Ameliorative effect of melatonin against gamma-irradiation-induced oxidative stress and tissue injury

Susceptibility to radiation adverse effects in veterans with Gulf War illness and healthy civilians

We evaluated whether veterans with Gulf War illness (VGWI) report greater ionizing radiation adverse effects (RadAEs) than controls; whether radiation-sensitivity is tied to reported chemical-sensitivity; and whether environmental exposures are apparent risk factors for reported RadAEs (rRadAEs). 81 participants (41 VGWI, 40 controls) rated exposure to, and rRadAEs from, four radiation types. The relations of RadAE-propensity (defined as the ratio of rRadAEs to summed radiation exposures) to Gulf War illness (GWI) presence and severity, and to reported chemical-sensitivity were assessed. Ordinal logistic regression evaluated exposure prediction of RadAE-propensity in the full sample, in VGWI, and stratified by age and chemical-sensitivity. RadAE-propensity was increased in VGWI (vs. controls) and related to GWI severity (p < 0.01) and chemical-sensitivity (p < 0.01). Past carbon monoxide (CO) exposure emerged as a strong, robust predictor of RadAE-propensity on univariable and multivariable analyses (p < 0.001 on multivariable assessment, without and with adjustment for VGWI case status), retaining significance in age-stratified and chemical-sensitivity-stratified replication analyses. Thus, RadAE-propensity, a newly-described GWI-feature, relates to chemical-sensitivity, and is predicted by CO exposure-both features reported for nonionizing radiation sensitivity, consistent with shared mitochondrial/oxidative toxicity across radiation frequencies. Greater RadAE vulnerability fits an emerging picture of heightened drug/chemical susceptibility in VGWI.

Adverse effect propensity: A new feature of Gulf War illness predicted by environmental exposures

A third of 1990-1 Gulf-deployed personnel developed drug/chemical-induced multisymptom illness, "Gulf War illness" (GWI). Veterans with GWI (VGWI) report increased drug/exposure adverse effects (AEs). Using previously collected data from a case-control study, we evaluated whether the fraction of exposures that engendered AEs ("AE Propensity") is increased in VGWI (it was); whether AE Propensity is related to self-rated "chemical sensitivity" (it did); and whether specific exposures "predicted" AE Propensity (they did). Pesticides and radiation exposure were significant predictors, with copper significantly "protective"-in the total sample (adjusted for GWI-status) and separately in VGWI and controls, on multivariable regression. Mitochondrial impairment and oxidative stress (OS) underlie AEs from many exposures irrespective of nominal specific mechanism. We hypothesize that mitochondrial toxicity and interrelated OS from pesticides and radiation position people on the steep part of the curve of mitochondrial impairment and OS versus symptom/biological disruption, amplifying impact of new exposures. Copper, meanwhile, is involved in critical OS detoxification processes.

Ameliorative Effects of some Natural Antioxidants against Blood and Cardiovascular Toxicity of Oral Subchronic Exposure to Silicon Dioxide, Aluminum Oxide, or Zinc Oxide Nanoparticles in Wistar Rats

The present study determines the possible protective role of fig fruit extract with olive oil and date palm fruit extract (FOD) in decreasing the oral subchronic blood and cardiovascular toxicity of SiO₂NPs, Al₂O₃NPs, or ZnONPs. The present study used 80 male Wistar rats (8 groups, n = 10) distributed according to the treatment. The FOD treatments were used at their recommended antioxidant doses. All nanoparticles (NPs) were given orally and daily at doses of 100 mg/kg for 75 days. The oral administration of different NPs alone led to dramatic, oxidative stress, inflammatory markers, blood coagulation, endothelial dysfunction markers, myocardial enzymes, hematological parameters, lipid profile, and histopathological features compared with the control group. The FOD-NP-treated groups recorded significantly ameliorated blood and cardiovascular toxicity hazards compared to the groups administered with the NPs alone. In conclusion, the administration of FOD provides considerable chemopreventive and ameliorative effects against NP toxicity.

Utility of melatonin in mitigating ionizing radiation-induced testis injury through synergistic interdependence of its biological properties

Background

Ionizing radiations (IR) have widespread useful applications in our daily life; however, they have unfavorable effects on reproductive health. Maintaining testicular health following IR exposure is an important requirement for reproductive potential. The current study explored the role of melatonin (MLT) in mitigating IR-induced injury in young adult rat testis.

Methods

Rats were given daily MLT (25 mg/kg) for 3 and 14 days after receiving 4 Gy γ-radiation.

Results

Serum MLT levels and other antioxidants, including glutathione content, and the activity of glutathione peroxidase and glutathione reductase in the testis of the irradiated rats were remarkably maintained by MLT administration in irradiated rats. Hence, the hydrogen peroxide level declined with remarkably reduced formation of oxidative stress markers, 4-hydroxynonenal, and 8-Hydroxy-2′-deoxyguanosine in the testis of irradiated animals after MLT administration. The redox status improvement caused a remarkable regression of proapoptotic protein (p53, Cyto-c, and caspase-3) in the testis and improved inflammatory cytokines (CRP and IL-6), and anti-inflammatory cytokine (interleukin IL-10) in serum. This is associated with restoration of disturbed sex hormonal balance, androgen receptor upregulation, and testicular cell proliferation activity in irradiated rats, explaining the improvement of sperm parameters (count, motility, viability, and deformation). Consequently, spermatogenic cell depletion and decreased seminiferous tubule diameter and perimeter were attenuated by MLT treatment post irradiation. Moreover, the testis of irradiated-MLT-treated rats showed well-organized histological architecture and normal sperm morphology.

Conclusions

These results show that radiation-induced testicular injury is mitigated following IR exposure through synergistic interdependence between the antioxidant, anti-inflammatory, anti-apoptotic, and anti-DNA damage actions of MLT.

Constant light exposure and/or pinealectomy increases susceptibility to trichloroethylene-induced hepatotoxicity and liver cancer in male mice

Exposure to light at night, pineal gland impairment, and the environmental pollutant trichloroethylene (TCE) have serious implications for health and contribute to illness, including liver cancer. The adverse effect of the association of continuous exposure to light with decreased melatonin levels and TCE-induced toxicity is not disclosed in target organs. This work explored the role of light and pineal impairment in increasing susceptibility to liver toxicity and cancer upon exposure to TCE. Male albino mice were divided into groups as follows: control group (12-h light/12-h dark cycle), constant light (24-h light), pinealectomized (Pnx) mice, sham surgically treated group, TCE-treated groups subjected to two doses (500 and 1000 mg/kg) at two different light regimens, and combination of Pnx and TCE-treated mice kept at a 12-h light/12-h dark cycle. Melatonin levels were significantly decreased in both Pnx mice and TCE-treated animals at both light regimens. Aspartate transaminase, alanine aminotransferase, activities, and serum bilirubin levels were significantly elevated, whereas albumin levels were markedly decreased in Pnx mice, TCE-treated mice, and the combination group. Histopathological investigations reflected changes in liver function parameters indicating liver injury and induction of cancer. These effects were accompanied by significant increase of the liver cancer biomarker alpha-fetoprotein and the expression of the metastatic markers CD44, TGFβ-1, and VEGF, along with increased oxidative stress indicators and inflammatory cytokines (IL-6, IL-1β, and TNF-α) in both Pnx and TCE-treated mice and the combination group at both light regimens. Taken together, our findings indicated that low melatonin levels, exposure to constant light, and the combination of both factors increases susceptibility to the toxic and carcinogenic effects of TCE on the liver.

