Glycogen at the Crossroad of Stress Resistance, Energy Maintenance, and Pathophysiology of Aging.

Glycogen is synthesized and stored to maintain postprandial blood glucose homeostasis and to ensure an uninterrupted energy supply between meals. Although the regulation of glycogen turnover has been well studied, the effects of glycogen on aging and disease development have been largely unexplored. In Caenorhabditis elegans fed a high sugar diet, glycogen potentiates resistance to oxidants, but paradoxically, shortens lifespan. Depletion of glycogen by oxidants or inhibition of glycogen synthesis extends the lifespan of worms by an AMPK-dependent mechanism. Thus, glycogen is not merely an inert storage molecule, but also an active regulator of energy balance and aging. Its depletion by oxidants may be beneficial in the treatment of hyperglycemia and glycogen-related diseases.