Marijuana’s effects on serotonin may explain how it can help anxiety and depression.
Many people have heard that marijuana can affect dopamine in the brain. But what about serotonin?
Serotonin is an important brain chemical that impacts everything from mood to appetite to sleep. Scientists have determined that the endocannabinoid system (the system that responds to marijuana) and the serotonin system are connected.
Specifically, cannabinoids can alter the activity level of serotonin neurons. Studies show that marijuana can increase serotonin.
Scientists believe this is why marijuana can be beneficial for depression and anxiety.
What is Serotonin?
Serotonin is one of many chemicals in the brain known as neurotransmitters. The body uses neurotransmitters to send chemical messages within the nervous system.
Different neurotransmitters are found in different regions of the brain and body. Each neurotransmitter is associated with different functions.
Serotonin regulates mood, emotion, appetite, and sleep. It is found in the brain, GI tract, and in blood platelets. The system of serotonin neurons is known as the serotonergic system.
Many well-known drugs target the serotonergic system. For example, a class of antidepressants known as SSRIs inhibit the enzymes that break down serotonin, thereby increasing serotonin levels in the brain.
Some recreational drugs such as LSD (acid), psilocybin mushrooms, and MDMA (ecstasy) also work by targeting serotonin.
How Does Marijuana Affect Serotonin?
Marijuana activates cannabinoid receptors, and the link between cannabinoid receptors and the serotonin system may help explain some of marijuana’s effects.
Activation of cannabinoid receptors increases serotonin, and blocking serotonin blocks many of the endocannabinoid system’s functions.
In a 2007 study, scientists found that 20% of mouse serotonin neurons had cannabinoid receptors. Endocannabinoids such as anandamide were also found in areas of the brain associated with serotonin.
Interestingly, cannabinoid receptors are found not only on serotonin neurons themselves, but also on inhibitory neurons nearby. This means that cannabinoids may be able to either increase or decrease serotonin system activity.
Researchers have also shown that cannabinoids (such as those found in marijuana) can increase serotonin activity in the brain.
In a 2004 study, researchers gave THC to mice, and serotonin levels increased. When they blocked CB1 receptors in mice, serotonin levels decreased.
Aside from THC, CBD is also linked to serotonin. Many of CBD’s effects are thought to be due to indirect activation of serotonin receptors.
Researchers believe that CBD’s anti-anxiety, antidepressant, antiepileptic, neuroprotective, antiemetic, and pain-relieving effects are all related to activation of a specific subtype of serotonin receptor.
What Are The Effects On The Body?
Scientists believe the link between the endocannabinoid system and the serotonergic system can explain many of marijuana’s effects.
The link between the two systems seems to explain marijuana’s benefits for anxiety and depression, as well as its mood-lifting effects.
This is because serotonin plays an important role in mood, emotions, and stress regulation. Low levels of serotonin may be linked to some mental health disorders, including depression and anxiety.
CBD’s antidepressant effect may be explained by a link to the serotonin system.
In a 2016 study, researchers administered a drug that mimics CBD to mice. The drug blocked the enzyme that breaks down endocannabinoids, increasing the amount of endocannabinoids in the body. This led to an antidepressant effect like CBD would have.
However, when the researchers gave a chemical that blocked serotonin, these effects went away. This implies that CBD’s effects on mood are related to the serotonergic system.
Blocking cannabinoid receptors causes depression and anxiety.
In 2006, a cannabinoid receptor blocker called rimonabant was introduced to the market as an anti-obesity drug. Since cannabinoids play an important role in appetite regulation, it was thought that the drug would reduce hunger.
However, these blockers had the unintended side effect of blocking serotonin, too. They caused depression and anxiety in the people who took them, and were taken off the market.
In a 2015 study, researchers found that genetically altered mice who lacked CB1 receptors in their serotonin neurons showed increased anxiety compared to normal mice.
Cannabinoids play an important role in how antidepressants work.
In a 2011 study, researchers found that increasing the levels of natural cannabinoids could make antidepressants more effective. They also found that blocking CB1 receptors stopped the antidepressants from working entirely.