Last week, over 32,000 neuroscientists met in San Diego for the annual Society for Neuroscience (SfN) conference. Joining them were members of IU’s Program in Neuroscience, including Dr. Andrea Hohmann, who is also a professor in the Department of Psychological and Brain Sciences in the College of Arts in Sciences and a Linda and Jack Gill Chair of Neuroscience in the Gill Center for Biomolecular Science.
Scientific conferences like SfN bring together scientists from all over the world to discuss their findings. Researchers attend SfN to discuss a wide variety of topics related to brain function and mental health. At the conference, Dr. Hohmann met not only with her colleagues, but also members of the press, who were interested in her lab’s research on the neurochemistry of pain. She described how the endocannabinoid system, a complex network of cells and receptors in the brain, is involved in pain perception and may be a useful target for pain relief drugs. The endocannabinoid system is currently a hot topic in neuroscience, partly because receptors in this system are targeted by THC, the psychoactive ingredient in marijuana and other synthetic marijuana-like compounds. When THC and other synthetic cannabinoids reach the brain, they act on cannabinoid receptors to elicit both psychoactive and pain-relieving effects. Marijuana is currently being considered for legalization in the US.
Dr. Hohmann has received funding from the National Institute on Drug Abuse to test compounds that could mimic the pain-relieving effects of these compounds without producing their other psychoactive effects. This is an exciting new avenue in drug research. As Dr. Hohmann puts it: “The most exciting aspect of this research is the potential to produce the same therapeutic benefits as opioid-based pain relievers without side effects like addiction risk or increased tolerance over time.”
Richard Slivicki, a graduate student in Dr. Hohmann’s lab, conducted an experiment to test the effects of THC-like drugs in mice with chronic pain. He showed that, when mice with chronic pain were given these compounds, their behavior changed dramatically. Rather than showing heightened responses that are typical of mice with chronic pain, they responded normally when pressure or cold stimulation was applied to their paws. Importantly, Slivicki also found that these effects were long-lasting. While other drugs that target the endocannabinoid system become less effective over time, this drug remained effective even after multiple exposures. “A common issue with current chronic pain therapies such as opioids is that tolerance follows chronic dosing with these compounds. With this approach we don’t find tolerance or other issues that plague current therapies,” Slivicki stated. Other benefits of these drugs are that they are more specific than THC, as they amplify the activity of the brain’s own cannabis-like compounds at only some cannabinoid receptors and not others. Further, the drugs do not possess addictive properties and mice do not show withdrawal symptoms after chronic treatment.
Not surprisingly, this finding was a hit at SfN. As marijuana becomes legal for recreational and medicinal use in an increasing number of American states, neuroscientists are working hard to understand how THC and other similar compounds produce their effects. Hohmann, Slivicki, and others will continue to search for ways to harness the pain-reducing benefits of these compounds to provide healthier and more effective alternatives to current pain management drugs.