GPR55: Is It the Third Cannabinoid Receptor?

GPR55 is an orphan receptor that responds to several cannabinoids, which is why some scientists have proposed calling it the third cannabinoid receptor, or CB3. It isn't officially recognized as one yet: it shares little structure with CB1 and CB2, and researchers are still debating how it fits into the endocannabinoid system. What we do know is that CBD appears to block it, which may be part of how CBD works.

The endocannabinoid system: a balancing act

The endocannabinoid system (ECS) is a complex biological network that plays a key role in regulating a wide range of physiological functions in the human body. It's made up of three main parts: cannabinoid receptors, signaling molecules (endocannabinoids) and the enzymes that build and break them down.

Cannabinoid receptors have traditionally been split into two types: CB1 and CB2. They're found throughout the body and switch on when ECS signaling molecules like anandamide and 2-arachidonoylglycerol (2-AG) bind to them. Together, these parts help maintain homeostasis, the body's state of internal balance.

Is GPR55 the third cannabinoid receptor?

CB1 and CB2 have gotten most of the attention in ECS research, but interest in GPR55 keeps growing. This G protein-coupled receptor (GPCR), a type of receptor that relays signals from outside the cell to the inside, shows up in many parts of the body, including the central nervous system, cancer cells and other tissues.

One curious thing about GPR55 is how little genetic homology it has with CB1 and CB2. In other words, it shares only a small slice of their genetic structure. Even so, because several cannabinoids act on it, some scientists have floated the idea that GPR55 could be considered a third cannabinoid receptor, or CB3.

How does CBD interact with GPR55?

One of the best-known cannabinoids is cannabidiol (CBD), which has earned a reputation for its potential health benefits, including pain relief. Research shows CBD also interacts with GPR55, though in a different way than it does with CB1 and CB2.

CBD doesn't switch GPR55 on. Instead, it appears to act as an antagonist, meaning it temporarily blocks the chemical signals that can make neurons more excitable through this receptor. That property may contribute to CBD's potential to ease pain and inflammation in the body.

What's next for CB3 and other receptors?

As our understanding of the ECS and how cannabinoids interact with it grows, more details are emerging about other possible receptors, like GPR18 and GPR119. Researchers are also studying these to pin down what they do and whether they qualify as cannabinoid receptors.

It's worth stressing that research on the ECS and cannabinoid receptors is still a developing field. As more studies come in, scientists may discover more receptors and get a clearer picture of how cannabinoids affect human biology.

GPR55 as a possible third cannabinoid receptor

The idea of a third cannabinoid receptor like GPR55 is still under active research and scientific debate, but its discovery offers an exciting glimpse into how complex the endocannabinoid system really is. As we learn more about how cannabinoids interact with these receptors, new opportunities could open up for cannabinoid-based therapies.

Science moves fast, and the study of cannabinoids and the ECS remains an exciting frontier, both for understanding human biology and for possible medical applications. As researchers keep unraveling how these systems work, it pays to stay on top of the latest findings in this fascinating field.

Comparing cannabinoids

These compounds have their differences, but they all have one thing in common: they're all cannabinoids. So what exactly is a cannabinoid?

Put simply, cannabinoids are the natural compounds found in the resin glands (trichomes) of cannabis plants. They're best known for a wide range of potential therapeutic and medicinal effects.

Cannabinoids work by interacting with the human endocannabinoid system, which may help with pain, anxiety, seizures and nausea. Research also points to anti-inflammatory effects and possible benefits for skin conditions like eczema and rashes.

Each cannabinoid has its own properties and potential benefits, but they can also work together synergistically, an idea often called the entourage effect.

What's the difference between CBD, CBG and CBN?

CBD

Alongside tetrahydrocannabinol (THC), cannabidiol (CBD) is the most popular cannabinoid, mostly because there's so much of it in the cannabis plant. In hemp specifically, it's the most abundant cannabinoid.

CBD is also popular because it's widely used for pain and inflammation without the psychoactive effects of THC. As a result, it's generally considered "safer" to consume. It's also the cheapest cannabinoid to extract and produce legally, which makes it a popular commercial choice.

In fact, CBD proved effective enough at reducing certain types of seizures that the US Food and Drug Administration (FDA) approved a CBD-based prescription drug, Epidiolex.

CBD is available as tinctures, gummies, capsules, topicals and more. It's most often used for inflammation, sleep, anxiety, seizures and spasms, addiction and pain.

CBN

Despite CBD's popularity, cannabinol (CBN) was actually the first cannabinoid to be identified, with its structure worked out in the 1930s. The plant doesn't make it directly: it forms as THC breaks down over time or with exposure to heat or oxygen. It has some intoxicating effects, but some research suggests CBN is only about a quarter as potent as THC.

CBN is often used for inflammation, pain relief and better sleep, and early research has looked at its potential to stimulate bone growth.

CBG

Cannabigerol (CBG) comes from its acidic precursor, cannabigerolic acid (CBGA), known as the "mother of all cannabinoids." All the cannabinoids we covered above start out as CBGA, which the plant converts into other cannabinoid acids that later break down with light and heat.

CBG is rare: most cannabis contains less than 1% of it. That's why it takes a delicate extraction process, which makes it valuable and expensive. Some hemp breeders are working on varieties that naturally hold high levels of CBGA without converting it into other compounds. It's still early days, but the results so far look promising.

Potential benefits of CBG under study include supporting the skin's microbiome, pain relief and muscle relaxation, plus anti-inflammatory, anti-anxiety and antidepressant properties. It's also being researched for glaucoma, has shown neuroprotective and antibacterial properties in lab studies, and may stimulate appetite in patients with HIV or eating disorders.

CBD and these other cannabinoids keep gaining ground, but it's important to get informed and talk to a health professional before using any of them. Cannabinoid wellness products don't work just because they contain a certain compound. They need to be properly formulated, made with high-quality ingredients and designed for a specific purpose.