Brain metabolic alteration at a late phase of immune fatigue model mice using parahydrogen-polarized [1-13C] pyruvate MRI.

Motivation: Long-lasting brain issues including cognitive impairments after infections have become a worldwide problem after COVID-19. Goal(s): Our goal was to detect brain metabolic alteration at a late phase of immune fatigue. Approach: Parahydrogen-polarized 13C MRI of pyruvate metabolism was applied in the brain of 3 days poly I:C treated mice. Results: Alteration of brain pyruvate metabolism toward glycolysis was observed in both acute phase at day 3 and late phase at day 14 of immune fatigue model mice, which was correlated with diminished dopamine signal marker and nighttime moving distance in open-field test. Impact: Our demonstration of a detectable alteration of brain pyruvate metabolism by parahydrogen-polarized 13C MRI at a late phase of immune fatigue mice can be a useful biomarker of cognitive impairments after infections such as brain fog of long-COVID.