Medical management of acute radiation syndrome

Acute radiation syndrome (ARS) is a clinical syndrome involving four organ systems, resulting in the hematopoietic syndrome (HS), gastrointestinal subsyndrome (GIS), neurovascular subsyndrome (NVS) and cutaneous subsyndrome (CS). Since few healthcare providers have seen an ARS case, evidence-based recommendations are needed to guide medical management in a mass casualty scenario. The authors reviewed recommendations from evidence-based and narrative reviews by expert consultants to the World Health Organisation (WHO), a subsequent review of published HS cases, and infectious disease guidelines for management of febrile neutropenia. The WHO Consultancy applied a rigorous grading system to evaluate treatment strategies described in published ARS cases as of 2009, strategies to manage HS in unirradiated persons, results of ARS studies in animal models of ARS, and recommendations of prior expert panels. Major findings for HS were (a) no randomised controlled studies have been performed, (b) data are restricted by the lack of comparator groups, and (c) reports of countermeasures for management of injury to non-hematopoietic organs are often incomplete. Strength of recommendations ranged from strong to weak. Countermeasures of potential benefit include cytokines and for a subgroup of HS patients, hematopoietic stem cell transplantation. These recommendations did not change in a subsequent analysis of HS cases. Recommendations also included fluoroquinolones, bowel decontamination, serotonin receptor antagonists, loperamide and enteral nutrition for GIS; supportive care for NVS; and topical steroids, antihistamines and antibiotics, and surgical excision/grafting for CS. Also reviewed are critical care management guidelines, the role of mesenchymal stem cells for CS, the potential of a platelet-stimulating cytokine for HS, and the author's approach to clinical management of microbial infections associated with ARS based on published guidelines of infectious disease experts. Today's management of HS is supported by evidence-based guidelines. Management of non-HS subsyndromes is supported by a narrative review of the literature and recommendations of infectious disease societies.

Melatonin-Caffeine Combination Modulates Gamma Radiation-induced Sperm Malformations in C57BL/6 Male Mice at Sublethal Dose of Gamma Radiation

Aims:

The aim of this study was to assess the protective effect of the melatonin–caffeine combination against γ radiation-induced alterations in the morphological characteristics of sperms.

Settings and Design:

C57BL/6 male mice (n = 30) were randomly divided into five groups: control, radiation (2 Gy), melatonin (100 mg/kg body wt.) + radiation (2 Gy), caffeine (30 mg/kg body wt.) + radiation (2 Gy), melatonin–caffeine (100–30 mg/kg body wt.) + radiation (2 Gy).

Materials and Methods:

All the mice were sacrificed 24 h postirradiation, and cauda epididymis was collected. In this study, sperm concentration along with any abnormality in their morphology (amorphous heads, pinheads, hookless, coiled tails, midpiece defect, and tail-less) was observed in the control and treatment group of animals.

Results:

Radiation exposure (2 Gy) considerably decreases the sperm count when compared with the control group. However, pretreatment with melatonin and melatonin–caffeine combination before gamma irradiation increased the sperm count (P < 0.05), but with caffeine alone could not produce a significant difference. The higher rate of abnormal sperms was observed in the γ-irradiated mice when compared with the control group (P < 0.05). Besides, the numbers of sperm that are hookless and coiled tails were significantly increased after irradiation. Melatonin significantly reduced the number of sperm with amorphous heads and coiled tails. Melatonin–caffeine combination further reduced sperm malformations when compared with the melatonin + 2 Gy radiation and caffeine + 2 Gy radiation group.

Conclusions:

This study suggests that caffeine exerts a protective effect when given in combination with melatonin against gamma irradiation in sperms of C57BL/6 mice and could be a potent combination for the development of radioprotector.

Melatonin exerts a neuroprotective effect against γ-radiation-induced brain injury in the rat through the modulation of neurotransmitters, inflammatory cytokines, oxidative stress, and apoptosis

The current study aimed to investigate the ameliorative effect of melatonin (MLT) against brain injury in rats undergoing whole-body exposure to γ-radiation. Male Wistar rats were whole-body exposed to 4-Gy γ-radiation from a cesium-137 source. MLT (10 mg/kg) was orally administrated 30 minutes before irradiation and continued once daily for 1 and 7 days after exposure. In the irradiated rats, the plasma levels of glutamate were increased, while the gamma-aminobutyric acid (GABA) levels were decreased, and MLT improved the disturbed glutamate and GABA levels. These effects paralleled an increase in pro-inflammatory cytokines (IL-1b, IL-6, and TNF-a) and C-reactive protein as well as a decrease in IL-10 in the plasma of the irradiated rats. MLT treatment markedly reduced these effects, indicating its anti-inflammatory impact. Immunohistochemical studies demonstrated a remarkable upregulation of caspase-3 and P53 expression, indicating the increased apoptosis in the brain of irradiated rats. MLT significantly downregulated the expression of these parameters compared with that in the irradiated rats, indicating its anti-apoptotic effect. Oxidative stress is developed in the brain as evidenced by increased levels of malondialdehyde; decreased activities of superoxide dismutase, catalase, and glutathione peroxidase; and decreased content of glutathione in the brain. MLT remarkably ameliorated the development of oxidative stress in the brain of the irradiated rats indicating its antioxidant impact. The histopathological results were consistent with the biochemical and immunohistochemical results and showed that MLT remarkably protected the histological structure of brain tissue compared with that in the irradiated rats. In conclusion, MLT showed potential neuroprotective properties by increasing the release of neurotransmitters, antioxidants, and anti-inflammatory factors and reducing pro-inflammatory cytokines and apoptosis in the brain of irradiated rats. MLT can be beneficial in clinical and occupational settings requiring radiation exposure; however, additional studies are required to elucidate its neuroprotective effect in humans.

Developmental Programming: Physiological Impacts of Prenatal Melatonin Administration on Reproductive Capacity and Serum Triiodothyronine of Adult Female Offspring Rat Born to Moms Exposed to Bisphenol A During Pregnancy

Gestational bisphenol A (BPA) exposure induced multiple programmed diseases in the adult offsprings. Thus, this study targeted exploring the physiological impacts of melatonin (MEL) as a reprogramming strategy against in utero BPA exposure on reproductive capacity of adult F1 female rat offspring. Forty adult pregnant albino female rats were divided equally into 5 groups (n = 8): group I (control), group II (low-dose BPA; 25 μg BPA/kg B.w.t.), group III (low-dose BPA + 10 mg MEL/kg B.w.t.), group IV (high-dose BPA; 250 μg/kg B.w.t.), and group V (high-dose BPA + MEL). Treatments were given daily by subcutaneous (s/c) injection from the fourth day of pregnancy until full term. After delivery, female offspring were selected, and on postnatal day 60, adult offspring were examined for estrus regularity and then were sacrificed at estrus to collect blood and tissue samples. Findings clarified that in utero BPA exposure (both doses) increased significantly (P < 0.05) the ovarian weights and the serum levels of estrogen but decreased that of triiodothyronine (T3) compared to control groups. Significant increasing of serum malondialdehyde (MDA) and decreasing of total antioxidant capacity (TAC) were also detected. Both doses of BPA disturbed remarkably the estrus cycles and caused marked aberrations in ovarian and uterine tissues. Interestingly, prenatal MEL co-treatment with BPA mitigated significantly all of these degenerative changes. Thus, this study first demonstrated that prenatal MEL therapy could be used as a potent reprogramming intervention against BPA-induced reproductive disorders in the adult F1 female rat offspring.

