Opioids and anxiety

Orgasms, sexual pleasure, and opioid reward mechanisms

INTRODUCTION

Sexual activity produces pleasure related to sexual arousal, desire, and genitosensory and erogenous stimulation. Orgasms produce a whole brain and body rush of ecstatic pleasure followed by relaxation and refractoriness. This pleasure results from the activation of neurochemical reward pathways in the brain. This is differentiated by spinal pathways that control climax, the particular motor movements of the pelvic floor and the experience of tension release.

OBJECTIVES

To relate the activation of key neurochemical reward and bonding systems, notably dopamine, oxytocin, and opioids, to the pleasure of sexual activity in general and orgasms in particular.

METHODS

A narrative review of the neurochemical and neuroanatomical mechanisms activated during sexual stimulation and orgasm in rats and humans, and how they are related overall to the generation of sexual pleasure and reward.

RESULTS

Appetitive sexual pleasure involves the activation of dopamine and oxytocin release in hypothalamic and mesolimbic regions that regulate sexual arousal and desire, and are reinforced by localized opioid activity. Orgasms are thought to result in part from a massive release of opioids into these regions that inhibits dopamine and oxytocin transmission, but that initiates molecular changes to sensitize both systems and induce sexually conditioned place and partner preferences. Serotonin is also activated at orgasm and contributes to feelings of satiety and refractoriness. Orgasm disorders are distressing, cause resentment and conflict in a relationship, and diminish overall sexual health and well-being.

CONCLUSIONS

Orgasms are an important component of sexual pleasure for humans and perhaps all vertebrates. Endogenous opioids like β-endorphin that bind to mu opioid receptors are likely responsible for sexual pleasure and reward.

Emergency palliative cancer care: anxiety and midazolam

BACKGROUND AND OBJECTIVE

Cancer patients treated with palliative intent often report anxiety. Anxiety is associated with dyspnoea, cancer pain, and reduced quality of life. Limited knowledge on variability and treatment effects warranted exploring factors associated with improvement in anxiety for hospitalised palliative cancer patients.

METHODS

This study is a cross-sectional secondary analysis. All patients admitted to an acute palliative care unit for one year were assessed and 164 patients satisfied the study inclusion criteria. The patients reported self-registered symptom intensities using the 11-point numeric rating scale. Demographic variables, patient reports, and medical management were analysed for associations with anxiety.

RESULTS

At admission, 37.8% of the patients reported moderate or severe anxiety, and of these 43.6% used benzodiazepines. The corresponding numbers for benzodiazepine use were 35.1% and 24.4% for patients with mild and no anxiety, respectively. Of all patients, 26.8% reported improved anxiety during their hospital stay. More patients with moderate or severe anxiety at admission reported improved anxiety during hospitalisation (50.0%) compared to the corresponding patients with mild anxiety (22.8%). Patients with moderate or severe anxiety reported less improvement in pain compared to patients with mild anxiety. Improved dyspnoea was the only factor statistically associated with improvement in anxiety, both for patients reporting mild anxiety and moderate and severe anxiety. Thirty-seven-point-1% of patients with moderate or severe anxiety at admission received no benzodiazepine treatment during the hospital stay. Patients receiving midazolam had more anxiety at admission, were younger, and had poorer performance status. Median dose and interquartile range [IQR] of midazolam in these patients were 2 mg/24 h [IQR: 2.0-6.0].

CONCLUSION

Improved dyspnoea was associated with reduced anxiety; however, the use of benzodiazepines was not.

