Protective effects of melatonin and vitamin E in brain damage due to gamma radiation

Abstract

Gamma radiation is known to cause serious damage in the brain, and many agents have been used for neuroprotection. In this study, lipid peroxidation levels and histopathological changes in brain tissues of whole-body irradiated rats with likely radiation injury were compared to those with melatonin and vitamin E protection. Forty rats in four equal groups were used. The control group received neither radiation nor medication. The remaining groups received doses of 720 cGy in two equal fractions 12 h apart. The second group received radiation but no medication, the third received radiation plus 100 mg/kg per day of vitamin E i.p., and the fourth received radiation plus 100 mg/kg per day of melatonin i.p. over 5 days. On the 10th postoperative day, all the rats were decapitated and specimens from parietal cortices were analyzed for tissue malondialdehyde (MDA) levels and histopathological changes. Increases in MDA were relatively well prevented by melatonin treatment but less so with vitamin E therapy. On histopathological examination, melatonin significantly reduced the rates of edema, necrosis, and neuronal degeneration, whereas vitamin E reduced only necrosis. Neither substance was capable of preventing vasodilatation. In conclusion, melatonin may be useful in preventing the pathological changes of secondary brain damage as a result of free oxygen radicals generated by irradiation.

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“…In recent studies radiation necrosis was demonstrated to vary depending on the total radiation dose, frequency, dose per fractions, duration of administration and the size of the exposed area [2,10]. A total dose of 20 Gy may be enough to cause radionecrosis.…”

“…A total dose of 20 Gy may be enough to cause radionecrosis. Various clinical studies suggested that higher total doses of radiation are associated with earlier formation of cerebral radionecrosis [1,10]. In addition, it was indicated that, patients who received a higher fractional dose had a significantly higher incidence of radionecrosis than those treated with a higher total dose but a lower fractional dose.…”

“…In addition, it was indicated that, patients who received a higher fractional dose had a significantly higher incidence of radionecrosis than those treated with a higher total dose but a lower fractional dose. For this reason, it was stressed that fractional dose is a very important factor affecting cerebral radionecrosis development [1,2,10]. Most authors agree that a total dose of 55 Gy, administered in fractions of 1.7 to 2 Gy is tolerated by the central nervous system.…”

“…Since it was known that free oxygen radicals have a role both in edema and necrosis development, the benefits of using antioxidants such as melatonin and vitamin E for protection purposes were indicated, especially in animal experiments [10]. However, familiar treatment approaches which can be clinically beneficial in radionecrosis cases consist of surgical treatment or corticosteroid treatment [1,2,10].…”

“…However, familiar treatment approaches which can be clinically beneficial in radionecrosis cases consist of surgical treatment or corticosteroid treatment [1,2,10]. As vasogenic edema commonly accompanies radionecrosis cases, clinical cures and the patients who benefited from corticosteroid treatment were reported [2].…”