Most studies of the biological effects of ionizing radiation have been done on a single acute dose, while clinically and environmentally exposures occur under chronic/repetitive conditions. It is important to study effects of different patterns of ionizing radiation. In this study, a rat model was used to compare the effects of repetitive and acute exposure. Groups: (I) control, (II, III) were exposed to fractionated doses (1.5 GyX4) and (2 GyX4), respectively/24h interval, and (IV, V) were exposed to 6 Gy and 8 Gy of whole-body gamma irradiation, respectively. The gene expression of MAPT and tau phosphorylation increased in all irradiated groups but the gene expression of PKN not affected. TGFβ% increased at dose of 2 GyX4 only. In addition, the cell cycle was arrested in S phase. Micronucleus (MN) increased and cell proliferation decreased. In conclusion, the dose and pattern of ionizing radiation do not affect the MAPT and PKN gene expression, but TGF-β, p-tau, MN assay and cell proliferation are significantly affected. The dose of 2 GyX4 showed distinctive effect. Repetitive exposure may increase TGF-β%, which causes radio-resistance and, G2/M delay. Thus, the cell cycle could be regulated in a different manner according to the dose and pattern of irradiation.

P UNICA granatum (Pg) is an edible fruit known as pomegranate, which is a rich source of polyphenolic compounds and has antioxidant activity. Many studies have been conducted on extracts of various parts of Pg which may have genotoxic effects. However, the purpose of the present study is to assess, for the first time, the radio-protective effect of Pg juice, the safest part of the fruit, against γ-irradiation-induced biochemical and cytogenetic damage in rats by modulating the lipid profile, and the esterases (acetylcholinesterase AchE, carboxylesterase CarE and paraoxonase PON) activity as biomarkers that provide information on the nervous system's integrity, metabolism, and anti-oxidative defenses respectively. Male rats were divided into six groups, group I is the control, group II received Pg juice (400 mg/kg/day) divided into two equal doses twice daily (with 12 h interval) for 30 days, group III and V received 4 Gy and 8 Gy of γ-radiation respectively, group IV and VI received Pg juice for 30 days before being irradiated with 4 and 8Gy of γ-radiation respectively. Radiation altered the levels of CarE and PON activity in plasma and liver, as well as plasma total cholesterol, triglycerides, high-density lipoprotein HDL, low-density lipoprotein LDL, and very low-density lipoprotein VLDL. In comparison to the control group, Pretreatment with Pg juice significantly improves these values and reduced DNA fragmentation significantly. It is possible to conclude that Pg juice protects against ionizing irradiation, which causes biochemical and cytogenetic damage, by modulating anti-oxidative defenses and metabolism.