Lack of a Time-dependent Effect of Melatonin on Radiation-induced Apoptosis in Cultured Rat Lymphocytes.
From: Baskent University Faculty of Medicine, Department of Medical Biology and Genetics, Ankara, Turkey.
Cell biology international
- Publish Date: Oct 2007
- ISSN: 1065-6995
- Volume: 31
- Issue: 10
- Pages: 1144-9
- Medium: Print
- Language: English
- Citation (JAMA): Yurtcu Erkan, Guney Yildiz, Ergun Mehmet Ali, et al. Lack of a Time-dependent Effect of Melatonin on Radiation-induced Apoptosis in Cultured Rat Lymphocytes.. Cell Biol. Int. Oct 2007;31:1144-9
Abstract
Ionizing radiation is widely used for the treatment of solid tumors and it is thought to act by directly targeting tumor clonogens, also known as stem cells. Apoptosis is a genetically programmed mechanism of cell death often characterized by internucleosomal DNA cleavage. Although it has been previously shown that lymphocytes readily undergo apoptosis in patients receiving anticancer drugs or treatment with ionizing radiation, this is the first study to investigate the influence of radiotherapy and melatonin on apoptosis in rat lymphocytes at two different times of the day. Melatonin, a free radical scavenger, is an endogenous neurohormone predominantly synthesized in and secreted by the pineal gland. It has been shown that melatonin inhibits apoptosis in normal cells but it increases the rate of apoptosis in various cancer cells. Therefore, in the present study, the effect of melatonin on apoptosis in cultured lymphocytes was studied after total body irradiation (TBI) was given to rats in the morning (1 HALO) or evening (13 HALO) with morphological and DNA fragmentation analysis. Two-way analysis of variance (ANOVA) revealed that radiation increased the rate of apoptosis in rat lymphocytes after TBI, and melatonin treatment did not reduce the rate of apoptosis after TBI at either time point. We conclude that the lack of an effect of melatonin on the apoptosis rate in rat lymphocytes might be due to the dose-dependent effect of melatonin, the time course of apoptosis investigated, or the cell type in which apoptosis was examined.
Mesh Headings (Keywords): Animals, Antioxidants, Apoptosis, Cells, Cultured, Dose-Response Relationship, Drug, Gamma Rays, Lymphocytes, Male, Melatonin, Rats, Rats, Wistar, Time Factors, Whole-Body Irradiation
Check for Full Text / PubMed Unique Identifier (PMID): 17482482
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