Metabolomic Analysis of the Serum in Rats with Methamphetamine-Induced Conditioned Place Preference

To understand what happens in the serum after methamphetamine (MA) administration, nuclear magnetic resonance-based metabolomics was performed to investigate the characteristic metabolite profile in the serum of rats with MA-induced conditioned place preference. The results showed that tyrosine concentration was significantly higher in the MA-induced group (1.68 × 10–5 ppm) than in the control group (0.99 × 10–5 ppm) (p = 0.004), uncharacterized lipid concentration was significantly higher in the control group (1.28 × 10–3 ppm) than in the MA-induced group (0.78 × 10–3 ppm) (p = 0.008), acetone concentration was significantly higher in the control (1.65 × 10–4 ppm) than in the and MA-induced group (1.10 × 10–4 ppm) (p = 0.005), and leucine concentration was significantly higher in the control (5.20 × 10–4 ppm) than in the MA-induced group (4.37 × 10–4) (p-value = 0.03). This decrease in acetone concentration in the MA-induced group may help elucidate why ketogenic diet has shown promise for many neurological disorders. Tyrosine is the precursor of dopamine and γ-aminobutyric acid, and leucine is the major nitrogen donor for glutamate synthesis. These results suggest that a disturbance in the substrate supply in the circulatory system partly explains MA toxicity in the central nervous system.