Page "Leptin" Paragraph 1

The effects of leptin were observed by studying mutant obese mice that arose at random within a mouse colony at the Jackson Laboratory in 1950.

These mice were massively obese and excessively voracious.

Ultimately, several strains of laboratory mice have been found to be homozygous for single-gene mutations that cause them to become grossly obese, and they fall into two classes: " ob / ob ", those having mutations in the gene for the protein hormone leptin, and " db / db ", those having mutations in the gene that encodes the receptor for leptin.

When ob / ob mice are treated with injections of leptin, they lose their excess fat and return to normal body weight.