Experts have long known that the brain has the ability to suspend the pain response in times of injury and great stress, even after traumatic incidents such as gunshot wounds.

Now, a new study in rats suggests marijuana-like neurochemicals called endocannabinoids may be key to this process.

The discovery may lead to a new class of painkillers with fewer side effects than existing pain medications, report researchers at the University of California, Irvine (UCI). Their study appears in the June 23 issue of Nature.