Machine learning and confirmatory factor analysis show that buprenorphine alters motor and anxiety-like behaviors in male, female, and obese C57BL/6J mice

Buprenorphine is an opioid approved for medication-assisted treatment of opioid use disorder. Used off-label, buprenorphine has been reported to contribute to the clinical management of anxiety. Although human anxiety is a highly prevalent disorder, anxiety is a latent construct that cannot be directly measured. The present study combined machine learning techniques and artificial intelligence with confirmatory factor analysis to evaluate the hypothesis that buprenorphine alters motor and anxiety-like behavior in C57BL/6J (B6) mice (n = 30) as a function of dose, sex, and body mass. After administration of saline (control) or buprenorphine, mice were placed on an elevated zero maze (EZM) for 5 min. Digital video of mouse behavior was uploaded to the cloud, and mouse position on the maze was tracked and analyzed with supervised machine learning and artificial intelligence. ANOVA and post hoc test showed that buprenorphine significantly altered five motor behaviors. Confirmatory factor analysis revealed that the latent construct of anxiety-like behavior accounted for a statistically significant amount of variance in all five motor behaviors.NEW & NOTEWORTHY Machine learning and pose estimation using a convolutional neural network accurately detected and objectively scored buprenorphine-induced changes in locomotor behaviors of mice on an elevated zero maze (EZM). Confirmatory factor analysis supports the interpretation that the anxiety-like construct accounted for the buprenorphine-induced changes in motor behavior. The results have noteworthy implications for the relationship between Darwin's story model of mammalian emotions and computational models of anxiety-like behavior in mice.

The impact of community-based, non-pharmaceutical interventions on anxiety and depression in fibromyalgia: A systematic review and network meta-analysis

BACKGROUND

Fibromyalgia syndrome (FMS) is often accompanied by anxiety and depression, seriously affecting the prognosis of patients. Active non-pharmacological therapies are the mainstay of treatment, but the optimal choice is still contentious.

METHODS

We did a network meta-analysis(NMA) of RCTs and compared 7 community-based non-pharmacological interventions based on 29 studies. We searched Embase, MEDLINE, PubMed, Scopus, Google Scholar, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) from the database inception to March 2022.

RESULTS

The NMA demonstrated that five out of six (83.34%) non-pharmacological interventions were associated with significant improvement in anxiety compared with usual care, with a standardized mean difference (SMD) ranging from -1.14 (95% CI: -1.76 to -0.51) for aquatic exercise to -0.39 (95% CI: 073-0.05) for meditation; six of the seven non-pharmacological interventions (85.71%) were associated with significant improvement in depression, with SMD ranged from -1.18 (95% CI: -1.68 to -0.68) for aquatic exercise to -0.46 (95% CI: -0.86 to -0.05) for education therapy.

LIMITATION

First of all, there were scale translation biases in this study caused by the different languages of the original study. In addition, there was a lack of direct comparison between the aquatic exercise group and the routine care group, and the third included intervention measures lacked unified implementation standards.

CONCLUSION

Aquatic exercise exhibited distinct advantages compared with other community-based non-pharmacological interventions and is likely to have optimal efficacy in improving anxiety and depression. The study protocol is registered with the Prospective Register of Systematic Reviews (PROSPERO, CRD 42022338406).

Ethanol for the management of alcohol withdrawal syndrome: a systematic review

INTRODUCTION

Alcohol withdrawal is typically managed using benzodiazepines. However, modulation of both γ-aminobutyric acid-A and N-methyl-d-aspartate-receptors through ethanol provision may provide an alternative management strategy. This systematic review critically analyses the evidence surrounding the use of oral or intravenous ethanol for the management of alcohol withdrawal syndrome.

METHODS

Systematic searches of ProQuest - American Psychological Association, PsycInfo, MEDLINE and PubMed Central, Web of Science and Embase were performed (Prospero registration number: CRD42023425224). Search criteria were: Population = Patients receiving pharmacological interventions to treat or prevent alcohol withdrawal in a healthcare setting. Intervention = intravenous or enteral ethanol. Comparator = standard care, benzodiazepines, carbamazepine, adjunct medications including sedatives, or no comparator. Outcomes = complication rates, symptom scores, length of stay in healthcare settings. Exclusions were: preclinical studies, participants less than 18 years old, non-peer reviewed literature, poor study design or poor data quality. Study quality was assessed using an adapted National Institute for Health and Care Research quality tool. A narrative data synthesis approach was adopted.

