Feeling queasy about making a big decision; butterflies in the stomach before a big date; wondering whether to trust a “gut” feeling—though they may seem to be completely separate organs, the brain and the gastrointestinal system are in constant communication. Stressed-out folks have long understood this relationship, and now recent studies reveal that the “gut-brain axis” plays a role in a long list of health conditions. As it turns out, cannabis may have an important role to play in keeping those lines of communication working smoothly.
Until relatively recently, people who suffer from anxiety, depression and other mental health conditions might have been told that their problem was “all in their head.” But recent research reveals that the opposite is more likely true. A complex and comprehensive network of neurotransmitters and hormones shared by both the brain and the digestive tract link these two systems.
Helped along by organisms in the gut biome, this axis of communication is anchored by the vagus nerve. The vagus nerve is the longest cranial nerve, running from the brain all the way to the abdomen. Although it actually consists of two branches, it’s usually referred to as one system.
Communication between the brain and the gut, which includes all parts of the digestive system from mouth to anus, is possible because many of the same neurotransmitters and receptors occur in both places—that’s why emotions generated in the brain can also be felt in the belly. A good example of this is irritable bowel syndrome, or IBS, a condition that often has no clear physical cause.
If the brain speaks to the gut, the opposite is also true. Dysfunction in the digestive system can be communicated to the brain, contributing to conditions such as anxiety and depression. More evidence for this connection comes from recent studies on treating anxiety disorders and depression by targeting the gut with dietary changes, probiotics and other remedies for gastric problems.
The gut-brain network also involves the central nervous system, the autonomic nervous system and a little known channel called the hypothalamic pituitary adrenal axis, or HPA. Because so many systems are engaged in this network, its function (or dysfunction) can affect just about every part of the body. But these systems aren’t the only ones to participate in the “crosstalk” along the gut-brain axis—the endocannabinoid system also plays a key role.
RELATED: WHAT IS THE ENDOCANNABINOID SYSTEM?
The bodies of humans and other mammals contain a far-flung network of cannabinoid receptors that occur in many organs, nerves, cells and tissues. The endocannabinoid system, or ECS, has two receptors, CB1 and CB2, which are activated by the body’s own cannabinoids: 2-AG and anandamide. These molecules behave similarly to compounds found in marijuana.
Tetrahydrocannabinol (THC) is the best known and most abundant of the compounds found in cannabis. It’s the psychoactive ingredient that’s responsible for the euphoric and relaxing “high,” but cannabis also contains over a hundred other substances. The second most prevalent of these is cannabidiol, or CBD, a compound that has no psychoactive qualities, but is able to work both with THC and on its own to affect the body’s immune system and many other functions.
Although the endocannabinoid system wasn’t discovered until the early 1990s, numerous studies since then have revealed just how deeply connected it is to the body’s other systems. Moreover, the studies have also discussed the important role cannabis can play in activating the ECS to fight disease and maintain good health. Some research suggests that the endocannabinoid system may actually be the body’s main regulatory system, acting as a sort of “controller” for other systems, including the gut-brain network.
The endocannabinoid receptor CB1 is found throughout the body, but particularly in the brain and central nervous system. CB2 receptors occur most often in white blood cells, the peripheral nervous system and the gastrointestinal tract. These associations mean that the ECS likely plays a role in regulating many essential functions including pain control, pleasure and reward, immune responses, memory and cognition, and mood.
Some studies suggest that low levels of natural cannabinoids contribute to diseases like fibromyalgia, migraines and IBS. They also speculate that consuming cannabis can help resolve that deficiency and eliminate symptoms of those disorders.
The systems that contribute to the gut-brain axis also contain endocannabinoid receptors, and the activity of these receptors can regulate dysfunctions in those other systems. For example, cannabis may ease the symptoms of IBS and reduce the nausea and vomiting associated with chemotherapy; it can also aid anxiety and depression. Because endocannabinoids regulate activity in the HPA pathways, cannabis may also help regulate body temperature and support homeostasis, the balance of the body’s physiological processes.
The discovery of the gut-brain axis also revealed a network of connections to many other essential systems, all engaged in constant “crosstalk.” But the endocannabinoid system has receptors in all those networks and more, and recent research suggests that the ECS may stand behind them all, regulating the crosstalk that keeps the body’s systems working in sync.
This relationship between the endocannabinoid system and the gut-brain axis can explain why conditions like anxiety and IBS seem to be connected. It also helps us understand why cannabis seems to have a powerful effect on health conditions of many kinds.
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