Control of carbohydrate metabolism in an anoxia-tolerant nervous system

Anoxia-tolerant animal models are crucial to understand protective mechanisms during low oxygen excursions. As glycogen is the main fermentable fuel supporting energy production during oxygen tension reduction, understanding glycogen metabolism can provide important insights about processes involved in anoxia survival. In this report we studied carbohydrate metabolism regulation in the central nervous system (CNS) of an anoxia-tolerant land snail during experimental anoxia exposure and subsequent reoxygenation. Glucose uptake, glycogen synthesis from glucose, and the key enzymes of glycogen metabolism, glycogen synthase (GS) and glycogen phosphorylase (GP), were analyzed. When exposed to anoxia, the nervous ganglia of the snail achieved a sustained glucose uptake and glycogen synthesis levels, which seems important to maintain neural homeostasis. However, the activities of GS and GP were reduced, indicating a possible metabolic depression in the CNS. During the aerobic recovery period, the enzyme activities returned to basal values. The possible strategies used by Megalobulimus abbreviatus CNS to survive anoxia are discussed.