Distinct µ-opioid ensembles trigger positive and negative fentanyl reinforcement.

Fentanyl is a powerful painkiller that elicits euphoria and positive reinforcement1. Fentanyl also leads to dependence, defined by the aversive withdrawal syndrome, which fuels negative reinforcement2,3 (that is, individuals retake the drug to avoid withdrawal). Positive and negative reinforcement maintain opioid consumption, which leads to addiction in one-fourth of users, the largest fraction for all addictive drugs4. Among the opioid receptors, µ-opioid receptors have a key role5, yet the induction loci of circuit adaptations that eventually lead to addiction remain unknown. Here we injected mice with fentanyl to acutely inhibit γ-aminobutyric acid-expressing neurons in the ventral tegmental area (VTA), causing disinhibition of dopamine neurons, which eventually increased dopamine in the nucleus accumbens. Knockdown of µ-opioid receptors in VTA abolished dopamine transients and positive reinforcement, but withdrawal remained unchanged. We identified neurons expressing µ-opioid receptors in the central amygdala (CeA) whose activity was enhanced during withdrawal. Knockdown of µ-opioid receptors in CeA eliminated aversive symptoms, suggesting that they mediate negative reinforcement. Thus, optogenetic stimulation caused place aversion, and mice readily learned to press a lever to pause optogenetic stimulation of CeA neurons that express µ-opioid receptors. Our study parses the neuronal populations that trigger positive and negative reinforcement in VTA and CeA, respectively. We lay out the circuit organization to develop interventions for reducing fentanyl addiction and facilitating rehabilitation.

Fentanyl dysregulates neuroinflammation and disrupts blood-brain barrier integrity in HIV-1 Tat transgenic mice.

Opioid overdose deaths have dramatically increased by 781% from 1999 to 2021. In the setting of HIV, opioid drug abuse exacerbates neurotoxic effects of HIV in the brain, as opioids enhance viral replication, promote neuronal dysfunction and injury, and dysregulate an already compromised inflammatory response. Despite the rise in fentanyl abuse and the close association between opioid abuse and HIV infection, the interactive comorbidity between fentanyl abuse and HIV has yet to be examined in vivo. The HIV-1 Tat-transgenic mouse model was used to understand the interactive effects between fentanyl and HIV. Tat is an essential protein produced during HIV that drives the transcription of new virions and exerts neurotoxic effects within the brain. The Tat-transgenic mouse model uses a glial fibrillary acidic protein (GFAP)-driven tetracycline promoter which limits Tat production to the brain and this model is well used for examining mechanisms related to neuroHIV. After 7 days of fentanyl exposure, brains were harvested. Tight junction proteins, the vascular cell adhesion molecule, and platelet-derived growth factor receptor-ß were measured to examine the integrity of the blood brain barrier. The immune response was assessed using a mouse-specific multiplex chemokine assay. For the first time in vivo, we demonstrate that fentanyl by itself can severely disrupt the blood-brain barrier and dysregulate the immune response. In addition, we reveal associations between inflammatory markers and tight junction proteins at the blood-brain barrier.

Relationship between optical coherence tomography findings and clinical variables in patients with opiate use disorder / Relação entre os achados da tomografia de coerência óptica e as variáveis clínicas em pacientes com transtorno por uso de opiáceos

ABSTRACT Purpose: This study aimed to examine optical coherence tomography findings in patients with opiate use disorder by comparing them with healthy controls. Methods: The study included 30 opiate use disorder patients and 30 controls. The participants' detailed biomicroscopic examinations, visual acuity, intraocular pressure, and both eye examinations were evaluated. A total of 120 eyes were evaluated using optical coherence tomography, measuring the central macular thickness, mean macular thickness, mean macular volume and retinal nerve fiber layer thickness. Moreover, all participants filled in the demographic data form and Barratt Impulsiveness Scale. Results: Upon examination of the optical coherence tomography findings, central macular thickness, mean macular thickness, and mean macular volume were thinner in both eyes in patients with opiate use disorder (p<0.01 in all measurements in both eyes). Similarly, the total values of the superior quadrant and retinal nerve fiber layer thickness were statistically significant in both eyes compared to that in the control group (p=0.007, p=0.002; p=0.049, p=0.007, in the right and left eyes, respectively). Only the left eye was positively correlated with retinal nerve fiber layer superior quadrant measurement and hospitalization (r=0.380, p=0.039). Conclusion: Our results revealed that the patients' central macular thickness, mean macular thickness, and mean macular volume values were thinner. Increase in the retinal nerve fiber layer thickness superior quadrant thickness and total value was also observed. Further studies with larger sampling groups that evaluate neuroimaging findings should be conducted.

