Pain and itch sensory neurons, shown in red. Photo courtesy NC State News
A neurotransmitter in the skin which plays a key role in transmitting the sensation of itch appears to have no role in pain transmission—a finding researchers say may aid in the development of more targeted itch mediation.
“For us, it is very important to understand the neural circuits or pathways so that we can develop therapies specifically for pain or itch, instead of targeting it as a whole system,” said corresponding author Santosh Mishra, PhD, assistant professor of neuroscience in North Carolina State University’s (NC State’s) College of Veterinary Medicine, in a press release. “This work shines a light on these different pathways for pain and itch.”
Dr. Mishra and his colleagues focused on the neurotransmitter brain natriuretic peptide (BNP), which Dr. Mishra had earlier established through work at the U.S. National Institutes of Health was involved in transmission of itch sensation from the skin to the brain in mice.
In this new research, Dr. Mishra’s team examined what role, if any, BNP played in transmitting acute, inflammatory, or neuropathic pain in mice. They found that the results were the same in control mice and those that lacked the BNP gene. Their findings were published in Molecular Pain (Oct. 16, 2017, online ahead of print).
“That means that BNP was not involved for any of these distinct types of pain,” said Dr. Mishra. “We know that if we target BNP, we will not be inhibiting pain; we will be inhibiting itch.”
Knowing how sensations of itch and pain are transmitted could allow researchers to design specific drugs or therapies to block the specific neurotransmitters involved, block the receptors for those neurotransmitters, or reduce the degree to which those neurotransmitters are effective, said Dr. Mishra. “I call these [neurotransmitters] the gatekeepers because they are sitting between the skin and the central nervous system.”
Ideally the goal would be to develop treatments that interrupt pain or itch closer to their source, said Dr. Mishra. “If we can block the sensation at the peripheral level, in the skin, that is a much friendlier way than to try to target the sensation once it reaches the brain.”
“We know the importance of pain management. Studying itching sensations is a relatively new field, but if we look at the number of diseases where itch is a major symptom, it includes not only atopic dermatitis but also nervous system disorders such as multiple sclerosis, as well as infection and end stage kidney disease. This work is an initial step in gaining a better understanding.”