Opioid receptors and their endogenous peptide ligands play important roles in the reward and reinforcement of drugs such as heroin, cocaine, and alcohol. The binding of dynorphins to the κ-opioid receptor has been shown to produce aversive states, which may prevent the development of reinforcement. We genotyped SNPs throughout OPRK1, encoding the κ-opioid receptor, and PDYN, which encodes its ligand prodynorphin, in a group of 1860 European American individuals from 219 multiplex alcohol dependent families. Family-based analyses demonstrated associations between alcohol dependence and multiple SNPs in the promoter and 3′ end of PDYN, and in intron 2 of OPRK1. Haplotype analyses further supported the association of PDYN. Thus, variations in the genes encoding both the κ-opioid receptor and its ligand, OPRK1 and PDYN, are associated with the risk for alcohol dependence; this makes biological sense as variations in either should affect signaling through the κ-opioid system.
- Single nucleotide polymorphism
- κ-opioid receptor