Monitoring changes of docosahexaenoic acid-containing lipids during the recovery process of traumatic brain injury in rat using mass spectrometry imaging

Shuai Guo,Tianjing Chen,Tiejun Li,Yupin Xu,Zhili Li,Mo Zhang,Yujie Liu,Dan Zhou

doi:10.1038/s41598-017-05446-2

Abstract

Brain lipid homoeostasis is critical during recovery process after traumatic brain injury (TBI). In this study, we integrated liquid extraction and electrosonic spray ionization technology to develop an ionization device coupled with a Fourier transform ion cyclotron resonance mass spectrometer for imaging of docosahexaenoic acid (DHA)-containing lipids on rat brain tissues. The ion images of the brain tissue sections from the normal rats and the rats after TBI at acute phase (0 and 1 day) and chronic phase (3, 5, and 7 days) were obtained. The imaging results indicate that the levels of DHA and lyso-phosphatidylethanolamine (22:6) in the injury area of TBI rats increased significantly at the acute phase and subsequently decreased at the chronic phase. But the levels of DHA-containing phospholipids including phosphatidylethanolamine (PE)(P-18:0/22:6), PE(18:0/22:6), and phosphatidylserine (18:0/22:6) decreased at the acute phase and gradually increased at the chronic phase in the injury area accompanied by the morphogenesis and wound healing. These findings indicate that the DHA may participate in the recovery process of brain injury. This is the first report to in situ detect the changes in the levels of DHA and DHA-containing lipids in the TBI model.

Highlights

Traumatic brain injury (TBI) is a major cause of death and permanent disability for people under the age of 451–3
The schematic diagram and physical photo of the LE-Electrosonic spray ionization (ESSI) are shown in Fig. 1A,B and Supplementary Figure S1, respectively
It was found that the nebulizing gas flowrate of 3.5 L/ min and the solvent flowrate of 145 μL/h could provide a short delay time of the extracted analytes (Fig. 1C) and high quality ion image (m/z 645.5210) along the X-axis direction corresponding to the lateral spatial resolution of approximately 50 μm (Fig. 1D)

Summary

Introduction

Traumatic brain injury (TBI) is a major cause of death and permanent disability for people under the age of 451–3 This injury occurs frequently in military personnel and professional athletes, leading to loss of limb function, speech impairment, memory disturbances, and emotional responses[4]. When equipped with a high mass resolution mass spectrometer such as Fourier transform ion cyclotron resonance mass spectrometer(FTICR MS), ion images of multiple peaks with high mass accuracy can be obtained[28, 29] This method has the challenges of complex sample preparation prior to analysis and the interferences of matrixes and/or matrix adducts for the detection of small molecules such as DHA. This technique employs two angled capillaries to form a liquid bridge on a sample surface, achieving a lateral resolution of 12 μm or even single cell level analysis[35,36,37]

Methods

Results

Discussion

Conclusion