Curbing action potential generation or ATP-synthase leads to a decrease in in-cell pyruvate dehydrogenase activity in rat cerebrum slices

Benjamin Grieb,Rachel Katz-Brull,Gal Sapir,J Moshe Gomori,Sivaranjan Uppala,David Shaul

doi:10.1038/s41598-021-89534-4

Abstract

Direct and real-time monitoring of cerebral metabolism exploiting the drastic increase in sensitivity of hyperpolarized 13C-labeled metabolites holds the potential to report on neural activity via in-cell metabolic indicators. Here, we followed the metabolic consequences of curbing action potential generation and ATP-synthase in rat cerebrum slices, induced by tetrodotoxin and oligomycin, respectively. The results suggest that pyruvate dehydrogenase (PDH) activity in the cerebrum is 4.4-fold higher when neuronal firing is unperturbed. The PDH activity was 7.4-fold reduced in the presence of oligomycin, and served as a pharmacological control for testing the ability to determine changes to PDH activity in viable cerebrum slices. These findings may open a path towards utilization of PDH activity, observed by magnetic resonance of hyperpolarized 13C-labeled pyruvate, as a reporter of neural activity.

Highlights

Direct and real-time monitoring of cerebral metabolism exploiting the drastic increase in sensitivity of hyperpolarized 13C-labeled metabolites holds the potential to report on neural activity via in-cell metabolic indicators
Preclinical studies showed a persistence of the hyperpolarized state in both [1-13C] lactate and [13C]bicarbonate in the brain of anesthetized rodents[12,13,14,15], and we have previously shown that cerebral metabolism can be measured using hyperpolarized [1-13C]pyruvate ex vivo—in perfused cerebral slices[4]
The temporal behavior of [1-13C]pyruvate metabolism was assessed by calculating the time-dependent production of [1-13C]lactate (LDH rate) and [ 13C]bicarbonate (PDH rate) for each acquisition

Summary

Introduction

Direct and real-time monitoring of cerebral metabolism exploiting the drastic increase in sensitivity of hyperpolarized 13C-labeled metabolites holds the potential to report on neural activity via in-cell metabolic indicators. The PDH activity was 7.4-fold reduced in the presence of oligomycin, and served as a pharmacological control for testing the ability to determine changes to PDH activity in viable cerebrum slices These findings may open a path towards utilization of PDH activity, observed by magnetic resonance of hyperpolarized 13C-labeled pyruvate, as a reporter of neural activity. We applied the product selective saturating-excitations approach in a study of cerebral slices to investigate whether changes in neural activity will be reflected in the metabolic activities of hyperpolarized [1-13C] pyruvate utilization To this end, we incubated cerebral slices with the canonical voltage-gated sodium-channel blocker tetrodotoxin (TTX) which is known to either diminish or altogether block action potential generation at concentrations of 0.2–10 μM20–23. The TTX effect was compared the effect of the antibiotic oligomycin (OLI27), which is an inhibitor of ATP-synthase

Methods

Results

Conclusion