Tuesday, February 11, 2014

Why the Naked Mole Rat is Probably Better than You

The naked mole rat. Native to parts of East Africa, it is also known as the desert mole rat, the sand puppy, Heterocephalus glaber, and, to me, the most hardcore mammal on earth. This cold blooded, never-aging demi-god of a mammal lives blind in oxygen-starved caves, fighting off snakes and scouting for potatoes. However, what probably makes the naked mole rat better than you is their invulnerability to pain and resistance to cancer.

Dispersed in the brain, spinal cord, and the peripheral nervous system are eleven amino acids that make up Substance P (C63H98N18O13S). This neuropeptide serves as a neurotransmitter specifically in transferring signals from the pain receptors.



Unlike humans, the naked mole rat lacks this chemical. Even when injected with acid equivalent to the acidity of lemon juice and active ingredients in chili peppers, the naked mole rat showed no pain. How did the naked mole rat evolve to lack any Substance P that many mammals have come to own? The answer is actually in the air around us. Normally, humans breathe in carbon dioxide levels of less than .1%, therefore any exposure to solutions with a small percentage of carbon dioxide will stimulate pain. However, naked mole rats live in environments up to 10% carbon dioxide levels. By exhaling higher levels of carbon dioxide, due to their small living spaces, the sand puppies become more acidic. Mole rats feel no pain from acid because they actually became more acidic! This insensitivity causes the naked mole rat to not develop any Substance P. It’s like living in Michigan for so long that you are desensitized from the cold (not really).

More recently, it was discovered that the naked mole harbors the resistance to cancer, specifically thanks to HMW-HA, high molecular weight hyaluronan.

HMW-HA, a long sugar polymer, prevents cells from overcrowding and forming tumors by filling in gaps between our cells. Actually, this sugar is common in all mammals. Apparently naked mole rats are HMW-HA producing gods as the HMW-HA they create is five times larger than any other animals’ HMW-HA. This abnormal HMW-HA production in the naked mole rat’s tissues is due to the protein HAS2 and perhaps several amino acid changes.  These changes may have increased the naked mole rat’s affinity for HAS2, which is in charge of HMW-HA synthesis. So how did these mole rats evolve to produce larger HMW-HA? Well given their underground life, they have developed higher concentrations of HMW-HA to provide the elasticity (the rubbery squishiness) in their skin in order to easily traverse their underground home. With this knowledge on the naked mole rat’s immunity to cancer, more avenues are open for cancer prevention in human medicines.


                                      If there were to be any real super heroes in the world…




                                                   the naked mole rat would top the list!

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Derek 
Student at Detroit Country Day, varsity policy debater, spring sailor, and a film junkie. Likes to think critically, travel to new places, and dogs.
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3 comments:

  1. AnonymousFebruary 11, 2014 at 11:24 AM

    Derek,
    I've heard of the naked mole rat before, but I never knew they had such interesting chemistry going on inside of them. Very cool! Thanks for the post.

    Quick question: When you suggest NMRs five times as much HMW-HA than other mammals, is that per kg, or simply five times any other mammals?

    Thanks.
    Mr. T

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    Replies
    1. UnknownFebruary 12, 2014 at 4:26 PM

      Mr.T

      Thanks for the comment! I mean it really, because you helped me find an error with the post. The naked mole rat produces HMW-HA five times LARGER compared to the HMW-HA other mammals produce. Sorry for the unprofessional blunder. However, quantity still plays a role in the naked mole rat's cancer immunity. Additionally, the naked mole rat recycles the HMW-HA at a slower rate, therefore it can accumulate larger amounts of HMW-HA in its tissues.

      Again, thanks for the comment and I'm happy to answer anymore questions.

      Derek

      Delete
  2. AnonymousFebruary 12, 2014 at 6:26 PM

    Derek,

    Excellent. I'm glad I could help with that. I wonder what the mechanism is for the cancer protection of the larger polymer of HMW-HA in the naked mole rat? At this point, I'd even guess the mechanism isn't known.

    Mr. T

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