Chunk #27 — Identifying Specific Genes Related to AOD Dependence — Genes Encoding Proteins Involved in Neurotransmission — Genes Involved in the Endogenous Cannabinoid System
Endogenous cannabinoids are compounds naturally produced in the body that have a similar structure to the psychoactive compounds found in the cannabis plant and which bind cannabinoid receptors. The endogenous cannabinoid system is thought to regulate brain circuits using the neurotransmitter dopamine, which likely helps mediate the rewarding experiences associated with addictive substances. The main cannabinoid receptor in the brain is called CB1 and is encoded by the CNR1 gene, which is located on chromosome 6. This gene is an excellent candidate gene for being associated with AOD dependence because the receptor encoded by this gene is crucial for generating the rewarding effects of the compound responsible for the psychoactive effects associated with cannabis use (i.e., Δ9-tetrahydrocannabinol). However, the findings regarding the association between CNR1 and AOD dependence to date have been equivocal, with some studies producing positive results (e.g., Zhang et al. 2004) and others producing negative results (e.g., Herman et al. 2006). Most recently, Hopfer and colleagues (2006) found that a SNP in the CNR1 gene was associated with cannabis dependence symptoms. 6 Moreover, this SNP was part
