Fraser Horton
Fraser Horton
Last Updated on June 7, 2021

In order to figure out how Cannabis Sativa affects our central nervous system, we must first understand cannabinoids and the role they play in our bodies. To do that, we have to look into how our nervous system works, which is also what Neuroscience focuses on studying. 

Basically, the main function of our nervous system is to transmit signals between different parts of the body by using specialized presynaptic cells – neurons. When our body needs to send a message to the nervous system from a particular neuron, it releases chemicals – neurotransmitters, that travel through the synapse – a neural junction, and attach themselves to a nearby neuron – a postsynaptic cell. The result of this action is the message that is passed along.

On the other hand, the endogenous cannabinoid system (EC) works backwards. After the activation of a postsynaptic neuron, cannabinoids that are made from the lipid cells are released from that cell, travel to the presynaptic neuron, and attach to the cannabinoid receptors. This way they decrease the amount of neurotransmitters, like dopamine, that get released which is how we feel the relaxation that comes from marijuana use.

So, let’s get into the receptors that are responsible for those effects and see where they are located in our bodies.

Cannabis and Its Main Cannabinoids THC and CBD

The main cannabinoids found in weed are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), and they both interact differently with the human body.

THC gives the psychoactive effects of cannabis, or as it’s commonly known, THC produces the “high” in users. The effects of THC may result in feelings of euphoria, relaxation, and amplified senses. Studies have shown that THC can affect the neurotransmitters norepinephrine and dopamine, and may also alter the levels of serotonin and Gamma aminobutyric acid (GABA).

CBD, on the other hand, is a non-psychoactive cannabinoid and provides therapeutic benefits to users without the high. Potential benefits of using CBD include anti-inflammatory responses in the body, pain and headache relief, and overall improved mood.

THC and Our Brain

Marijuana directly interacts with our central nervous system and this interaction isn’t limited to the psychoactive “high” and the sense of euphoria. This pleasurable “high” is a result of the presence of THC that acts through the cannabinoid receptors and stimulates the brain’s reward system in order to increase the levels of dopamine in the body. Given that THC has a similar chemical structure to the brain chemical anandamide, it can alter the amount of neurotransmitters that get released from neurons.  

THC affects the frontal lobe in the brain which is responsible for dopamine-sensitive neurons, but also short-term memory, motivation, and attention. But, marijuana users should be aware that overconsumption and long-term cannabis use may lead to a dysfunction in the frontal lobe, according to this study.

This cannabinoid alters the function of the hippocampus and the orbitofrontal cortex which are responsible for new memories and focus. It also disrupts the function of the cerebellum and basal ganglia which regulate balance, coordination, and reaction time, and that is the reason why you shouldn’t drive after smoking marijuana.

Effects of Cannabis on the Endocannabinoid System

The Endocannabinoid system (ECS) is made of cannabinoid receptors, endogenous cannabinoids (endocannabinoids – the cannabinoids that our body produces on its own), and the enzymes responsible for the synthesis and degradation of the endocannabinoids

Its primary function is to assist the body in maintaining homeostasis (balance) and it regulates the metabolism, intracellular communication, appetite, memory, as well as other functions.

ECS has two types of cannabinoid receptors – CB1 and CB2. Each receptor affects different systems in the ECS, and each consumed cannabinoid affects different receptors. The cannabinoid receptors are responsible for the effects of marijuana on our bodies and our central nervous system.

Where in the Nervous System Are the Cannabinoid Receptors That Marijuana Affects  

As cited in the article “CB1 and CB2 Receptor Pharmacology”, ”the CB1 and CB2 endocannabinoid receptors are members of the G protein-coupled receptor (GPCR) family that were identified over 20 years ago. CB1Rs and CB2Rs mediate the effects of delta-9-tetrahydrocannabinol (Δ9-THC), the principal psychoactive constituent of marijuana, and subsequently identified endogenous cannabinoids (endocannabinoids) anandamide and 2-arachidonoyl glycerol.”

