Megan Cherubino, Sandra Voors, Marissa Dear, Ryan Dressler

IntroductionThere are several ways to define pain. Pain depends on many factors such as

culture, environmental, and emotional; Pain is how you respond to an unpleasant sensation. This explains why some people handle pain better than others.

Chronic pain- Long-term pain such as arthritis

Acute Pain- A temporary pain like such as stubbing your toe.

Pain is a survival mechanism. Warns something is wrong.

StatisticsIn America, 50 million residents live with

chronic pain.Pain forces around 36 million of these

residents to miss work every year.Pain results in approximately 70 million

doctor visits per year.

Shutting Off PainNew lab experiments have shown it is

possible to turn off pain sensitive neurons using an agent that acts as a photosensitive switch.

The chemical QAQ (ammonium-azobenzene-quaternary-ammonium) forms this switch to turn off pain.

Half of QAQ resembles one of the active parts of lidocaine which is a local anesthetic commonly used at the dentist.

LightThey activate and inactivate the pain by

certain rays of light.The light silences the neurons in our body

that sense pain.

How do we feel pain?Nociceptor: “A sensory receptor that sends

signals that cause the perception of pain in response to potentially damaging stimuli” ScienceDaily

Free nerve endings located throughout the body

Transmit signals through spinal columnNociception: activity in the nerve pathways

Arthritis M.D.

Chemistry of PainNociceptors depolarize

Send message to the spinal cord and to the brain

Message does not become “pain” until the brain interprets it

A Visit to the Dentist?Lidocaine – a local anaesthetic

Temporarily blocks pathway of pain signals NetDoctor

Stops Na from entering the nerve endings at site of pain

Causes numbness and relieves pain

What is QAQ?Ammonium–azobenzene–quaternary ammonium

(QAQ)A molecule devoloped at UC BerkeleyHas 2 sides, cis and transThe trans side is very similar to Lidocaine and is a

straight chain in structure, blocking the ion channels that send pain signals

The cis side is inactive and is bent in an L-shaped form.

QAQ slowly reverts to the trans side, which can be achieved much more quickly by…

LightNot just any old

light.500 nm will

accelerate this process

Ultraviolet light reactivates the neurons

All well and good but…

What makes lidocaine effective in dentists is it can cross cell membranes. But can QAQ do the same?

Rodent experiment.

So not quite like LidocaineHowever, this lack of permeability gives QAQ

the potential to be a selective anesthetic in a way Lidocaine is not. (ie not numbing entire face)

TRPV1An Ion channel found in nociceptive neuronsAllowing QAQ to enter the nervesActivated by a chemical called Capsaicin

Capsaicin, found in chili peppers

Capsaicin making the TRPV1 dilate allows entry for a bigger molecule like QAQ into the channel

The absence of TRPV1 in other nerves makes it possible to selectively target the nerves sensing pain

Can be turned on and off with a flick of a switch!

In conclusionThe chemical QAQ can form a off switch

for pain by blocking the nociceptors.QAQ can be turned on and off with

different wavelengths of light.QAQ is similar to Lidocaine from the

dentist.QAQ can be selective to nerve cells

actively sensing pain, unlike Lidocaine.

The Pain-Free FutureThe researchers still say

“It’s a long way off” due to the fact the light is not able to pass through human skin.

But wouldn’t it be amazing to be able to just turn off pain?

With more research, the possibilities are unless.

Some day we might be painless from just the flip of switch.

Works Citedhttp://www.netdoctor.co.uk/skin-and-hair/medicines/versatis-medicated-plasters.html

http://www.guardian.co.uk/science/neurophilosophy/2012/feb/21/1

http://www.livescience.com/600-pain-truth-hurt.html

http://www.sciencedaily.com/releases/2012/02/120222093506.htm

http://www.arthritismd.com/tens_unit.html

http://www.sciencedaily.com/articles/n/nociceptor.htm

http://www.embedds.com/ultraviolet-light-box-for-pcb-exposure/

http://robertsontrainingsystems.com/blog/should-we-train-people-in-pain/