A new class of hormones
We've known for some time that adipose tissue produces hormones. Leptin for example. In the fall of 2008, the journal Cell reported the discovery of yet another adipose hormone. What's unusual about this one is that it is a lipokine . . . a new class of hormone that is not a steroid or protein. It is a fatty acid.
The newly discovered liopkine is called C16:1n7-palmitoleate. Or more simply, palmitoleate—pronounced PAL-mih-TOH-lee-ayt . Hmmm . . . still quite a mouthful, eh? I sure hope a shorter, snappier name is adopted for this hormone. It's a particular version of a sixteen-carbon chain derived from the monunsaturated fatty acid palmitoleic acid illustrated here:
The new lipokine activity was discovered in mice but is expected to behave similarly in humans. It's a fatty acid not commonly found circulating in high quantities in the blood. But it was found in high concentration in genetically altered super-healthy mice.
The new lipokine apparently has several actions that promote health, including:
- increases the response of muscle tissue to insulin
- regulates the liver's handling of fats, reducing buildup of harmful fats
- reduces the inflammation mediators normally produced by adipose tissue (possibly reducing the inflammation associated with diabetes, heart disease, and other health problems)
At this early stage of discovery, the hope is that more investigation of the new hormone will lead to more effective treatments of obesity or health problems associated with obesity.
Want to learn more?
Identification of a Lipokine, a Lipid Hormone Linking Adipose Tissue to Systemic Metabolism
Cao, et al. Cell, Vol 134, 933-944, 19 September 2008
This is the original article (abstract is FREE; full article requires subscription or per-article payment)
Listen to an audio conversation from the journal Cell regarding the new discovery
Harvard press release
published online September 18,2008
summarizes the discovery
First Lipid Hormone Discovered
Science News (web edition, September18, 2008)
Summarizes the discovery.
Discovery Of 'Lipokine' Signaling Could Eventually Lead To New Treatments For Obesity-Related Conditions
Medical News Today September 19, 2008
Another summary of the discovery
We'll have to wait and see whether the discovery holds true for humans and what implications it really has for understanding human metabolism. And whether additional lipokines will be added to the list. But when I discuss "the two major categories" of hormones in my course I will now probably qualify that statement with a mention of this discovery.