RESUMO Objetivo: O objetivo foi investigar foi, os achados da tomografia de coerência óptica em pacientes com transtorno do uso de opiáceos, comparando-os com controles saudáveis. Métodos: O estudo incluiu 30 pacientes com transtorno do uso de opiáceos e 30 controles. Os exames biomicroscópicos detalhados de todos os participantes, acuidade visual, pressão intraocular e ambos os exames oculares foram avaliados com tomografia de coerência óptica. Um total de 120 olhos foram avaliados usando tomografia de coerência óptica, e a espessura macular central, espessura macular média, volume macular médio e a espessura da camada de fibra nervosa da retina dos participantes foram medidos. Além disso, todos os participantes preencheram o Formulário de Dados Demográficos e a Escala de Impulsividade Barratt (BIS-11). Resultados: Quando os achados de tomografia de coerência óptica foram examinados, espessura macular central, espessura macular média e volume macular médio eram mais finos de acordo com controles saudáveis em ambos os olhos em pacientes com transtorno do uso de opiáceos (p<0,01 em todas as medições em ambos os olhos). Da mesma forma, os valores totais do quadrante superior e espessura da camada de fibra nervosa da retina estavam mais em níveis estatisticamente significativos em ambos os olhos em comparação com o grupo controle (p=0,007, p=0,002; p=0,049, p=0,007, no olho direito e esquerdo, respectivamente). Estar internado em hospital e apenas a medida do quadrante superior da espessura da camada de fibra nervosa da retina do olho esquerdo associou-se positivamente (r=0,380, p=0,039). Conclusão: Em nossos resultados, descobrimos que os valores de espessura macular central, espessura macular média e volume macular médio dos pacientes eram mais finos. Verificamos também espessamento no quadrante superior e valor total da espessura da camada de fibra nervosa da retina. Nosso estudo deve ser apoiado por novos estudos com grupos de amostragem maiores, nos quais os achados de neuroimagem são avaliados.

Opioid-induced fragile-like regulatory T cells contribute to withdrawal.

Dysregulation of the immune system is a cardinal feature of opioid addiction. Here, we characterize the landscape of peripheral immune cells from patients with opioid use disorder and from healthy controls. Opioid-associated blood exhibited an abnormal distribution of immune cells characterized by a significant expansion of fragile-like regulatory T cells (Tregs), which was positively correlated with the withdrawal score. Analogously, opioid-treated mice also showed enhanced Treg-derived interferon-γ (IFN-γ) expression. IFN-γ signaling reshaped synaptic morphology in nucleus accumbens (NAc) neurons, modulating subsequent withdrawal symptoms. We demonstrate that opioids increase the expression of neuron-derived C-C motif chemokine ligand 2 (Ccl2) and disrupted blood-brain barrier (BBB) integrity through the downregulation of astrocyte-derived fatty-acid-binding protein 7 (Fabp7), which both triggered peripheral Treg infiltration into NAc. Our study demonstrates that opioids drive the expansion of fragile-like Tregs and favor peripheral Treg diapedesis across the BBB, which leads to IFN-γ-mediated synaptic instability and subsequent withdrawal symptoms.

Picking a (neuroimmune) fight against fragile regulation of addiction.

T cells and their derived cytokines have been shown to modulate brain function. In this issue of Cell, Zhu, Yan, and colleagues demonstrate that opioid use impacts the crosstalk between the CNS and the peripheral immune system. Regulatory T cell (Treg)-derived IFN-γ signaling translates into synaptic weakening in the nucleus accumbens (NAc) to impart withdrawal-induced behavioral dysfunction.

