Pharmacoproteomics Profile in Response to Acamprosate Treatment of an Alcoholism Animal Model

Acamprosate effect on neuropathic pain in rats: With emphasis on the role of ERK/MAPK pathway and SCN9A sodium channel

BACKGROUND

Neuropathic pain is a chronic pain owing to nerve damage or diseases of the central nervous system (CNS). The expression of SCN9A, which encodes the Nav1.7 voltage-gated sodium channel and ERK have been found to change significantly in many cases of neuropathic pain. Here, we investigated effects of acamprosate on neuropathic pain, taking into account the crucial roles of SCN9A, the ERK signaling pathway, and inflammatory markers in a rat model of chronic constriction injury (CCI).

METHODS

Acamprosate (300 mg/kg) was injected intraperitoneally (i.p.) for 14 days. The tail-immersion, acetone, and formalin tests were used to determine behavioral tests such as heat allodynia, cold allodynia, and chemical hyperalgesia, respectively. Lumbar spinal cord was extracted and processed for Nissl staining. The amount of spinal SCN9A expression and ERK phosphorylation were examined using ELISA assay.

RESULTS

The expression of SCN9A, ERK, inflammatory cytokines (IL-6 and TNF-α), allodynia and hyperalgesia significantly increased on days 7 and 14 following CCI. The treatment not only reduced neuropathic pain but also blocked CCI's effects on SCN9A upregulation and ERK phosphorylation.

CONCLUSION

This research demonstrated that acamprosate reduces the neuropathic pain induced by CCI of the sciatic nerve in rats by preventing cell loss, inhibiting spinal SCN9A expression, ERK phosphorylation, and inflammatory cytokines, suggesting potential therapeutic implications of acamprosate administration for the treatment of neuropathic pain.

Proteomics and weighted gene correlated network analysis reveal glutamatergic synapse signaling in diazepam treatment of alcohol withdrawal

Background: Alcohol use disorder (AUD) is characterized by chronic excessive alcohol consumption, often alternating with periods of abstinence known as alcohol withdrawal syndrome (AWS). Diazepam is the preferred benzodiazepine for treatment of alcohol withdrawal syndrome under most circumstances, but the specific mechanism underlying the treatment needs further research. Methods: We constructed an animal model of two-bottle choices and chronic intermittent ethanol exposure. LC-MS/MS proteomic analysis based on the label-free and intensity-based quantification approach was used to detect the protein profile of the whole brain. Weighted gene correlated network analysis was applied for scale-free network topology analysis. We established a protein-protein interaction network based on the Search Tool for the Retrieval of Interacting Genes (STRING) database and Cytoscape software and identified hub proteins by CytoHubba and MCODE plugins of Cytoscape. The online tool Targetscan identified miRNA-mRNA pair interactions. Results: Seven hub proteins (Dlg3, Dlg4, Shank3, Grin2b, Camk2b, Camk2a and Syngap1) were implicated in alcohol withdrawal syndrome or diazepam treatment. In enrichment analysis, glutamatergic synapses were considered the most important pathway related to alcohol use disorder. Decreased glutamatergic synapses were observed in the late stage of withdrawal, as a protective mechanism that attenuated withdrawal-induced excitotoxicity. Diazepam treatment during withdrawal increased glutamatergic synapses, alleviating withdrawal-induced synapse inhibition. Conclusion: Glutamatergic synapses are considered the most important pathway related to alcohol use disorder that may be a potential molecular target for new interventional strategies.

Ibudilast attenuates alcohol cue-elicited frontostriatal functional connectivity in alcohol use disorder

BACKGROUND

Ibudilast, a novel neuroimmune modulator being studied to treat alcohol use disorder (AUD), was shown in a randomized controlled trial (NCT03489850) to reduce ventral striatum (VS) activation in response to visual alcohol cues. The present study extended this finding by probing the effects of ibudilast on alcohol cue-elicited functional connectivity (i.e., temporally correlated activation) with the VS seed. The study also tests the association between functional connectivity and alcohol use during the trial.

METHODS

Non-treatment-seeking participants (n = 45) with current alcohol use disorder were randomized to receive twice-daily dosing with either ibudilast (50 mg; n = 20) or placebo (n = 25). Upon reaching the target dosagee of the medication or placebo, participants completed a functional neuroimaging alcohol cue reactivity paradigm. Drinks per drinking day were assessed at baseline and daily during the 2-week trial.

RESULTS

Ibudilast reduced alcohol cue-elicited functional connectivity between the VS seed and reward-processing regions including the orbitofrontal and anterior cingulate cortices compared with placebo (p < 0.05). Cue-elicited functional connectivity was correlated with drinks per drinking day (R2  = 0.5351, p < 0.001), and ibudilast reduced this association in similar reward-processing regions compared with placebo.

CONCLUSIONS

Ibudilast's effects on drinking outcomes may be related to the attenuation of functional connectivity in frontostriatal circuits related to reward processing. These results provide an important proof of concept for this novel pharmacotherapy and support the clinical utility of incorporating neuroimaging-and especially functional connectivity-analyses into medication development.