Taurine abates the liver damage induced by γ-irradiation in rats through anti-inflammatory and anti-apoptotic pathways

BACKGROUND

Radiotherapy is the most common regimen for treating human cancers; however, ionizing radiation (IR) has hazardous effects on metabolically active organs such as the liver.

AIM

This study aimed to investigate the possible protective (prophylactic and therapeutic) action of taurine against liver damage induced by gamma irradiation at different time intervals as well as the mechanisms by which taurine could provide its potential amelioration actions.

METHODS

In this study, 90 adult male rats (∼150 g) were randomly divided into five groups. Group 1 is the control group, group 2 received an oral daily dose (500 mg/kg) of taurine for two weeks, group 3 was exposed to a whole-body single dose of γ-irradiation (6 Gy), and groups 4 and 5 received taurine before or after γ-irradiation, respectively. Six rats from each group were sacrificed after 1, 2, and 3 weeks.

RESULTS

Over the period of the 3 weeks studied, there were significant increases in MDA, NO, TNF-α, and cytochrome-c levels and ALT, caspases-9 and -3 activities and significant decreases in GSH, SOD, CAT, and GPx in the irradiated group when compared with the relevant control. The liver of irradiated rats showed dilatation in the central and portal veins, edema, and degenerated hepatocytes.

CONCLUSIONS

Taken together, IR caused maximum devastation in the liver 2 weeks after exposure as shown by elevation of the inflammatory and apoptotic markers and reducing the antioxidants. Taurine was able to alleviate the deleterious biochemical and histological effects whether given before or after IR. The magnitude of the observed protective effects was in both cases very similar.

Protective Role of <i>Juniperus phoenicea</i> L. Leaves Extract against Gamma-irradiation-induced Oxidative Stress

BACKGROUND AND OBJECTIVE

Radiation exposure can cause several harmful effects in biological systems due to free radical production. Several antioxidants have been tested as potential hepatoprotective agents against ionizing radiation as they lower oxidative stress in normal cells induced by Reactive Oxygen Species (ROS). The present study was conducted to evaluate the possible ameliorative effects of Juniperus phoenicea L.

MATERIALS AND METHODS

Aqueous leaves extract on different biochemical and histopathological parameters against whole body gamma-irradiation-induced oxidative stress, organ dysfunction and metabolic disturbances in experimental Swiss Albino rats. After a single dose of gamma-radiation (6 Gy), there was a significant reduction in albumin, total protein and globulin levels and a significant increase in the liver enzymes (ALT, AST, ALP and GGT) and lipid profile parameters (cholesterol, triglyceride, HDL-cholesterol and LDL-cholesterol) in gamma-irradiated rats unlike in normal controls.

RESULTS

The gamma-irradiated rats pre-treated with J. phoenicea leaf extracts, however, showed a significant increase in albumin, total protein and globulin levels and a significant reduction in liver enzymes and lipid profile parameters as opposed to the untreated ones. The gamma-irradiated rats showed toxic changes in the liver, whereas, the rats pre-treated with J. phoenicea leaves extract demonstrated a protective effect. Additionally, gamma- irradiation caused myocardial degenerative changes, interstitial edema between muscle fibers, necrosis and inflammatory cells infiltration and fibrotic and cellular damages to the heart, but J. phoenicea leaves extract were found to ameliorate the gamma-irradiation-induced changes in the heart.

CONCLUSION

The results suggested that treatment with J. phoenicea leaves extract is possibly safe and can ameliorate gamma-irradiation-induced oxidative damage and tissue injury in rats. The leaves of J. phoenicea could serve as a potential source of therapeutic antioxidants.

Melatonin a Promising Candidate for DNA Double-Stranded Breaks Reduction in Patients Undergoing Abdomen-Pelvis Computed Tomography Examinations

BACKGROUND AND OBJECTIVE

Cancer incidence is 24% higher in children and young adults exposed to Computed Tomography (CT) scans than those unexposed. Non-repairing of ionizing radiation-induced DNA Double-Strand Breaks (DSBs) can initiate carcinogenesis. In the present study, we aimed to investigate the radioprotective potential of melatonin against DSBs in peripheral blood lymphocytes of patients undergoing abdomen-pelvis CT examinations.

METHODS

This double-blind, placebo-controlled clinical trial was conducted on thirty patients. These patients were divided into two groups; group one (control) patients who have undergone the CT examination received a single oral dose of placebo, while in group two, patients received a single oral dose of 100mg melatonin. In both the groups, blood samples were collected 5-10min before and 30 minutes after the CT examination. The lymphocytes from these samples were isolated and DSBs were analyzed using γH2AX immunofluorescence microscopy.

RESULTS

Compared to the control group, the use of melatonin 1h before the CT examination caused a significant reduction in γH2AX-foci, indicating a reduction in DSBs. In addition, no side effect was observed in patients following 100mg melatonin administration.

CONCLUSION

For the first time, this study has shown that melatonin has protective effects against radiationinduced genotoxicity in peripheral blood lymphocytes of patients undergoing abdomen-pelvis CT examinations. Therefore, melatonin can be considered as a promising candidate for reducing DSBs in patients undergoing abdomen-pelvis CT examinations.

Direct effects of low-energy electrons on including sulfur bonds in proteins: a second-order Møller-Plesset perturbation (MP2) theory approach

In an attempt to describe how low-energy electrons (LEEs) damage the polypeptide chain at disulfide bridges, ab initio electronic structure estimates on LEE interactions with cysteine-cysteine (Cys-Cys) disulfide bond model have been performed. Here, the fundamental mechanisms in LEE impression on S-S and C-S bond ruptures in the Cys-Cys model have been discussed. The electronic energy was calculated using the MP2 method with a Hartree-Fock exchange during the SCF and the Møller-Plesset correlation energy correction on the converged HF orbitals with 6-311++G(d,p) atomic orbital basis set. Further, six more sets of diffuse s and p functions with extra basis on the sulfur and relevant carbon atoms were used to describe the added electron to located away as much as possible from the nuclei in anions. The bonds rupture mechanisms involve the primary placement of LEEs to the π* orbital of the model to construct the shape-resonance state following by an adiabatic or nonadiabatic electron migration to either S-S or C-S bond σ* orbital. The formed radical anion undergoes S-S or C-S bonds cleavage by energy barriers of ca. 5.68 and 9.19 kcal/mol, respectively, to produce either (2-amino-2-carboxyethyl) sulfanyl (cysteine radical), aziridine-2-carboxylic acid or mercapto-L-cysteine lesions. In SMD solvent, calculations suggest electronically stable of the formed π* and σ* states by solvation, something that induces either S-S or C-S bond break even when the electron energy is near zero. The required barrier energy of only 0 to < 0.4 eV indicates a high kinetic favorable fragmentation for involved sulfur polypeptides with LEEs.Communicated by Ramaswamy H. Sarma.

