Age dependent effects of oxytetracycline in ob/ob mice

The effects of daily oxytetracycline injections on the metabolism and growth of prepubertal, 10 and 24-week old ob/ob and lean mice were examined. Drug treatment (100 mg/kg) between 17 and 28 days of age similarly reduced body weight gain and skeletal growth of both ob/ob and lean mice, but had little effect on obesity, serum glucose, or IRI levels. In older obese mice, 6 days of oxytetracycline led to substantial reductions of serum glucose, serum IRI, and obesity when compared with either ad libitum fed obese mice or food-restricted ob/ob mice serving as weight loss controls. In lean mice oxytetracycline also significantly reduced body weight and serum glucose, while no effects on obesity or IRI levels were noted. The present data show that oxytetracycline reduces the severity of many of the diabetic symptoms of ob/ob mice, but that only the ameliorative effects on obesity and hyperinsulinaemia appear to be specific to the ob/ob genotype.