Relationship between optical coherence tomography findings and clinical variables in patients with opiate use disorder.

PURPOSE: This study aimed to examine optical coherence tomography findings in patients with opiate use disorder by comparing them with healthy controls. METHODS: The study included 30 opiate use disorder patients and 30 controls. The participants' detailed biomicroscopic examinations, visual acuity, intraocular pressure, and both eye examinations were evaluated. A total of 120 eyes were evaluated using optical coherence tomography, measuring the central macular thickness, mean macular thickness, mean macular volume and retinal nerve fiber layer thickness. Moreover, all participants filled in the demographic data form and Barratt Impulsiveness Scale. RESULTS: Upon examination of the optical coherence tomography findings, central macular thickness, mean macular thickness, and mean macular volume were thinner in both eyes in patients with opiate use disorder (p<0.01 in all measurements in both eyes). Similarly, the total values of the superior quadrant and retinal nerve fiber layer thickness were statistically significant in both eyes compared to that in the control group (p=0.007, p=0.002; p=0.049, p=0.007, in the right and left eyes, respectively). Only the left eye was positively correlated with retinal nerve fiber layer superior quadrant measurement and hospitalization (r=0.380, p=0.039). CONCLUSION: Our results revealed that the patients' central macular thickness, mean macular thickness, and mean macular volume values were thinner. Increase in the retinal nerve fiber layer thickness superior quadrant thickness and total value was also observed. Further studies with larger sampling groups that evaluate neuroimaging findings should be conducted.

Chronic Kidney Disease from Polyvinylpyrrolidone Deposition in Persons with Intravenous Drug Use.

BACKGROUND AND OBJECTIVES: Persons with intravenous drug use have a higher risk of developing CKD compared with the general population. In Norway, deposits of polyvinylpyrrolidone have been observed in kidney biopsies taken from persons with opioid addiction and intravenous drug use since 2009. Polyvinylpyrrolidone is an excipient commonly used in pharmaceuticals, and the polyvinylpyrrolidone deposits observed in these patients were caused by intravenous injection of a specific oral methadone syrup containing very high molecular weight polyvinylpyrrolidone. Here, we present the clinicopathologic findings from 28 patients with CKD associated with polyvinylpyrrolidone deposition in the kidney. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: The 28 patients and their kidney biopsies were included when polyvinylpyrrolidone deposition was recognized, either retrospectively or at the time of diagnostic evaluation. Biopsies were taken between 2009 and 2016. We collected laboratory parameters and clinical data from digital patient charts. For each kidney biopsy, the glomerular volume, extent of polyvinylpyrrolidone deposition, and tubulointerstitial area with tubular atrophy were assessed quantitatively. RESULTS: All patients (mean age: 37 years) had CKD (mean eGFR: 33 ml/min per 1.73 m2) and normal urine protein or non-nephrotic-range proteinuria. Biopsies showed moderate to severe tubular atrophy (mean extent: 65%) and interstitial infiltrates of vacuolated macrophages containing polyvinylpyrrolidone (mean share of biopsy area: 1.5%). Underperfused and ischemic glomeruli were common findings. In 22 samples, ultrastructural investigation revealed polyvinylpyrrolidone-containing vacuoles in the mesangial or endothelial cells of glomeruli. At the last follow-up, most patients had stable or improved eGFR. Two patients had developed kidney failure and underwent hemodialysis. CONCLUSIONS: Intravenous injection of a specific oral methadone syrup caused polyvinylpyrrolidone deposition in the kidney in persons with opioid addiction and intravenous drug use. Kidney biopsy findings suggested an association between polyvinylpyrrolidone deposition and tubular atrophy.

Fentanyl-induced changes in brain activity in awake nonhuman primates at 9.4 Tesla.

