The Endocannibinoid System:Inside all mammals is an intricate network of receptors that play important roles in health, healing, and homeostasis. The endocannabinoid system (ECS) was discovered in the early 1990s, but evolutionary evidence indicates that some version of an ECS has been preserved in all vertebrates (as well as sea squirts and nematodes) for at least 600 million years, suggesting that these receptors and the substances that bind to them play a crucial role in the functioning of life. Â There are three main receptors associated with the ECS: CB1, CB2, and TRPV1. According to Raphael Mechoulam, the chemist who first isolated THC in the 1960s, these receptors are most abundant in the brain and they are not found everywhere â they persist in specific areas that are involved in important bodily processes like coordination & movement, emotions, memory, reduction of pain, and reproduction. Â CB1 was discovered in 1990 and is cited as one of the most common receptors found in the brain, again a testament to this systemâs key role in neurological processes. CB2 was the second receptor to be discovered. It is largely found in immune cells, although it can be found in other parts of the body including the digestive system and peripheral nervous system. TRPV1 is involved in pain response, inflammation, and regulation of body temperature. It is known as the attachment site for capsaicin â the compound responsible for the burning sensation we associate with chili peppers. The receptors mentioned above are nothing without the substances that attach to and activate them â the endogenous cannabinoids that our bodies produce. The most studied of these endocannabinoids are AEA (nicknamed anandamide after the Sanskrit word for âblissâ) and 2-AG. Both can attach to CB1 and CB2, although AEA prefers CB1 and 2-AG prefers CB2. Dustin Sulak, an Osteopath who uses cannabis in his practice, describes these endocannabinoids as keys that open the same locks (receptors). Depending on which keys are used, the locks will open to different doors. This system, which is responsible for maintaining various bodily processes, can become imbalanced in various ways: receptors can be over or under active and endocannabinoid levels can be too low or too high. Itâs interesting to note that in individuals with some cancers like breast, gliomas, and lymphomas, cells tend to have more CB1 and CB2 receptors. Some researchers think that this phenomenon is part of the bodyâs effort to fix the disorder. Â As research into this system continues, scientists are looking into the relationship between the ECS and certain diseases. The following table taken from a review article about the ECS lists various conditions in humans and their associated effects on the ECS:Â http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3684164/ If the ECS is imbalanced, what can be done to bring it back to normal? Medications, alternative therapies, supplements, and life-style choices can all influence an individualâs ECS. In animal studies, certain opiates and steroids enhanced endocannabinoid activity. In mice & rats, supplements and alternative therapies have been shown to influence the ECS: probiotics modulated CB1 activity and acupuncture increased CB2 activity in skin tissues. Intense exercise has been found to increase AEA levels in both dogs and humans â scientists think that this may account for the ârunnerâs highâ that is apparent after heavy exercise. Â This idea of supplementing a troubled ECS brings us to the elephant in the room: cannabis and the phytocannabinoids that are found so abundantly in this plant.
What is CBD?Phytocannabinoids are substances found in plants (most notably in Cannabis sativa) that are able to stimulate the same ECS receptors mentioned previously. There are at least 113 known phytocannabinoids in the cannabis plant; the most well-known and studied of these phytocannabinoids is THC but in recent years, this moleculeâs non-psychoactive counterpart, CBD, has received much media attention. Â CBD or cannabidiol was first isolated in 1963 by Raphael Mechoulam â one year before the chemist elucidated the structure of THC. Â Both substances can modulate the ECS, but CBD does not alter the mind or behavior in the same way THC does. THC attaches directly to CB1 and CB2, much like the endocannabinoids AEA and 2-AG. CBDâs effects are achieved in a different manner: the molecule affects these receptors, but not by directly attaching to them in the same way as THC and AEA. Newer research indicates that CBD does attach to CB1âjust not at the same receptor site as THC or AEA. By attaching to a different area, it is thought that CBD can change the shape of the receptor and thus influence how this receptor will interact with the other substances that bind to it. Â CBD can also influence the ECS in other ways: it can suppress the enzyme that breaks down AEA, thereby prolonging the endocannabinoidâs effects. It can also directly attach to TRPV1 and other receptors that play roles in the cardiovascular and neurological systems. CBDâs ability to influence the ECS may account for the historical and anecdotal evidence that suggests its positive role in a number of conditions including: Dravetâs syndrome, some cancers, and various types of pain. Â In pre-clinical studies involving animal models, CBD has been shown to have the following properties: anti-inflammatory, antioxidant, anti-nausea, anticonvulsant, anti-anxiety and neuroprotective. CBD is also anti-proliferative in regards to certain cancer cells.