EAAT2 Expression in the Hippocampus, Subiculum, Entorhinal Cortex and Superior Temporal Gyrus in Alzheimer's Disease

Alzheimer’s disease (AD) is a neuropathological disorder characterized by the presence and accumulation of amyloid-beta plaques and neurofibrillary tangles. Glutamate dysregulation and the concept of glutamatergic excitotoxicity have been frequently described in the pathogenesis of a variety of neurodegenerative disorders and are postulated to play a major role in the progression of AD. In particular, alterations in homeostatic mechanisms, such as glutamate uptake, have been implicated in AD. An association with excitatory amino acid transporter 2 (EAAT2), the main glutamate uptake transporter, dysfunction has also been described. Several animal and few human studies examined EAAT2 expression in multiple brain regions in AD but studies of the hippocampus, the most severely affected brain region, are scarce. Therefore, this study aims to assess alterations in the expression of EAAT2 qualitatively and quantitatively through DAB immunohistochemistry (IHC) and immunofluorescence within the hippocampus, subiculum, entorhinal cortex, and superior temporal gyrus (STG) regions, between human AD and control cases. Although no significant EAAT2 density changes were observed between control and AD cases, there appeared to be increased transporter expression most likely localized to fine astrocytic branches in the neuropil as seen on both DAB IHC and immunofluorescence. Therefore, individual astrocytes are not outlined by EAAT2 staining and are not easily recognizable in the CA1–3 and dentate gyrus regions of AD cases, but the altered expression patterns observed between AD and control hippocampal cases could indicate alterations in glutamate recycling and potentially disturbed glutamatergic homeostasis. In conclusion, no significant EAAT2 density changes were found between control and AD cases, but the observed spatial differences in transporter expression and their functional significance will have to be further explored.

Resveratrol impairs acquisition, reinstatement and precipitates extinction of alcohol-induced place preference in mice

OBJECTIVE

Alcohol abuse causes several neurological disorders. Resveratrol is a natural polyphenol that occurs as a phytoalexin. In different studies, it has been investigated that resveratrol has positive effects on various mechanisms that are important in drug addiction or substance use disorder. The objective of the present study was to examine the effect of resveratrol on alcohol-induced conditioned place preference (CPP) in mice.

METHODS

CPP was induced by intraperitoneal (i.p.) administration of ethanol (2 g/kg) in an 8-day conditioning program. The influence of reference drug, acamprosate and resveratrol on the rewarding properties of ethanol was tested in mice given treatment of acamprosate (300 mg/kg, i.p.) and resveratrol (25, 50, and 75 mg/kg, i.p.) 30 minutes prior to ethanol administration. Once established, CPP was extinguished by repeated testing, through which conditioned mice were administered acamprosate, various doses of resveratrol or saline daily. Subsequently, the potency of acamprosate and resveratrol in preventing reinstatement of CPP provoked by priming with low-dose ethanol (0.4 g/kg, i.p.) was also evaluated.

RESULTS

The present findings confirm that resveratrol impairs acquisition, reinstatement and precipitates the extinction of preference for alcohol-induced CPP. Resveratrol presented a similar effect in the CPP phases to the acamprosate.

CONCLUSIONS

The effect of resveratrol on ethanol-induced CPP in mice demonstrated for the first time. As a conclusion, these findings may shed light on the fact that resveratrol can be utilized as an agent which is potentially beneficial to prevent the various harmful effects of ethanol, however, more research is needed to completely elucidate this attribute.

Neurogranin Regulates Alcohol Sensitivity through AKT Pathway in the Nucleus Accumbens

Dysfunction of glutamate neurotransmission in the nucleus accumbens (NAc) has been implicated in the pathophysiology of alcohol use disorders (AUD). Neurogranin (Ng) is exclusively expressed in the brain and mediates N-methyl-d-aspartate receptor (NMDAR) hypo-function by regulating the intracellular calcium-calmodulin (Ca²⁺ -CaM) pathway. Ng null mice (Ng^-/- mice) demonstrate increased alcohol drinking compared to wild-type mice, while also showing less tolerance to the effect of alcohol. To identify the molecular mechanism related to alcohol seeking, both in vivo microdialysis and label-free quantification proteomics comparing Ng genotype and effects of alcohol treatment on the NAc are utilized. There is significant difference in glutamate and gamma-aminobutyric acid (GABA) neurotransmission between genotypes; however, alcohol administration normalizes both glutamate and GABA levels in the NAc. Using label-free proteomics, 427 protein expression changes are identified against alcohol treatment in the NAc among 4347 total proteins detected. Bioinformatics analyses reveal significant molecular differences in Ng null mice in response to acute alcohol treatment. Ingenuity pathway analysis found that the AKT network is altered significantly between genotypes, which may increase the sensitivity of alcohol in Ng null mice. The pharmacoproteomics results presented here illustrate a possible molecular basis of the alcohol sensitivity through Ng signaling in the NAc.

MS1 ion current-based quantitative proteomics: A promising solution for reliable analysis of large biological cohorts

The rapidly-advancing field of pharmaceutical and clinical research calls for systematic, molecular-level characterization of complex biological systems. To this end, quantitative proteomics represents a powerful tool but an optimal solution for reliable large-cohort proteomics analysis, as frequently involved in pharmaceutical/clinical investigations, is urgently needed. Large-cohort analysis remains challenging owing to the deteriorating quantitative quality and snowballing missing data and false-positive discovery of altered proteins when sample size increases. MS1 ion current-based methods, which have become an important class of label-free quantification techniques during the past decade, show considerable potential to achieve reproducible protein measurements in large cohorts with high quantitative accuracy/precision. Nonetheless, in order to fully unleash this potential, several critical prerequisites should be met. Here we provide an overview of the rationale of MS1-based strategies and then important considerations for experimental and data processing techniques, with the emphasis on (i) efficient and reproducible sample preparation and LC separation; (ii) sensitive, selective and high-resolution MS detection; iii)accurate chromatographic alignment; (iv) sensitive and selective generation of quantitative features; and (v) optimal post-feature-generation data quality control. Prominent technical developments in these aspects are discussed. Finally, we reviewed applications of MS1-based strategy in disease mechanism studies, biomarker discovery, and pharmaceutical investigations.