The article Pharmacology of cannabinoid receptor ligands written in 1999, also dives into the subject of the body’s cannabinoid receptors and explains the existence of “cannabinoid receptor ligands that show marked sensitivity for CB1 and CB2 receptors that are found in mammalian tissues.”

CB1 Receptors

CB1 receptors are the receptors that are located for the most part in the brain and the spinal cord. In the brain, they’re located in the basal ganglia, the hippocampus, and very close to the brain – the cerebellum (little brain), but they’re also found in the reproductive organs. The cannabinoid that engages most with the CB1 receptors is THC and it provides psychoactive effects to users.

These receptors are also located in the amygdala which processes emotions and memories, and the hypothalamus which controls our appetite, so it’s pretty logical that marijuana affects appetite, emotions, and produces feelings of euphoria. 

On the other hand, CB1 receptors aren’t found in the medulla oblongata and the brain stem which are responsible for cardiovascular and respiratory functions in the body. That is probably the reason why there haven’t been any overdoses related to cannabis since it doesn’t affect these parts of the central nervous system, and is probably the reason why some people use marijuana in place of opioids.

The receptors help with:

  • Balancing the immune system;
  • Increasing appetite;
  • Inhibiting tumor growth;
  • Decreasing feelings of nausea;
  • Modulating stress and anxiety.

CB2 Receptors

These receptors are located in the peripheral nervous system and the immune system. You can find CB2 receptors in the tonsils, thymus gland, and the spleen, and they work as anti-inflammatory agents. 

The cannabinoid CBD is linked with the CB1 receptors and the reaction in immune and inflammatory processes in the body. As cannabis possesses anti-inflammatory properties, it’s most active for treating autoimmune diseases where the body’s immune system attacks the healthy cells. For example, CBD has been used in treatments for multiple sclerosis and Parkinson’s disease.

Effects of Marijuana on the Central Nervous System

When consumed, marijuana directly impacts the central nervous system through the endocannabinoid system. THC replicates the anandamide receptor system in the central nervous system which is responsible for balancing brain function.

A few ways that THC impacts the CNS include:

  • Inhibition of the enzyme adenylate cyclase which passively shuts down the A-type potassium channel (this is responsible for functions like regulating neurotransmitter release, smooth muscle contraction, insulin secretion, and others);
  • Suppression of calcium and sodium channels by replicating the anandamide receptor system, so it inhibits the release of neurotransmitters, L- glutamate, GABA, noradrenaline, 5-HT and acetylcholine;
  • Activation of mitogen-activated protein (MAP) kinase enzymes in the body which contributes to regular cellular activities like gene expression, cell proliferation, differentiation, and even the apoptotic pathway (which may help with the research concerning anti-tumor properties of the cannabinoids).

Effects of Marijuana on Neurological Symptoms

Certain neurological reactions are very common when cannabis is consumed.

  • Cannabinoids are strong anti-inflammatory agents, according to studies, which interact with the immune system to reduce inflammation, and they may even help with the treatment for neurodegenerative disorders like multiple sclerosis, Alzheimer’s disease, and Parkinson’s disease;
  • Cannabinoids relieve chronic pain and neuropathic pain due to the interaction with the spinal cord where they intercept and reduce the pain signals that go to the brain;
  • Cannabinoids reduce seizures in patients with epilepsy, according to this study, and they help reduce pain and spasms in patients with multiple sclerosis, which is researched in this study.

Final Thoughts on Cannabinoid Receptors and Marijuana 

We have figured out that cannabinoid receptors are present all throughout our bodies, and when activated, they help with regulating our appetite, pain-sensation, memory, and mood. These receptors are how our bodies process marijuana and affect the way our nervous system sends signals.

While marijuana may provide a number of health benefits, like the reduction of chronic pain and anti-inflammatory properties, you should be mindful when using it. When taking high doses, marijuana users may experience acute psychosis that can cause side effects like hallucinations, impaired memory, disorientation, and a loss of the sense of personal identity. Your best bet is to exercise caution, and if you do decide to try this plant, start with a low dose.

Disclaimer

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