Brain-imaging study links cannabinoid receptors to post-traumatic stress disorder: First pharmaceutical treatment for PTSD within reach
May 14, 2013
Science Daily/NYU Langone Medical Center
In a first-of-its-kind effort to illuminate the biochemical impact of trauma, researchers at NYU Langone Medical Center have discovered a connection between the quantity of cannabinoid receptors in the human brain, known as CB1 receptors, and post-traumatic stress disorder, the chronic, disabling condition that can plague trauma victims with flashbacks, nightmares and emotional instability.
Their findings, which appear online today in the journal Molecular Psychiatry, will also be presented this week at the annual meeting of the Society of Biological Psychiatry in San Francisco.
CB1 receptors are part of the endocannabinoid system, a diffuse network of chemicals and signaling pathways in the body that plays a role in memory formation, appetite, pain tolerance and mood. Animal studies have shown that psychoactive chemicals such as cannabis, along with certain neurotransmitters produced naturally in the body, can impair memory and reduce anxiety when they activate CB1 receptors in the brain. Lead author Alexander Neumeister, MD, director of the molecular imaging program in the Departments of Psychiatry and Radiology at NYU School of Medicine, and colleagues are the first to demonstrate through brain imaging that people with PTSD have markedly lower concentrations of at least one of these neurotransmitters -- an endocannabinoid known as anandamide -- than people without PTSD. Their study, which was supported by three grants from the National Institutes of Health, illuminates an important biological fingerprint of PTSD that could help improve the accuracy of PTSD diagnoses, and points the way to medications designed specifically to treat trauma.
"There's not a single pharmacological treatment out there that has been developed specifically for PTSD," says Dr. Neumeister. "That's a problem. There's a consensus among clinicians that existing pharmaceutical treatments such as antidepressant simple do not work. In fact, we know very well that people with PTSD who use marijuana -- a potent cannabinoid -- often experience more relief from their symptoms than they do from antidepressants and other psychiatric medications. Clearly, there's a very urgent need to develop novel evidence-based treatments for PTSD."
The study divided 60 participants into three groups: participants with PTSD; participants with a history of trauma but no PTSD; and participants with no history of trauma or PTSD. Participants in all three groups received a harmless radioactive tracer that illuminates CB1 receptors when exposed to positron emissions tomography (PET scans). Results showed that participants with PTSD, especially women, had more CB1 receptors in brain regions associated with fear and anxiety than volunteers without PTSD. The PTSD group also had lower levels of the neurotransmitter anandamide, an endocannabinoid that binds to CB1. If anandamide levels are too low, Dr. Neumeister explains, the brain compensates by increasing the number of CB1 receptors. "This helps the brain utilize the remaining endocannabinoids," he says.
Much is still unknown about the effects of anandamide in humans but in rats the chemical has been shown to impair memory. "What is PTSD? It's an illness where people cannot forget what they have experienced," Dr. Neumeister says. "Our findings offer a possible biological explanation for this phenomenon."
Current diagnostics for PTSD rely on subjective measures and patient recall, making it difficult to accurately diagnose the condition or discern its symptoms from those of depression and anxiety. Biological markers of PTSD, such as tests for CB1 receptors and anandamide levels, could dramatically improve diagnosis and treatment for trauma victims.
Among the 1.7 million men and women who have served in the wars in Iraq and Afghanistan, an estimated 20% have PTSD. But PTSD is not limited to soldiers. Trauma from sexual abuse, domestic violence, car accidents, natural disaster, violent assault or even a life-threatening medical diagnosis can lead to PTSD. The condition affects nearly 8 million Americans annually.
These findings were made possible through the collaborative efforts of researchers at NYU School of Medicine, Yale School of Medicine, Harvard Medical School, the Department of Veterans Affairs National Center for PTSD and the University of California at Irvine.
https://www.sciencedaily.com/releases/2013/05/130514085016.htm
New way to boost potency of natural pain relief chemical in body
November 21, 2011
Science Daily/University of California - Irvine
UC Irvine and Italian researchers have discovered a new means of enhancing the effects of anandamide -- a natural, marijuana-like chemical in the body that provides pain relief.
Led by Daniele Piomelli, UCI's Louise Turner Arnold Chair in the Neurosciences, the team identified an "escort" protein in brain cells that transports anandamide to sites within the cell where enzymes break it down. They found that blocking this protein -- called FLAT -- increases anandamide's potency.
Previous work by the researchers indicates that compounds boosting anandamide's natural abilities could form the basis of pain medications that don't produce sedation, addiction or other central nervous system side effects common with existing painkillers, such as opiates.
"These findings raise hope that the analgesic properties of marijuana can be harnessed for new, safe drugs," said Piomelli, a professor of pharmacology. "Specific drug compounds we are creating that amplify the actions of natural, marijuana-like chemicals are showing great promise."
For the study, which appears in the Nov. 20 online version of Nature Neuroscience, he and his colleagues used computational methods to understand how FLAT binds with anandamide and escorts it to cell sites to be degraded by fatty acid amide hydrolase (FAAH) enzymes.
Anandamide has been dubbed "the bliss molecule" for its similarities to the active ingredient in marijuana. A neurotransmitter that's part of the body's endocannabinoid system, it's been shown in studies by Piomelli and others to play analgesic, antianxiety and antidepressant roles. It's also important in regulating food consumption. Blocking FAAH activity enhances several effects of anandamide without generating the "high" seen with marijuana.
Piomelli and his collaborators speculate that inhibiting FLAT (FAAH-like anandamide transporters) might be particularly useful in controlling certain forms of pain -- that caused by damage to the central nervous system, for example -- and curbing addiction to such drugs as nicotine and cocaine.
Researchers from UCI, Italy's University of Parma and University of Bologna, and the Italian Institute of Technology participated in the study, which was supported by grants from the U.S. National Institute on Drug Abuse, the U.S. National Institute on Alcohol Abuse & Alcoholism, and the U.S. National Institute of General Medical Sciences.
https://www.sciencedaily.com/releases/2011/11/111121142501.htm