Cannabinoid receptors are part of our bodies’ central nervous system and help mediate many effects of cannabinoids and endocannabinoids. They can be found in two forms: the cannabinoid 1 and cannabinoid 2 receptors, each of which mediates different functions. This article will look at what role cannabinoid receptors play in the central nervous system and what functions they have an impact on.
What are Cannabinoid Receptors?
Cannabinoid receptors are part of the endocannabinoid system and have an important role in many physiological and pathophysiological functions in our bodies. They are G-protein coupled receptors that are located throughout the body, including the central nervous system (CNS), peripheral nervous systems, and peripheral tissues. The receptors are divided into two classes: cannabinoid receptors 1 (CB1R) and 2 (CB2R). CB1R is the most prominent of the two because of its high expression levels in the CNS (1) and its importance in brain function activities.
How are Cannabinoid Receptors and Cannabis Related?
Three main groups can activate cannabinoid receptors in the body. They are groups of ligands known as endocannabinoids, plant cannabinoids and synthetic cannabinoids. The link between cannabis and the cannabinoid receptors is strong because of a plant cannabinoid named Δ9-tetrahydrocannabinol (Δ9-THC or THC). It is the active ingredient in cannabis and binds to the CB1 receptor, and the receptor manages the effects of THC on the body (2).
However, it is important to note that with or without cannabis, these components, such as endocannabinoids and cannabinoid receptors, will still function and play a role in the body’s regulation of appetite, memory, mood, sleep and monitor the side effects of substances such as THC. The connection between THC and the endocannabinoid system (ECS) is that THC binds to both CB1 and CB2 receptors and can impact a range of psychoactive effects on the brain and body (3). In the following section, we will look at what functions are managed by cannabinoid receptors and how this affects us.
What is the Function of Cannabinoid Receptors?
The cannabinoid receptors are responsible for various functions, such as how we feel pain, certain immune activities and regulating our moods. When cannabinoid receptors are activated by endocannabinoids, or agonists like tetrahydrocannabinol (THC), they regulate our bodily functions by sending signals to other neurotransmitters. These receptors can control the levels and the activities of neurotransmitters and make adjustments based on what is needed, such as alertness or hunger (2).
Fig.n.1: Agonist activation of a neuronal CB receptors and consequent downstream effects (4).
CB1 Receptors
The CB1 receptors are found in high levels in several parts of the brain but can also be found in lower levels on peripheral nerves and places like the eye, liver and spleen (1). The primary function of CB1 receptors is to manage the psychoactive effects of cannabinoids and play a part in addiction processes, alcohol and drug dependence, and CNS diseases such as bipolar, depression and anxiety disorders (5).
Additionally, CB1 receptors regulate processes such as:
- Hunger and feeding behavior
- Inflammation
- Memory
- Pain
CB2 Receptors
CB2 receptors are mainly found on nonneural cells and their primary function is to manage our immune system. These receptors control active inflammation and are often used to manage neurodegenerative conditions and other prevalent illnesses in which pain is prevalent (6).
The key function of CB2 receptors include:
- Managing inflammation
- Managing pain
- Regulating immune responses
- Used in therapeutic treatments for certain cancers, diseases and other illnesses (7).
To summarize the key functions of cannabinoid receptors in the central nervous system, they are crucial to regulating a range of roles in our bodies. These roles range from appetite and mood regulation to managing inflammation and pain. They are vital to the functioning of the immune system. Human peripheral blood immune cells are reported to have different degrees of cannabinoid receptor expression with the following rank order: B cells > NK cells > monocytes > polymorphonuclear neutrophils > CD8 lymphocytes > CD4 lymphocytes (8). The CB1 receptors are densely expressed in the central nervous system and mediate neurobehavioral effects. The expression levels of CB2 receptors in immune cells are 10–100 times greater than CB1 receptors. They are used to treat the symptoms and side effects of many diseases because of their anti-inflammatory and pain management properties.
Celtarys and Cannabinoid Receptors
Celtarys has developed a range of technologies that can be used to bind receptors and activate their functions. This is a key step in understanding the properties of how THC, CBD and other compounds interact with the cannabinoid receptors and what role they have in the human body.
We supply two fluorescent ligands for cannabinoid receptors, the CELT-335 hCB1/CB2 and CELT-331 hCB2, that will bind with CB1 and CB2 receptors. These ligands allow scientists to analyze cells via fluorescence microscopy and further investigate cannabinoid receptors, their role, and what advantages this has for treatments and therapies.
For more information on cannabinoid receptors, ligands, or their applications, contact us today and we’ll be happy to answer any questions you have.
References
- Kendall, D. A., & Yudowski, G. A. (2017). Cannabinoid receptors in the central nervous system: their signaling and roles in disease. Frontiers in cellular neuroscience, 294.
- Zimmer, A., Zimmer, A. M., Hohmann, A. G., Herkenham, M., & Bonner, T. I. (1999). Increased mortality, hypoactivity, and hypoalgesia in cannabinoid CB1 receptor knockout mice. Proceedings of the National Academy of Sciences, 96(10), 5780-5785.
- Vučković, S., Srebro, D., Vujović, K. S., Vučetić, Č., & Prostran, M. (2018). Cannabinoids and pain: new insights from old molecules. Frontiers in pharmacology, 9, 1259.
- Bow, E. W., & Rimoldi, J. M. (2016). The structure–function relationships of classical cannabinoids: CB1/CB2 modulation. Perspectives in medicinal chemistry, 8, PMC-S32171.
- Leweke, F. M., & Koethe, D. (2008). Cannabis and psychiatric disorders: it is not only addiction. Addiction biology, 13(2), 264-275.
- Bie, B., Wu, J., Foss, J. F., & Naguib, M. (2018). An overview of the cannabinoid type 2 (CB2) receptor system and its therapeutic potential. Current opinion in anaesthesiology, 31(4), 407.
- Mandal, A. (2019) Cannabinoid Receptors. News Medical Life Sciences.
- Galiègue, S., Mary, S., Marchand, J., Dussossoy, D., Carrière, D., Carayon, P., ... & Casellas, P. (1995). Expression of central and peripheral cannabinoid receptors in human immune tissues and leukocyte subpopulations. European journal of biochemistry, 232(1), 54-61.