POSSIBLE PROTECTIVE MECHANISMS OF ALPHA-KETOGLUTARATE ON FRUIT FLY DROSOPHILA MELANOGASTER CANTON S UNDER EXPOSURE TO DIFFERENT STRESSORS

Alpha-ketoglutaric acid is an important intermediate in Krebs cycle and in metabolism of amino acids. In recent years, the role of alpha-ketoglutaric acid as a powerful natural detoxifying agent was demonstrated. This work aimed to study the ability of the sodium salt of alpha-ketoglutaric acid (AKG) to alleviate the toxic effects of sodium nitroprusside on the larvae development and to increase the resistance of D. melanogaster Canton S flies to cold stress. Sodium nitroprusside (SNP) is widely used as a donor of nitric oxide in medicine but may be toxic for many organisms at high concentrations due to the induction of oxidative/nitrosative stress. This study shows, that food supplementation with AKG alleviates the inhibitory effect of SNP on D. melanogaster Сanton S pupation. The number of larvae reached the pupa stage on diet with 10 mM AKG and 1 mM SNP was 20% higher than on diet with 1 mM SNP. The reduced food intake of larvae grown on medium with SNP was not changed by AKG supplementation, and AKG also did not affect the levels of total iron and nitrite ions released from SNP. SNP decomposition is also accompanied by the release of highly toxic cyanide moieties, and the ability of AKG to interact with cyanide ions was reported earlier. It seems that the cyanidebinding capability may be important in prevention of the toxic effects of SNP on D. melanogaster. Two-day-old adult Сanton S flies reared on 10 mM AKG were more resistant to cold stress treatment and faster recovered from chill coma (0°C for 15 min) than control ones. Flies reared on AKG had the higher catalase activity and the higher levels of high- and low-molecular mass thiols comparing with the controls. Proline level was 1.4-fold higher in AKG-reared females in comparison with control females. The obtained results suggest, that dietary AKG provides cold stress resistance of two-day-old D. melanogaster flies due to the enhancement of antioxidant system capacity and synthesis of cryoprotective amino acids, such as proline