Molecular and Epigenetic Aspects of Opioid Receptors in Drug Addiction and Pain Management in Sport

An OPRM1-SNAP-tag/CMC method to directly identify drug components in sewage

The scourge of drug addiction and abuse poses a significant challenge to society. Opioid drugs acting on μ-opioid receptor (OPRM1) make it one of the pivotal targets for drug addiction. In the past decade, sewage analysis has become a prevalent method of drug monitoring. However, traditional methods of detecting drugs in sewage are cumbersome, and rapid detection methods are relatively lacking. To address this, an innovative OPRM1-SNAP-tag/CMC method to directly identify drug components in sewage was established. Cell membrane chromatography (CMC) is an affinity chromatography technique which effectively detects receptor affinity substances. Cells constructed with high expression of specific receptor could be used to screen for compounds acting on the receptor. CMC based on OPRM1 provides a potentially convenient and effective tool for the detection of targeted drug components in sewage. In this study, the selectivity, reproducibility, column lifetime, and carryover of the CMC column had been assessed. Initially, we eluted the collected domestic sewage with methanol and acetonitrile, and the retention peaks were observed on the CMC system. Subsequently, without any preliminary sample preparation, we directly injected filtered samples of suspicious sewage into the OPRM1-SNAP-tag/CMC system, where we observed retention peaks as well. The retained components were further identified as morphine by using UPLC-MS/MS. In conclusion, the OPRM1-SNAP-tag/CMC method stands out as a reliable and robust model for the detection of drug components in sewage. It provides a valuable analytical tool for frontline drug control efforts, enhancing our capacity to monitor and mitigate the impact of drug abuse on society.

Mechanisms of delta opioid receptor inhibition of parallel fibers-purkinje cell synaptic transmission in the mouse cerebellar cortex

Delta opioid receptors (DORs) are widely expressed throughout the central nervous system, including the cerebellum, where they play a regulatory role in neurogenesis. In the cerebellar cortex, Purkinje cells (PCs), the sole output neurons, receive glutamatergic synaptic input from parallel fibers (PFs)-the axonal extensions of granule cells-forming PF-PC synapses. However, the precise distribution of DORs within these synapses and their impact on synaptic transmission remain unclear. In this study, we utilized whole-cell patch-clamp recordings and neuropharmacological approaches to explore the effects of DORs activation on PF-PC synaptic transmission in the mouse cerebellar cortex and to elucidate the underlying mechanisms. We found that the selective DORs agonist DPDPE significantly reduced the amplitude and area under the curve (AUC) of PF-PC evoked excitatory postsynaptic currents (eEPSCs), accompanied by an increase in the paired-pulse ratio (PPR). This inhibitory effect was blocked by the DORs antagonist Naltrindole. Additionally, DPDPE decreased the frequency of PF-PC miniature excitatory postsynaptic currents (mEPSCs) without affecting their amplitude, indicating a presynaptic site of action. When the protein kinase A (PKA) inhibitor PKI was added to the internal solution of the recording electrode, it did not alter the DPDPE-induced suppression of PF-PC mEPSC frequency. However, this suppression was reversed by KT5720, a cell-permeable PKA-specific inhibitor. These findings suggest that DPDPE inhibits PF-PC synaptic transmission through the preferential activation of presynaptic DORs, with this process being dependent on the cyclic adenosine monophosphate (cAMP)-PKA signaling pathway.

Neuronal biomarkers as potential therapeutic targets for drug addiction related to sex differences in the brain: Opportunities for personalized treatment approaches

Biological sex disparities manifest at various stages of drug addiction, including craving, substance abuse, abstinence, and relapse. These discrepancies are underpinned by notable distinctions in neurobiological substrates, encompassing brain structures, functions, and neurotransmitter systems implicated in drug addiction. Neuronal biomarkers, such as neurotransmitters, signaling proteins, and genes may be associated with the diagnosis, prognosis, and treatment outcomes in both biological sexes afflicted by drug abuse. Sex differences in the neural reward system, mainly through dopaminergic transmission during drug abuse, can be attributed to modifications in neurotransmitter systems and signaling pathways. This results in distinct patterns of neural activation and responsiveness to addictive substances in males and females. Sex hormones, the estrus/menstrual cycle, and cerebral neurochemistry contribute to the progression of psychological and physiological dependence in both male and female individuals grappling with addiction. Moreover, the alteration of sex hormone balance and neurotransmitter release plays a pivotal role in substance use disorders, subsequently modulating cognitive functions pertinent to reward, including memory formation, decision-making, and locomotor activity. Comparative investigations reveal distinctions in brain region volume, gene expression, neuronal firing, and circuitry in substance use disorders affecting individuals of both biological sexes. This review examines prevalent substance use disorders to elucidate the impact of sex hormones as therapeutic biomarkers on the mesocorticolimbic neurotransmitter systems via diverse mechanisms within the addicted brain. We underscore the imperative necessity of considering these variations to gain a deeper comprehension of addiction mechanisms and potentially discern sex-specific neuronal biomarkers for tailored therapeutic interventions.

