Structural and functional damages of whole body ionizing radiation on rat brain homogenate membranes and protective effect of amifostine.

PURPOSE: To investigate the effects of whole body ionizing radiation at a sublethal dose on rat brain homogenate membranes and the protective effects of amifostine on these systems at molecular level. MATERIALS AND METHODS: Sprague-Dawley rats, in the absence and presence of amifostine, were whole-body irradiated at a single dose of 8 Gy and decapitated after 24 h. The brain homogenate membranes of these rats were analyzed using Fourier Transform Infrared (FTIR) spectroscopy. RESULTS: Ionizing radiation caused a significant increase in the lipid to protein ratio and significant decreases in the ratios of olefinic = CH/lipid, CH2/lipid, carbonyl ester/lipid and CH3/lipid suggesting, respectively, a more excessive decrease in the protein content and the degradation of lipids as a result of lipid peroxidation. In addition, radiation changed the secondary structure of proteins and the status of packing of membrane lipid head groups. Furthermore, it caused a decrease in lipid order and an increase in membrane fluidity. The administration of amifostine before ionizing radiation inhibited all the radiation-induced alterations in brain homogenate membranes. CONCLUSIONS: The results revealed that whole body ionizing radiation at a sublethal dose causes significant alterations in the structure, composition and dynamics of brain homogenate membranes and amifostine has a protective effect on these membranes.

Amifostine, a radioprotectant agent, protects rat brain tissue lipids against ionizing radiation induced damage: an FTIR microspectroscopic imaging study.

Amifostine is the only approved radioprotective agent by FDA for reducing the damaging effects of radiation on healthy tissues. In this study, the protective effect of amifostine against the damaging effects of ionizing radiation on the white matter (WM) and grey matter (GM) regions of the rat brain were investigated at molecular level. Sprague-Dawley rats, which were administered amifostine or not, were whole-body irradiated at a single dose of 800 cGy, decapitated after 24 h and the brain tissues of these rats were analyzed using Fourier transform infrared microspectroscopy (FTIRM). The results revealed that the total lipid content and CH(2) groups of lipids decreased significantly and the carbonyl esters, olefinic=CH and CH(3) groups of lipids increased significantly in the WM and GM after exposure to ionizing radiation, which could be interpreted as a result of lipid peroxidation. These changes were more prominent in the WM of the brain. The administration of amifostine before ionizing radiation inhibited the radiation-induced lipid peroxidation in the brain. In addition, this study indicated that FTIRM provides a novel approach for monitoring ionizing radiation induced-lipid peroxidation and obtaining different molecular ratio images can be used as biomarkers to detect lipid peroxidation in biological systems.

Screening of protective effect of amifostine on radiation-induced structural and functional variations in rat liver microsomal membranes by FT-IR spectroscopy.

In this study, the protective effect of amifostine, which is the only FDA-approved radioprotective agent, was investigated against the deleterious effects of ionizing radiation on rat liver microsomal membranes at molecular level. Sprague-Dawley rats, which were either administered amifostine or not, were whole-body irradiated with a single dose of 800 cGy and decapitated after 24 h. The microsomal membranes isolated from the livers of these rats were investigated using FT-IR spectroscopy. The results revealed that radiation caused a significant decrease in the lipid-to-protein ratio and the degradation of lipids into smaller fragments that contain less CH(2) and more carbonyl esters, olefinic═CH and CH(3) groups, which could be interpreted as a result of lipid peroxidation. Radiation altered the secondary structure of proteins by inducing a decrease in the ß-sheet structures and an increase in the turns and random coil structures. Moreover, a dramatic increase in lipid order and a significant decrease in the membrane dynamics were observed in the irradiated group. The administration of amifostine before ionizing radiation inhibited all the radiation induced compositional, structural, and functional damages. In addition, these results suggest that FT-IR spectroscopy provides a novel approach to monitoring radiation-induced damage on biological membranes.

17Beta-estradiol induced compositional, structural and functional changes in rainbow trout liver, revealed by FT-IR spectroscopy: a comparative study with nonylphenol.

Steroidal hormones produced by humans and animals are constantly being excreted into the environment. It has been demonstrated that sewage effluent discharged to surface water contains natural estrogens and synthetic estrogenic chemicals. As estrogen levels continuously increase in the aquatic environment, it is very important to have a detailed understanding of estrogens' effects on fish. In the present study, juvenile rainbow trout (Oncorhynchus mykiss) were exposed to 17beta-estradiol (E2) for 3 weeks and the effects of E2 on rainbow trout livers were investigated at the molecular level using Fourier transform infrared spectroscopy. The results revealed that E2 induced significant alterations in the liver tissues. A decrease in glycogen levels and protein concentration, and an increase in both the population of hepatic lipids, especially triglycerides, as well as the relative content of nucleic acids was observed in the E2 treated liver. In addition, a decrease in the membrane fluidity and an increase in lipid order were found in the cells of treated samples. In order to compare the effect of E2 with that of NP at molecular level, the fish were also treated with an estrogenic compound, nonylphenol (NP). The NP-treated fish liver spectra were found to be quite similar to those of E2-treated fish confirming that NP mimics the effect of E2 in immature rainbow trout.

FT-IR spectroscopic analysis of rainbow trout liver exposed to nonylphenol.

Nonylphenol (NP) is a biodegradation product of nonylphenol ethoxylates (NPEs) belonging to the alkylphenol ethoxylates (APEs) group. APEs are widely used nonionic surfactants in detergents, herbicides, pesticides, paints, and cosmetics. The present work investigates the effects of NP on rainbow trout (Oncorhynchus mykiss) livers at the molecular level using Fourier transform infrared (FT-IR) spectroscopy. The FT-IR spectra revealed dramatic differences between the NP-treated and control tissues, which mainly indicated that the level of triglycerides increased, the lipid order increased, and the protein concentration decreased in the treated samples. Moreover, it was also found that glycogen levels significantly decreased and the relative content of nucleic acids increased in NP-treated fish. The 17beta-Estradiol-treated fish liver spectra were found to be quite similar to those of NP-treated fish. All these results implied that rainbow trout may offer considerable promise to be used as a bioindicator for NP in the future.