Functional magnetic resonance imaging (fMRI) has been used to study the influence of opioids on neural circuitry implicated in opioid use disorder, such as the cortico-striatal-thalamo-cortical (CSTC) circuit. Given the increase in fentanyl-related deaths, this study was conducted to characterize the effects of fentanyl on patterns of brain activation in awake nonhuman primates. Four squirrel monkeys were acclimated to awake scanning procedures conducted at 9.4 Tesla. Subsequently, test sessions were conducted in which a dose of fentanyl that reliably maintains intravenous (IV) self-administration behavior in monkeys, 1 µg/kg, was administered and the effects on patterns of brain activity were assessed using: (1) a pharmacological regressor to elucidate fentanyl-induced patterns of neural activity, and (2) seed-based approaches targeting bilateral anterior cingulate, thalamus, or nucleus accumbens (NAc) to determine alterations in CSTC functional connectivity. Results showed a functional inhibition of BOLD signal in brain regions that mediate behavioral effects of opioid agonists, such as cingulate cortex, striatum and midbrain. Functional connectivity between each of the seed regions and areas involved in motoric, sensory and cognition-related behavior generally decreased. In contrast, NAc functional connectivity with other striatal regions increased. These results indicate that fentanyl produces changes within CSTC circuitry that may reflect key features of opioid use disorder (e.g. persistent drug-taking/seeking) and thereby contribute to long-term disruptions in behavior and addiction. They also indicate that fMRI in alert nonhuman primates can detect drug-induced changes in neural circuits and, in turn, may be useful for investigating the effectiveness of medications to reverse drug-induced dysregulation.

Evaluation of Factors Relevant to Pain Control Among Patients After Surgical Treatment.

Importance: Opioids are often prescribed after elective surgical treatment despite the potential for misuse. Although various pain control regimens exist, patient preferences for acute postoperative pain management are unknown. Objective: To describe patient-reported key attributes of postoperative pain management. Design, Setting, and Participants: This decision analytical model used responses from a survey based on conjoint analysis to investigate the value patients placed on different aspects of postoperative pain management. Participants were patients aged 18 years or older who underwent elective hand surgical procedures between July 1, 2018, and July 23, 2019, at a single academic center. The survey was completed on a web-based platform and took place between November 2019 and January 2020. Data were analyzed from May through July 2021. Exposures: Participants were presented with a series of discrete-choice tasks and asked to select between 2 postoperative medication options that changed from question to question and had varying characteristics. Main Outcomes and Measures: Attribute importance scores and part-worth utility values for the queried aspects of pain control were calculated. Results: Of 710 individuals invited, 321 (45.2%) completed the survey; there were 212 (66.0%) women and 108 (33.6%) men, and the most common age category was 60 to 69 years (102 participants [31.8%]). Most patients reported previous opioid use (282 individuals [87.9%]). Factors in the decision-making process with the highest attribute importance scores (SDs) were risk of addiction (26.3% [13.0%]) and amount of pain relief (25.6% [14.6%]). Adverse effects 13.9% (7.2%), functional independence 11.8% (7.3%), and level of trust in the prescriber 11.4% (5.8%) had intermediate attribute importance scores (SDs). Cost 7.9% (4.4%) and stigma 3.1% (1.3%) had the lowest attribute importance scores (SDs) in patient decisions. Conclusions and Relevance: These findings suggest that multimodal pain control regimens that are associated with optimized pain relief and minimized risk of addiction are preferable to treat acute postoperative pain. The results suggest that identifying procedures for which patients prioritize minimizing risk of addiction over pain relief and incorporating patient preferences into decision-making may be associated with decreased postoperative opioid prescribing.

Clinical Performance of a Gene-Based Machine Learning Classifier in Assessing Risk of Developing OUD in Subjects Taking Oral Opioids: A Prospective Observational Study.