Pharmacological management of ionizing radiation injuries: current and prospective agents and targeted organ systems

Introduction: There is a limited array of currently available medicinals that are useful for either the prevention, mitigation or treatment of bodily injuries arising from ionizing radiation exposure.Area covered: In this brief article, the authors review those pharmacologic agents that either are currently being used to counter the injurious effects of radiation exposure, or those that show promise and are currently under development.Expert opinion: Although significant, but limited progress has been made in the development and fielding of safe and effective pharmacotherapeutics for select types of acute radiation-associated injuries, additional effort is needed to broaden the scope of drug development so that overall health risks associated with both short- and long-term injuries in various organ systems can be reduced and effectively managed. There are several promising radiation countermeasures that may gain regulatory approval from the government in the near future for use in clinical settings and in the aftermath of nuclear/radiological exposure contingencies.

Arabinoxylan rice bran (MGN-3/Biobran) enhances radiotherapy in animals bearing Ehrlich ascites carcinoma†

This study examines the ability of arabinoxylan rice bran (MGN-3/Biobran) to enhance the anti-cancer effects of fractionated X-ray irradiation of Ehrlich solid tumor-bearing mice. Swiss albino mice bearing tumors were exposed to the following: (i) Biobran treatment (40 mg/kg/day, intraperitoneal injections) beginning on day 11 post-tumor cell inoculation until day 30; (ii) ionizing radiation (Rad) 2 Gy at three consecutive doses on days 12, 14 and 16; or (iii) Biobran + Rad. Final tumor weight was suppressed by 46% for Biobran, 31% for Rad and 57% for the combined treatment (Biobran + Rad) relative to control untreated mice. Biobran and Rad also arrested the hypodiploid cells in the sub-G1-phase, signifying apoptosis by +102% and +85%, respectively, while the combined treatment induced apoptosis by +123%, with similar results in the degree of DNA fragmentation. Furthermore, Biobran + Rad upregulated the relative gene expression and protein level of p53 and Bax in tumor cells, down-regulated Bcl-2 expression, and increased the Bax/Bcl-2 ratio and caspase-3 activity, with the combined treatment greater than for either treatment alone. Additionally, the combined treatment modulated the decrease in body weight, the increase in liver and spleen weight, and the elevation of liver enzymes aspartate aminotransferase, alanine aminotransferase and gamma-glutamyl transferase to be within normal values. We conclude that Biobran enhances radiation therapy-induced tumor regression by potentiating apoptosis and minimizing toxicities related to radiation therapy, suggesting that Biobran may be useful in human cancer patients undergoing radiotherapy and warranting clinical trials.

Protective Effect of Melatonin Against Radiotherapy-Induced Small Intestinal Oxidative Stress: Biochemical Evaluation

Background and Objectives: Radiation enteritis is a common side effect after radiotherapy for abdominal and pelvic malignancies. The aim of the present study was to investigate the protective effect of melatonin, known for its free radical scavenging ability, against radiotherapy-induced small intestinal oxidative damage. Materials and Methods: Thirty male Wistar rats were randomly assigned to six groups (5 rats in each) as follows: Group I (control group) rats received neither radiation nor melatonin; group II rats received only 8 Gy single dose of gamma radiation to their abdomen and pelvis regions; group III (administered with only 50 mg/kg melatonin); group IV (administered with only 100 mg/kg melatonin); group V (50 mg/kg melatonin + 8 Gy radiation), group VI (100 mg/kg melatonin + 8 Gy radiation). All rats were sacrificed after 5 days for biochemical assessments of their intestinal tissues. Results: Treatment with melatonin post irradiation significantly reduced malondialdehyde (MDA) levels as well as increased both superoxide dismutase (SOD) and catalase (CAT) activities of the irradiated intestinal tissues. In addition, melatonin administration with different doses pre irradiation led to protection of the tissues. Moreover, the 100 mg/kg dose was more effective compared to 50 mg/kg. Conclusions: The results of our study suggest that melatonin has a potent protective effect against radiotherapy-induced intestinal damage, by decreasing oxidative stress and increasing antioxidant enzymes. We recommend future clinical trials for more insights.

Pioglitazone ameliorates hepatic damage in irradiated rats via regulating anti-inflammatory and antifibrogenic signalling pathways

Hepatic irradiation during radiotherapy is associated with liver damage. The current study was designed to investigate the possible modulatory effects of pioglitazone against γ irradiation-induced hepatic damage in rats. Animals were exposed to a single dose of 6 Gy and received pioglitazone (10 mg/kg/day) orally for 4 weeks starting on the same day of irradiation. Results showed that irradiation increased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities as well as serum triglyceride (TG) and total cholesterol (TC) levels. Furthermore, it elevated inflammatory mediators; tumour necrosis factor alpha (TNF-α), interleukin-6 (IL-6); nuclear factor kappa B (NF-κB) and inducible nitric oxide synthase (iNOS) in hepatic tissues. Moreover, it increased levels of serum fibrotic markers; hyaluronic acid (HA), laminin (LN), and type III procollagen (PCIII). Additionally, hepatic fibrotic markers; transforming growth factor-β1 (TGF-β1) and hydroxyproline (HP) levels were elevated. Histological analysis of H&E and MT staining of liver sections exhibited cellular infiltration and fibrous deposition in irradiated rats. It was observed that pioglitazone modulated the described deviations. In conclusion, pioglitazone could serve as a promising therapeutic tool for attenuating radiation-induced liver injury in patients with radiotherapy which might be attributed to its anti-inflammatory and antifibrotic activities.

Hepatotoxicity and renal toxicity induced by gamma-radiation and the modulatory protective effect of Ficus carica in male albino rats

It is well-known that gamma radiation initiates generation of free radicals which prompting serious cellular damages in biological systems. In the present study, we investigated the role of Ficus carica, a natural antioxidant substance, in modulating changes in liver and kidney functions, antioxidant enzyme's gene expression, and apoptosis, in male albino rats exposed to gamma radiation. A total of 40 rats were used in this experiment and divided equally into 4 groups: Group 1, rats administered distilled H₂O (Control); Group 2, rats administered F. carica; Group 3, rats irradiated; and Group 4, rats treated with F. carica and irradiated. Groups 3 and 4 were exposed to whole-body gamma radiations at a dose level of 8 Gy and with a dose rate of 0.762 Gy/min. F. carica was administered to rats by gavage, for 3 consecutive weeks, before exposure to radiation. Five rats were sacrificed from each group at intervals of 24 and 72 h after cessation of treatment. The results revealed marked increases in alanine aminotransferase and aspartate aminotransferase levels in liver, a decrease in albumin level and increase in urea level in kidney. Irradiation resulted in cytotoxic effects as indicated by elevation in antioxidant enzyme's gene expression at 24 h, the opposite was observed at 72 h. Immunohistochemical analysis revealed that cytochrome c and p53 expressions significantly increased following exposure to radiation. Oral administration of F. carica pre-irradiation as a natural product plays a modulatory protective and anti-apoptotic role against cells damaged by free radicals induced by whole-body irradiation.

