Which hormone is primarily responsible for promoting glycolysis, cellular uptake, glycogenesis, and lipogenesis?

• A. Insulin
• B. Glucagon
• C. Epinephrine
• D. Cortisol

Answer: (A)

Insulin coordinates the fed-state anabolic metabolism that takes up glucose, stores it, and uses it for energy. When it binds its receptor, it triggers a PI3K-AKT signaling cascade that promotes GLUT4 translocation to the cell surface, increasing glucose uptake into muscle and adipose tissue for immediate use and storage. It enhances glycolysis by activating key glycolytic enzymes and raising fructose-2,6-bisphosphate to stimulate PFK-1, pushing glucose through the glycolytic pathway for energy or for generating building blocks. For storage, insulin activates glycogen synthase, promoting glycogen formation in liver and muscle while inhibiting glycogenolysis. In lipid metabolism, it drives lipogenesis in liver and adipose tissue by activating acetyl-CoA carboxylase and other lipogenic enzymes, and it suppresses lipolysis by inhibiting hormone-sensitive lipase. In contrast, glucagon, epinephrine, and cortisol promote glucose production and tissue breakdown, not storage, so they do not predominantly drive these processes.