animal, and human studies to compare stable isotope dilution (SID) and chemical isotope labeling (CIL) for precise lipid quantification with metabolic tracing strategies that resolve synthesis, turnover, pathway contribution, and lipid trafficking. We examine their implementation across mass spectrometry, NMR, vibrational spectroscopy (VS), and imaging platforms, together with kinetic and flux-modeling frameworks that connect isotope-enrichment patterns to pathway activity. We further highlight spatially and cell-type-resolved isotope measurements that extend lipid analysis from bulk abundance to regional and cellular metabolic organization. These advances establish a framework linking lipid composition with metabolic dynamics and provide mechanistic insight into CNS physiology, neurological disease, myelin repair, and metabolic intervention strategies.