Cannabis assists the endocannabinoid system in supporting neurogenesis.
Neurogenesis (growing new brain cells), in adults is critical to learning, mood regulation, and maintaining brain health; the endocannabinoid system plays an active role in the neurogene process. Interestingly, many psychiatric disorders like depression and schizophrenia accompany an impaired neurogene process.
The brain begins the neurogenesis process immediately following injury. It does so by increasing its proliferation of neural progenitor cells (NPCs). In this way, the brain attempts to heal the injury and prevent further damage.
What Role Does the Endocannabinoid System Play in Growing New Brain Cells?
The endocannabinoid system is the body’s own system of cannabinoid molecules and cannabinoid receptors. They predominantly appear in the brain and throughout the immune system. However, these receptors also appear throughout the organs and tissues of your body. Following a brain injury, as in a stroke, or force related traumatic injury, the endocannabinoid system ramps up production of endocannabinoid molecules and receptors. Scientists believe this is evidence that the endocannabinoid system is involved in neural regeneration.
Scientists confirmed the participation of the endocannabinoid system in neurogenesis through animal studies. In an animal model of brain injury, mice bred to lack cannabinoid receptor CB1 or mice with the activity of the CB1 receptor blocked, reduced neurogenesis. In in vitro studies on neural cells, growth and division of NPCs were inhibited when the activity of the CB1 and CB2 receptors were blocked.
Can CBD Help the Neurogene Process?
Cannabidiol (CBD) increases neurogenesis in animals. For example, one study on an animal model of chronic stress found that CBD could undo the reduced neurogenesis and the anxiety. Animal studies have also shown that neurogenesis only occurs after long term administration of cannabinoids, so it doesn’t have an immediate effect.
Looking more closely at the brain leads to further evidence for the role of the endocannabinoid system in neurogenesis. High levels of CB1 and CB2 receptors were found in the part of the brain that is known to be responsible for containing NPCs and promoting neuron growth and differentiation, the subventricular zone (SVZ). The two kinds of diacylglycerol lipases (DAGLs), enzymes that help synthesize the endocannabinoid 2-arachidonoylglycerol (2-AG), are also in this part of the brain. Their presence also points to an active role of the endocannabinoid system in neurogenesis.
The mechanism seems to involve both cannabinoid receptors, CB1 and CB2. A variety of protein signalling cascades have always resulted in neural regeneration. This is in both animals and brain cells studied in vitro. These signaling pathways, once activated by cannabinoid molecules binding to the cannabinoid receptors, encourage NPCs to grow and divide. Scientists call this process “proliferation.”
Helping Cell Maintenance and the Neurogene Process
After the population of NPCs grows, they begin to migrate to different parts of the brain. Once there, they undergo a transformation into the type of cell the brain needs. Scientists call this “differentiation.” Cannabinoids also mediate this process. After differentiation, cannabinoid receptors remain on the cells. Scientists believe they play a part in signalling three things; Whether the cell should continue to live, should undergo programmed cell death, or should receive cell maintenance.
The psychoactive side effects of activating the CB1 receptor limit the practical use of cannabis for encouraging neural regeneration. Some researchers examine other ways of manipulating the endocannabinoid system to encourage neurogenesis. Their work is administering drugs to prevent endocannabinoids from breaking down in the brain. This increases the numbers of endocannabinoids present in the brain and exerst proliferative effects while limiting any undesirable psychoactive effects.
Update: More Research Confirms Cannabis’ Positive Role in the Neurogene Process
Since the above article was initially published, more research has confirmed the role of cannabis in neurogenesis. In this study, THC was the focus, instead of CBD. However, throughout this study, the researchers found that “∆9-THC enhanced the markers involved in all stages” of the brain’s mechanism for neurogenesis. The researchers found that ultimately, adding THC to the brain improved neurogenesis. The researchers saw positive results in the hippocampus specifically. This means that THC can be said to have improved the cognitive function of the rats.
Scientists wouldn’t do research on rats if their brain chemistry did not resemble humans. This means that there is a good likelihood that THC helps improve cognitive function in humans as well.