| Popis: |
Opioid craving and the vulnerability to relapse is associated with severe and persistent disruptions to sleep and circadian rhythms. Investigations into the cellular and molecular pathways in the human brain underlying the relationship between circadian rhythms and OUD remain limited. In human subjects with OUD, previous transcriptomics work implicated a role for circadian regulation of synaptic processes in key cognitive- and reward-related brain regions, dorsolateral prefrontal cortex (DLPFC) and nucleus accumbens (NAc). To provide further insights into the synaptic alterations associated with OUD, we used mass-spectrometry based proteomics to deeply profile protein alterations in tissue homogenates and synaptosomes from both NAc and DLPFC of unaffected and OUD subjects. Between unaffected and OUD subjects, we identified 43 differentially expressed (DE) proteins in NAc homogenates and 55 DE proteins in DLPFC homogenates. In synaptosomes, we found 56 DE proteins in NAc of OUD subjects and 161 DE proteins in DLPFC. Examining synaptosome enrichment of specific proteins enabled us to identify brain region- and synapse-specific pathway alterations in NAc and DLPFC associated with OUD. Across both regions, we found OUD-associated protein alterations primarily in pathways involved in GABAergic and glutamatergic synaptic functions, as well as circadian rhythms. Using time-of-death (TOD) analyses, where the TOD of each subject is used as a time-point across a 24-hour cycle, we were able to map circadian-related changes in the synaptic proteomes in NAc and DLPFC associated with OUD. In OUD, TOD analysis revealed significant circadian changes in endoplasmic reticulum to Golgi vesicle-mediated transport and protein membrane trafficking in NAc synapses, accompanied by changes in platelet derived growth factor receptor beta signaling in DLPFC synapses. Together, our results lend further support for molecular disruption of circadian regulation of synaptic signaling in the human brain as a key factor in opioid addiction. |