Biophysical Studies of Some Bee Products as Radioprotectors.. [DOI: 10.1101/472233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The study had been planned to evaluate some antioxidant ingredients in honey and propolis. Also, a study on ionizing gamma irradiated rats was done to assess these antioxidants as radioprotectors. Bioactive ingredients, such as phenols, flavonoids and trace elements, were explored using FTIR, UV-Vis and AAS spectroscopic techniques. Animals were exposed to fractionated gamma radiation doses. Honey, propolis and their combination were administrated before and during the irradiation period. Serum levels of total protein, albumin and uric acid were estimated. Also, the osmotic fragility of Red Blood Corpuscles (RBCs) membranes and a microscopic examination of blood films were investigated. The analysis demonstrated that the level of phenolic, flavonoid and trace elements are higher in propolis than honey. The levels of total protein and albumin decreased post irradiation while the level of uric acid increased. Likewise, osmotic fragility of RBCs membranes was increased with a sticking forming RBCs aggregation. It had been found that administration of the natural antioxidants induced amelioration in most of the studied parameters. It can be concluded that natural antioxidants produced a modulation against oxidative stress induced by ionizing radiation.

Summary Statement

Assessment of some antioxidant ingredients in honey and propolis. Also, a study on ionizing gamma irradiated rats was done to assess these antioxidants as radioprotectors.

Blueberry extract attenuates γ-radiation-induced hepatocyte damage by modulating oxidative stress and suppressing NF-κB in male rats

Radiation exposure is known to produce many harmful effects in biological systems, and these effects are often mediated by oxygen free radicals. Because blueberries are rich in antioxidant compounds such as anthocyanins and phenolic acids, we divided forty adult rats into four treatment groups of 10 (G1-4) as follows: G1 rats were used as a control, G2 rats were irradiated with 8 Gy at 2 Gy/week at a dose rate of 0.5 Gy/min, G3 rats were administered blueberry extract (200 mg/kg) and G4 rats were administered blueberry extract during the same irradiation period. In subsequent determinations, γ-irradiated rats had increased levels of cholesterol, triglyceride, high density lipoprotein (HDL) and low density lipoprotein (LDL), and significantly elevated liver enzyme activities, including alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP), and total bilirubin. In contrast, significant reductions in albumin, total protein and globulin were observed, whereas gamma irradiation decreased activities of the antioxidant enzymes glutathione (GSH), catalase (CAT), xanthine dehydrogenase (XDH) and superoxide dismutase (SOD). We also observed incremental increases in DNA fragmentation percentages and histopathological changes in liver tissues. Serum pro-inflammatory cytokine levels (IL-6, IL-10 and TNF-α) were significantly elevated and hepatic NF-кB was upregulated. In G4 rats, treatments with blueberry extract restored liver pro-oxidant status, reduced cytokine levels, ameliorated histopathological parameters and reduced DNA damage. In conclusion, γ-radiation exerts toxic effects in the rat livers, and blueberry extract is protective against these.

Melatonin and cancer: From the promotion of genomic stability to use in cancer treatment

Cancer remains among the most challenging human diseases. Several lines of evidence suggest that carcinogenesis is a complex process that is initiated by DNA damage. Exposure to clastogenic agents such as heavy metals, ionizing radiation (IR), and chemotherapy drugs may cause chronic mutations in the genomic material, leading to a phenomenon named genomic instability. Evidence suggests that genomic instability is responsible for cancer incidence after exposure to carcinogenic agents, and increases the risk of secondary cancers following treatment with radiotherapy or chemotherapy. Melatonin as the main product of the pineal gland is a promising hormone for preventing cancer and improving cancer treatment. Melatonin can directly neutralize toxic free radicals more efficiently compared with other classical antioxidants. In addition, melatonin is able to regulate the reduction/oxidation (redox) system in stress conditions. Through regulation of mitochondrial nction and inhibition of pro-oxidant enzymes, melatonin suppresses chronic oxidative stress. Moreover, melatonin potently stimulates DNA damage responses that increase the tolerance of normal tissues to toxic effect of IR and may reduce the risk of genomic instability in patients who undergo radiotherapy. Through these mechanisms, melatonin attenuates several side effects of radiotherapy and chemotherapy. Interestingly, melatonin has shown some synergistic properties with IR and chemotherapy, which is distinct from classical antioxidants that are mainly used for the alleviation of adverse events of radiotherapy and chemotherapy. In this review, we describe the anticarcinogenic effects of melatonin and also its possible application in clinical oncology.

Diplomats' Mystery Illness and Pulsed Radiofrequency/Microwave Radiation

Importance: A mystery illness striking U.S. and Canadian diplomats to Cuba (and now China) "has confounded the FBI, the State Department and US intelligence agencies" (Lederman, Weissenstein, & Lee, 2017). Sonic explanations for the so-called health attacks have long dominated media reports, propelled by peculiar sounds heard and auditory symptoms experienced. Sonic mediation was justly rejected by experts. We assessed whether pulsed radiofrequency/microwave radiation (RF/MW) exposure can accommodate reported facts in diplomats, including unusual ones. Observations: (1) Noises: Many diplomats heard chirping, ringing or grinding noises at night during episodes reportedly triggering health problems. Some reported that noises were localized with laser-like precision or said the sounds seemed to follow them (within the territory in which they were perceived). Pulsed RF/MW engenders just these apparent "sounds" via the Frey effect. Perceived "sounds" differ by head dimensions and pulse characteristics and can be perceived as located behind in or above the head. Ability to hear the "sounds" depends on high-frequency hearing and low ambient noise. (2) Signs/symptoms: Hearing loss and tinnitus are prominent in affected diplomats and in RF/MW-affected individuals. Each of the protean symptoms that diplomats report also affect persons reporting symptoms from RF/MW: sleep problems, headaches, and cognitive problems dominate in both groups. Sensations of pressure or vibration figure in each. Both encompass vision, balance, and speech problems and nosebleeds. Brain injury and brain swelling are reported in both. (3) Mechanisms: Oxidative stress provides a documented mechanism of RF/MW injury compatible with reported signs and symptoms; sequelae of endothelial dysfunction (yielding blood flow compromise), membrane damage, blood-brain barrier disruption, mitochondrial injury, apoptosis, and autoimmune triggering afford downstream mechanisms, of varying persistence, that merit investigation. (4) Of note, microwaving of the U.S. embassy in Moscow is historically documented. Conclusions and relevance: Reported facts appear consistent with pulsed RF/MW as the source of injury in affected diplomats. Nondiplomats citing symptoms from RF/MW, often with an inciting pulsed-RF/MW exposure, report compatible health conditions. Under the RF/MW hypothesis, lessons learned for diplomats and for RF/MW-affected civilians may each aid the other.

Radioprotective effect of Date syrup on radiation- induced damage in Rats

Ionizing radiation has cytotoxic and genotoxic effects caused mainly by the oxidative damage induced by free radical release. The need for radioprotectives is increasing to protect normal tissues during radiotherapy. In the present study, we investigated the radioprotective effect of Date syrup in rats subjected to whole body radiation at 6 Gy through biochemical, molecular and histopathological analysis. Significant elevations were recorded in the activities of serum ALT, AST, ALP and LDH and in the levels of all lipid profiles parameters, while the level of HDL-C was reduced. The concentration of liver MDA was elevated with depletion of hepatic glutathione (GSH) and catalase. DNA damage was evidenced by increased DNA strand breakage and DNA-protein crosslinks. Significant elevations were observed in the expression of liver TNF-α and serum activity of matrix metalloproteinase (MMP-9). Pretreatment of rats with Date syrup ameliorated the tissue damage induced by radiation as evidenced by the improvement of liver function, antioxidant status and reduction of DNA damage. Besides, liver TNF-α expression and serum MMP-9 activity were reduced. In conclusion, Date syrup could alleviate the toxic effects of ionizing radiation and thus is useful as a radioprotective in radiotherapy regimen.

