Cannabinoids sensory systems

THC was first isolated from hashish in 1964 by Raphael Mechoulam (1930-) and Yehiel Gaoni at the Weizmann Institute. Mechoulam had obtained 5 kg hashish from Israeli police officials and the earliest scientific work on THC and cannabinoids used this source. In the early 1990s, the specific brain receptors affected by THC were identified. These receptors are activated by a cannabinoid neurotransmitter called arachidonylethanolamide, known as anandamide. Anandamide was named by Mechoulam using ananda, which is the Sanskrit word for ecstasy. Anandamide is thought to be associated with memory, pain, depression, and appetite. THC is able to attach to and activate anandamide receptors. These receptors are actually called THC receptors rather than anandamide receptors because researchers discovered that THC attaches to these receptors before anandamide was discovered. The areas of the brain with the most THC receptors are the cerebellum, the cerebral cortex, and the limbic system. This is why marijuana affects thinking, memory, sensory perception, and coordination. 

The fact that the hypotensive action of anandamide is absent in knockont mice lacking CBj receptors (Ledent et al., 1999) snggests that any action via vanilloid receptors on sensory nerves is only of minor importance in the hemodynamic profile of systemically administered cannabinoids. In nrethane-anesthetized rats, there is a triphasic cardiovascnlar response to systemic intravenons administration of anandamide, bnt it appears that only the initial rapid hypotensive and bradycardic phase involves VRj receptors (Malinowska et al., 2001, Smith and McQneen, 2001), and this phase is not associated with vasodilatation (Gardiner et al., 2002a). 

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