Effect of Low-Dose Gamma Radiation and Lipoic Acid on High- Radiation-Dose Induced Rat Brain Injuries

Abstract

Aim This work aims to investigate the possible radio-adaptive mechanisms induced by low-dose (LD) whole-body γ-irradiation alone or combined with alpha-lipoic acid (ALA) administration in modulating high-dose (HD) head irradiation–induced brain injury in rats. Materials and Methods Rats were irradiated with LD (.25 Gy) 24 hours prior HD (20 Gy), and subjected to ALA (100 mg/kg/day) 5 minutes after HD and continued for 10 days. At the end of the experiment, animals were sacrificed and brain samples were dissected for biochemical and histopathological examinations. Results HD irradiation-induced brain injury as manifested by elevation of oxidative stress, DNA damage, apoptotic, and inflammatory markers in brain tissue. Histological examination of brain sections showed marked alterations. However, LD alone or combined with ALA ameliorated the changes induced by HD. Conclusion Under the present experimental conditions, LD whole-body irradiation exhibited neuroprotective activity against detrimental effects of a subsequent HD head irradiation. This effect might be due to the adaptive response induced by LD that activated the anti-oxidative, anti-apoptotic, and anti-inflammatory mechanisms in the affected animals making them able to cope with the subsequent high-dose exposure. However, the combined LD exposure and ALA supplementation produced a further modulating effect in the HD-irradiated rats.

Low-Dose Gamma Radiation Modulates Liver and Testis Tissues Response to Acute Whole Body Irradiation

“…Moreover, it has been demonstrated that exposure to low doses of ionizing radiation provided resistance to oxidative injuries in different tissues triggered by high-dose radiation, doxorubicin, and snake venom. 7,36,37 Also, low doses intensified the antioxidant, antiapoptotic, and anti-inflammatory effects of exogenous antioxidants administered to rats against liver and testis injuries induced by different toxicants. 13,38,39 As well, the clinical trial recorded by Yu et al showed that low dose radiation-mediated radioadaptive response can alleviate high dose radiation toxicities, improve the short-term efficacy of radiotherapy, and improve the survival of the lung cancer patients.…”

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“…It can able to cross cell membranes and quench the free radicals through its redox couple, dihydrolipoic acid (DHLA) directly by scavenging excess generation of free radicals or indirectly via maintaining endogenous enzymatic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase or and non-enzymatic antioxidants such as α-tocopherol, ascorbate, glutathione and/or both [96][97][98] . The therapeutic efficacy of LA against several disorders such as diabetic neuropathy, alzheimers disease, cancer, obesity, disorders like schizophernia, and disorders of central nervous system such as multiple sclerosis is gaining importance in the field of biomedicine 36 .…”