Fasting-induced torpor in Mus musculus and its implications in the use of murine models for human obesity studies

1. Fasting at room temperature for 24-48 hr can induce shallow daily torpor in mice of several strains. 2. Genetically-obese (ob/ob) C57B1/6 mice show torpor even in the presence of food. 3. Chemically-obese (gold-thioglucose or bipiperidyl mustard) mice of C57B1/6 and T/O strains appear resistant to torpor. 4. During cold acclimation (3-5 degree) fasting also induces torpor in lean mice, with gradually improving rates of arousal. 5. In acute cold shock (3-5 degree), previously weight-reduced ob/ob mice show resistance to change in body temperature, while control ob/ob mice drift immediately towards hypothermia.