Optimization of protective effects of melatonin in prevention of induced gamma radiation by chromosomal aberration assay

Abstract

The chromosome aberration test using cultured mammalian cells is one of the sensitive methods to predict environmental mutagens and/or carcinogens, From our recent survey of 951 chemicals which have been tested for their clastogenicity in cultured mammalian cells such as Chinese hamster fibroblasts or human lymphocytes, it was noted that 47% of them are consistently positive either with or without metabolic activation. Environmental exposures can result in increased mutation rate, and the increased is the mutation rate in the target cells the higher is the cancer risk. The first event in the multistep carcinogenesis (i.e., the initiation) is a mutagenesis requiring cell proliferation in the target cells. Melatonin, a secretory product of the pineal gland in human brain, has been reported to participate in the regulation of a number of important physiological and pathological processes. The importance of the environmental harmful effects in the worldwide increase of cancer incidence is established. The present investigation was carried to find out cellular effects of gamma radiation on blood lymphocytes and radioprotector using cytogenetic biomarker (chromosomal aberration assay). 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  from 2 Gy  to 12 Gy of gamma radiation. Immediately after exposure to the radiation, the lymphocytes were examined to determine the extent of primary DNA damage.