15 years of genetic approaches in vivo for addiction research: Opioid receptor and peptide gene knockout in mouse models of drug abuse.

Title15 years of genetic approaches in vivo for addiction research: Opioid receptor and peptide gene knockout in mouse models of drug abuse.
Publication TypeJournal Article
Year of Publication2014
AuthorsCharbogne P, Kieffer BL, Befort K
Volume76 Pt B
Date Published2014 Jan
KeywordsAnimals, Biomedical Research, Disease Models, Animal, History, 20th Century, History, 21st Century, Humans, Mice, Mice, Knockout, Opioid Peptides, Receptors, Opioid, Substance-Related Disorders

The endogenous opioid system is expressed throughout the brain reinforcement circuitry, and plays a major role in reward processing, mood control and the development of addiction. This neuromodulator system is composed of three receptors, mu, delta and kappa, interacting with a family of opioid peptides derived from POMC (β-endorphin), preproenkephalin (pEnk) and preprodynorphin (pDyn) precursors. Knockout mice targeting each gene of the opioid system have been created almost two decades ago. Extending classical pharmacology, these mutant mice represent unique tools to tease apart the specific role of each opioid receptor and peptide in vivo, and a powerful approach to understand how the opioid system modulates behavioral effects of drugs of abuse. The present review summarizes these studies, with a focus on major drugs of abuse including morphine/heroin, cannabinoids, psychostimulants, nicotine or alcohol. Genetic data, altogether, set the mu receptor as the primary target for morphine and heroin. In addition, this receptor is essential to mediate rewarding properties of non-opioid drugs of abuse, with a demonstrated implication of β-endorphin for cocaine and nicotine. Delta receptor activity reduces levels of anxiety and depressive-like behaviors, and facilitates morphine-context association. pEnk is involved in these processes and delta/pEnk signaling likely regulates alcohol intake. The kappa receptor mainly interacts with pDyn peptides to limit drug reward, and mediate dysphoric effects of cannabinoids and nicotine. Kappa/dynorphin activity also increases sensitivity to cocaine reward under stressful conditions. The opioid system remains a prime candidate to develop successful therapies in addicted individuals, and understanding opioid-mediated processes at systems level, through emerging genetic and imaging technologies, represents the next challenging goal and a promising avenue in addiction research. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Alternate JournalNeuropharmacology
PubMed ID24035914
PubMed Central IDPMC3858501
Grant ListAA16658 / AA / NIAAA NIH HHS / United States
DA05010 / DA / NIDA NIH HHS / United States
P50 DA005010 / DA / NIDA NIH HHS / United States
U01 AA013481 / AA / NIAAA NIH HHS / United States
U01 AA016658 / AA / NIAAA NIH HHS / United States