20.500.12556/DiRROS-20857 Initial glutathione depletion during short-term bed rest pinpointing synthesis and degradation checkpoints in the γ-glutamyl cycle Initial glutathione depletion during short-term bed rest: pinpointing synthesis and degradation checkpoints in the gamma-glutamyl cycle Hypokinesia triggers oxidative stress and accelerates the turnover of the glutathione system via the γ-glutamyl cycle. Our study aimed to identify the regulatory checkpoints controlling intracellular glutathione levels. We measured the intermediate substrates of the γ-glutamyl cycle in erythrocytes from 19 healthy young male volunteers before and during a 10-day experimental bed rest. Additionally, we tracked changes in glutathione levels and specific metabolite ratios up to 21 days of bed rest. Using gas chromatography-mass spectrometry and the internal standard technique, we observed a 9 ± 9% decrease in glutathione levels during the first 5 days of bed rest, followed by an 11 ± 9% increase from the 5th to the 10th day, nearly returning to baseline ambulatory levels. The cysteinyl-glycine-to-glutathione ratio, reflecting γ-glutamyl cyclotransferase activity (a key enzyme in glutathione breakdown), rose by 14 ± 22% in the first 5 days and then fell by 10 ± 14% over the subsequent 5 days, again approaching baseline levels. Additionally, the γ-glutamyl cysteine-to-cysteine ratio, indicative of γ-glutamyl cysteine synthetase activity (crucial for glutathione synthesis), increased by 12 ± 30% on day 5 and by 29 ± 41% on day 10 of bed rest. The results observed on day 21 of bed rest confirm those seen on day 10. By calculating the ratio of product concentration to precursor concentration, we assessed the efficiency of these key enzymes in glutathione turnover. These results were corroborated by directly measuring glutathione synthesis and degradation rates in vivo using stable isotope techniques. Our findings reveal significant changes in glutathione kinetics during the initial days of bed rest and identify potential therapeutic targets for maintaining glutathione levels. antioxidant muscle unloading glutathion turnover γ-glutamyl cycle gamma-glutamyl cycle antioksidant razbremenitev mišic obnova glutationa γ-glutamilni cikel gama-glutamilni cikel true false true Angleški jezik Slovenski jezik © 2024 by the authors Neznano 2024-11-21 15:16:32 2024-11-21 15:16:33 2024-12-10 09:39:11 0000-00-00 00:00:00 2024 0 0 Nasl. z nasl. zaslona; Soavtorji: Filippo Mearelli, Mariella Sturma, Nicola Fiotti, Kaja Teraž, Alja Ivetac, Alessio Nunnari, Pierandrea Vinci, Boštjan Šimunič, Rado Pišot, Gianni Biolo; Opis vira z dne 21. 11. 2024; str. 1-16 issue 12, [article no.] 1430 Vol. 13 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 2024-11-05 2024-11-13 2024-11-21 612.744:546 2076-3921 10.3390/antiox13121430 216000515 24_11_21_101_Teraz_216000515.pdf 24_11_21_101_Teraz_216000515.pdf 1 A87F64433A9BF7AFAD7FA97D901FB789 569528950b01f05c71a1cea2c938c536ca67e1eacdd8d57a850e02fe610d2597 853c0970-a813-11ef-ba3f-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=29466 https://www.mdpi.com/2076-3921/13/12/1430 0 2599816a-b6d2-11ef-ba3f-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=29638 Znanstveno-raziskovalno središče Koper / Centro di Ricerche Scientifiche Capodistria 0 0 0