Opioid and Cannabinoid Systems in Pain: Emerging Molecular Mechanisms and Use in Clinical Practice, Health, and Fitness

Pain is an unpleasant sensory and emotional experience. Adequate pain control is often challenging, particularly in patients with chronic pain. Despite advances in pain management, drug addiction, overtreatment, or substance use disorders are not rare. Hence the need for further studies in the field. The substantial progress made over the last decade has revealed genes, signalling pathways, molecules, and neuronal networks in pain control thus opening new clinical perspectives in pain management. In this respect, data on the epigenetic modulation of opioid and cannabinoid receptors, key actors in the modulation of pain, offered new perspectives to preserve the activity of opioid and endocannabinoid systems to increase the analgesic efficacy of opioid- and cannabinoid-based drugs. Similarly, upcoming data on cannabidiol (CBD), a non-psychoactive cannabinoid in the marijuana plant Cannabis sativa, suggests analgesic, anti-inflammatory, antioxidant, anticonvulsivant and ansiolitic effects and supports its potential application in clinical contexts such as cancer, neurodegeneration, and autoimmune diseases but also in health and fitness with potential use in athletes. Hence, in this review article, we summarize the emerging epigenetic modifications of opioid and cannabinoid receptors and focus on CBD as an emerging non-psychoactive cannabinoid in pain management in clinical practice, health, and fitness.

Postoperative Multimodal Analgesia Strategy for Enhanced Recovery After Surgery in Elderly Colorectal Cancer Patients

Enhanced Recovery After Surgery (ERAS) protocols have substantially proven their merit in diminishing recuperation durations and mitigating postoperative adverse events in geriatric populations undergoing colorectal cancer procedures. Despite this, the pivotal aspect of postoperative pain control has not garnered the commensurate attention it deserves. Typically, employing a multimodal analgesia regimen that weaves together nonsteroidal anti-inflammatory drugs, opioids, local anesthetics, and nerve blocks stands paramount in curtailing surgical complications and facilitating reduced convalescence within hospital confines. Nevertheless, this integrative pain strategy is not devoid of pitfalls; the specter of organ dysfunction looms over the geriatric cohort, rooted in the abuse of analgesics or the complex interplay of polypharmacy. Revolutionary research is delving into alternative delivery and release modalities, seeking to allay the inadvertent consequences of analgesia and thereby potentially elevating postoperative outcomes for the elderly post-colorectal cancer surgery populace. This review examines the dual aspects of multimodal analgesia regimens by comparing their established benefits with potential limitations and offers insight into the evolving strategies of drug administration and release.

Unraveling the Hippocampal Molecular and Cellular Alterations behind Tramadol and Tapentadol Neurobehavioral Toxicity

Tramadol and tapentadol are chemically related opioids prescribed for the analgesia of moderate to severe pain. Although safer than classical opioids, they are associated with neurotoxicity and behavioral dysfunction, which arise as a concern, considering their central action and growing misuse and abuse. The hippocampal formation is known to participate in memory and learning processes and has been documented to contribute to opioid dependence. Accordingly, the present study assessed molecular and cellular alterations in the hippocampal formation of Wistar rats intraperitoneally administered with 50 mg/kg tramadol or tapentadol for eight alternate days. Alterations were found in serum hydrogen peroxide, cysteine, homocysteine, and dopamine concentrations upon exposure to one or both opioids, as well as in hippocampal 8-hydroxydeoxyguanosine and gene expression levels of a panel of neurotoxicity, neuroinflammation, and neuromodulation biomarkers, assessed through quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemical analysis of hippocampal formation sections showed increased glial fibrillary acidic protein (GFAP) and decreased cluster of differentiation 11b (CD11b) protein expression, suggesting opioid-induced astrogliosis and microgliosis. Collectively, the results emphasize the hippocampal neuromodulator effects of tramadol and tapentadol, with potential behavioral implications, underlining the need to prescribe and use both opioids cautiously.

Neuronal dysfunction and gene modulation by non-coding RNA in Parkinson's disease and synucleinopathies

Over the last few decades, emerging evidence suggests that non-coding RNAs (ncRNAs) including long-non-coding RNA (lncRNA), microRNA (miRNA) and circular-RNA (circRNA) contribute to the molecular events underlying progressive neuronal degeneration, and a plethora of ncRNAs have been identified significantly misregulated in many neurodegenerative diseases, including Parkinson's disease and synucleinopathy. Although a direct link between neuropathology and causative candidates has not been clearly established in many cases, the contribution of ncRNAs to the molecular processes leading to cellular dysfunction observed in neurodegenerative diseases has been addressed, suggesting that they may play a role in the pathophysiology of these diseases. Aim of the present Review is to overview and discuss recent literature focused on the role of RNA-based mechanisms involved in different aspects of neuronal pathology in Parkinson's disease and synucleinopathy models.

Molecular Advances on Cannabinoid and Endocannabinoid Research

Since ancient times, cannabis has been used for recreational and medical purposes [...].

Exploring the Therapeutic Potential of Cannabinoid Receptor Antagonists in Inflammation, Diabetes Mellitus, and Obesity

Recently, research has greatly expanded the knowledge of the endocannabinoid system (ECS) and its involvement in several therapeutic applications. Cannabinoid receptors (CBRs) are present in nearly every mammalian tissue, performing a vital role in different physiological processes (neuronal development, immune modulation, energy homeostasis). The ECS has an essential role in metabolic control and lipid signaling, making it a potential target for managing conditions such as obesity and diabetes. Its malfunction is closely linked to these pathological conditions. Additionally, the immunomodulatory function of the ECS presents a promising avenue for developing new treatments for various types of acute and chronic inflammatory conditions. Preclinical investigations using peripherally restricted CBR antagonists that do not cross the BBB have shown promise for the treatment of obesity and metabolic diseases, highlighting the importance of continuing efforts to discover novel molecules with superior safety profiles. The purpose of this review is to examine the roles of CB1R and CB2Rs, as well as their antagonists, in relation to the above-mentioned disorders.