As a member of the order of Rodentia, jerboa (Jaculus orientalis) is a natural deep hibernator and lives in subdesert highland in many parts of the world, including Morocco. Its small size (adult body weight ~100 g), availability in the wild, tolerance to laboratory conditions, and some unique peroxisomal properties make it a suitable research subject for exploring peroxisome biogenesis under prehibernating and hibernating states. During 3 w, animals referred to as the prehibernator group were exposed to cold temperature (5 to 7°C) with food ad libitum. Part of the prehibernator group entered deep hibernation 24 to 48 h after starvation. Animals were sacrificed 4 and 6 d after starting hibernation. As a control, a third group, consisting of active animals, was maintained at 22°C. Concerning hibernation, results from plasma analysis showed an increased level for both ketonemia and ureamia, while triglyceredemia was decreased. Liver acyl-CoA oxidase activity, a peroxisomal b-oxidation enzyme, increased during hibernation. Liver peroxisomal urate oxidase was induced only during the prehibernating state and remained at an increased level until the fourth day of hibernation. The variations were concomitant to a decrease in peroxisomal protein yield and a differential change in peroxisomal protein pattern in sodium dodecyl sulfate-polyacrylamide gel electrophoresis during prehibernating or hibernating states. These preliminary results show that cold exposure and hibernation affect biogenesis of liver peroxisomes in jerboa. JAOCS 75, xxx-xxx (1998).Hibernation and torpor are adaptive strategies that several mammal and bird species use to survive food scarcity and low ambient temperature. Under such inhospitable conditions, hibernation helps some mammals, particularly small ones, to pass the winter in a torpid or lethargic state, which is characterized by low body temperature and depressed metabolism. Survival to extreme low body temperature and ability to rewarm from such a low temperature require a special adaptation of cell metabolism. These physiological changes require a strict control of lipid metabolism, which plays a critical role in supplying the energy requirements during hibernation.Previous studies on peroxisomes have shown that cold adaptation provokes remarkable biochemical and ultrastructural changes in rat tissues, i.e., liver and brown fat (1-4). In the cold-adapted rat, nonshivering thermogenesis was greatly increased in response to low ambient temperature (3,5). Strong increases in tissue metabolism and heat production were observed in the rat brown adipose tissue, concomitant with induction of peroxisomal β-oxidation (2). Peroxisomes, single membrane-bound organelles that contain H 2 O 2 -producing oxidases and H 2 O 2 -decomposing catalase, are known to be the sites for β-oxidation of long-chain fatty acids, as well as for ether-lipid biosynthesis (6), and play a key role in lipid homeostasis. Interestingly, the first step in the peroxisomal β-oxidation system does not carry provision for the conserv...