Long-term effects of low-dose mouse liver irradiation involve ultrastructural and biochemical changes in hepatocytes that depend on lipid metabolism

The aim of the study was to investigate long-term effects of radiation on the (ultra)structure and function of the liver in mice. The experiments were conducted on wild-type C57BL/6J and apolipoprotein E knock-out (ApoE^-/-) male mice which received a single dose (2 or 8 Gy) of X-rays to the heart with simultaneous exposure of liver to low doses (no more than 30 and 120 mGy, respectively). Livers were collected for analysis 60 weeks after irradiation and used for morphological, ultrastructural, and biochemical studies. The results show increased damage to mitochondrial ultrastructure and lipid deposition in hepatocytes of irradiated animals as compared to non-irradiated controls. Stronger radiation-related effects were noted in ApoE^-/- mice than wild-type animals. In contrast, radiation-related changes in the activity of lysosomal hydrolases, including acid phosphatase, β-glucuronidase, N-acetyl-β-D-hexosaminidase, β-galactosidase, and α-glucosidase, were observed in wild type but not in ApoE-deficient mice, which together with ultrastructural picture suggests a higher activity of autophagy in ApoE-proficient animals. Irradiation caused a reduction of plasma markers of liver damage in wild-type mice, while an increased level of hepatic lipase was observed in plasma of ApoE-deficient mice, which collectively indicates a higher resistance of hepatocytes from ApoE-proficient animals to radiation-mediated damage. In conclusion, liver dysfunctions were observed as late effects of irradiation with an apparent association with malfunction of lipid metabolism.

Renal and hepatic effects following neonatal exposure to low doses of Bisphenol-A and 137Cs

137-Cesium (¹³⁷Cs) is one of the most important distributed radionuclides after a nuclear accident. Humans are usually co-exposed to various environmental toxicants, being Bisphenol-A (BPA) one of them. Exposure to IR and BPA in early life is of major concern, due to the higher vulnerability of developing organs. We evaluate the renal and hepatic effects of low doses of ionizing radiation (IR) and BPA. Sixty male mice (C57BL/6J) were randomly assigned to six experimental groups (n=10) and received a single subcutaneous dose of 0.9% saline solution, ¹³⁷Cs and/or BPA on postnatal day 10: control, BPA (25 μg/kgbw), Cs4000 (4000 Bq ¹³⁷Cs/kgbw), Cs8000 (8000 Bq ¹³⁷Cs/kgbw), BPA/Cs4000 and BPA/Cs8000. At the age of two months, urines (24h) and blood samples were collected from animals of each group to determine biochemical parameters. Finally, kidneys and liver were removed to quantify DNA damage (8-OHdG), as well as to determine CYP1A2 mRNA expression. Data suggest that both BPA and ¹³⁷Cs induced renal and liver damage evidenced by oxidative stress. However, when there is a co-exposure, it seems that there are compensatory mechanisms that may reverse the damage induced by each toxic itself. Notwithstanding, more studies are necessary to better understand the synergistic mechanisms behind.

Hydrogen-water ameliorates radiation-induced gastrointestinal toxicity via MyD88's effects on the gut microbiota

Although radiation therapy is a cornerstone of modern management of malignancies, various side effects are inevitably linked to abdominal and pelvic cancer after radiotherapy. Radiation-mediated gastrointestinal (GI) toxicity impairs the life quality of cancer survivors and even shortens their lifespan. Hydrogen has been shown to protect against tissue injuries caused by oxidative stress and excessive inflammation, but its effect on radiation-induced intestinal injury was previously unknown. In the present study, we found that oral gavage with hydrogen-water increased the survival rate and body weight of mice exposed to total abdominal irradiation (TAI); oral gavage with hydrogen-water was also associated with an improvement in GI tract function and the epithelial integrity of the small intestine. Mechanistically, microarray analysis revealed that hydrogen-water administration upregulated miR-1968-5p levels, thus resulting in parallel downregulation of MyD88 expression in the small intestine after TAI exposure. Additionally, high-throughput sequencing showed that hydrogen-water oral gavage resulted in retention of the TAI-shifted intestinal bacterial composition in mice. Collectively, our findings suggested that hydrogen-water might be used as a potential therapeutic to alleviate intestinal injury induced by radiotherapy for abdominal and pelvic cancer in preclinical settings.

Role of drugs in the prevention and amelioration of radiation induced toxic effects

As the use of radiation technology for nuclear warfare or for the benefits of mankind (e.g. in radiotherapy or radio-diagnosis) is increasing tremendously, the risk of associated side effects is becoming a cause of concern. These effects, ranging from nausea/vomiting to death, may result from accidental or deliberate exposure and begin in seconds. Through this review paper, efforts have been done to critically review different compounds which have been investigated as radioprotectors and radiation mitigators. Radioprotectors are compounds which are administered just before or at the time of irradiation so as to minimize the radiation induced damage to normal tissues. And radiation mitigators are the compounds which can even minimize or ameliorate post irradiaion-toxicity provided they are administered before the onset of toxic symptoms. A variety of agents have been investigated for their preventive and ameliorative potential against radiation induced toxic effects. This review article has focused on various aspects of the promising representative agents belonging to different classes of radioprotectors and mitigators. Many compounds have shown promising results, but till date only amifostine and palifermin are clinically approved by FDA. To fill this void in pharmacological armamentarium, focus should be shifted towards novel approaches.

Environmental exposure to low-doses of ionizing radiation. Effects on early nephrotoxicity in mice

Nuclear accidents of tremendous magnitude, such as those of Chernobyl (1986) and Fukushima (2011), mean that individuals living in the contaminated areas are potentially exposed to ionizing radiation (IR). However, the dose-response relationship for effects of low doses of radiation is not still established. The present study was aimed at investigating in mice the early effects of low-dose internal radiation exposure on the kidney. Adult male (C57BL/6J) mice were divided into three groups. Two groups received a single subcutaneous (s.c.) doses of cesium (¹³⁷Cs) with activities of 4000 and 8000Bq/kg bw. A third group (control group) received a single s.c. injection of 0.9% saline. To evaluate acute and subacute effects, mice (one-half of each group) were euthanized at 72h and 10 days post-exposure to ¹³⁷Cs, respectively. Urine samples were collected for biochemical analysis, including the measurement of F2-isoprostane (F2-IsoP) and kidney injury molecule-1 (KIM-1) levels. Moreover, the concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a sensitive marker of oxidative DNA damage, were measured in renal tissue. Urinary excretion of total protein significantly increased at 72h in mice exposed to Cs4000. Uric acid and lactate dehydrogenase (LDH) decreased significantly at both times post-exposure in animals exposed to Cs8000. After 72h and 10d of exposure to Cs4000, a significant increase in the γ-glutamil transferase (GGT) and N-acetyl-β-D-glucosaminidase (NAG) activities was observed. In turn, F2-IsoP levels increased -mainly in the Cs4000 group- at 72h post-exposure. Following irradiation (¹³⁷Cs), the highest level of KIM-1 was corresponded to the Cs4000 group at 72h. Likewise, the main DNA damage was detected in mice exposed to Cs4000, mainly at 10d after irradiation. The alterations observed in several biomarkers suggest an immediate renal damage following exposure to low doses of IR (given as ¹³⁷Cs). Further investigations are required to clarify the mechanisms involved in the internal IR-induced nephrotoxicity.

