Megan Cherubino, Sandra Voors, Marissa Dear, Ryan Dressler

Introduction There 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.

Statistics In 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 Pain New 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.

Light They 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 column Nociception: activity in the nerve pathways Arthritis M.D.

Chemistry of Pain Nociceptors 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 developed at UC Berkeley Has 2 sides, cis and trans The 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…

Light Not 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 Lidocaine However, this lack of permeability gives QAQ the potential to be a selective anesthetic in a way Lidocaine is not. (ie numbing entire face)

TRPV1 An Ion channel found in nociceptive neurons Allowing QAQ to enter the nerves Activated 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 conclusion The 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 Future The 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 Cited plasters.html