What Is The Endo Cannabinoid System?
Endo Cannabinoid System
The endogenous cannabinoid system, named after the plant that led to its discovery, is perhaps the most important physiologic system involved in establishing and maintaining human health. Endocannabinoids and their receptors are found throughout the body: in the brain, organs, connective tissues, glands, and immune cells. In each tissue, the cannabinoid system performs different tasks, but the goal is always the same: homeostasis, the maintenance of a stable internal environment despite fluctuations in the external environment.
Cannabinoids promote homeostasis at every level of biological life, from the sub-cellular, to the organism, and perhaps to the community and beyond. Here's one example: autophagy, a process in which a cell sequesters part of its contents to be self-digested and recycled, is mediated by the cannabinoid system. While this process keeps normal cells alive, allowing them to maintain a balance between the synthesis, degradation, and subsequent recycling of cellular products, it has a deadly effect on malignant tumor cells, causing them to consume themselves in a programmed cellular suicide. The death of cancer cells, of course, promotes homeostasis and survival at the level of the entire organism.
The two main receptors that form the endocannabinoid system are the CB1 and CB2 cannabinois receptors. It has been accepted recently that the orphan receptor GPR55 can be considered as the third receptor for cannabinoid activity. All these receptors are transmembrane proteins capable of sending out a an extracellular signal into the interior of a cell.
CB1 receptors are metabotropic receptors expressed most abundantly in the brain and their distribution has been widely characterised in humans. CB1 receptors are highly expressed in the hippocampus, basal ganglia, cortex and cerebellum.They are less expressed in the amygdala, hypothalamus, nucleus accumbens, thalamus, periapeduncular grey matter and the spinal cord, as well as in other brain areas, mainly in the telencephalon and diencephalum. CB1 receptors are also expressed in several peripheral organs. Thus, they are present in adipocytes, liver, lungs, smooth muscle, gastrointestinal tract, pancreatic ß -cells, vascular endothelium, reproductive organs, immune system, sensorial peripheral nerves and sympathetic nerves.
The distribution of CB2 receptors is quite different and mainly restricted to the periphery in the immune system cells, such as macrophages, neutrophils, monocytes, B-lymphocytes, T-lymphocytes and microglial cells. Recently, CB2 receptor expression has also been shown in skin nerve fibres and keratinocytes, bone cells such as osteoblasts, osteocytes and osteoclasts, liver and somatostatin secreting cells in the pancreas. The presence of CB2 receptors has also been demonstrated at the CNS, in astrocytes, microglial cells and brainstem neurons. There is evidence of staining with the CB2 antibody of human neurons. The presence of functional CB2 receptors is still debated. Recent evidences suggest that the CB2 receptor mediates emotional behaviours, such as schizophrenia, anxiety, depression, memory and nociception, supporting the presence of neuronal CB2 receptors or the involvement of glial cells in emotional behaviours.
Our body is an independent entity capable of receiving certain information from the outside world through the senses and then interpreting and elaborating on it in the brain, to finally allow the rest of our body to interact with such data. This arrangement allows our body to meet needs such as feeding or reproduction, in addition to being aware of both its own self and the outside world. Something much more complex to understand, is the fact that our body is formed by a colony of millions of cells. Each cell is independent, has its individual needs for energy sources and has its own biochemical process to obtain it. These cells are organised according to their function and structural diversity, thus building the different organs. Each organ plays an specific function in the human body in order to keep the whole organism alive. The organ in charge of keeping and controlling the different organ functioning, as well as processing the outside stimuli, is the brain.
We could say that the Endocannabinoid system is a intercellular communication system. It basically is a neurotransmission system, although it is much more than that, as it can also be found in other organs and body tissues than the brain. The endocannabinoid system seems to be the enhanced version of an ancestral intercellular communication system found in plants too; the arachidonic acid system. In fact, the Endocannabinoids' nature is directly related to arachidonic acid.
Arachidonic acid is an omega-6 fatty acid that participates in the signalling processes of plants and animals. It regulates the defences against infections and the signalling of stress in plants. It also controls animal muscle growth, platelet cumpling, vasodilatation and inflammation.