How The Mouse Grimace Scale Will Help Us Cope With Pain

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How The Mouse Grimace Scale Will Help Us Cope With Pain

http://www.medicalnewstoday.com/articles/188227.php

A new study by McGill University Psychology Professor Dr. S. Mogil shows

that mice, like humans, express pain through facial expressions. The research

will not only be an important tool in helping scientists ensure that laboratory

animals don't suffer unnecessarily, but could lead to new and better pain-relief

drugs for humans.

Mogil, UBC Psychology Prof. Craig and their respective teams have

discovered that when subjected to moderate pain stimuli, mice showed discomfort

through facial expressions in the same way humans do. Their study, published

online May 9 in the journal Nature Methods, also details the development of a

Mouse Grimace Scale that could inform better treatments for humans and improve

conditions for lab animals.

Because pain research relies heavily on rodent models, an accurate measurement

of pain is paramount in understanding the most pervasive and important symptom

of chronic pain, namely spontaneous pain, says Mogil.

" The Mouse Grimace Scale provides a measurement system that will both accelerate

the development of new analgesics for humans, but also eliminate unnecessary

suffering of laboratory mice in biomedical research, " says Mogil. " There are

also serious implications for the improvement of veterinary care more

generally. "

This is the first time researchers have successfully developed a scale to

measure spontaneous responses in animals that resemble human responses to those

same painful states.

Mogil, graduate student Dale Langford and colleagues in the Pain Genetics Lab at

McGill analyzed images of mice before and during moderate pain stimuli - for

example, the injection of dilute inflammatory substances, as are commonly used

around the world for testing pain sensitivity in rodents. The level of pain

studied could be comparable, researchers said, to a headache or the pain

associated with an inflamed and swollen finger easily treated by common

analgesics like Aspirin or Tylenol.

Mogil then sent the images to Craig's lab at UBC, where facial pain coding

experts used them to develop the scale. Craig's team proposed that five facial

features be scored: orbital tightening (eye closing), nose and cheek bulges and

ear and whisker positions according to the severity of the stimulus. Craig's

laboratory is a leader in studying facial expression as the standard for

assessing pain in human infants and others with verbal communication

limitations. This work is an example of successful " bedside-to-bench "

translation, where a technique known to be relevant in our species is adapted

for use in laboratory experiments.

Continuing experiments in the lab will investigate whether the scale works

equally well in other species, whether analgesic drugs given to mice after

surgical procedures work well at their commonly prescribed doses, and whether

mice can respond to the facial pain cues of other mice.

Dr. Mogil, the E.P. Professor of Pain Studies at McGill, is a repatriated

Canadian who was recruited in 2001 from the University of Illinois at

Urbana-Champaign, where he first identified sex-specific genetic circuitry that

governs the way males and females respond to pain. Dr. Mogil generally explores

the genetic and environmental influences that combine to govern reactions to

pain. He holds the Canada Research Chair in the Genetics of Pain (Tier 1).

McGill University is renowned for its historic contributions to pain research,

including the internationally recognized McGill Pain Questionnaire, developed by

psychology professor Dr. Melzack in 1975 and still the standard today.