|MadSci Network: Neuroscience|
In answer to your questions in brief: 1. Yes THC receptors do exist in the brain and 2. They do have a purpose other than binding to THC, which is only found in Marijuana. What follows is a short discussion on this topic (modified from an online site on the effects of Marijuana). The THC or cannabinoid receptor is a typical member of the largest known family of receptors: the G-protein-coupled receptors with their distinctive pattern in which the receptor molecule spans the cell membrane seven times.THC receptors are very abundant in the brain. The Endogenous Cannabinoid System For any drug for which there is a receptor, the logical question is, "Why does this receptor exist?" The short answer is that there is probably an endogenous agonist (that is, a compound that is naturally produced in the brain) that acts on that receptor. The long answer begins with a search for such compounds in the area of the body that produce the receptors and ends with a determination of the natural function of those compounds. So far, the search has yielded several endogenous compounds that bind selectively to cannabinoid receptors. The best studied of them are anandamide and arachidonyl glycerol. However, their physiological roles are not yet known. Anandamide The first endogenous cannabinoid to be discovered was arachidonylethanolamine, named anandamide from the Sanskrit word ananda, meaning "bliss." Anandamide appears to have both central (in the brain) and peripheral (in the rest of the body) effects. The precise neuroanatomical localization of anandamide and its function are not yet known. hope this helps, gabriel vargas md/phd References: Abood ME, Martin BR. 1996. Molecular neurobiology of the cannabinoid receptor. International Review of Neurobiology 39:197-221. Calignano A, La Rana G. Giuffrida A, Piomelli D. 1998. Control of pain initiation by endogenous cannabinoids. Nature 394:277-281. Childers SR, Breivogel CS. 1998. Cannabis and endogenous cannabinoid systems. Drug and Alcohol Dependence 51:173-187. Devane WA, Hanus L, Breuer A, Pertwee RG, Stevenson LA, Griffing F. Gibson D, Mandelbaum A, Etinger A, Mechoulam R. 1992. Isolation and structure of a brain constituent that binds to the cannabinoid receptor. Science 258: 1946- 1949. Dewey WL. 1986. Cannabinoid pharmacology. Pharmacology Review 38:151-178.
Try the links in the MadSci Library for more information on Neuroscience.