By Jonny Lupsha, Wondrium Staff Writer
April sales of legalized marijuana in Oregon were more than $89 million, NBC affiliate KGW8 reported. Marijuana dispensaries in many states have been deemed “essential” and kept open for business throughout the coronavirus pandemic. How does pot interact with the brain?
According to KGW8, a number of tax benefits come from the sale of legalized marijuana. “Oregon’s annual tax revenue from recreational marijuana sales exceeds $100 million,” the article said. “The state collects 17 percent tax on retail cannabis sales, while counties or cities can apply a three percent tax. Legal pot has provided a steady stream of tax revenue when other sources like personal income or state lottery revenues are less predictable due to the struggling economy and stay-at-home orders.”
When it comes to marijuana use, its specific chemical effect on the brain wasn’t well-known until the late 1980s. Since then, science has developed a much clearer view of pot and the human brain.
The Straight Dope on Cannabinoids
The hemp plant from which marijuana is derived is called Cannabis sativa.
“Marijuana, hashish, and hash oil are all derived from hemp,” said Dr. Thad Polk, an Arthur F. Thurnau Professor in the Department of Psychology and the Department of Electrical Engineering and Computer Science at the University of Michigan. “Marijuana is basically dried pieces of the hemp plant, hashish is dried resin from the plant, and hash oil is a more concentrated form of the resin. All three forms are usually smoked and inhaled, although they’re also sometimes eaten, for example, being baked into brownies.”
The connecting factor of all three forms of cannabis is that they contain “cannabinoids,” which are chemicals that are often psychoactive. Dr. Polk said that this means when cannabinoids enter the bloodstream and reach the brain, they can produce psychological and behavioral effects. The cannabinoid that produces most of the psychoactive effects in cannabis is called delta-9-tetrahydrocannabinol (THC). For a long time, nobody knew how THC managed to affect the brain.
“But that changed in 1988, when William Devane, Allyn Howlett, and their colleagues at the St. Louis University medical school found evidence for cannabinoid receptors in the brain,” Dr. Polk said.
This Is Your Brain on Drugs
“Neurotransmitters bind to specific molecules called receptors in the brain,” Dr. Polk said. “Most psychoactive drugs produce their effects by mimicking neurotransmitters and binding to natural brain receptors. Cannabinoids are no exception to that rule, and the receptors that they bind to were even named after them; that’s why they’re called cannabinoid receptors.”
According to Dr. Polk, there are two main types of cannabinoid receptors in the body—CB1 receptors and CB2 receptors. CB2 receptors are tied to the immune system, so CB1 receptors are believed to be affected by cannabis use.
The scientific community doesn’t believe that our bodies evolved specifically with cannabis use in mind, so instead they began looking for brain chemicals that bind to those cannabinoid receptors. Since 1992, they’ve found several.
“These natural chemicals that are produced in the brain itself are sometimes called endogenous cannabinoids, or just endocannabinoids for short,” Dr. Polk said. “Endocannabinoids are actually quite different from most other neurotransmitters in the brain. Most neurotransmitters are stored in neurons and then released when the neuron fires, but endocannabinoids appear to be made only when they’re needed, rather than being stored.”
Many scientists believe that the function of endocannabinoids is to regulate neural communication. Dr. Polk said they have the ability to turn off excitatory and inhibitory synapses, which suggests that they can stop our brains from engaging in too much excitation or too much inhibition. Other research suggests endocannabinoids help us forget things that we need to forget—for example, where we parked the car yesterday as opposed to today.
Congress is currently considering marijuana reform to stimulate more state economies.
Dr. Thad A. Polk contributed to this article. Dr. Polk is an Arthur F. Thurnau Professor in the Department of Psychology and the Department of Electrical Engineering and Computer Science at the University of Michigan. He received a B.A. in Mathematics from the University of Virginia and an interdisciplinary Ph.D. in Computer Science and Psychology from Carnegie Mellon University.