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What is the Endocannabinoid system?

By Andrew Megahy • 11月 21, 2019 • 4 min

We’ve covered a wide range of topics in the blogs so far, but we’ve yet to touch upon the root of the entire CBD business: the Endocannabinoid System. This is going to a real chonker of a blog because there’s a lot to chew through regarding the ECS. There’s also going to be a small appendix of abbreviations at the end in case you need to refresh.

To begin with, we need to look at how the nervous system sends signals. Whenever your brain sends signals to the various parts of your body (for example, if you wanted to bend your knee, the brain sends a signal to your quad muscles that tells them to contract) these signals travel along your nerve cells via the help of neurotransmitters. Neurotransmitters are small chemicals your body produces to transfer the signal between two nerve cells. You can imagine them as a ferry, transferring a messenger from one bank of a river to the other. The more messengers you have to transport, the more ferries/neurotransmitters are required. And of course, the ferry has to dock somewhere. In the body, the docking points are the cell receptors. There are hundreds of known receptors and many more have yet to be studied (Dautzenberg & Hauger, 2002).

Now that we understand roughly how the nervous system sends signals, we can specifically look at the ECS. The ECS is composed of two specific receptors and their relevant neurotransmitters, and is present in both the central nervous system (CNS) and peripheral nervous system (PNS). The two receptors are known as CB1 and CB2, and their relevant neurotransmitters are called anandamide (AEA) and 2-arachidonoylglycerol (2-AG) respectively. These neurotransmitters are called endocannabinoids (‘endo’ meaning ‘within’, since these chemicals are produced in the body) and are where the name of the ECS comes from.

Some scientific papers describe the effects of these phytocannabinoids by not so much as replacing the body’s natural endocannabinoids, but rather that they ‘kickstart’ the production of them.

But how does the signalling actually occur? Well, the ECS is a bit of a novelty in that it was discovered in 1988 to be the first of these kinds of signalling systems that actually works backwards (Moore, 2018). Normally neurotransmitters are released from the upstream nerve cell (neuron) and received by the downstream neuron. But in the ECS the neurotransmitters travel backwards, against the flow of information, a process known as retrograde signalling. The importance of this in how the endocannabinoid system affects the human body is very interesting, but would unfortunately most likely need a full blog of its own. All that you need to know is: its status as a retrograde signalling system is what gives it so many of its effects on the human body.

Some scientific papers describe the effects of these phytocannabinoids by not so much as replacing the body’s natural endocannabinoids, but rather that they ‘kickstart’ the production of them.

So hopefully we now know how cell signalling works and how the ECS fits into this function of the nervous system. How then do extracts from the cannabis plant come into this jigsaw puzzle?

Currently there are ~113 phytocannabinoids that have been identified in the cannabis plant. Phytocannabinoids are so named because they originate in plants (‘phyto’ literally means ‘relating to plants’). Here we’re going to look at just the two “main” phytocannabinoids: CBD and THC. The reason we’re only interested in these two molecules is because, due to some very interesting evolution mechanics, CBD and THC are considered mimetic of 2-AG and AEA respectively. This means that they have the same pharmacological profile – CBD causes the same effects as 2-AG, and THC causes the same effects as AEA (Zou & Kumar, 2018). Some scientific papers describe the effects of these phytocannabinoids by not so much as replacing the body’s natural endocannabinoids, but rather that they ‘kickstart’ the production of them.

Some scientific papers describe the effects of these phytocannabinoids by not so much as replacing the body’s natural endocannabinoids, but rather that they ‘kickstart’ the production of them.

So hopefully we now know how cell signalling works and how the ECS fits into this function of the nervous system. How then do extracts from the cannabis plant come into this jigsaw puzzle?

To make matters even more confusing, there is mounting evidence as to the effects of phytocannabinoids on other signalling systems in the body. Many of the effects of CBD on aspects like anxiety, mood and sleep are thought to be a result of it affecting the 5-HT receptors in the serotonergic system (Russo et al. 2005, Yi P.L et al. 2008). Basically we can think of it as if CBD can catch a lift across the river from lots of different ferries, not just the ones for the ECS. There is constant research underway to identify what other signalling systems CBD and the other phytocannabinoids can affect.

So. Quite a complex topic. Hopefully after this we have a reasonable grasp on what a signalling system is, how the ECS works as a signalling system, and what effects the phytocannabinoids have on the ECS, as well as their impact on other systems. I could genuinely spend 3 or 4 pages going into depth on this topic but I have serious doubts anyone bar other scientists would read to the end. Cell signalling is one of the more complex topics in biology, so kudos if you’ve followed the whole thing.

Abbreviations:

ECS = Endocannabinoid System

CNS = Central Nervous System

PNS = Peripheral Nervous System

AEA = Anandamide

2-AG = 2-arachidonoylglycerol

CBD = Cannabidiol

THC = Tetrahydrocannabivarin