Taking aim at chronic pain



The 500,000 Canadians who suffer from chronic pain due to nerve injury triggered by circumstances, such as an accident or a fall, or an illness, such as cancer or shingles, all seek one thing: relief.

The scientists have found that low doses of this new molecule alleviate chronic pain in animal models.

An international research team led by Gabriella Gobbi, professor in the Department of Psychiatry at McGill University and researcher at the McGill University Health Centre, is focused on a substance that selectively targets the MT2 melatonin receptor (melatonin is a sleep hormone released by the body). The scientists have found that low doses of this new molecule alleviate chronic pain in animal models. The drug must still move to clinical trials but Dr. Gobbi hopes to one day get approval to market a medication that could replace opioids, which are potent analgesics that often lead to addiction.

In 2011, after initially setting out to find an alternative to melatonin pills—whose effectiveness is limited because they simultaneously act on two receptors (MT1 and MT2) with opposite effects—Dr. Gobbi and her Italian and Mexican collaborators discovered the therapeutic benefits of high doses of the molecule in patients with sleep disorders. The researchers only recently observed that low doses of the substance switch off the neurons that trigger pain and stimulate those that relieve it. More specifically, like a key in a lock, the molecule only activates the MT2 melatonin receptor in the part of the brain that processes pain.

The findings suggest that low doses of the drug could be used to ease pain during the day and treat insomnia at night. Given that 50 to 70% of patients who suffer from neuropathic pain also have trouble sleeping, the discovery could hit two targets with one bullet.