OBJECTIVE: To reduce the incidence of Opioid Use Disorder (OUD), multiple guidelines recommend assessing the risk of OUD prior to prescribing oral opioids. Although subjective risk assessments are available to help classify subjects at risk for OUD, we are aware of no clinically validated objective risk assessment tools. An objective risk assessment based on genetics may help inform shared decision-making prior to prescribing short-duration oral opioids. METHODS: A multicenter, observational cohort of adults exposed to prescription oral opioids for 4-30 days was conducted to determine the performance of an OUD classifier derived from machine learning (ML). From this cohort, the demographics of the U.S. adult opioid-prescribed population were used to create a blinded, random, representative group of subjects (n=385) for analysis to accurately estimate the performance characteristics in the intended use population. Genotyping was performed via a qualitative SNP microarray on DNA extracted from buccal samples. RESULTS: In the study subjects, the classifier demonstrated 82.5% sensitivity (95% confidence intervals: 76.1%-87.8%) and 79.9% specificity (73.7-85.2%), with no statistically significant differences in clinical performance observed based on gender, age, length of follow-up from opioid exposure, race, or ethnicity. CONCLUSION: This study demonstrates an ML classifier may provide additional objective information regarding a patient's risk of developing OUD. This information may enable subjects and healthcare providers to make more informed decisions when considering the use of oral opioids.

Endogenous and exogenous opioid effects on oligodendrocyte biology and developmental brain myelination.

The elevated presence of opioid receptors and their ligands throughout the developing brain points to the existence of maturational functions of the endogenous opioid system that still remain poorly understood. The alarmingly increasing rates of opioid use and abuse underscore the urgent need for clear identification of those functions and the cellular bases and molecular mechanisms underlying their physiological roles under normal and pathological conditions. This review is focused on current knowledge on the direct and indirect regulatory roles that opioids may have on oligodendrocyte development and their generation of myelin, a complex insulating membrane that not only facilitates rapid impulse conduction but also participates in mechanisms of brain plasticity and adaptation. Information is examined in relation to the importance of endogenous opioid function, as well as direct and indirect effects of opioid analogues, which like methadone and buprenorphine are used in medication-assisted therapies for opioid addiction during pregnancy and pharmacotherapy in neonatal abstinence syndrome. Potential opioid effects are also discussed regarding late myelination of the brain prefrontal cortex in adolescents and young adults. Such knowledge is fundamental for the design of safer pharmacological interventions for opioid abuse, minimizing deleterious effects in the developing nervous system.

Characterization of neonatal opioid withdrawal syndrome in Arizona from 2010-2017.

In this paper, we describe a population of mothers who are opioid dependent at the time of giving birth and neonates exposed to opioids in utero who experience withdrawal following birth. While there have been studies of national trends in this population, there remains a gap in studies of regional trends. Using data from the Arizona Department of Health Services Hospital Discharge Database, this study aimed to characterize the population of neonates with neonatal opioid withdrawal syndrome (NOWS) and mothers who were opioid dependent at the time of giving birth, in Arizona. We analyzed approximately 1.2 million electronic medical records from the Arizona Department of Health Services Hospital Discharge Database to identify patterns and disparities across socioeconomic, ethnic, racial, and/or geographic groupings. In addition, we identified comorbid conditions that are differentially associated with NOWS in neonates or opioid dependence in mothers. Our analysis was designed to assess whether indicators such as race/ethnicity, insurance payer, marital status, and comorbidities are related to the use of opioids while pregnant. Our findings suggest that women and neonates who are non-Hispanic White and economically disadvantaged, tend be part of our populations of interest more frequently than expected. Additionally, women who are opioid dependent at the time of giving birth are unmarried more often than expected, and we suggest that marital status could be a proxy for support. Finally, we identified comorbidities associated with neonates who have NOWS and mothers who are opioid dependent not previously reported.

Increase of Cry 1 expression is a common phenomenon of the disturbed circadian clock in ischemic stroke and opioid addiction.

Increasing evidences suggest the involvement of disrupted circadian clock in various pathologies including stroke and substance abuse. Here we took an attempt to do a comparative study on the regulation of circadian clock gene expression under two pathological circumstances - Opioid addiction and Ischemic stroke in the same cell line model (human neuroblastoma SH-SY5Y cells). To mimic in vivo ischemic stroke condition cells were placed in a hypoxia chamber and incubated for 10 h in balanced salt solution lacking glucose, aerated with an anaerobic gas mixture (95% N2 and 5% C02). For opioid addiction cells were treated with morphine sulphate at 10 µM dose for 48 h. We found that although circadian clock gets disturbed in both states, pattern of alteration of clock gene expressions were different and change was more severe in ischemic stroke than addiction. Interestingly, increase in expression of Cry1 showed as a common factor to both the diseases. This paper also emphasizes the interconnection between the severities of neuronal injury induced by ischemic stroke or opioid abuse to circadian system. Finally, this study will further enrich our knowledge towards the pattern of circadian rhythm disturbances under different pathological states.

