The overall goal of this research is to determine how the nociceptin receptor (NOPR) modulates dopamine (DA) transmission and behavioral responses associated with drug addiction. Central administration of NOPR agonists inhibits the rewarding effects of commonly abused drugs including cocaine, morphine, amphetamine, and alcohol in conditioned place preference assays. NOPR is widely expressed in the brain, but preliminary data shows that NOPR activation in DA neurons of the ventral tegmental area (VTA) is sufficient to inhibit cocaine preference. We hypothesize that this effect is due to the demonstrated ability of NOPR activation to inhibit DA transmission to the nucleus accumbens. However, NOPR signaling has never been studied directly in midbrain DA neurons, and how it regulates DA transmission is unknown. The research objectives of this five year K01 award are: (1) to determine the intracellular signaling responses generated by NOPR activation in real-time within midbrain DA neurons, (2) to identify cellular and molecular mechanisms that control NOPR desensitization and internalization in midbrain DA neurons, and (3) to determine how NOPR signaling suppresses cocaine-induced increases in dopamine transmission. I have expertise in techniques for subcellular optogenetic manipulation and measurement of G protein coupled receptor (GPCR)-mediated signaling that make me uniquely qualified to achieve these aims. However, I require additional training in the use of primary neuronal cultures, genetic and viral methods, and for measuring dopamine uptake and dopamine transporter trafficking. My outstanding co-mentors, Drs. Michael Bruchas and N. Gautam, as well as our collaborators here at Washington University School of medicine will provide the required training. Washington University School of Medicine. Successful completion of my research and training goals, and my transition to scientific independence, will be ensured through regular interactions with my co-mentors, as well as my in-house advisory committee including Drs. Karen O'Malley, Robert Gereau, and Theodore Cicero. Overall, this Mentored Research Scientist Development Award will greatly facilitate my goal to establish myself as a leading contributor to our understanding of GPCR regulation of neurotransmission in reward and addiction circuitry.
Identification of novel drug targets for addiction will require a more complete understanding of the receptors and signal transduction pathways in the mammalian brain. The studies here have the potential to open new avenues for targeting the nociceptin system in drug abuse.