# Hydrogen Peroxide-Induced Re-Expression of Repressor Element 1-Silencing Transcription Factor Contributes to Cardiac Vagal Dysfunction in Type 2 Diabetes Mellitus

## TL;DR

This study shows that hydrogen peroxide increases REST in T2DM, which reduces cardiac vagal function and worsens heart complications.

## Contribution

The study identifies a new H2O2-REST-Cav2.2 signaling pathway involved in cardiac vagal dysfunction in T2DM.

## Key findings

- H2O2 treatment increases REST and decreases Cav2.2-α in NG108-15 cells.
- REST shRNA improves cardiac vagal function and cell excitability in T2DM rats.
- Catalase reduces REST levels in AVG neurons of T2DM rats.

## Abstract

Diabetes mellitus, especially type 2 diabetes mellitus (T2DM), is a major health problem worldwide and has become a leading cause of mortality. As a common complication of patients with T2DM, cardiac autonomic dysfunction (including sympathetic overactivation and reduced vagal tone) is associated with a higher risk of arrhythmia-related sudden cardiac death. Our previous study found that T2DM-elevated hydrogen peroxide (H2O2) levels in atrioventricular ganglion (AVG) neurons contribute to the decrease in cardiac vagal function and ventricular arrhythmogenesis through inhibition of N-type Ca2+ channels (Cav2.2). In the present study, treatment with exogenous H2O2 in differentiated NG108-15 cells increased REST expression and decreased Cav2.2-α expression. Adenoviral catalase gene transfection into the AVG neurons significantly reduced the REST levels elevated by a high-fat diet plus streptozotocin-induced T2DM. Lentiviral REST shRNA transfection markedly increased Cav2.2-α expression in the AVG neurons from T2DM rats. REST shRNA also activated N-type Ca2+ channels and increased cell excitability of AVG neurons in T2DM rats. Additionally, REST shRNA markedly improved cardiac vagal activation in T2DM rats. The present study suggests that the H2O2-REST-Cav2.2 channel signaling axis could be a potential therapeutic target to normalize cardiac vagal dysfunction and its related cardiac complications in T2DM.