RESULTS

Eight thousand two hundred and four studies were retrieved. Ten were included in the final analysis. Overall study quality was poor. Seven studies reported treatment outcomes that were comparable to a control arm or in which ethanol conferred no detrimental effect. Three studies reported positive outcomes, and one study reported worse outcomes following ethanol administration.

DISCUSSION

The review identified heterogeneity in study design and limited reporting surrounding patient demographics, patient alcohol use history and the practicalities of ethanol administration. As such, implementation of ethanol prescribing for the management of alcohol withdrawal is currently limited due to the quality and translatability of existing data surrounding its use.

CONCLUSIONS

Further studies are required with more transparent and complete outcome reporting and practical implementation recommendations in order to facilitate the translation of ethanol prescribing for the management of alcohol withdrawal syndrome.

The Limbic System in Co-Occurring Substance Use and Anxiety Disorders: A Narrative Review Using the RDoC Framework

Substance use disorders (SUDs) and anxiety disorders (ADs) are highly comorbid, a co-occurrence linked to worse clinical outcomes than either condition alone. While the neurobiological mechanisms involved in SUDs and anxiety disorders are intensively studied separately, the mechanisms underlying their comorbidity remain an emerging area of interest. This narrative review explores the neurobiological processes underlying this comorbidity, using the Research Domain Criteria (RDoC) framework to map disruptions in positive valence, negative valence, and cognitive systems across the three stages of the addiction cycle: binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation. Anxiety and substance use play a reciprocal role at each stage of addiction, marked by significant psychosocial impairment and dysregulation in the brain. A more thorough understanding of the neural underpinnings involved in comorbid SUDs and anxiety disorders will contribute to more tailored and effective therapeutic interventions and assessments.

Anxiety disorders: Treatments, models, and circuitry mechanisms

Anxiety disorders are one of the most prevalent mental health conditions worldwide, imposing a significant burden on individuals affected by them and society in general. Current research endeavors aim to enhance the effectiveness of existing anxiolytic drugs and reduce their side effects through optimization or the development of new treatments. Several anxiolytic novel drugs have been produced as a result of discovery-focused research. However, many drug candidates that show promise in preclinical rodent model studies fail to offer any substantive clinical benefits to patients. This review provides an overview of the diagnosis and classification of anxiety disorders together with a systematic review of anxiolytic drugs with a focus on their targets, therapeutic applications, and side effects. It also provides a concise overview of the constraints and disadvantages associated with frequently administered anxiolytic drugs. Additionally, the study comprehensively reviews animal models used in anxiety studies and their associated molecular mechanisms, while also summarizing the brain circuitry related to anxiety. In conclusion, this article provides a valuable foundation for future anxiolytic drug discovery efforts.

Analysis of Salivary Neuropeptides in Anxiety and Depression Using the Luminex MAGPIX® System

BACKGROUND

Anxiety and depressive disorders are highly prevalent mental health conditions, affecting millions worldwide. Advancements in neurobiology have identified the effects of various neuropeptides in modulating mood and stress responses. Some of the well-researched neuropeptides in plasma are oxytocin (OXT), alpha-melanocyte-stimulating hormone (alpha-MSH), beta-endorphin, neurotensin, and substance P. In this study, we used methods of liquid biopsy to acquire saliva samples to analyze the concentrations of neuropeptides associated with depression.

METHODS

The study was conducted in Bratislava, Slovakia, from January to June 2022. Participants were 20 subjects treated for depression and anxiety without medication; the control group consisted of 20 healthy individuals with no personal history of depression or anxiety. Salivary samples were collected using buccal swabs to measure the concentrations of the examined neuropeptides. Laboratory analysis was based on detecting fluorescent signals performed on the Luminex MAGPIX® System (Luminex Corporation, Austin, Texas). Means and standard deviations were calculated for individual neuropeptide levels. To determine if there are statistically significant differences in neuropeptide levels between individuals with and without depression, independent t-tests and a one-way ANOVA were conducted.

