Cannabis is well known as a herbal painkiller, but is also increasingly being used in other conditions involving the limbic system, sometimes referred to as the mid or so-called reptilian brain. So, just how does Cannabis cause these effects? Cannabis contains over 500 compounds, 80 of which are cannabinoids. Many of these compounds have medicinal value and research continues to provide more knowledge about how they work. The medicinal effects of Cannabis are mediated by the Endocannabinoid System (ECS). The system includes two neurotransmitters (anandamide and 2AG) two receptors (CB1 and CB2) and two enzymes (MAGL and FAAH). The ECS is responsible for modulating neurotransmission and cannabinoids regulate the ECS. There are two types of cannabinoids, those produced by the human body, endogenous cannabinoids, and those sourced from the Cannabis plant, the phytocannabinoids. An increase in cannabinoids, either endogenous or phyto, increases the amount of the neurotransmitter dopamine to the brain.
Cannabinoids work differently to any other neurotransmitter. Instead of stimulating the next neuron on the pathway up the central nervous system, endocannabinoids actually double back to the presynaptic neuron from the post synaptic neuron they just stimulated and de-polarise the pre-synaptic neuron. This is referred to as retrograde inhibition. This depolarisation of the pre-synaptic neuron occurs by causing release of dopamine, which reverses the concentration of sodium and potassium inside and outside the cell. This depolarisation makes it harder for the pre-synaptic neuron to be stimulated by the next neural impulse being transmitted by the nervous system. The effect of this is a slowing down of neurotransmission which is ideal in pain management and control.
Migraines are caused by an overload of the electrical circuits in a certain part of the brain, so slowing down the speed of neurotransmission leads to fewer neural impulses. This in turn decreases the likelihood or severity of a migraine. That is not the only effect, Cannabis is an anti-nauseant as well, but probably exerts that effect in some other manner. The same thing is true of people who have panic attacks, if the negative thoughts are moving to the brain at warp speed, the limbic system (emotional control centre of the brain), is overwhelmed and there is little or no time for the frontal cortex to override the more primitive mid or reptilian brain. This makes us more likely to act before we think. That is because the reptilian brain sees things in terms of black and white, life and death. This mechanism may have served our ancestors well in the time of sabre-toothed tigers, but in modern day it is more often not very helpful. Much in modern life is shades of grey and more nuanced than life and death.
Cannabis slows down the speed of neurotransmission, exposing the cerebral cortex to fewer slower moving neural stimuli. This allows the higher centres of the brain to more rationally assess relative danger or the negativity and put a more rational point of view on that sensory input, often taking the edge off anxiety or preventing a panic attack. In medical school, doctors are taught 70% of the brain exists to turn off the other 30%. Dopamine is one of the “off switches” that helps modulate sensory input. One suggestion is that Cannabis and cannabinoids increase the amount of free dopamine in the brain by preventing the dopamine from binding to another neurochemical dopamine transporter. The transporter and dopamine form an electrochemical bond that ties up the dopamine so that it is not free to act as an “off switch”. These cannabinoids replace the dopamine and the amount of free dopamine available to depolarise the presynaptic neuron also increases.
And that’s just pain and anxiety. There are a host of conditions that appear to be tied to an endocannabinoid deficiency syndrome that has been postulated by such scientists as pharmacologist Danielle Piomelli, PhD and neurologist, Ethan Russo, MD. The possible cause of an endocannabinoid deficiency syndrome is most likely genetic and due to the fact that most, if not all, human characteristics are distributed on a bell shaped curve – some of us have less of the constituents of the ECS and some have more. It is not clear that is the explanation or the only explanation for Clinical Endocannabinoid Deficiency (CECD), however, if there is a lower amount of free dopamine present in the brain, neural impulses will likely move more rapidly.
This mechanism of slowing the speed of neurotransmission, retrograde inhibition, contributes to the treatment of many conditions that respond to cannabinoids and Cannabis. Cannabinoids compete with dopamine for the binding sites on the dopamine transporter, and in sufficient quantity they win, which frees up more dopamine to slow down the speed of neurotransmissions. This, according to many cannabinoid researchers, is responsible for much of the therapeutic value of Cannabis in such conditions as migraines, seizure disorder, ADD, ADHD, Crohn’s disease, Irritable Bowel Syndrome (IBS), Social Anxiety and Autism Spectrum Disorder, to name some of the more obvious.