One of the best known roles for the cannabinoid 1 receptor is orexia (appetite) : stimulating the desire for food and promoting eating behavior. Disruptions to the ECS have been associated with disordered eating (restrictive, compulsive, or inflexible eating patterns), metabolic disruptions (diabetes/obesity/wasting syndrome), and gastrointestinal motility problems (nausea, constipation, diarrhea, or gastroparesis). These conditions are an indication that the ECS is not functioning optimally. Because the ECS is found in the brain and in the gastrointestinal (GI) system (and everywhere in between) it is a common thread uniting the body/mind. It relays communication between nerves, tissues (such as muscle cells and glands that secrete hormones and enzymes into the GI tract) and between the nervous central nervous and GI systems.
Research strongly suggests that the ECS plays an important role in our survival by stimulating hunger, enhancing our desire for food, and regulating our expenditure of calories. The ECS controls food intake through specific structures in the brain, including the hypothalamus, a major hub involved as a relay station in the regulation of body temperature, emotional responses, and feeding and energy balance.
Cannabis has been used as an appetite regulator from ancient times. Cannabis activates the ECS by THC binding to both of the cannabinoid receptors (CB1 and CB2). THC is considered a partial agonist at these receptor, but has an affinity (ease of forming a chemical bond) stronger than that of our natural endocannabinoid compounds. Cannabis is well-known for causing the munchies. Munchies, or hedonic eating, are a sudden surge in appetite and desire for certain foods after using cannabis. This is a drive to eat for pleasure, even when calories are not needed. This can be a great benefit for some (such as those undergoing cancer therapies) and perhaps a pitfall for others!
From the womb, we are endowed with a natural reflex for sucking in preparation for our first encounter with food, previously provided by the placenta. In a famous study performed in neonatal mice (the first few days of life) by Israeli scientist Esther Fride in 2002, blockade of the CB1 receptor by a drug given intravenously (IV) demonstrated the importance of the ECS in the suckling reflex. In these CB1-blocked mice, their growth was halted and, further, led to the death of the animals. The cause of death was an oral motor defect, the result their sucking reflex; they could not eat to survive. This experiment shows how the ECS, from the beginning of life, is paramount for our survival!
The ECS also interacts with the many bacteria that live in our gastrointestinal tracts (the microbiome). The hypothalamus-gut-axis (HGA) or, more commonly, the gut-brain axis, is a two-way street, where the enteric nervous system, a specialized nervous system in the gut, the microbiome, and specialized immune tissue in the gut are all communicating with the brain.
Imbalances in the microbiome, known as dysbiosis, has been associated with broad health outcomes such GI and mood disorders. Our GI tube is also rich with ECS function, in the nerves, intestinal epithelial cells, secretory cells, smooth muscle responsible for peristalsis, and in the huge immune tissue lining our entire digestive tract. (How interesting that so much of our immune tissue is so close to the outside world!) One of the access points for the outside world to the inside world, or transducers of the outside world to the inside world, is the microbiome lining the gut.
Imbalances in the gut microbiome can arise from antibiotic use, probiotic use, high “bad” fat (as in saturated and omega-6 fatty acids), and highsugar diets. When things are out of control, the microbiome can adhere to the epithelial layer, forming a biofilm that is resistant to being killed off by bacteria. These manipulations also can change our ECS, such as affecting the expression of the CB1R or CB2R. Toning the ECS is a key to help keep our gut in homeostasis.
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