Differential Effects of Cocaine and Morphine on the Diurnal Regulation of the Mouse Nucleus Accumbens Proteome

Cocaine and morphine induce shared and divergent transcriptional regulation in nucleus accumbens D1 and D2 medium spiny neurons

Substance use disorders (SUDs) induce widespread molecular dysregulation in nucleus accumbens (NAc), a brain region pivotal for coordinating motivation and reward, which is linked to neural and behavioral disturbances promoting addiction. Despite the overlapping symptomatology of SUDs, different drug classes exert partly unique influences on neural circuits, cell types, physiology, and gene expression. To better understand common and divergent molecular mechanisms governing SUD pathology, we characterized the cell-type-specific restructuring of the NAc transcriptional landscape after psychostimulant or opioid exposure. We combined fluorescence-activated nuclei sorting and deep RNA sequencing to profile NAc D1 and D2 medium spiny neurons (MSNs) across cocaine and morphine exposure paradigms, including initial exposure, prolonged withdrawal after repeated exposure, and re-exposure post-withdrawal. Our analyses reveal that D1 MSNs display many convergent transcriptional responses between the two drug classes, whereas D2 MSNs manifest highly divergent responses, with morphine causing more adaptations in this cell type. Utilizing multiscale embedded gene co-expression network analysis (MEGENA), we discerned transcriptional regulatory networks subserving biological functions altered by cocaine vs. morphine. We observed largely integrative engagement of overlapping gene networks across drug classes in D1 MSNs, but opposite regulation of key D2 networks, highlighting potential therapeutic gene network targets within MSNs. Analysis of gene regulatory systems at the level of enhancers revealed that morphine engages a unique enhancer landscape in D2 MSNs compared to cocaine. Our findings, and future work leveraging this dataset, will open avenues for the development of targeted therapeutic interventions, addressing the urgent need for more effective treatments for SUDs.

Cocaine-Induced Remodeling of the Rat Brain Peptidome: Quantitative Mass Spectrometry Reveals Anatomically Specific Patterns of Cocaine-Regulated Peptide Changes

Addiction to psychostimulants, including cocaine, causes widespread morbidity and mortality and is a major threat to global public health. Currently, no pharmacotherapies can successfully treat psychostimulant addiction. The neuroactive effects of cocaine and other psychostimulants have been studied extensively with respect to their modulation of monoamine systems (particularly dopamine); effects on neuropeptide systems have received less attention. Here, we employed mass spectrometry (MS) methods to characterize cocaine-induced peptidomic changes in the rat brain. Label-free peptidomic analysis using liquid chromatography coupled with tandem MS (LC-MS/MS) was used to describe the dynamic changes of endogenous peptides in five brain regions (nucleus accumbens, dorsal striatum, prefrontal cortex, amygdala, and hypothalamus) following an acute systemic cocaine challenge. The improved sensitivity and specificity of this method, coupled with quantitative assessment, enabled the identification of 1376 peptides derived from 89 protein precursors. Our data reveal marked, region-specific changes in peptide levels in the brain induced by acute cocaine exposure, with peptides in the cholecystokinin and melanin-concentrating hormone families being significantly affected. These findings offer new insights into the region-specific effects of cocaine and could pave the way for developing new therapies to treat substance use disorders and related psychiatric conditions.

Endogenous opiates and behavior: 2023

This paper is the forty-sixth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2023 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug and alcohol abuse (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Decoding cocaine-induced proteomic adaptations in the mouse nucleus accumbens

Cocaine use disorder (CUD) is a chronic neuropsychiatric condition that results from enduring cellular and molecular adaptations. Among substance use disorders, CUD is notable for its rising prevalence and the lack of approved pharmacotherapies. The nucleus accumbens (NAc), a region that is integral to the brain's reward circuitry, plays a crucial role in the initiation and continuation of maladaptive behaviors that are intrinsic to CUD. Leveraging advancements in neuroproteomics, we undertook a proteomic analysis that spanned membrane, cytosolic, nuclear, and chromatin compartments of the NAc in a mouse model. The results unveiled immediate and sustained proteomic modifications after cocaine exposure and during prolonged withdrawal. We identified congruent protein regulatory patterns during initial cocaine exposure and reexposure after withdrawal, which contrasted with distinct patterns during withdrawal. Pronounced proteomic shifts within the membrane compartment indicated adaptive and long-lasting molecular responses prompted by cocaine withdrawal. In addition, we identified potential protein translocation events between soluble-nuclear and chromatin-bound compartments, thus providing insight into intracellular protein dynamics after cocaine exposure. Together, our findings illuminate the intricate proteomic landscape that is altered in the NAc by cocaine use and provide a dataset for future research toward potential therapeutics.