University of Minnesota researchers are on a bit of a roll. Last month, they got some international attention with research showing an inexpensive and common substance could halt the spread of the HIV virus in monkeys.
Today neuroscientists at the U have tackled a more common problem : the itch. They report both the itch and the relief from scratching comes from cells in the spinal cord, rather than an impulse in the brain.
And, again, monkeys are at the heart of the research, the New York Times reports:
In the study, led a postdoctoral student, Steve Davidson, researchers isolated in monkeys cellular connections that run from the surface of the foot to the spinal cord and then to the thalamus, a clearinghouse for sensations in the brain, down through the spinal cord to the surface of the foot. They induced the sensation by injecting histamines under the skin.
The scientists took single-cell recordings in an area at the base of the spinal cord, in the lower back, in so-called spinothalamic neurons. These cells are sprinkled throughout the spinal cord. Most are sensitive to pain, and some to both pain and itch. The cells apparently detected the injection and began firing immediately afterward. And when the researchers scratched the itchy skin on the monkeys' feet, it quieted the cells' activity.
Stories about the findings also reveal this nugget: Scientists don't call it "itching." It's known as pruritus.
It is important to be aware how animal subjects like this are treated. Monkeys used for this research are cage-bound, isolated, and often not sedated for surgical procedures. Does the research outcome justify subjecting primates to painful, sad lives? It is easy to ignore it, but they suffer for this information.