What Causes Chronic Pain? A Summary of Ganter’s Presentation on his Study of Allodynia

Pain minimizes injury and death, but some people suffer from chronic pain or pain that lasts after an injury (allodynia). Because chronic pain costs 600 million dollars and affects 100 million people, we need to understand it.


Since fruit flies (Drosophila) have eighty-percent of human diseases and have similar nervous system to humans, Drosophila are perfect organisms to help researchers understand pain and disease.

 

Knowing this, Geoffrey Ganter and his team at the department of biology of University of New England (UNE) began experiments using Drosophila trying to understand allodynia.

To get a sense of how much pain Drosophila can feel, Ganter’s team used probes as hot as 50°C to poke the fruit flies to see how much stimuli they can handle. They found that the pain was minimal and compared to each other, equal.

Because the flies didn’t respond, Ganter’s team gave Drosophila an extreme sunburn and, with 41°C (a non-lethal dose), Ganter probed them to see how much pain they felt. The sunburned Drosophila felt 80% of the chronic pain.

Pain Receptors

To find what causes allodynia, UNE researchers wanted to study pain receptors.

Receptors are, when activated by environmental pressures, proteins that signal binding elements to attach to the correct DNA sequence to make a specific protein.

Nociceptors are receptors that get activated by pain.

Leading to a Breakthrough

To do understand chronic pain, they started with the protein decapentaplegic (DPP). This specific protein forms the limbs and organs in Drosophila.

When they removed DPP, normal Drosophila felt 7% to 20% of pain. With more DPP, normal Drosophila felt 40% of the pain. By doing this procedure, they found four more receptors (“tks”, “sax”, “gbb”, and “wit”) involved with experiencing pain.

UNE researchers discovered so much more. There’s a protein receptor, “punt,” that blocks pain sensation. They also found proteins, “MAD” and “MED”, that activate pain receptor gene-coding.

They also discovered the proteins that repress these genes (repressors). UNE found that the more pain someone feels in one place less the repressors.

The knowledge of the six proteins, the activator proteins, and repressors could lead to better painkillers and therapy.


Reference: 

Ganter, G. (2016, Feb. 1). Can flies help us understand chronic pain? Address at the University of New England, ME.