Effects of Very Low Dose Fast Neutrons on Cell Membrane And Secondary Protein Structure in Rat Erythrocytes

Abstract

The effects of ionizing radiation on biological cells have been reported in several literatures. Most of them were mainly concerned with doses greater than 0.01 Gy and were also concerned with gamma rays. On the other hand, the studies on very low dose fast neutrons (VLDFN) are rare. In this study, we have investigated the effects of VLDFN on cell membrane and protein secondary structure of rat erythrocytes. Twelve female Wistar rats were irradiated with neutrons of total dose 0.009 Gy (241Am-Be, 0.2 mGy/h) and twelve others were used as control. Blood samples were taken at the 0, 4th, 8th, and 12th days postirradiation. Fourier transform infrared (FTIR) spectra of rat erythrocytes were recorded. Second derivative and curve fitting were used to analysis FTIR spectra. Hierarchical cluster analysis (HCA) was used to classify group spectra. The second derivative and curve fitting of FTIR spectra revealed that the most significant alterations in the cell membrane and protein secondary structure upon neutron irradiation were detected after 4 days postirradiation. The increase in membrane polarity, phospholipids chain length, packing, and unsaturation were noticed from the corresponding measured FTIR area ratios. This may be due to the membrane lipid peroxidation. The observed band shift in the CH2 stretching bands toward the lower frequencies may be associated with the decrease in membrane fluidity. The curve fitting of the amide I revealed an increase in the percentage area of α-helix opposing a decrease in the β-structure protein secondary structure, which may be attributed to protein denaturation. The results provide detailed insights into the VLDFN effects on erythrocytes. VLDFN can cause an oxidative stress to the irradiated erythrocytes, which appears clearly after 4 days postirradiation.

Metabolic Dysregulation after Neutron Exposures Expected from an Improvised Nuclear Device

“…Although DNA damage and repair products have been identified as significantly increased with neutrons, whether that is assessed with micronuclei (22), comet assay (39) or chromosomal changes (40, 41), small molecules associated with such a process or DNA repair were not identified in the biofluids through a global LC-MS approach. The exception was uric acid, which was previously identified in higher levels in urine of exposed mice (42) and humans (12).…”

“…Early decrease of fatty acids, such as arachidonic acid, can be attributed directly to increased oxidative stress, which can lead to lipid peroxidation and protein alterations (43, 44). In addition, others have shown that membrane fluidity is decreased even with low doses of neutrons (0.9 cGy) and decreased lipid-to-protein ratios in membranes may be a consequence of increased lipid peroxidation and degradation (39). Changes in membrane solubilization and osmotic fragility after exposure to fast neutrons were also observed in erythrocytes (45).…”

Soft X-ray induced radiation damage in thin freeze-dried brain samples studied by FTIR microscopy

“…1 and 2 and Tables 1 and 2). This suggests lipid oxidation and saturation of the double bonds (Saeed et al, 2015). Low radioresilience of these bonds follows from their high chemical reactivity.…”

Oxidative Stress, a Bridge that Links Radioadaptive Responses Induced by Ionizing Radiation to Those Induced by Non-Ionizing Radiation

“…Currently, there is a controversy over the cellular responses following exposure to low doses of ionizing radiation [15]. Substantial data indicate that exposure to ionizing radiation can lead to the induction of oxidative stress in plants [16], animals [17,18], and humans [19]. On the other hand, it has been shown that low doses of ionizing radiation may cause some bio-positive effects through preventing oxidative stress [20][21][22].…”