Karslioglu Ihsan, Ertekin Mustafa Vecdi, Taysi Seyithan, Koçer Ibrahim, Sezen Orhan, Gepdiremen Akçahan, Koç Mehmet, Bakan Nuri
Department of Radiation Oncology, Atatürk University, Erzurum, Turkey.
J Radiat Res. 2005 Jun;46(2):277-82. doi: 10.1269/jrr.46.277.
One of the mechanisms proposed to explain lens opacification is the oxidation of crystallins, either by radiation or reactive oxygen species (ROS). It has been shown that melatonin has both an anti-peroxidative effect on several tissues and a scavenger effect on ROS. The purpose of this study was to determine the antioxidant role of melatonin (5 mg/kg/day) against radiation-induced cataract in the lens after total-cranium irradiation of rats with a single dose of 5 Gy. Sprague-Dawley rats were divided into four groups. Control group received neither melatonin nor irradiation. Irradiated rats (IR) and melatonin+irradiated rats (IR+Mel) groups were exposed to total cranium irradiation of 5 Gy in a single dose by using a cobalt-60 teletherapy unit. IR+Mel and melatonin (Mel) groups were administered 5 mg/kg melatonin daily by intraperitoneal injections during ten days. Chylack's cataract classification was used in this study. At the end of the 10th day, the rats were killed and their eyes were enucleated to measure the antioxidant enzymes i.e. the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and lipid peroxidation level (malondialdehyde (MDA)). Irradiation significantly increased the MDA level, as an end product of lipid peroxidation, and also significantly decreased SOD and GSH-Px activity, emphasizing the generation of increased oxidative stress. Rats injected with melatonin only did not cause cataract formation. Melatonin supplementation with irradiation significantly increased the activity of SOD and GSH-Px enzymes and significantly decreased the MDA level. Total cranium irradiation of 5 Gy in a single dose enhanced cataract formation, and melatonin supplementation protected the lenses from radiation-induced cataract formation. Our results suggest that supplementing cancer patients with adjuvant therapy of melatonin may reduce patients suffering from toxic therapeutic regimens such as chemotherapy and/or radiotherapy and may provide an alleviation of the symptoms due to radiation-induced organ injuries.
一种被提出用于解释晶状体混浊的机制是晶状体蛋白的氧化，其可由辐射或活性氧（ROS）引起。研究表明，褪黑素对多种组织具有抗过氧化作用，并且对ROS具有清除作用。本研究的目的是确定褪黑素（5毫克/千克/天）在大鼠单次接受5 Gy全颅照射后对晶状体辐射诱导性白内障的抗氧化作用。将Sprague-Dawley大鼠分为四组。对照组既未接受褪黑素也未接受照射。照射组（IR）和褪黑素+照射组（IR+Mel）使用钴-60远距离治疗装置单次接受5 Gy全颅照射。IR+Mel组和褪黑素组（Mel）在十天内每天通过腹腔注射给予5毫克/千克褪黑素。本研究采用齐拉克白内障分级法。在第10天结束时，处死大鼠并摘除眼球，以测量抗氧化酶，即超氧化物歧化酶（SOD）和谷胱甘肽过氧化物酶（GSH-Px）的活性以及脂质过氧化水平（丙二醛（MDA））。作为脂质过氧化终产物的MDA水平在照射后显著升高，同时SOD和GSH-Px活性也显著降低，这表明氧化应激增加。仅注射褪黑素的大鼠未形成白内障。照射时补充褪黑素显著提高了SOD和GSH-Px酶的活性，并显著降低了MDA水平。单次5 Gy全颅照射会促进白内障形成，而补充褪黑素可保护晶状体免受辐射诱导性白内障的形成。我们的结果表明，用褪黑素辅助治疗癌症患者可能会减少患者因化疗和/或放疗等毒性治疗方案而遭受的痛苦，并可能减轻因辐射引起的器官损伤所致的症状。
