Canadian researchers note that they have recently discovered a critical role that microglia—a class of cells present in the brain and spinal cord—play in the development of chronic pain. The signaling pathways identified through their studies, they suggest, could lead to important targets for the development of therapeutic strategies to deal with chronic pain.

According to a news release from the Canadian Association for Neuroscience, microglia constitute about 10% of the cells in the adult brain and spinal cord. According to the release, it was initially thought that microglia simply had a role in supporting neurons. However, researchers suggest that microglia have an important role in the spinal response following a nerve injury, by blocking the inhibition of pain-transmitting neurons and making transmission of the pain signal more efficient.

The research team’s findings also suggest that microglia-to-neuron signaling is crucial not only in the development of pain hypersensitivity after injury but also for one of the effects that morphine and other opioids sometimes produce called hyperalgesia, which is an increase in pain sensitivity caused by drugs prescribed to alleviate pain.

“We’re developing a new understanding of the control of microglia-neuron interactions that may be critical for individualizing pain therapies,” says the team’s lead researcher, Michael Salter, MD, PhD, a senior scientist and head of neurosciences and mental health at The Hospital for Sick Children (aka, SickKids), Toronto, professor of physiology at the University of Toronto, and Canada Research Chair in Neuroplasticity and Pain.

“Exciting new discoveries indicate that microglia not only play a critical role in disease states but also in the normal development and functioning of the brain and spinal cord,” Salter continues. “We are looking at these cells in an entirely new light.”

Per the release, research from Salter and his team shows how the experience of pain can change the nervous system to make it more sensitive to further painful experiences, to feel pain in response to events that do not cause pain in most people, and how opioids can paradoxically cause more pain. Salter states in the release that he hopes targeting the pathways identified in these studies could lead to development of therapeutic strategies to deal with chronic pain.

Salter presented his team’s findings recently at the 9th Annual Canadian Neuroscience Meeting in Vancouver.

[Source(s): Canadian Association for Neuroscience, Science Daily]