Background: Despite the high cost and widespread prevalence of alcohol use disorders, treatment options are limited, underscoring the need for new, effective medications. Previous results using protein kinase C epsilon (PKCε) knockout mice, RNA interference against PKCε and peptide inhibitors of PKCε predict that small-molecule inhibitors of PKCε should reduce alcohol consumption in humans. Methods: We designed a new class of PKCε inhibitors based on the Rho-associated protein kinase (ROCK) inhibitor Y-27632. In vitro kinase and binding assays were used to identify the most potent compounds. Their effects on ethanol-stimulated synaptic transmission; ethanol, sucrose, and quinine consumption; ethanol-induced loss of righting; and ethanol clearance were studied in mice. Results: We identified two compounds that inhibited PKCε with Ki <20 nM, showed selectivity for PKCε over other kinases, crossed the blood-brain barrier, achieved effective concentrations in mouse brain, prevented ethanol-stimulated gamma-aminobutyric acid release in the central amygdala, and reduced ethanol consumption when administered intraperitoneally at 40 mg/kg in wild-type but not in Prkce−/− mice. One compound also reduced sucrose and saccharin consumption, while the other was selective for ethanol. Both transiently impaired locomotion through an off-target effect that did not interfere with their ability to reduce ethanol intake. One compound prolonged recovery from ethanol-induced loss of righting but this was also due to an off-target effect since it was present in Prkce−/− mice. Neither altered ethanol clearance. Conclusions: These results identify lead compounds for development of PKCε inhibitors that reduce alcohol consumption.
Bibliographical noteFunding Information:
This work was supported by National Institutes of Health Grant Nos. AA13588 (to ROM), AA017072 (to ROM), AA015566 (to MR), and AA013498 (to MR); funds provided by the State of California for medical research for alcohol and substance abuse through the University of California, San Francisco (to ROM); and Graduate Research Fellowship Grant No. DGE-1110007 (to MP) from the National Science Foundation.
- Kinase inhibitor
- Protein kinase C epsilon