Cannabis, cannabinoid receptors and endocannabinoid system

Cannabis sativa, also popularly known as marijuana, has been cultivated and used for recreational and medicinal purposes for many centuries. The main psychoactive content in cannabis is Δ⁹-tetrahydrocannabinol (THC). In addition to plant Cannabis sativa, there are two classes of cannabinoids – the synthetic cannabinoids (e.g., WIN55212-2) and the endogenous cannabinoids (eCB), anandamide (ANA) and 2-arachidonoylglycerol (2-AG). The biological effects of cannabinoids are mainly mediated by two members of the G-protein coupled receptor family, cannabinoid receptors 1 (CB₁R) and 2 (CB₂R). The endocannabinoids, cannabinoid receptors and the enzymes/proteins responsible for their biosynthesis, degradation and re-updating constitute the endocannabinoid system. In recent decades, the endocannabinoid system has attracted considerable attention as a potential therapeutic target in numerous physiological conditions, such as energy balance, appetite stimulation, blood pressure, pain modulation, embryogenesis, nausea and vomiting control, memory, learning and immune response, as well as in pathological conditions suchlike Parkinson's disease, Huntington's disease, Alzheimer's disease, and multiple sclerosis. This special issue consists of 13 articles including original research or review articles, some authors of which are international recognized scientists in cannabinoid research field. Spanning from molecular to behavioral investigations, these articles involves different experimental techniques such as behavioral testing, neuronal imaging, computational simulation and other methods in molecular/cell biology, biophysics, electrophysiology and receptor pharmacology. Here we provide a broad perspective on current advances in cannabinoid studies, and hopefully this special issue will build a foundation for future developments in cannabinoid research.