Anandamide: Anandamide (or arachidonyl-ethanolamide) is an endocannabinoid or endogenous ligand to the cannabinoid receptor. It was the first to be discovered, in 1992. Cannabinoids: The term "cannabinoid" has different meanings. In a more narrow sense, it designates the natural cannabinoids of the cannabis plant. In the broadest sense, it includes all chemicals that bind to the cannabinoid receptors and related compounds. The endogenous ligands of the cannabinoid receptors have been termed endocannabinoids. Cannabinoid Receptors: Several cells in the brain and other organs contain specific protein receptors that recognize THC and some other cannabinoids and trigger cell responses. Other cannabinoids do not bind to these cannabinoid receptors and exert their effects by other ways. The discovery of specific cannabinoid receptors prompted the search for putative naturally-occurring chemicals that interact with the receptors, the endocannabinoids. There are at least two cannabinoid receptor types, CB1 receptors, and CB2 receptors. CB1 receptors are found in high concentrations within the brain and spinal cord. They are also present in certain peripheral cells and tissues (some neurons, some endocrine glands, leukocytes, spleen, heart and parts of the reproductive, urinary and gastrointestinal tracts). CB2 receptors are expressed primarily by immune cells und tissues (leukocytes, spleen and tonsils). Cannabis: Cannabis sativa L. is the botanical name and Latin binomial of hemp. Until now, there are 483 different identifiable chemical constituents known to exist in cannabis. The most distinctive and specific class of compounds are the cannabinoids (66 known), that are only known to exist in the cannabis plant. Other constituents of the cannabis plant are: nitrogenous compounds (27 known), amino acids (18), proteins (3), glycoproteins (6), enzymes (2), sugars and related compounds (34), hydrocarbons (50), simple alcohols (7), aldehydes (13), ketones (13), simple acids (21), fatty acids (22), simple esters (12), lactones (1), steroids (11), terpenes (120), non-cannabinoid phenols (25), flavonoids (21), vitamins (1) and pigments (2), elements (9). The very most of these compounds are found in other plants and animals and are not of pharmacological relevance with regard to the effects exerted by cannabis preparations. Dronabinol: Dronabinol is another name for the naturally occurring (-)-trans-isomer of delta-9-THC, often used in a medical context in the scientific literature. There is no chemical or pharmacological difference between the natural dronabinol found in the plant and dronabinol that is manufactured synthetically or semi-synthetically. Endocannabinoids: The endogenous ligands of the cannabinoid receptors have been termed endogenous cannabinoids or endocannabinoids. Endocannabinoids are produced by the body of humans and animals. Some endocannabinoids are arachidonyl-ethanolamide (anandamide), 2-arachidonyl glycerol (2-AG), 2-arachidonylglyceryl ether (noladin ether), arachidonyl-ethanolamine (virodhamine), and N-arachidonoyl-dopamine (NADA). Endogenous: Produced by the body, not delivered from external sources. The endogenous cannabinoids are called endocannabinoids. Hashish: Hashish is an Arabic name for cannabis resin or compressed resin glands, containing 5-20% or even more THC. Hemp: Hemp (Cannabis sativa L.) is an annual plant, normally dioecious, with male and female flowers developing on separate plants. Depending on THC and CBD content hemp can be divided into fibre and drug types. There are regional differences in the employment of the terms cannabis, hemp and marijuana. In the USA and Canada the term "hemp" is usually only applied to fibre hemp in contrast to the term "marijuana", while in many regions of Europe hemp ("Hanf") can be applied to drug types as well (in the sense of the old term "Indian hemp"). Ligand: A ligand binds to a specific receptor. The ligands of the cannabinoid receptor are called cannabinoids. The endogenous ligands of the cannabinoid receptor are called endocannabinoids. Marijuana: Marijuana (marihuana) is a colloquial name for dried leaves and flowers of drug cannabis varieties rich in THC (1-20% THC). The median content of THC of confiscated marijuana in the USA in 1997 was 4.2%. Marijuana available on prescription in the Netherlands contains 15% or 18% THC. Marinol: Marinol is a preparation of synthetic dronabinol, dissolved in sesame oil, as capsules of 2.5, 5, and 10 mg dronabinol. Nabilone: Nabilone is a synthetic derivative of delta-9-THC with a slightly modified molecular structure, available in some countries on prescription. THC: THC (tetrahydrocannabinol) usually refers to the naturally existing isomer of delta-9-THC, but also may include delta-8-THC. Delta-9-tetrahydrocannabinol and delta-1-tetrahydrocannabinol are two names for the same molecule according to different numbering systems (monoterpenoid and dibenzopyran nomenclature). Generally the natural (-)-trans-isomer of delta-9-THC of the cannabis plant, the (-)-delta-9-trans-tetrahydrocannabinol or dronabinol is designated. Chemically, delta-9-THC is defined as (6aR-trans)-6a,7,8,10a-tetrahy-dro6,6,9-trimethyl-3-pentyl-6H-dibenzo[b,d]pyran-1-ol with a molecular weight of 314.47 Da.