engleski

HORMESIS EFFECT IN CHICKEN EMBRYOS AFTER LOW-DOSE IRRADIATION

Hormesis is a dose-depend-response effect where a low-dose phenomenon stimulates protective mechanisms of a biological system while a high-dose inhibits it. The effects of low-dose radiation are very difficult to observe and highly controversial. On basis of our previous measurements we study the hormesis effect of low-doses gamma radiation by analyzing the activity of the antioxidant GSH-Px, as a first-line defense in cells, and the concentration of the lipid peroxide (malondialdehyde, MDA), as a measure of the harmfulness of ionizing radiation, in chick embryonic livers. Fertilized eggs of COBB 500 broiler breed were irradiated with gamma-rays of 60Co source on the 19th day of incubation with the doses of 0.05, 0.15, 0.3, 0.5, and 0.8 Gy and the dose rate of 0.0117 Gy/s. GSH-Px activities and MDA concentrations have been measured at 1, 3, 6, 12, and 24 hours after irradiation. Activities of GSH-Px were significantly increased for doses of 0.15 and 0.3 Gy, compared with control values. The temporal dynamics analysis revealed a statistically significant almost linear increase of activity of GSH-Px within 24 hours for doses from 0.05 to 0.5 Gy. The analysis of dependence activity on doses at 12 and especially at 24 hours after radiation showed a sharp increase at very low doses, relatively steady activities between 0.05 and 0.3 Gy, and a decrease at the control values at higher doses. A combination of all three analyses showed that there was no recognizable consistent dependence of MDA concentrations on radiation doses. We could assume that in conditions of our experiment low radiation could have a beneficial effect on chicken embryos because there is an increase of the GSH-Px activity while MDA concentration is steady. Our results were obtained from three different analyses. As we have shown earlier those results are more reliable. We found clear and reliable evidence of hormesis effect by low-dose radiation in chick embryos on the 19th day of incubation at 12 and 24 hours after irradiation.

hormesis effect, chicken embryos, low-dose irradiation, malondialdehyde, glutathione peroxidase

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