A large-scale retrospective study of opioid poisoning in New York State with implications for targeted interventions.

Opioid overdose related deaths have increased dramatically in recent years. Combating the opioid epidemic requires better understanding of the epidemiology of opioid poisoning (OP). To discover trends and patterns of opioid poisoning and the demographic and regional disparities, we analyzed large scale patient visits data in New York State (NYS). Demographic, spatial, temporal and correlation analyses were performed for all OP patients extracted from the claims data in the New York Statewide Planning and Research Cooperative System (SPARCS) from 2010 to 2016, along with Decennial US Census and American Community Survey zip code level data. 58,481 patients with at least one OP diagnosis and a valid NYS zip code address were included. Main outcome and measures include OP patient counts and rates per 100,000 population, patient level factors (gender, age, race and ethnicity, residential zip code), and zip code level social demographic factors. The results showed that the OP rate increased by 364.6%, and by 741.5% for the age group > 65 years. There were wide disparities among groups by race and ethnicity on rates and age distributions of OP. Heroin and non-heroin based OP rates demonstrated distinct temporal trends as well as major geospatial variation. The findings highlighted strong demographic disparity of OP patients, evolving patterns and substantial geospatial variation.

Epigenome-wide study of brain DNA methylation following acute opioid intoxication.

BACKGROUND: Opioid abuse poses significant risk to individuals in the United States and epigenetic changes are a leading potential biomarker of opioid abuse. Current evidence, however, is mostly limited to candidate gene analysis in whole blood. To clarify the association between opioid abuse and DNA methylation, we conducted an epigenome-wide analysis of DNA methylation in brain samples of individuals who died from acute opioid intoxication and group-matched controls. METHODS: Tissue samples were extracted from the dorsolateral prefrontal cortex of 153 deceased individuals (Mage = 35.42; 62 % male; 77 % European ancestry). The study included 72 opioid samples, 53 psychiatric controls, and 28 normal controls. The epigenome-wide analysis was implemented using the Illumina MethylationEPIC BeadChip; analyses adjusted for sociodemographic characteristics, negative control principal components, ancestry principal components, cellular composition, and surrogate variables. Horvath's epigenetic age and Levine's PhenoAge were calculated, and gene set enrichment analyses were performed. RESULTS: Although no CpG sites survived false-discovery rate correction for multiple testing, 13 sites surpassed a relaxed significance threshold (p < 1.0 × 10-5). One of these sites was located within Netrin-1, a gene implicated in kappa opioid receptor activity. There was an association between opioid use and accelerated PhenoAge (b = 2.24, se = 1.11, p = .045). Gene set enrichment analyses revealed enrichment of differential methylation in GO and KEGG pathways broadly related to substance use. CONCLUSIONS: Netrin-1 may be associated with opioid overdose, and future research with larger samples across stages of opioid use will elucidate the complex genomics of opioid abuse.

SnapShot: Neurobiology of opioid use disorder.

The use of opioid drugs and related overdose deaths, which rose to epidemic proportions over the past decade, have been exacerbated by the COVID pandemic, a time of great uncertainty and isolation. Much is known about opioid pharmacology and related neural circuits that, combined with novel emerging neurobiological insights, can help guide new treatment strategies. To view this SnapShot, open or download the PDF.

Acute opioid use may cause choroidal thinning and retinal nerve fiber layer increase.

