Mental & Emotional Health
Nature’s Balm for the Stressed Brain
New findings on nociception, a system in the brain that naturally moderates the effects of stress, shows promise for the development of therapies for anxiety and addiction. Collaborating scientists at The Scripps Research Institute, the National Institutes of Health, and the University of Camerino in Italy published their results in the January 8th in the Journal of Neuroscience.
A release from Scripps quotes principal investigator Marisa Roberto as stating, “We were able to demonstrate the ability of this nociceptin anti-stress system to prevent and even reverse some of the cellular effects of acute stress in an animal model.” Roberto is an associate professor in Scripps’ addiction research department, the Committee on the Neurobiology of Addictive Disorders. The article on the findings was published The release reports thatnociceptin, which is produced in the brain, belongs to the family of opioid neurotransmitters. But the resemblance essentially ends there. Nociceptin binds to its own specific receptors called NOP receptors and doesn’t bind well to other opioid receptors. The scientists who discovered it in the mid-1990s also noted that when nociceptin is injected into the brains of mice, it doesn’t kill pain—it makes pain worse.
The molecule was eventually named for this “nociceptive” (pain-producing) effect. However, subsequent studies demonstrated that, by activating its corresponding receptor NOP, nociceptin acted as an antiopioid and not only affected pain perception, but also blocked the rewarding properties of opioids such as morphine and heroin.
Perhaps of greatest interest, several studies in rodents have found evidence that nociceptin can act in the amygdala, a part of the brain that controls basic emotional responses, to counter the usual anxiety-producing effects of acute stress. There have been hints, too, that this activity occurs automatically as part of a natural stress-damping feedback response.
Scientists have wanted to know more about the anti-stress activity of the nociceptin/NOP system, in part because it might offer a better way to treat stress-related conditions. The latter are common in modern societies, including post-traumatic stress disorder as well as the drug-withdrawal stress that often defeats addicts’ efforts to kick the habit.
For the new study, Roberto and her collaborators looked in more detail at the nociceptin/NOP system in the central amygdala. First, Markus Heilig’s laboratory at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the NIH, measured the expression of NOP-coding genes in the central amygdala in rats. Heilig’s team found strong evidence that stress changes the activity of nociceptin/NOP in this region, indicating that the system does indeed work as a feedback mechanism to damp the effects of stress. In animals subjected to a standard laboratory stress condition, NOP gene activity rose sharply, as if to compensate for the elevated stress.