Methylene Blue Reduces Neuronal Apoptosis and Improves Blood-Brain Barrier Integrity After Traumatic Brain Injury.

Jun Shen,Jianning Zhang,Yalong Gao,Qifeng Li,Wenqiang Xin,Lili Yuan

doi:10.3389/fneur.2019.01133

Abstract

Objective: To investigate whether methylene blue (MB) treatment can reverse neuronal mitochondrial dysfunction caused by oxygen glucose deprivation/reoxygenation (OGD) injury and then investigate whether MB treatment can reduce neuronal apoptosis and improve blood-brain barrier (BBB) integrity in traumatic brain injury (TBI) animals.Methods: Reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and adenosine triphosphate (ATP) were used to evaluate mitochondrial function. The terminal deoxynucleotidyl transferase-dUTP nick end labeling (TUNEL) assay was used to assess neuronal apoptosis in vitro. TUNEL and immunofluorescence staining for neuronal nuclei (NeuN) were combined to assess neuronal apoptosis in vivo. An Evans blue (EB) permeability assay and brain water content (BWC) were used to measure BBB permeability in vivo. The Morris water maze (MWM), rotarod test, and modified Neurological Severity Score (mNSS) test were employed to assess the prognosis of TBI mice.Results: MB treatment significantly reversed neuronal mitochondrial dysfunction caused by OGD injury. Both in vitro and in vivo, MB treatment reduced neuronal apoptosis and improved BBB integrity. In TBI animals, treatment with MB not only improved cognitive and motor function caused by TBI but also significantly improved overall neurological function.Conclusions: Our findings suggest that MB is a potential candidate for the treatment of TBI. Future research should focus on other therapeutic effects and mechanisms of MB in secondary brain injury.

Highlights

Traumatic brain injury (TBI) is the most common cause of mortality and disability among workingage adults and young individuals worldwide [1]
The stability of the neuronal Membrane Potential (MMP) was significantly reduced in the OGD group compared with the normal incubation group (P = 0.011), while Methylene blue (MB) treatment significantly reversed the decline of MMP stability caused by OGD injury (P = 0.033)
Mitochondrial dysfunction plays a pivotal role in the pathological processes of secondary brain damage following TBI, and mitochondriatargeted treatment of TBI may have the potential to improve the prognosis of TBI

Summary

Introduction

Traumatic brain injury (TBI) is the most common cause of mortality and disability among workingage adults and young individuals worldwide [1]. In the United States, ∼2 million people suffer a TBI each year, and TBI accounts for nearly one-third of all trauma-related mortality [1, 2]. TBI damages brain tissue through two pathological processes, primary and secondary injury. Primary injury is Methylene Blue Attenuates Brain Damage characterized by immediate bleeding and loss of brain tissue when a blunt or sharp object impacts the head. Mitochondrial dysfunction has been demonstrated to be a key participant in the pathological processes of secondary brain injury [9, 10]

Methods

Results

Discussion

Conclusion