Nano-selenium Protects New Zealand Rabbits against Heat Stress – induced DNA Damage and Mutagenicity

Background: This study was designed to investigate the potential protective effects of nano-Se (a new form of selenium), organic selenium (O-Se) and inorganic selenium (Na-Se) on DNA and genetic damage of growing rabbits reared under heat stress (HS). Methods: A total number of 60 unsexed weaned New Zealand White (NZW) rabbits, aged 6 weeks and averaged 660±3 gm body weight were randomly divided into four experimental groups (15 rabbits of each). Each treatment was divided into three equal replicates (5 rabbits/each). The 1st group (control group) received 2 ml of distilled water orally every day, while the 2nd, 3rd and 4th groups were orally received three forms of selenium (Se), nano- Se, organic (O-Se) and inorganic (Sodium selenite, Na-Se), respectively, at the level of 0.3 mg/kg body weight every day using stomach tube for 6 weeks under HS exposure to a temperature of 38 °C daily for 4 hours. Results: The results revealed that the percentage of chromosomal aberrations (gaps, breaks, fragments and deletions) in bone marrow cells was significantly high in HS exposed group (+Ve control). However, treatment with nano-Se caused a significant decrease in all types of somatic chromosomal aberrations compared to control and other forms of Se treated groups. The same findings were found in the DNA fragmentation and micronucleus frequency, which were significantly high in HS exposed group. However, treatment with nano-Se caused a significant decrease in DNA fragmentation and micronucleus frequency compared to control and the other forms of Se treated groups. In addition, DNA damage % detected by comet assay increased significantly in HS exposed group (control). While, the treatment with Nano-Se caused a significant decrease in comet assay score compared to control and the other forms of Se treated groups. Conclusion: Nano-se supplementation has a protective effect against DNA and genetic toxicity induced by HS under hot climate conditions due to its antioxidant capacity.