A new case for cannabis?

Xia Zhang
Xia Zhang

“We should allow pharmaceutical companies to use marijuana in developing new drugs to treat brain and other types of disorders.”

– Xia Zhang

The use of cannabis to treat various illnesses has long polarized the medical community, partly because of its undesirable effects on memory. But a major international study led by University of Ottawa researcher Xia Zhang throws new light on how memory is affected by marijuana—and may help lay that controversy to rest.

The groundbreaking study, which was published in early 2012 in the scientific journal Cell, has created a buzz in the science world that has propelled Zhang, a professor in the departments of Psychiatry and Cellular and Molecular Medicine and the director of the Translational Neuroscience Laboratory at the University of Ottawa Institute of Mental Health Research, to star status. “I have been receiving phone calls from all over the world,” says Zhang. “China, France… it has been very busy.”

The research shows for the first time that astrocytes, or astroglial cells, the most abundant cell in the human brain, play a pivotal role in regulating memory and controlling neurons. This contradicts the long-held notion among scientists that the starburst-shaped cells act only in a supporting role by protecting and assisting in the function and repair of neurons. Zhang and his team of 17 scientists from North America, Asia and Europe found that neurons do not operate alone in impairing memory under the effects of marijuana. In fact, marijuana’s unwanted side effects on memory arise from the drug’s action on astroglia.

Zhang has also discovered a link between cannabinoid type-1 CB1 receptors— receptors that react to marijuana—and working memory. These particular receptors are located in the hippocampus, the area of the brain responsible for higher brain function, while working memory is the brain system that allows you to simultaneously store and process information for complex tasks such as learning and reasoning.

This is extremely significant because it may be possible to isolate which CB1 receptors are activated by cannabis and which are not, making it easier to determine which cells and body systems are affected. In treating illnesses such as epilepsy and Alzheimer’s, for instance, it might be possible to trigger a response from receptors in the corresponding brain systems governing these conditions, while mitigating unwanted side effects such as memory impairment.

CB1 receptors react to both cannabinoids (the active chemicals in marijuana) derived from the cannabis plant and endogenous cannabinoids produced naturally by our bodies. Since the human body makes its own endocannabinoids, why would it be necessary to turn to marijuana? Unfortunately, explains Zhang, the regulation and production of endocannabinoids by the human body is still a mys­tery. The most consistent and effective source of the compounds remains cannabis.

With this study, Zhang has taken brain research to a new frontier, where it is possible to harness the medicinal benefits of cannabis while controlling certain receptors, turning them on and off to elicit specific responses without hurting memory. Ultimately, his discovery has the potential to aid in the treatment of pain, seizures and a whole series of ailments and to expand our knowledge of the human body, from sleep and sexual function to memory and neurological processes.

“I believe our findings can be used in neuroscience research,” says Zhang. “People can find out more about the importance of astroglial cells in high brain function such as working memory and thinking.”

After the excitement of his breakthrough dies down, Zhang plans to continue working on ways to turn his knowledge on the effects of marijuana on the brain into practical application. “In my opinion,” he says, “we should allow pharmaceutical companies to use mari­juana in developing new drugs to treat brain and other disorders.” While the concept is still contentious, Zhang’s research is a major step in building a case for cannabis in medical treatment.

 

by Nancy Ceresia

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