Whole-body γ-irradiation decelerates rat hepatocyte polyploidization

Hepatoprotective effect of the radiation countermeasure flagellin in the long term after irradiation of mice

PURPOSE

Purpose is to study the hepatoprotective effect of a new promising radiation countermeasure flagellin, in the long term after irradiation. The results of the study can be useful for mitigating the consequences of man-made radiation accidents, protecting professional contingents, reducing the toxic effect of radiation therapy, and expanding the range of drug use.

MATERIALS AND METHODS

Effect of flagellin was investigated 10 months after its administration of irradiated male of mice F1 (CBAхC57Bl/6). Flagellin (0.2 mg/kg) was administrated once intraperitoneally before exposure of mice to low-intensive (10 mGy/min) γ-radiation at a dose of 12.65 Gy. The effect was evaluated in three groups: control, irradiated mice without of flagellin and with the administration flagellin 30 minutes before irradiation. Cytogenetic and cytotoxic effect in bone marrow was studied with micronucleus assay (OECD 474), in liver - with the original technique for cytome analysis of hepatocytes after fixation of liver pieces with 10% formalin, dissociation of cells with 50% KOH, staining with aceto-orcein and light green. The proportion of cells 2n, 2n + 2n, 4n, 4n + 4n, ≥8n and ≥8n + 8n was determined. Cytogenetic disorders were counted as cells with micronuclei, nuclear buds, and internuclear bridges. The ploidy index and nuclearity index were defined.

RESULTS

In all studied groups of mice, the frequency of polychromatic bone marrow erythrocytes with micronuclei and hepatocytes with cytogenetic disorders did not exceed the background level. A decrease in the ploidy index of hepatocytes by 4.3 times was established 10 months after exposure to low-power ionizing radiation. In mice treated with flagellin before irradiation, the ploidy index was normalized to control.

CONCLUSIONS

A decrease in the ploidy of hepatocytes was revealed 10 months after exposure to a high dose of low-power ionizing radiation, which may indicate the initiation of carcinogenesis. For the first time, a new aspect of the anti-radiation effect of promising radiation countermeasure flagellin was established and its hepatoprotective properties were determined in the long term after exposure to ionizing radiation.

The Role of Immunomodulator Betaleukin in Recovery of Hepatocytic Ploidy Profile in Delayed Terms after Irradiation

We studied the radioprotective effect of betaleukin administered to (CBA×C57Bl/6)F1 mice in single doses of 50 and 3 μg/kg 2 and 22 h, respectively, prior to long-term (21 h) whole-body low-intensity (10 mGy/min) γ-radiation (¹³⁷Сs; total dose 12.65 Gy). Hepatocyte ploidy, a biomarker of metabolic disorders of the liver, was evaluated, and nuclearity and ploidy indices were calculated. In 10 months after irradiation, a significant decrease in the ploidy index was revealed in the group of irradiated mice, while in animal receiving 3 or 50 μg/kg betaleukin, this parameter did not differ and even surpassed the control level, respectively. Thus, in vivo assessment of hepatocytic ploidy profile in mice revealed negative delayed effects of γ-irradiation in a dose of 12.65 Gy and a protective effect a single injection of immunomodulator betaleukin.