Effects of fasting on liver glycogen structure in rats with type 2 diabetes

• Published in: Carbohydrate polymers 2020-06, Vol.237, p.116144-116144, Article 116144
• Main Authors: Wang, Liang, Liu, Qinghua, Wang, Mengmeng, Du, Yan, Tan, Xinle, Xu, Bingju, Cheung, Ut, Li, Enpeng, Gilbert, Robert G., Tang, Daoquan
• Format: Article
• Language: English
• Subjects: Diabetes; Glycogen; Molecular structure; Size exclusion chromatography
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2020.116144

•Diabetic rats have more glycogen (a blood-sugar reservoir) than healthy rats.•Diabetic glycogen is fragile, readily breaking up to smaller particles with DMSO.•Molecular glycogen size was seen to be reduced after extended starvation.•Diabetic fragility still present after 30 h fasting; fasted diabetic glycogen has shorter chains.•Fasted glycogen with shorter chains may be resistant to degradation. Liver glycogen, a highly branched glucose polymer, is important for blood sugar homeostasis. It comprises α particles which are made of linked β particles; the molecular structure changes diurnally. In diabetic liver, the α particles are fragile, easily breaking apart into β particles in chaotropic agents such as dimethyl sulfoxide. We here use size-exclusion chromatography to study how fasting changes liver-glycogen structure in vivo for mice in which type-2 diabetes had previously been induced. Diabetic glycogen degraded enzymatically more quickly in the fasted animals than did glycogen without fasting, with fewer α particles, which however were still fragile. The glycogen had fewer long chains and more shorter chains after fasting. This study gives an overview of the in vivo dynamic changes in α-particles under starvation conditions in both normal and diabetic livers.