Seasonal modulation of free radical metabolism in estivating land snails Helix aspersa.
We investigated the regulation of free radical metabolism in Helix aspersa snails during a cycle of 20-day estivation and 24-h arousal in summer in comparison with estivation/arousal in winter-snails. In winter-snails (J. Exp. Biol. 206, 675-685, 2003), we had already observed an increase in the selenium-dependent glutathione-peroxidase (Se-GPX) activity in foot muscle and hepatopancreas and in the contents of hepatopancreas GSH-equivalents (GSH-eq=GSH+2 GSSG) during estivation compared with 24-h aroused snails. Summer-estivation prompted a 3.6-fold increase in Se-GPX activity in hepatopancreas, though not in foot muscle. Total-superoxide dismutase and catalase activities in hepatopancreas decreased (by 30-40%) during summer-estivation; however, no changes occurred in the activities of glutathione reductase, glutathione S-transferase and glucose-6-phosphate dehydrogenase in the two organs. GSH-eq levels were increased (by 54%) in foot muscle during estivation, but were unchanged in hepatopancreas. In contrast with winter-snails, oxidative stress markers (lipid peroxidation, carbonyl protein, and the GSSG/GSH-eq ratio) were unaltered during estivation/arousal in summer. These results demonstrate that seasonality modulates not only the absolute activities/levels of antioxidants (enzymes and GSH-eq) in H. aspersa, but also the regulatory process that controls the snail's antioxidant capacity during estivation/arousal. These results suggest that H. aspersa has an "internal clock" controlling the regulation of free radical metabolism in the different seasons.
Ramos-Vasconcelos
Gabriella R
GR
Oxyradical Research Group, Departamento de Biologia Celular, Universidade de Brasília, Brasília, 70910-900, DF, Brazil.
Cardoso
Luciano A
LA
Hermes-Lima
Marcelo
M
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001143:Arousal / Q000502:physiology; D002374:Catalase / Q000378:metabolism; D004956:Estivation / Q000502:physiology*; D005609:Free Radicals / Q000378:metabolism*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006372:Helix, Snails / Q000378:metabolism*; D015227:Lipid Peroxidation; D018384:Oxidative Stress / Q000502:physiology; D012621:Seasons; D013482:Superoxide Dismutase / Q000378:metabolism
D000975:Antioxidants; D005609:Free Radicals; D005954:Glucosephosphate Dehydrogenase; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D005978:Glutathione