Targeting Opioid Receptors in Addiction and Drug Withdrawal: Where Are We Going?

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.

Substance Addiction Rehabilitation Drugs

The relapse rate of substance abusers is high, and addiction rehabilitation adjunct drugs need to be developed urgently. There have been numerous reports on blocking the formation of substance addiction, but studies on drugs that can alleviate withdrawal symptoms are very limited. Both the dopamine transporter (DAT) hypothesis and D3 dopamine receptor (D3R) hypothesis are proposed. DAT activators reduce the extracellular dopamine level, and D3R antagonists reduce the neuron's sensitivity to dopamine, both of which may exacerbate the withdrawal symptoms subsequently. The D3R partial agonist SK608 has biased signaling properties via the G-protein-dependent pathway but did not induce D3R desensitization and, thus, may be a promising drug for the withdrawal symptoms. Drugs for serotoninergic neurons or GABAergic neurons and anti-inflammatory drugs may have auxiliary effects to addiction treatments. Drugs that promote structural synaptic plasticity are also discussed.

Treatment of Moderate-to-Severe Pain in Hepatocellular Carcinoma with Transcutaneous Electrical Acupoint Stimulation: A Randomized Controlled Trial

Objective

Moderate-to-severe pain is the most common clinical symptom in patients with hepatocellular carcinoma (HCC).This trial aimed to analyze the clinical efficacy of Transcutaneous electrical acupoint stimulation (TEAS) in patients of HCC with severe pain and provide a reliable reference for optimizing the clinical diagnostic and therapeutic strategies of HCC.

Methods

A total of 104 eligible patients were randomly allocated to experimental and control groups in a ratio of 1:1.The treatment was administered for 1 week continuously. Patients in both groups were followed up 1 week after the end of the treatment.The primary outcome measure was the Numerical Rating Scale (NRS) score, whereas the secondary outcome measures included Brief Pain Inventory BPI-Q3, Q4, Q5 scores, analgesic dose, frequency of opioid-induced gastrointestinal side effects, Karnofsky Performance Status (KPS), Quality of Life Scale - Liver Cancer (QOL-LC), and Brief Fatigue Inventory (BFI) scores.

Results

The NRS scores of experimental group was significantly lower after treatment and at the follow-up than baseline (average P<0.01), there were also statistical differences between the groups at the above time points (average P<0.01). BPI-Q3, -Q4, and -Q5 scores in the experimental group were decreased after treatment when compared with those before treatment (average P<0.01). Furthermore, there were significant improvements of gastrointestinal side effects, KPS, QOL-LC and BPI in the experimental group after treatment, and the above results were statistically significant compared to the control group.

Conclusion

7-day TEAS treatment can significantly enhance the analgesic effect and maintain for the following week, also reduce the incidence of gastrointestinal side effects caused by opioids, and improve the quality of life of patients with moderate-to-severe HCC-related pain, which has reliable safety and certain clinical promotion value.

Navigating the brain: the role of exosomal shuttles in precision therapeutics

Brain diseases have become one of the leading roots of mortality and disability worldwide, contributing a significant part of the disease burden on healthcare systems. The blood-brain barrier (BBB) is a primary physical and biological obstacle that allows only small molecules to pass through it. Its selective permeability is a significant challenge in delivering therapeutics into the brain for treating brain dysfunction. It is estimated that only 2% of the new central nervous system (CNS) therapeutic compounds can cross the BBB and achieve their therapeutic targets. Scientists are exploring various approaches to develop effective cargo delivery vehicles to promote better therapeutics targeting the brain with minimal off-target side effects. Despite different synthetic carriers, one of the natural brain cargo delivery systems, "exosomes," are now employed to transport drugs through the BBB. Exosomes are naturally occurring small extracellular vesicles (EVs) with unique advantages as a therapeutic delivery system for treating brain disorders. They have beneficial innate aspects of biocompatibility, higher stability, ability to cross BBB, low cytotoxicity, low immunogenicity, homing potential, targeted delivery, and reducing off-site target effects. In this review, we will discuss the limitations of synthetic carriers and the utilization of naturally occurring exosomes as brain-targeted cargo delivery vehicles and highlight the methods for modifying exosome surfaces and drug loading into exosomes. We will also enlist neurodegenerative disorders targeted with genetically modified exosomes for their treatment.