The endocannabinoid system (ECS)
The endocannabinoid system (ECS) is a complex regulatory network in our body that plays a key role in maintaining our internal balance (homeostasis). Its components consist of endogenous cannabinoid signals and the receptors that recognise them. It regulates numerous physiological processes, such as metabolism, the immune response, pain perception, hormonal responses, as well as emotions and behaviour. Below we present the main components of the ECS and its role in regulating individual processes.
The most important parts of the endocannabinoid system are:
CB1 receptor: A cannabinoid receptor found mainly in the nervous system (central nervous system). Its role is to regulate signal transmission and to influence processes responsible for, for example, memory, mood and motor coordination. CB1 is also responsible for the psychoactive effects of cannabis, as THC binds to it.
CB2 receptor: Found in the largest quantities on the surface of immune cells (e.g. blood cells, spleen). It is mainly involved in regulating the immune response and inflammation. Activation of CB2 can dampen inflammatory processes and contributes to the body's defence responses.
Anandamide (AEA): The first endogenous cannabinoid to be discovered. It is the body's own “internal marijuana-like” molecule, which activates both CB1 and CB2 receptors. Anandamide is synthesised and broken down by certain enzymes of nerve and immune cells.
2-Arachidonoylglycerol (2-AG): The other main endocannabinoid, which also binds to CB1 and CB2 receptors as a signalling molecule. 2-AG is found primarily in the nervous system and may play a role in, among other things, the stress response and appetite regulation.
In addition, the formation and breakdown of endocannabinoid signals are regulated by various enzymes (e.g. FAAH for the breakdown of anandamide and MAGL for the breakdown of 2-AG).
Homeostasis and general regulatory role
One of the main tasks of the ECS is homeostasis, i.e. maintaining the balance of the internal environment. This means that the system strives to balance the body's internal processes in response to changes in the environment. For example, the ECS intervenes when the body is affected by injury, stress or infection – it then helps the body adapt by immediately modifying signal transmission. In this way, the ECS regulates, among other things, food intake, fat storage and appetite, the immune response, and the various neurotransmitter networks of the nervous system. All in all, the endocannabinoid system provides network-level regulation responsible for the body's internal balance, which is part of nervous, hormonal and immune regulation at the same time.
Stress responses
The ECS also plays an important role in modulating stress responses. The stress hormones produced by the hypothalamic–pituitary–adrenal (HPA) axis, which is activated by stress, are inhibited by CB1 receptor activity. Specifically, the CB1 receptor reduces the release of corticotropin-releasing hormone (CRH) in the hypothalamus and moderates the release of ACTH and cortisol via the pituitary gland and the adrenal glands. Through a feedback mechanism, this prevents excessive activation of the HPA axis in chronic stress. In the short term, the ECS thus dampens the stress response, while in the longer term, chronic stress can weaken CB1 receptor signalling (which is associated with anxiety states).
Anxiety and mood
The endocannabinoid system is also significant in regulating anxiety and mood. CB1 receptors are particularly abundant in emotional brain areas (e.g. the amygdala and hippocampus), where they influence neural signal transmission. According to preliminary research, enhancing the ECS (e.g. by blocking the enzymes that break down anandamide) may result in anxiety-reducing (anxiolytic) and mood-improving (antidepressant) effects. In contrast, inhibition or absence of the CB1 receptor causes anxiety and depression-like symptoms[6]. In summary, the ECS has a balancing, calming effect on emotional states: it increases stress tolerance and may reduce anxiety, thereby contributing to mood stabilisation.
Sleep and circadian rhythm
The ECS also influences the sleep–wake cycle and the circadian rhythm in general. Experimental data suggest that activation of cannabinoid receptors may promote falling asleep and improve sleep quality. In fact, the daily fluctuation of endocannabinoid levels is linked to waking and sleeping states: for example, anandamide concentration is higher in the morning and lower before bedtime (sleep deprivation can disrupt this rhythm). Activation of CB1 has a calming effect on the central nervous system, which can support more restful sleep and alertness after waking. Overall, the balance of the ECS is therefore important for maintaining a healthy sleep rhythm.
Immune system and inflammation
The ECS also regulates inflammatory and immune processes, mainly through the CB2 receptor. CB2 receptors are found on various immune cells (e.g. macrophages, lymphocytes), and by activating them the ECS can inhibit excessive inflammatory responses. CB2-mediated signalling reduces the production of inflammatory cytokines and restrains the movement of immune cells, thereby making the immune response more regulated. (The CB1 receptor is also present on some immune cells, but it is CB2 that is most associated with immunomodulation.) The ECS therefore plays a role in the body's defence: it is activated when needed (e.g. in case of injury or infection) and helps prevent the development of chronic inflammation.
Pain relief
The endocannabinoid system also has a pain-relieving effect. CB1 receptors are located at key nodes of the pain-sensing pathway, where they inhibit the transmission of both somatosensory (physical) pain and the emotional component of pain[8]. At the same time, CB2 receptors regulate immune and glial cells (e.g. microglia) in the central nervous system and the periphery; in chronic pain, increased CB2 activity may reduce inflammation and pain transmission. Based on experimental results, interventions targeting both CB1 and CB2 can moderate pain perception in various acute and chronic pain models. In this way, the ECS naturally helps endogenous pain relief and also has potential applications in pain therapy.
Metabolism and appetite
The ECS also influences the body's energy balance, appetite and metabolism. Activation of the CB1 receptor, for example, stimulates appetite and food intake, and increases fat deposition and insulin levels[9]. According to clinical observations, increased ECS activity and elevated endocannabinoid levels often occur in obese people, and overactivity of CB1 receptors is associated with increased appetite and weight gain. Endocannabinoids can also enhance the perception of the taste and smell of food, so the ECS can act as a strong appetite-increasing signal. Overall, the ECS maintains the balance between nutrient intake and energy expenditure, and intervention may influence the regulation of appetite and metabolism.
Sources: According to scientific review articles, the ECS plays a leading role in
regulating the processes mentioned.
[1] The Role of Endocannabinoids in Physiological Processes and Disease Pathology: A Comprehensive Review
https://www.mdpi.com/2077-0383/14/8/2851
[2] [3] [4] The CB2 Receptor in Immune Regulation and Disease: Genetic Architecture, Epigenetic Control, and
Emerging Therapeutic Strategies | MDPI
https://www.mdpi.com/2673-8856/5/4/59
[5] The endocannabinoid system in modulating fear, anxiety, and stress
– PMC
https://pmc.ncbi.nlm.nih.gov/articles/PMC7605023/
[6] Role of Endocannabinoid Signaling in Anxiety and Depression – PMC
https://pmc.ncbi.nlm.nih.gov/articles/PMC3808114/
[7] Endocannabinoid signalling: has it got rhythm? – PMC
https://pmc.ncbi.nlm.nih.gov/articles/PMC2931554/
[8] Frontiers | Cannabinoids in Chronic Pain: Therapeutic Potential Through Microglia Modulation
https://www.frontiersin.org/journals/neural-circuits/articles/10.3389/fncir.2021.816747/full
[9] The endocannabinoid system in appetite regulation and treatment of obesity – PMC
https://pmc.ncbi.nlm.nih.gov/articles/PMC11409765/
