Adaptations métaboliques et digestives des espèces hibernantes

Some animals hibernate to spare energy during winter. They alternate torpor bouts (hypometabolism and hypothermia) and arousals (eumetabolism and euthermia). Food-storing species feed during these periodic arousals whereas fat-storing species fast throughout hibernation. This article describes the metabolic differences between these two strategies. In fat-storing animals, energy needs are covered by the hydrolysis of triglycerides of the white adipose tissue, whereas gluconeogenesis helps maintaining glycemia. In food-storing species, adiponectin stimulates lipolysis, which contributes to ketogenesis, but inhibits gluconeogenesis as a significant decrease in glycemia is observed during torpor. The maintenance of a functional digestive system ensures the absorption of nutrients and especially glucose during arousals in these species, allowing a transient restoration of glycemia. The quality of fat or food reserves determines the efficiency of hibernation and therefore, the body condition of animals at emergence, on which greatly depend survival and reproductive performances.