Knocking out the gene for a peptide associated with insulin was shown to protect mice against the harmful effects of a high-fat diet. Urocortin 3 plays a role in the increased production of insulin in response to high caloric intake in animals.

Scientists found that by removing the urocortin 3 gene from mice, they did not develop the age-related insulin resistance and high blood sugar observed in the normal control mice. The metabolisms of normal mice were compared to the metabolisms of those without the urocortin 3 gene. When placed on a high caloric diet for three months, the mice without the urocortin 3 gene packed on the same amount of weight but had lower insulin levels. But these mice also had lower blood sugar, improved glucose tolerance curves and they did not develop the fatty livers the control mice experienced.

Scientists hypothesize that by curtailing the abnormally high insulin levels, they were able to manipulate insulin sensitivity and avoid some of the untoward consequences of the high food intake and weight gain. Like many of us diabetics already know too well - while insulin is effective at lowering blood sugar it also promotes fat storage. This is a natural protective response to prepare for times when food may not be available. When insulin is produced at too high a level for too long, the body becomes insulin resistant and blood sugar and certain blood lipids gradually creep up, which can cause progressive damage to multiple organs.

Urocortin 2 and urocortin 3 are part of the system that governs the body's response to insulin. Scientists already know that mice on a high-fat diet do better if either urocortin 2 or urocortin 3 is removed. Now they want to know if the mice will respond even better if both are missing. Such results may instruct us how best to develop therapeutic means to exploit these powerful effects.