ANTIOXIDANT DEFENSES AND METABOLIC DEPRESSION IN A PULMONATE LAND SNAIL

During arousal from estivation oxygen consumption by land snails (Otal a lactea) increases severalfold. To determine whether snails prepared for an accompanying rise in the rates of oxyradical generation by alte ring their antioxidant defense mechanisms, changes in the activities o f antioxidant enzymes and lipid peroxidation products were quantified in foot and hepatopancreas of control, 30-day estivating, and aroused snails. Compared with controls, estivating O. lactea showed significan t increases in the activities of foot muscle superoxide dismutase (SOD ) (increasing by 56-67%), catalase (51-72%), and glutathione S-transfe rase (79-108%), whereas, in hepatopancreas, SOD (57-78%) and glutathio ne peroxidase (93-144%) increased. within 40 min after arousal began, hepatopancreas glutathione peroxidase activity had returned to control values, but SOD showed a further 70% increase in activity but then re turned to control levels by 80 min. Estivation had no effect on total glutathione (GSH + 2 GSSG) concentrations in tissues, but GSSG content had increased about twofold in both organs of 30-day dormant snails. Lipid peroxidation (quantified as thiobarbituric acid reactive substan ces) was significantly enhanced at the onset of arousal from dormancy, indicating that oxidative stress and tissue damage occurred at this t ime. The data suggest that antioxidant defenses in snail organs are in creased while snails are in the hypometabolic state as a preparation f or oxidative stress during arousal.