Lipokines--a new class of hormones

And it continues . . .

. . . yet another hormone has been identified in the mammalian system.

[FYI, I announced this last Saturday by way of a voice mail message at The A&P Professor sample drop at drop.io . . . of which you would have been notified if you are subscribed to the drop. Click here for the how-to.]

When we begin our study of the endocrine system, I always tell my students, "there is coming a day when we'll have to include every tissue in the body as part of the endocrine system." Then a moment later, "and we'll soon see a time when a new hormone will be discovered every day [except perhaps major holidays!]."

OK, that's hyperbole. A commonly used teaching technique.

Now I'm wondering how "hyper" this particular hyperbole is!

We've known for some time that adipose tissue produces hormones. Last Friday, 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 lipid hormone that is not a steroid or protein. It is a fatty acid.

The newly discovered liopkine is called C16:1n7-palmitoleate. Oh my, if this turns out to be a central hormone that should be discussed in A&P class, can you just imagine the spelling errors that we are going to see! Let's hope they find a snappier name for it before we have to start using it regularly!

The new lipokine (notice how I'm avoiding use of its specific name!) 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
doi:10.1016/j.cell.2008.07.048
This is the original article (abstract is FREE; full article requires subscription or per-article payment)

First Lipid Hormone Discovered
Science News (web edition, September18, 2008)
Summarizes the discovery.

There's more in an expanded version of this article at The A&P Professor website!
There, you'll find a diagram of the molecule, pronunciation guides, additional references, and more.

We'll have to wait and see whether the discovery holds true for humans and what implications it really has for understanding human metabolism. 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.