Expression Levels of Two DNA Repair-related Genes under 8 Gy Ionizing Radiation and 100 Mg/Kg Melatonin Delivery In Rat Peripheral Blood

BACKGROUND

After radiation therapy (RT), some health hazards including DNA damages may occur where melatonin can play a protective role due to free radical generation. On the other hand, serious accidental overexposures may occur during RT due to nuclear accidents which necessitate the need for study on exposure to high-dose radiations during treatments.

OBJECTIVE

The aim of this study was to study the expression level of two genes in non-homologous end joining (NHEJ) pathways named Xrcc4 and Xrcc6 (Ku70) in order to examine the effect of melatonin on repair of DNA double-strand breaks (BSBs) caused by 8Gy ionizing radiation.

METHODS

One hundred eight male Wistar rats were irradiated with a whole body gamma radiation dose of 8Gy with or without melatonin pretreatments. They were divided into six different groups of control, 100 mg/kg melatonin alone, 8Gy irradiation alone, vehicle alone, vehicle plus 8Gy irradiation and 100 mg/kg melatonin plus 8Gy irradiation. Peripheral blood samples were collected at 8, 24 and 48 h after irradiation. Ku70 and Xrcc4 gene expression were evaluated by real-time quantitative polymerase chain reaction (qPCR) technique and analyzed by one-way ANOVA test.

RESULTS

Expression of Ku70 and Xrcc4 genes normalized against Hprt gene showed significant difference in melatonin plus irradiation group at 8h compared to the control group (p<0.05). At 24h post irradiation, gene expression changes were significantly upregulated in irradiation-alone group as well as melatonin plus irradiation group (p<0.05). No significant change was found in any groups compared to control group at 48 h time point.

CONCLUSION

We concluded that, by increasing expression level of Ku70 and Xrcc4 genes, 100 mg/kg melatonin administration 8 and 24 h before 8 Gyionizing radiation can significantly affect the repair of DNA DSBs in NHEJ pathway.

Lethal and sublethal effects of a methomyl-based insecticide in Hoplobatrachus rugulosus

The aim of this study was to investigate the lethal and sublethal toxicity of a methomyl-based insecticide in Hoplobatrachus rugulosus, as methomyl-based insecticides are applied in massive amounts and agrochemicals have effects on the decline in amphibian populations. To evaluate the toxic effects of methomyl from agricultural application, a methomyl-based insecticide containing 40% methomyl was selected. The median lethal concentration of 96 hours of methomyl exposure was 8.69 ppm for H. rugulosus tadpoles. The lethal concentration also produced severe histological damage in the livers and kidneys of the exposed tadpoles. The sublethal concentration used for methomyl was 144 ppb during the metamorphosis period. It was found that the sublethal concentration of the methomyl compound could decrease growth, metamorphosis time, and size, disturb biochemical parameters, and produce histological damage. In livers, methomyl effects increased oxidative stress and dramatically decreased the glycogen level of the treated froglets. Mononuclear infiltration, blood congestion, amorphous substances, and hepatocytes vacuolization were observed throughout liver tissue. The methomyl-based insecticide also increased oxidative stress and decreased nitric oxide levels in the kidneys of the exposed froglets. Renal tissue damage including blood congestion, amorphous substances, and Bowman’s capsule spaces reduction were found in the methomyl exposure group. The methomyl compound also produced vacuoles in various stages of oocytes, but no histological damage was found in testicular tissue. Our results indicated strong toxic effects of the methomyl-based insecticide on H. rugulosus, a broadly tolerant anuran.

Melatonin controlled apoptosis and protected the testes and sperm quality against bisphenol A-induced oxidative toxicity

Epidemiological reports have indicated a correlation between the increasing bisphenol A (BPA) levels in the environment and the incidence of male infertility. In this study, the protective effects of melatonin on BPA-induced oxidative stress and apoptosis were investigated in the rat testes and epididymal sperm. Melatonin (10 mg/kg body weight (bw)) was injected concurrently with BPA (50 mg/kg bw) for 3 and 6 weeks. The administration of BPA significantly increased oxidative stress in the testes and epididymal sperm. This was associated with a decrease in the serum testosterone level as well as sperm quality, chromatin condensation/de-condensation level, and the percentage of haploid germ cells in the semen. BPA administration caused a significant increase in apoptosis accompanied by a decrease in the expression of the antiapoptotic proteins Bcl-2 in the testes and epididymal sperm. The concurrent administration of melatonin decreased oxidative stress by modulating the levels of glutathione, superoxide dismutase, and catalase as well as the malondialdehyde and hydrogen peroxide concentrations in the testes and sperm. Melatonin sustained Bcl-2 expression and controlled apoptosis. Furthermore, melatonin maintained the testosterone levels, ameliorated histopathological changes, increased the percentages of seminal haploid germ cells, and protected sperm chromatin condensation process, indicating appropriate spermatogenesis with production of functional sperm. In conclusion, melatonin protected against BPA-induced apoptosis by controlling Bcl-2 expression and ameliorating oxidative stress in the testes and sperm. Thus, melatonin is a promising pharmacological agent for preventing the potential reproductive toxicity of BPA following occupational or environmental exposures.

Neuroprotective effect of acute melatonin treatment on hippocampal neurons against irradiation by inhibition of caspase-3

Neuronal cell apoptosis is associated with various factors that induce neurological damage, including radiation exposure. When administered prior to exposure to radiation, a protective agent may prevent cellular and molecular injury. The present study aimed to investigate whether melatonin exerts a neuroprotective effect by inhibiting the caspase cell death pathway. Male Sprague-Dawley rats were administered melatonin (100 mg/kg body weight) 30 min prior to radiation exposure in red light during the evening. In order to elucidate whether melatonin has a neuroprotective role, immunohistochemistry, terminal deoxynucleotidyl transferase dUTP nick-end labeling, Nissl staining, reverse transcription-quantitative polymerase chain reaction, reactive oxygen species analysis and western blotting were performed. At 24 h post-melatonin treatment, caspase-3 mRNA and protein expression levels were significantly decreased. These results demonstrated that melatonin may protect hippocampal neurons via the inhibition of caspase-3 when exposed to irradiation. Therefore, caspase-3 inhibition serves a neuroprotective and antioxidant role in the interventional treatment of melatonin. The results of the present study suggested that melatonin may have a potential therapeutic effect against irradiation; however, further studies are required in order to elucidate the underlying antioxidant mechanisms.

