Reiter R J, Herman T S, Meltz M L
Department of Radiology/Division of Radiation Oncology, University of Texas Health Science Center, San Antonio 78284, USA.
Mutat Res. 1998 Feb 2;397(2):203-8. doi: 10.1016/s0027-5107(97)00211-x.
Peripheral blood samples were collected from human volunteers 5-10 min before, and at 1 and 2 h after a single oral dose of 300 mg of melatonin. At each time point: (1) the concentration of melatonin in the serum and in the leukocytes was determined; and (2) the whole blood was exposed in vitro to 100 cGy of gamma radiation. Immediately after exposure to the radiation, the lymphocytes were examined to determine the extent of primary DNA damage, viz., single strand breaks and alkali labile lesions (determined from the length of DNA migration and fluorescence intensity of migrated DNA in the comet tail), using the alkaline comet assay. For each volunteer, the results showed a significant increase in the concentration of melatonin in the serum and in the leukocytes at 1 h after the oral dose of melatonin, as compared to the sample collected at 0 hour. The lymphocytes in the blood samples collected at 1 and 2 h after melatonin ingestion and exposed in vitro to 100 cGy gamma radiation exhibited a significant decrease in the extent of primary DNA damage, as compared with similarly irradiated lymphocytes from the blood sample collected before melatonin ingestion. The extent of the melatonin-associated decrease in primary DNA damage did not correspond with the decrease reported earlier in the incidence of chromosomal aberrations and micronuclei; the latter assays required an additional postirradiation incubation of the cells at 37 +/- 1 degrees C for 48 and 72 h, respectively.
在300毫克褪黑素单次口服前5 - 10分钟以及口服后1小时和2小时，从人类志愿者身上采集外周血样本。在每个时间点：(1)测定血清和白细胞中褪黑素的浓度；(2)将全血在体外暴露于100 cGy的γ辐射。在暴露于辐射后立即使用碱性彗星试验检查淋巴细胞，以确定原发性DNA损伤的程度，即单链断裂和碱不稳定损伤（根据彗星尾中DNA迁移的长度和迁移DNA的荧光强度确定）。对于每位志愿者，结果显示与0小时采集的样本相比，口服褪黑素后1小时血清和白细胞中褪黑素的浓度显著增加。与褪黑素摄入前采集的血样中经类似辐照的淋巴细胞相比，在褪黑素摄入后1小时和2小时采集并在体外暴露于100 cGyγ辐射的血样中的淋巴细胞，其原发性DNA损伤程度显著降低。褪黑素相关的原发性DNA损伤减少程度与早期报道的染色体畸变和微核发生率的降低不相符；后一种检测分别需要在37±1℃下对细胞进行额外的辐照后孵育48小时和72小时。
