Researchers identify new class of hormone

Scientists at the Harvard School of Public Health have discovered a new class of hormones in mice.

All hormones, until now, were thought to be steroid or protein based. However Professor Gökhan Hotamisligil and colleagues have rewritten medical science with their discovery of lipokines, or lipid hormones.

Previous experiments by the group had shown that an unidentified factor in the fat of genetically engineered mice sent signals to regulate metabolism in muscles and the liver. The researchers thought that the factor may be of significance, so they set out to identify it. Eventually, they found C16:1n7-palmitoleate, a fatty acid which is released into the bloodstream by fat cells.

C16:1n7-palmitoleate improves cell sensitivity to insulin and blocks fat accumulation in the liver, it also appears to suppress inflammation. Further research showed that C16:1n7-palmitoleate production is significantly higher in genetically-engineered mice whose fat cells lack “chaperone” or carrier proteins, which help fat absorbed from food to be deposited in  fat cells. Additional research revealed that as these mice are unable to store much dietary fat, their fat cells manufacture their own fat, which, in turn, increases C16:1n7-palmitoleate production, thus promoting a healthy metabolism. The mice were also found to be resistant to the problems associated with a long-term consumption of a high-fat diet, such as heart disease, fatty liver, and diabetes.
 
The researchers believe that the discovery of lipokines could potentially lead to new treatments for metabolic disorders.

Cao H, Gerhold K, Mayers JR, Wiest MM, Watkins SM, Hotamisligil GS. Identification of a Lipokine, a Lipid Hormone Linking Adipose Tissue to Systemic Metabolism. Cell 2008;134:933-944.