Hemp and Marijuana: What's the difference?Hemp and marijuana are both derived from the same plant species:Â Cannabis sativa.Â Â Within C. sativa are many plant varieties that are bred for various purposes.Â Plants grown to produce fiber and seed products are called âhempâ and plants grown for medicinal or recreational purposes (traditionally, a high THC content) are referred to as âmarijuana.âÂ These definitions have let to the conventional notion that marijuana products are high in THC while hemp products contain little or no THC and are high in CBD.Â As the cannabis industry continues to grow and research attempts to further elucidate genetic differences between cannabis and hemp, this terminology and how we classify cannabis plants could (and should) change. For policymakers, a limited and often misinformed knowledge in cannabis genetics makes differentiating hemp and marijuana a difficult and superficial task.Â In the 1970âs Canadian scientist Ernest Small published a taxonomic report in which he drew an arbitrary line: he decided that 0.3% THC in a sifted batch of cannabis flowers was what determined the difference between hemp and marijuana.Â This decision, written 30 years ago in obscurity has had far reaching ramifications for how countries all over the world regulate cannabis.Â In the US, any cannabis plant with a THC content higher than 0.3% is deemed marijuana and therefore federally illegal.Â
Cannabidiol, Canines, and Anecdotal Evidence:In 1991, Harvey et al. compared the metabolism of CBD in rats, dogs, and humans (1). While they did find that CBD is metabolized differently among these animals, they concluded that overall, the way these animals metabolized the CBD showed the same trends.Â The human and canine CBD metabolic process may vary, but this has not stopped pet owners from using hemp products in an attempt to combat the symptoms and diseases that both species seem to share. In the spring of 2016, the American Veterinary Medical Association (AVMA) published a study that investigated the growing trend of pet owners who use hemp products on their pets. What they found suggests that some pet owners believe that hemp products help alleviate numerous conditions with minimal side effects. The authors of this study conducted a survey of visitors to one hemp product company website for one month in 2015.Â Of the 631 respondents who said they use hemp products on their dogs, the majority indicated that they use them for conditions diagnosed by their veterinarian, with the most common being cancer, seizures, anxiety, and arthritis. They also reported that these products were moderate to very helpful in improving their petâs well-being and that they had a positive impact in relieving pain and anxiety, as well as helping with sleep. Side effects reported were minimal: sedation and over-active appetite. Overall, owners seem to be using hemp because they either prefer ânatural productsâ and want to supplement conventional therapies.Â While this study group was limited and subject to the biases of each individual pet owner, the findings bring to light some interesting trends and reinforce much of the anecdotal evidence reported by media outlets of cannabisâ ability to mitigate certain disorders.
Resources and Links:Medical Marijuana & CBD:
- Comprehensive Resource on CBD
- Dr. Sanjay Guptaâs CNN Special on Medical Marijuan Titled âWeedâ
- WebMD:Â Medical Marijuana: What the Research Shows
- National Cancer Institute on Cannabis & Cannabinoids
- Book: Â Cannabis and CBD Science for Dogs
- Book: Â Pot for Pets
- Dr Becker Interview With Cannabis Expert, Dr. Rob Silver
- Dr. Rob Silverâs website on cannabis for pets
- BARk Magazine Article: Medical Cannabis: Is It Good for Our Dogs 9.2015
- Bay Woof Article: Medical Marijuana for Pets by Dr. Gary Richter
- Dogs Naturally Magazine Article: Cannabis for Your Dog
- NY Times Article:Â Pets on Pot
- Cannabis for Intractable Epilepsy by Dr. Narda Robinson