Czupryn et al. "Transplanted Hypothalamic Neurons Restore Leptin Signaling and Ameliorate Obesity in db/db Mice" Science, 2011.

We'll start with the db/db mouse [...]. This mouse is genetically designed to develop severe morbid obesity and diabetes soon after birth. This is because it lacks a receptor for a hormone called leptin. Leptin is a hormone that plays a major role in appetite and metabolism. Decreasing your sensitivity to leptin, by decreasing leptin receptors, say (as in the the db/db mouse), produces striking obesity and...