Description of a new model of genetic obesity: the dbPas mouse

A new strain of genetically obese mouse, the dbPas mouse, has been studied in terms of fat pad cellularity, serum parameters and thermogenesis. This obesity was observed in the inbred DW strain of mice at the Institut Pasteur-France, and is due to a recessive mutation on chromosome 4 at the diabetes locus. The mice became grossly obese, gaining weight until at least 16 mo of age. By 6 mo of age they exhibited hyperphagia, hypercholesterolemia, severe hyperinsulinemia, hypertrophy and hyperplasia of adipocytes, and impaired fertility. In contrast with other diabetic strains of mice, glycemia was normal in females and slightly elevated in males. This result indicates that the mutation of the db locus does not necessarily lead to a frank diabetes. Body temperature was normal either at 22 degrees C or after a cold exposure at 4 degrees C. GDP (guanosine diphosphate) binding to brown adipose tissue mitochondria was normal in obese mice as compared to lean. These data differentiate this model from other genetic obesities in mice and rats. This new model of genetic obesity offers interesting characteristics for the study of obesity.