Investigation of Biochemical Alterations in Ischemic Stroke Using Fourier Transform Infrared Imaging Spectroscopy—A Preliminary Study

Abstract

Objective: Brain damage, long-term disability and death are the dreadful consequences of ischemic stroke. It causes imbalance in the biochemical constituents that distorts the brain dynamics. Understanding the sub-cellular alterations associated with the stroke will contribute to deeper molecular understanding of brain plasticity and recovery. Current routine approaches examining lipid and protein biochemical changes post stoke can be difficult. Fourier Transform Infrared (FTIR) imaging spectroscopy can play a vital role in detecting these molecular alterations on a sub-cellular level due to its high spatial resolution, accuracy and sensitivity. This study investigates the biochemical and molecular changes in peri-infract zone (PIZ) (contiguous area not completely damaged by stroke) and ipsi-lesional white matter (WM) (right below the stroke and PIZ regions) nine weeks post photothrombotic ischemic stroke in rats. Materials and Methods: FTIR imaging spectroscopy and transmission electron microscopy (TEM) techniques were applied to investigate brain tissue samples while hematoxylin and eosin (H&E) stained images of adjacent sections were prepared for comparison and examination the morphological changes post stroke. Results: TEM results revealed shearing of myelin sheaths and loss of cell membrane, structure and integrity after ischemic stroke. FTIR results showed that ipsi-lesional PIZ and WM experienced reduction in total protein and total lipid content compared to contra-lesional hemisphere. The lipid/protein ratio reduced in PIZ and adjacent WM indicated lipid peroxidation, which results in lipid chain fragmentation and an increase in olefinic content. Protein structural change is observed in PIZ due to the shift from random coli and α-helical structures to β-sheet conformation. Conclusion: FTIR imaging bio-spectroscopy provide novel biochemical information at sub-cellular levels that be difficult to be obtained by routine approaches. The results suggest that successful therapeutic strategy that is based on administration of anti-oxidant therapy, which could reduce and prevent neurotoxicity by scavenging the lipid peroxidation products. This approach will mitigate tissue damage in chronic ischemic period. FTIR imaging bio-spectroscopy can be used as a powerful tool and offer new approach in stroke and neurodegenerative diseases research.

Secondary Degeneration of White Matter After Focal Sensorimotor Cortical Ischemic Stroke in Rats

“…Previous studies suggest the decrease in FA in the chronic stage (after 3 weeks) mainly reflects chronic WM degeneration ( Jung et al, 2017 ). Recently, studies with transmission electron microscopy also found the loss of structural integrity of axons in the WM bundles right below the sensorimotor cortex ischemic lesion site in a similar animal model ( Rakib et al, 2019 ), which agrees well with the decreased FA in the ipsilesional external capsule that we found in this study.…”

From Mouse to Human: Comparative Analysis between Grey and White Matter by Synchrotron-Fourier Transformed Infrared Microspectroscopy

“…On the other hand, it is known that free radicals mainly react with carbon double bond sites present in unsaturated lipids, resulting in carbonyl compound formation and lipid chain fragmentation [ 30 , 31 , 32 , 33 ]. Therefore, the high expression of C=O groups is related to the stable end-products of lipid peroxidation and, in consequence, the analyses of lipid oxidation status, measuring C=O/CH 2 content by μFTIR, have been performed in different studies [ 15 , 27 , 34 ]. Taking these data into account, our observations suggest that the lipids in GM could be more oxidized than in WM.…”

Fourier Transform Infrared Imaging—A Novel Approach to Monitor Bio Molecular Changes in Subacute Mild Traumatic Brain Injury

“…A FTIR micro-spectrometer (Agilent Cary 620, Cary, NC, USA) was used to record the FTIR spectra and maps within the range of 4000-700 cm −1 (spectral resolution 4 cm −1 ). More detailed instrument configurations and parameters used for this study were conducted as in our previous studies [15,16,25,41,42]. The FTIR spectra from two identical anatomical brain regions in the cortex and corpus callosum of different animals from each group were extracted from the FTIR images.…”

“…Lipid molecular and structural alterations, lipid/protein band ratios (that provide facts about the protein-lipid asymmetry and environmental changes, which lead to devastating effect on the cellular function), vector normalization, and second derivatives of raw spectra were used and calculated according to the details explained in our previous studies [15]. Relative quantification of the protein content and the distribution of amide I components were determined according to our previous studies [15,16,25,41,42]. The mean was generated for each animal group along with their standard deviation (significant level p < 0.0001).…”

“…The non-appearance of the injuries on traditional imaging studies and the unintentional perception of an expected appearing and performing individuals are the two challenging factors to diagnose this injury [ 41 ]. In our previous study, the molecular changes in different brain regions due to stroke and mTBI 3 h after the injury were investigated by FTIR imaging [ 40 , 41 , 42 ]. In this paper, we aimed to investigate the imbalance in biochemical components in the cortex (Co) and corpus callosum (CC) of mTBI after 24 h from the injury by FTIR imaging for their greater implication on accuracy and sensitivity as a research tool.…”