The number of optical coherence tomography (OCT) examinations in substance use disorders is gradually increasing. However, OCT findings in opioid use disorder (OUD) have not yet been investigated. In this study, we compared the retinal nerve fiber layer (RNFL), the ganglion cell layer (GCL), the inner plexiform layer (IPL), and choroid thickness (CT) of OUD and control groups. We included 43 male patients and 43 healthy male controls of similar age (p = 0.296) in the study, prospectively. On the day of OCT application, urine toxic screening test results of all OUD patients were positive for opioid use. There was a significant difference between OUD and control groups in terms of CT (p < 0.05), nasal superior (NS), and nasal (N) sectors of the RNFL (p < 0.05) values of both eyes. According to the binary logistic regression analysis, the sensitivity of mean NS (p = 0.001) and mean CT (p = 0.007) related to the diagnosis of OUD was 72.1 percent, and the specificity was 65.1 percent. Receiver operating characteristic (ROC) analysis revealed that the sensitivity and specificity of mean CT for the diagnosis of OUD were 18.6% and 97.7%, respectively. This is the first study to investigate the OCT findings in OUD. Our findings are important in terms of showing thinning in the choroidal layer and an increase in the volume of the NS and N sectors of RNFL while detecting opioids in the body/urine. Further studies are needed to clarify whether these differences are due to the acute and/or chronic effects of opioids.

Opioid use as a potential risk factor for pancreatic cancer in the United States: An analysis of state and national level databases.

Pancreatic cancer (PC) rate is increasing in the U.S. The use of prescription and illicit opioids has continued to rise nationally in recent years as well. Opioids have been shown to have a deleterious effect on multiple types of cancer with recent data suggesting opium use as a risk factor for PC. Using national databases, we tested whether opioid usage pattern over time could explain the state and national-based variations in PC rates in the U.S. Opioid death rate (as a surrogate for prescription and illicit opioid use) was extracted from the CDCs Wonder online data through the Vital Statistics Cooperative Program. Incidence of pancreatic cancer was retrieved from the online CDCs data base gathered from the U.S. Cancer Statistics Working Group. Prevalence of obesity, tobacco and alcohol use was collected from Behavioral risk factor surveillance system. Mixed-effects regression models were used to test the association between levels of PC rate and opioid death/use rates during the years 1999-2016. A rise in PC was seen over time at the national and state levels. Similarly, the opioid death rates increased over time. Among other potential PC risk factors, only obesity prevalence showed an increase during the study period. A state's opioid death rate at 4 years prior significantly predicted initial incidence of PC (ß = 0.1848, p<0.0001) and had a significant effect on the estimated annual change in the rate of PC (ß = -.0193,p<0.0001). Opioid use may be an un-identified risk factor contributing to the increasing incidence of PC in the U.S. These novel findings need to be verified by population-based studies.

Glutamatergic Systems and Memory Mechanisms Underlying Opioid Addiction.

Glutamate is the main excitatory neurotransmitter in the brain and is of critical importance for the synaptic and circuit mechanisms that underlie opioid addiction. Opioid memories formed over the course of repeated drug use and withdrawal can become powerful stimuli that trigger craving and relapse, and glutamatergic neurotransmission is essential for the formation and maintenance of these memories. In this review, we discuss the mechanisms by which glutamate, dopamine, and opioid signaling interact to mediate the primary rewarding effects of opioids, and cover the glutamatergic systems and circuits that mediate the expression, extinction, and reinstatement of opioid seeking over the course of opioid addiction.

Does a hypoxic injury from a non-fatal overdose lead to an Alzheimer Disease?

Long term consequence of non-fatal overdose in people who use opioids are not well understood. The intermittent exposure to non-fatal overdose leads to a tauopathy that is often accompanied by abrogated neuroprotective response, abnormal amyloid processing and other pathologies. The scope and limitations of available literature are discussed including neuropathologies associated with opioid and overdose exposures, contributing comorbidities and proteinopathies. Contrasting postmortem data of overdose victims with animal models of opioid neuropathologies and hypoxic injury paints a picture distinct from other proteinopathies as well as effects of moderate opioid exposure. Furthermore the reported biochemical changes and potential targets for therapeutic intervention were mapped pointing to underlying imbalance between tau kinases and phosphatases that is characteristic of Alzheimer Disease.