Chocolate and the Nervous System
Adam Drewnowski at the University of Michigan researched whether chocolate triggers the production of opioids. Opioids are chemicals, such as those found in opium, that produce a feeling of well-being (euphoria). Drewnowski found that eating chocolate causes the brain to produce natural opiates, which dulI pain. Researchers at the Neurosciences Institute in San Diego looked into the chemical components of chocolate. They found three substances in chocolate that “could act as cannabinoid mimics either directly (by activating cannabinoid receptors) or indirectly (by increasing anandamide levels).
A receptor is a structure on the surface of a cell that interacts with certain chemicals. Receptors have different shapes, and thus interact with specific molecules. diTomaso describes this interaction like this: “the active compound will lock itself to the protein and that triggers a reaction inside the cell.” Cannabinoids are substances that act like cannabis, also known as marijuana. The active chemical in marijuana is called tetrahydrocannabinol (THC), and there are receptors in the brain that bind THC. When THC binds to these receptors, the person feels “high.” Anandamide is a lipid that is normally found in the brain; it can bind to the same receptors as THC and thus produce a similar effect to “being high.”
Does chocolate affect the brain in the same way marijuana does? There are chemicals in chocolate that act like THC, resulting in production of dopamine, a neurotransmitter. One of the compounds in chocolate is anandamide, which is already produced in your brain. If anandamide is already in your brain, then why don’t you feel happy all the time? Well, anandamide is broken down quickly, so it isn’t around long in your brain to make you smile. But chocolate may extend the feelings of well being. Piomelli’s research indicates that there are two chemicals in chocolate which inhibit the natural breakdown of anandamide. This may be a reason why we like to eat chocolate! And dark chocolate contains more of these compounds than milk chocolate.
Eating a bar of chocolate will not make you feel giddy or “high.” This may be because anandamide and the two compounds that enhance its effect are short-lived and localized in the brain. THC activates many receptors throughout the brain, so it has a much larger effect. Chocolate’s effect is limited because anandamide is not present all over the brain. Scientists doubt if anandamide and other chemicals in chocolate have much effect because they are present only in small amounts. Christian Felder at the National Institute of Mental Health estimates that a 130-pound person would have to eat 25 pounds of chocolate at one time to get any marijuana-like effect. Also, because these compounds are eaten, it’s difficult to determine how much enters the bloodstream and actually reaches the brain. There may also be other explanations for the feelings caused by chocolate and these may have nothing to do with cannabinoids, anandamide, or receptors. There are many other components in chocolate that may play a role in its popularity. Eating chocolate may be pleasurable because of a unique interaction among a few of its components.
Chocolate also contains phenylethylamine ( PEA), a chemical related to amphetamines. Like amphetamines, this chemical causes blood pressure and blood-sugar levels to rise, resulting in a feeling of alertness and contentment. Phenylethylamine has been called the “love-drug” because it quickens your pulse, as if you are in love. Caffeine in chocolate may also cause feelings of alertness and a pounding heart. Other stimulants in chocolate include Theobromine and Methylxanthines. These caffeine-relatives are weaker than caffeine-you’d have to eat more than 12 Hershey bars to get as much caffeine as there is in one cup of coffee. All of these stimulants increase the activity of neurotransmitters in the brain.
Anandamide, also known as N-arachidonoylethanolamine or AEA, is an essential fatty acid neurotransmitter derived from the non-oxidative metabolism of eicosatetraenoic acid (arachidonic acid) an essential ω-6 polyunsaturated fatty acid. The name is taken from the Sanskrit word ananda, which means “joy, bliss, delight”, and amide. It is synthesized from N-arachidonoyl phosphatidylethanolamine by multiple pathways. It is degraded primarily by the fatty acid amide hydrolase (FAAH) enzyme, which converts anandamide into ethanolamine and arachidonic acid. As such, inhibitors of FAAH lead to elevated anandamide levels and are being pursued for therapeutic use. Anandamide is also known as N-arachidonoylethanolamine or AEA, and is an endogenous analogue of tetrahydrocannabinol, or THC. Anandamide has an effect on both the CB₁ and CB₂ receptors; with the CB₁ receptors more affected in the central nervous system and the CB₂ receptors more affected in the periphery.
Chemical properties of anandamide
Anandamide belongs to a class of bioactive lipids known as fatty acid amides (FAAs). However, anandamide is also said to belong to the class of eicosanoids, a group of lipids derived from arachidonic acid and other essential fatty acids (EFAs). Anandamide is a large molecule made up of oxygen, hydrogen, nitrogen and carbon atoms, with the molecular formula C₂₂H₃₇NO₂ and a molar mass of 347.53 g/mol. As well as a hydroxyl group (an oxygen atom joined by covalent bond to a hydrogen atom), the anandamide molecule consists of a single nitrogen-hydrogen pairing and a hydrocarbon tail. The hydrocarbon tail of a molecule is hydrophobic but lipophilic, meaning that it is soluble in fat but does not dissolve in water. This hydrophobic property is common to all lipids and all known cannabinoids, which are lipidic in nature.
How the body produces anandamide
Anandamide is produced in the cell membranes and tissues of the body. In order to synthesise the molecule, the precursor molecule N-arachidonoyl phosphatidylethanolamine (NAPE) is needed. NAPE itself is made by the bonding of arachidonic acid (an omega-6 EFA) and a free amine through the action of the enzyme N-acyltransferase. Variations in dietary consumption of arachidonic acid can alter the levels of anandamide present in the brain. Anandamide is degraded by the fatty acid amide hydrolase (FAAH) enzyme, which converts the molecule back into arachidonic acid and ethanolamine, another amine. Due to its comparatively short half-life and high fat solubility, anandamide is considered a “fragile” molecule, and its effects are short-lived—unlike THC, which can remain in the fatty tissues for several weeks.
The effects of anandamide
Anandamide plays an important role in the regulation of appetite, pleasure and reward, and elevated levels may increase the pleasure experienced on consumption of food. Anandamide has been found in chocolate, and is thought to be partly responsible for the intense enjoyment experienced while eating it. Anandamide may also be partly responsible for pain regulation and sleep patterns. Anandamide also has an important and as yet poorly understood role in hormonal balance and the reproductive system. During ovulation, plasma levels of anandamide are at their highest, as are levels of the sex hormones gonadotrophin and estradiol (a type of estrogen). However, it is not clear exactly what relationship these substances have with each other. Anandamide is also vital in ensuring the healthy implantation of the young embryo into the epithelium (wall) of the uterus in early pregnancy.