Medical marijuana
Medical marijuana. Dreamstime

Marijuana is getting a lot of love lately, from newly legal recreational users in a few American states, and doctors alike. Researchers are uncovering lots of ways in which THC, the chemical responsible for most of the herb’s psychological effects, can help treat medical conditions, reducing chronic pain or shrinking tumors. But from a medical perspective THC isn’t all good, man! Frequent exposure can lead to memory loss, anxiety, or dependence. Now a team of European researchers using mice as test subjects found a way to separate THC’s good effects from those seen as less medically desirable, according to a study published today in PLOS Biology.

THC affects the brain through a series of cell membrane receptors called cannabinoid receptors. These receptors can influence everything from a person’s appetite to mood to how sensitive she or he is to pain. But because marijuana research has been impeded by government restriction in the past, researchers didn’t have a good understanding of which parts receptors affect which behaviors.

In the study, the researchers tested THC on mice that were lacking a particular receptor that responds to serotonin. They found that while these mice experienced THC’s pain-killing effects, they didn’t experience amnesia as the researchers expected in normal mice. When they looked at this receptor and THC is a petri dish, they also found that they are also integral in forming memories. The researchers don’t address whether or not the mice with the damaged receptor felt less “high,” though if the mice aren’t getting as much serotonin (a brain chemical often associated with happiness) from the THC, chances are that they don’t feel as good as they would with normal receptors.

If the same holds true in humans, the researchers hope that this information could someday help them create synthetic marijuana that only targets the desired pathways. This would help make medical marijuana safer—and maybe even more acceptable to those who still disapprove of its use.