Astrocytes contribute to signals of Hyperpolarized 13C pyruvate in the brain

Motivation: Hyperpolarized MR (HP-MR) 13C pyruvate is a valuable probe for evaluating glycolytic flux, but it remains unknown which cells contribute to the HP-MR signals in the brain. Goal(s): To verify whether astrocyte metabolism is involved in the signal of HP-MR 13C pyruvate in the brain. Approach: We perturbed Gq-GPCR/calcium (Ca2+) signaling in astrocytes using the hM3Dq DREADD system and examined the fluctuations of the HP-MR pyruvate signals in awake mice. Results: In HP-MR experiments conducted 30 minutes after the elevation of astrocyte Ca2+, the lactate/pyruvate ratio decreased compared to the control, and the bicarbonate/pyruvate ratio also decreased. Impact: Investigating the involvement of astrocyte metabolism in brain hyperpolarized MR(HP-MR) 13C pyruvate signals, astrocyte GPCR/Ca2+ signaling was perturbed using DREADD, revealing a decrease in lactate/pyruvate and bicarbonate/pyruvate ratios in HP-MR experiments, suggesting metabolic alterations in response to astrocyte GPCR/Ca2+ modulation.