Structural Changes of Amyloid Beta in Hippocampus of Rats Exposed to Ozone: A Raman Spectroscopy Study

Abstract

The aim of this work was to study the effect of oxidative stress on the structural changes of the secondary peptide structure of amyloid beta 1–42 (Aβ 1–42), in the dentate gyrus of hippocampus of rats exposed to low doses of ozone. The animals were exposed to ozone-free air (control group) and 0.25 ppm ozone during 7, 15, 30, 60, and 90 days, respectively. The samples were studied by: (1) Raman spectroscopy to detect the global conformational changes in peptides with α-helix and β-sheet secondary structure, following the deconvolution profile of the amide I band; and (2) immunohistochemistry against Aβ 1–42. The results of the deconvolutions of the amide I band indicate that, ozone exposure causes a progressively decrease in the abundance percentage of α-helix secondary structure. Furthermore, the β-sheet secondary structure increases its abundance percentage. After 60 days of ozone exposure, the β-sheet band is identified in a similar wavenumber of the Aβ 1–42 peptide standard. Immunohistochemistry assays show an increase of Aβ 1–42 immunoreactivity, coinciding with the conformational changes observed in the Raman spectroscopy of Aβ 1–42 at 60 and 90 days. In conclusion, oxidative stress produces changes in the folding process of amyloid beta peptide structure in the dentate gyrus, leading to its conformational change in a final β-sheet structure. This is associated to an increase in Aβ 1–42 expression, similar to the one that happens in the brain of Alzheimer’s Disease (AD) patients.

Label-free imaging of amyloid plaques in Alzheimer’s disease with stimulated Raman scattering microscopy

“…2C ). This Raman frequency representing β sheet conformation agrees very well with previous spontaneous Raman measurements ( 26 , 28 , 31 ). To extract the contents of lipids, normal proteins, and amyloid plaques, we applied the linear decomposition algorithm that has been commonly used previously ( 39 , 42 , 46 ).…”

In Vivo Fiber Optic Raman Spectroscopy of Muscle in Preclinical Models of Amyotrophic Lateral Sclerosis and Duchenne Muscular Dystrophy

“…In addition, oxidative stress, known to occur in the muscles of both mouse models, 31 , 32 has been shown to cause similar structural changes in different tissues/cells. 33 − 35 …”

Ultrasound-Responsive Nutlin-Loaded Nanoparticles for Combined Chemotherapy and Piezoelectric Treatment of Glioblastoma Cells

“…Horiba). LabSpec 6 software has been used to obtain the signal maps; signals of the PNPs (β-phase: 820 cm -1 > Raman shift > 880 cm -1 ), cell proteins (amide I region [46]: 1600 cm -1 > Raman shift > 1700 cm -1 ), and nuclei (DNA [47,48]: 760 cm -1 > Raman shift > 790 cm -1 ) were used, with a pixel intensity proportional to the integrated peak area.…”