A new organ associated with the awareness of pain was recently uncovered by scientists, which could result in the creation of more effective painkilling medication.
The cells that encompass the pain-detecting nerve cells which reach into the external layer of skin, seem to be directly linked in the pain-sensing phenomenon. This suggests a new organ that plays a significant role in the sensation of experiencing physical hurt.
“The major question for us now is whether these cells are actually the cause for certain kinds of chronic pain disorders,” says Professor Patrik Ernfors, a co-author of the research from the Karolinska Institute in Sweden.
The previously underappreciated cells are a kind of Schwann cell, which swaddle and envelop nerve cells and assist with keeping them alive. After studying tissues, the researchers discovered that the body of the cells are located underneath the external layer of the skin, though the cells possess lengthy extensions that surround the ends of pain-detecting nerve cells that lead up to the surface epithelium of the skin.
The scientists were somewhat perplexed by this discovery since the general understanding was that the end of nerve cells in the skin were exposed.
“In the pain field, we talk about free nerve endings that are responsible for pain sensation. But actually they are not free,” says Ernfors.
Optogenetic experiments on mice
The realization that these Schwann cells could detect pain was made with the use of optogenetics, a neuroscience technique which involved the genetic alteration of mice that made the Schwann cells in the skin on their feet to generate a protein that’s capable of absorbing light. When light hits the cells, the mice raised their feet and displayed indications that the stimulation of the Schwann cells resulted in pain; the behaviour included licking, shaking, and shielding their paws. With more frequent light pulses came an increased amount of nearby nerve cells firing, which substantiates the notion that the Schwann cells deliver signals to the brain via the nerve cells.
Expert in sensory systems, Professor Peter McNaughton from King’s College London, said, “If borne out by subsequent studies, this paper will be a paradigm shift showing that pain-sensitive nerve cell terminals are not in fact always directly driven by a painful stimulus, but instead can be driven by associated cells”.