The epigenetically regulated PP1α expression by KDM1A may contribute to oxycodone conditioned place preference in mice.

The lysine-specific demethylase 1 (KDM1A) is reported to be a regulator in learning and memory. However, the effect of KDM1A in oxycodone rewarding memory has yet to be studied. In our study, rewarding memory was assessed by using conditioned place preference (CPP) in male mice. Next generation sequencing and chromatin immunoprecipitation-PCR were used to explore the molecular mechanisms. Oxycodone significantly decreased PP1α mRNA and protein levels in hippocampal neurons. Oxycodone significantly increased KDM1A and H3K4me1 levels, while significantly decreased H3K4me2 levels in a time- and dose-dependent manner. Behavioral data demonstrated that intraperitoneal injection of ORY-1001 (KDM1A inhibitor) or intra-hippocampal injection of KDM1A siRNA/shRNA blocked the acquisition and expression of oxycodone CPP and facilitated the extinction of oxycodone CPP. The decrease of PP1α was markedly blocked by the injection of ORY-1001 or KDM1A siRNA/shRNA. Oxycodone-induced enhanced binding of CoRest with KDM1A and binding of CoRest with the PP1α promoter was blocked by ORY-1001. The level of H3K4me2 demethylation was also decreased by the treatment. The results suggest that oxycodone-induced upregulation of KDM1A via demethylation of H3K4me2 promotes the binding of CoRest with the PP1α promoter, and the subsequent decrease in PP1α expression in hippocampal neurons may contribute to oxycodone reward.