title: Dietary nucleotides protect thymocyte DNA from damage induced by cyclophosphamide in mice.
abstract: The effects of dietary nucleotides on thymocyte DNA damages induced by cyclophosphamide (CP) in mice were examined. First, phase I experiment was conducted to determine the optimal timing of detecting thymocyte DNA damages induced by CP (150 mg/kg body weight) in mice. Thymocyte DNA damages was determined at 6, 12, 18, 24 h by single-cell gel electrophosphoresis assay (comet assay) after intraperitoneal injection of CP. The levels of DNA damage at 6, 12, 18, 24 h were all significantly higher than that of the control group (p < 0.01). The highest level of DNA damage appeared at 18 h and then decreased at 24 h. Therefore, 18 h was selected to determine DNA damages induced by CP in subsequent experiments. In phase II experiment, 30 male KunMing mice were divided into three treatments: negative control (NC), positive control (PC) and nucleotides group (NG). Mice in NC and PC were fed nucleotide-free diet, and mice in NG were fed nucleotide-supplemented diet (supplemented with 0.25% nucleotides, a mixture containing equal amounts of AMP, CMP, GMP and UMP). Mice in PC and NG groups were injected with CP (150 mg/kg body weight) at 21 days. DNA damage in thymocytes was evaluated at 18 h after CP treatment. The results indicate that dietary nucleotides do not affect the weights of the thymus and the spleen, or their organ indices (p > 0.05), but significantly decrease the percentage of comet cells and comet tail sizes (p < 0.01). This study demonstrates that dietary nucleotides could reduce the level of thymocyte DNA damage induced by CP in mice.
authors.affiliation: Department of Preventive Medicine, School of Medicine, Tongji University, Shanghai, China. lanfangwlf@yahoo.com.cn
authors.forename: L-F
authors.initials: LF
authors.lastname: Wang
authors.forename: X
authors.initials: X
authors.lastname: Gong
authors.forename: G-W
authors.initials: GW
authors.lastname: Le
authors.forename: Y-H
authors.initials: YH
authors.lastname: Shi
mesh_terms: D000821:Animal Feed; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D020552:Comet Assay / Q000379:methods*; D003520:Cyclophosphamide / Q000633:toxicity; D004249:DNA Damage / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D009153:Mutagens / Q000633:toxicity; D009711:Nucleotides / Q000008:administration & dosage*; D009929:Organ Size; D011897:Random Allocation; D013154:Spleen; D013950:Thymus Gland / Q000166:cytology* / Q000187:drug effects; D013997:Time Factors
chemical_list: D009153:Mutagens; D009711:Nucleotides; D003520:Cyclophosphamide