1. Medical Physics Department, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Cell J. 2011 Summer;13(2):79-82. Epub 2011 Aug 24.
Ocular morbidity is widely observed when radiotherapy includes the orbit. Oxidative stress generated by irradiation is responsible for this complication. In different studies, it has been shown that melatonin has antioxidative properties and a radioprotective role. The aim of this study was to evaluate the antioxidant role of melatonin against radiation-induced oxidative injury in rats' lenses after total cranial irradiation.
Thirty-six adult female Sprague-Dawley rats were divided into six groups. Group I was the control group, group II only received total cranial gamma irradiation of 5 Gy, group III was exposed as the second group but at the dose of 8 Gy, group IV received 30 mg/kg melatonin 30 minutes prior to radiation plus total cranial irradiation of 5 Gy plus 5 mg/kg melatonin daily through intraperitoneal injection for ten days after irradiation, group V was treated similar to the fourth group, i.e. received irradiation plus melatonin, but at the dose of 8 Gy, and group VI only received melatonin (30 mg/kg on the first day and 5 mg/kg on the following days). Ten days after irradiation, all rats were sacrificed and their eyes were enucleated to measure the biochemical parameters i.e. malondialdehyde (MDA) and glutathione (GSH).
The levels of MDA in rat lenses increased and the levels of glutathione in lenses decreased after gamma ray irradiation but these parameters were still within normal limits in rats that received melatonin.
It could be concluded that melatonin is useful in preventing radiation-induced oxidative injury due to its antioxidative and free radical scavenging properties.
当放射治疗包括眼眶时，会广泛观察到眼部疾病。辐照产生的氧化应激是导致这种并发症的原因。在不同的研究中，已经表明褪黑素具有抗氧化特性和放射保护作用。本研究的目的是评估褪黑素对大鼠全颅照射后晶状体辐射诱导氧化损伤的抗氧化作用。
36 只成年雌性 Sprague-Dawley 大鼠分为六组。第 I 组为对照组，第 II 组仅接受 5Gy 的全颅γ射线照射，第 III 组暴露于第二组，但剂量为 8Gy，第 IV 组在照射前 30 分钟给予 30mg/kg 褪黑素，并在照射后每天通过腹腔注射 5mg/kg 褪黑素 10 天，第 V 组接受与第 IV 组相似的治疗，即接受照射加褪黑素，但剂量为 8Gy，第 VI 组仅给予褪黑素（第 1 天给予 30mg/kg，第 2 天给予 5mg/kg）。照射后 10 天，所有大鼠被处死，眼球被取出以测量生化参数，即丙二醛（MDA）和谷胱甘肽（GSH）。
γ射线照射后大鼠晶状体中 MDA 水平升高，GSH 水平降低，但接受褪黑素治疗的大鼠这些参数仍在正常范围内。
可以得出结论，褪黑素具有抗氧化和清除自由基的特性，因此可用于预防辐射诱导的氧化损伤。
