Anyone who has been pricked by a needle knows how this process goes: first there is a pierce, then a sharp pain, followed by a wince and even an urge to pull away. This is a nearly universal reaction, but the exact circuitry behind it is not fully understood. Scientists suggest that they may have just found a piece to the puzzle with the discovery of this previously unknown sensory organ inside of the skin.
As published in the journal Science, the nociceptive glio-neural complex is not quite like the typical picture of a complex organ, rather it is a simple organ made up of a network of glial cells that surround and support nerve cells. The glial cells form a mesh like structure between the skin’s outer and inner layers with filament like protrusions that extend into the outer layer.
Up until this discovery nociceptive fibers were thought to be the main starting points to this kind of pain, but according to the scientists the organ appears to play important roles in perception of mechanical pain and discomfort caused by pressure, pricking, and other impacts to skin.
“We have been thinking for probably a hundred years that pain is started from nerves in the skin,” says coauthor Patrik Ernfors of the Karolinska Institutet. “But what we show now is that pain can also be started in these glial cells.”
This organ was first identified in mice, and functionality was measured by responses to different types of pain; the animals were observed to have a normal response to thermal pain, or discomfort from heat/cold, but showed a reduced response to mechanical pain when the glial complex was deactivated using gene editing technology.
Although not yet tested to see if this organ exists in humans the scientists suggest that the probability of it existing as being high. “Considering that all other previously known sensory organs in mice also exist in humans, it is possible if not likely that this sensory organ also is present in our skin,” says Ernfors.
If these findings hold true for humans this may help to develop treatments for a variety of neuropathic pain disorders which affect an estimated 10% of the population in America, and 10% in Europe.
“This is a very appealing discovery,” says Luana Colloca of the University of Maryland School of Medicine who was not involved with the study. “It’s exciting to know that there is a system that is much more than the nociceptive fibers that we teach about to our students.”