Efficacy of polysaccharide from Alcaligenes xylosoxidans MSA3 administration as protection against γ-radiation in female rats

Damage to normal tissues is a consequence of both therapeutic and accidental exposures to ionizing radiation. A water-soluble heteropolysaccharide called AXEPS, composed of glucose, galactose, rhamnose and glucouronic acid in a molar ratio of nearly 1.0:1.6:0.4:2.3, respectively, was isolated from culture medium of strain Alcaligenes xylosoxidans MSA3 by ethanol precipitation followed by freeze-drying. Chemical analysis, Fourier-transform infrared (FTIR) and chromatographic studies revealed that the molecular weight was 1.6 × 10(4) g mol(-1). This study was designed to investigate the radioprotective and biological effects of AXEPS in alleviating the toxicity of ionizing radiation in female albino rats. A total of 32 female albino rats were divided into four groups. In the control group, rats were administered vehicle by tube for four weeks. The second group was administered AXEPS (100 mg/kg) orally by gavage for four weeks. Animals in the third group were exposed to whole-body γ-rays (5 Gy) and remained for 2 weeks without treatment. The fourth group received AXEPS (100 mg/kg) orally by gavage for two weeks before being exposed to whole-body γ-rays (5 Gy), then 24 h post γ-rays, they received AXEPS (100 mg/kg) in a treatment continuing till the end of the experiment (15 days after the whole-body γ-irradiation). Oral administration of AXEPS (100 mg/kg) significantly reversed the oxidative stress effects of radiation, as evidenced by the decrease in DNA damage in the bone marrow. Assessment of apoptosis and cell proliferation markers revealed that caspase-3 significantly increased in the irradiated group. Moreover, a significant decrease in the hematological constituents of peripheral blood, the chemotactic index and CD8+ T cells were observed in animals in the irradiation-only group, whereas an increase in the lymphocyte index was observed in animals in that group. In contrast, AXEPS treatment prevented these alterations. From our results, we conclude that AXEPS is a potent antioxidant and treatment agent for protection from γ-rays.

Melatonin's protective effect on the salivary gland against ionized radiation damage in rats

OBJECTIVES

The aim of this study was to examine the effects of melatonin on ionized radiation-induced salivary gland damage using an experimental model.

MATERIALS AND METHODS

Thirty-two rats were randomized into four groups: (i) the control group (C, n = 8) that received intraperitoneal (i.p.) 0.9% NaCl; (ii) the melatonin group (M, n = 8) that received i.p. 5 mg/kg melatonin; (iii) the radiotherapy group (RT, n = 8) that underwent irradiation; (iv) the melatonin plus radiotherapy group (M+RT, n = 8) that received i.p. 5 mg/kg of melatonin, followed by irradiation 30 min later; and (v) the radiotherapy plus melatonin group (RT+M, n = 8) that received irradiation followed by i.p. 5 mg/kg of melatonin 30 min later. The medications and irradiation were administered for 5 days and the salivary glands of the rats were excised 10 days later; the histopathological changes in the salivary glands were assessed and biochemical analyses were conducted (tissue levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI)).

RESULTS

Regardless of whether melatonin was administered before or after radiotherapy, melatonin decreased the radiation-induced parotid and submandibular histological damage. In addition, regardless of whether administration occurred before or after radiotherapy, melatonin decreased oxidative stress markers, such as MDA, TOS, and OSI. On the contrary, levels of antioxidative markers, such as CAT and GPx, were increased by melatonin.

CONCLUSIONS

Melatonin may have a significant protective effect on salivary gland damage secondary to ionizing radiation.

Melatonin: A Potential Anti-Oxidant Therapeutic Agent for Mitochondrial Dysfunctions and Related Disorders

Mitochondria play a central role in cellular physiology. Besides their classic function of energy metabolism, mitochondria are involved in multiple cell functions, including energy distribution through the cell, energy/heat modulation, regulation of reactive oxygen species (ROS), calcium homeostasis, and control of apoptosis. Simultaneously, mitochondria are the main producer and target of ROS with the result that multiple mitochondrial diseases are related to ROS-induced mitochondrial injuries. Increased free radical generation, enhanced mitochondrial inducible nitric oxide synthase (iNOS) activity, enhanced nitric oxide (NO) production, decreased respiratory complex activity, impaired electron transport system, and opening of mitochondrial permeability transition pores have all been suggested as factors responsible for impaired mitochondrial function. Because of these, neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and aging, are caused by ROS-induced mitochondrial dysfunctions. Melatonin, the major hormone of the pineal gland, also acts as an anti-oxidant and as a regulator of mitochondrial bioenergetic function. Melatonin is selectively taken up by mitochondrial membranes, a function not shared by other anti-oxidants, and thus has emerged as a major potential therapeutic tool for treating neurodegenerative disorders. Multiple in vitro and in vivo experiments have shown the protective role of melatonin for preventing oxidative stress-induced mitochondrial dysfunction seen in experimental models of PD, AD, and HD. With these functions in mind, this article reviews the protective role of melatonin with mechanistic insights against mitochondrial diseases and suggests new avenues for safe and effective treatment modalities against these devastating neurodegenerative diseases. Future insights are also discussed.

Phototherapeutic Effect of Low-Level Laser on Thyroid Gland of Gamma-Irradiated Rats

One inescapable feature of life on the earth is exposure to ionizing radiation. The thyroid gland is one of the most sensitive organs to gamma-radiation and endocrine disrupters. Low-level laser therapy (LLLT) has been used to stimulate tissue repair, and reduce inflammation. The aim of this study was to gauge the value of using Helium-Neon laser to repair the damaged tissues of thyroid gland after gamma-irradiation. Albino rats were used in this study (144 rats), divided into control, gamma, laser, and gamma plus laser-irradiated groups, each group was divided into six subgroups according to time of treatment (total six sessions). Rats were irradiated once with gamma radiation (6 Gy), and an external dose of laser (Wavelength 632.8 nm, 12 mW, CW, Illuminated area 5.73 cm(2), 2.1 mW cm(-2) 120 s, 1.4 J, 0.252 J cm(-2)) twice weekly localized on thyroid region of the neck, for a total of six sessions. Animals were sacrificed after each session. Analysis included thyroid function, oxidative stress markers, liver function and blood picture. Results revealed improvement in thyroid function, liver function and antioxidant levels, and the blood cells count after LLLT.

Mechanisms of cardiac radiation injury and potential preventive approaches

In addition to cytostatic treatment and surgery, the most common cancer treatment is gamma radiation. Despite sophisticated radiological techniques however, in addition to irradiation of the tumor, irradiation of the surrounding healthy tissue also takes place, which results in various side-effects, depending on the absorbed dose of radiation. Radiation either damages the cell DNA directly, or indirectly via the formation of oxygen radicals that in addition to the DNA damage, react with all cell organelles and interfere with their molecular mechanisms. The main features of radiation injury besides DNA damage is inflammation and increased expression of pro-inflammatory genes and cytokines. Endothelial damage and dysfunction of capillaries and small blood vessels plays a particularly important role in radiation injury. This review is focused on summarizing the currently available data concerning the mechanisms of radiation injury, as well as the effectiveness of various antioxidants, anti-inflammatory cytokines, and cytoprotective substances that may be utilized in preventing, mitigating, or treating the toxic effects of ionizing radiation on the heart.

A strategy for effective radioprotection by chitosan-based long-circulating nanocarriers

Effective radioprotection is achieved by chitosan-based long-circulating nanocarriers with radioprotective agents. The stable encapsulation does not reduce its radioprotective capability and exhibits prolonged retention time, thereby showing more beneficial effects.