RESULTS

Our findings indicate a significant decrease in all studied neuropeptides in subjects compared to healthy controls. Reductions in mean levels were observed for OXT (7.3), alpha-MSH (3.9), beta-endorphin (2.9), neurotensin (15.1), and a 6.9-fold decrease for substance P. Alpha-MSH and beta-endorphin showed higher variability in measured levels within both groups.

CONCLUSION

The results of this study indicate that the levels of the studied salivary neuropeptides, OXT, alpha-MSH, beta-endorphin, neurotensin, and substance P, are statistically significantly reduced in individuals with depression compared to healthy controls.

Erectile dysfunction among male patients receiving methadone maintenance treatment: focusing on anxiety-related symptoms

Background

Erectile dysfunction (ED) in patients receiving methadone maintenance treatment (MMT) is a relatively neglected issue.

Aim

In this study we sought to determine the actual prevalence of ED and risky sexual behaviors in patients receiving MMT and identify clinically relevant risk factors for ED, particularly mental health conditions, that may contribute to achieving holistic healthcare and improving treatment adherence in this patient population.

Methods

A cross-sectional study of male Chinese MMT patients was conducted. Comprehensive demographic and clinical data regarding age, obesity, history of major mental and physical illness, HIV infection, other substance use, methadone dose/duration, and associated risky sexual behaviors were all collected. Assessment tools, including the 5-item International Index of Erectile Function, the Chinese Health Questionnaire, and the Taiwanese Depression Questionnaire were administered.

Outcomes

The relationship between mental health-related factors and ED was fully analyzed and elaborated.

Results

The prevalence of ED among male patients in a methadone maintenance therapy outpatient clinic was 55.7%. The prevalence rate of ED among the individuals treated for longer than 6 months was 56.8%, whereas that for untreated individuals was 52.0%. Additionally, methadone-treated individuals were older and had a higher proportion of condom use and drug-assisted sexual activity than untreated individuals. Pearson correlation revealed that higher Chinese Health Questionnaire and Taiwanese Depression Questionnaire scores were negatively correlated with lower scores on the 5-item International Index of Erectile Function. In the multivariate regression model, anxiety and other psychosomatic symptoms were associated with more severe ED, whereas individuals who consumed alcohol within the past month had less severe ED after adjustment for other demographic and clinical variables. The findings of the present study revealed no association between ED and methadone treatment duration or dosage.

Clinical Implications

Healthcare professionals should discuss mental health issues in patients on MMT with ED, especially anxiety symptoms and recent alcohol use.

Strengths and Limitations

This study is one of the few reports within the limited body of research highlighting a significant association of ED with anxiety-related symptoms in patients undergoing MMT. Our study had some limitations. First, the sample size of HIV-infected individuals was insufficient. Second, the cross-sectional study design could not definitively demonstrate a causal mechanism.

Conclusion

In patients undergoing MMT, individuals who reported less severe anxiety symptoms and alcohol consumption in the past month tended to have less severe ED, regardless of the MMT duration or dosage.

The Roles of Endogenous Opioids in Placebo and Nocebo Effects: From Pain to Performance to Prozac

Placebo and nocebo effects have been well documented for nearly two centuries. However, research has only relatively recently begun to explicate the neurobiological underpinnings of these phenomena. Similarly, research on the broader social implications of placebo/nocebo effects, especially within healthcare delivery settings, is in a nascent stage. Biological and psychosocial outcomes of placebo/nocebo effects are of equal relevance. A common pathway for such outcomes is the endogenous opioid system. This chapter describes the history of placebo/nocebo in medicine; delineates the current state of the literature related to placebo/nocebo in relation to pain modulation; summarizes research findings related to human performance in sports and exercise; discusses the implications of placebo/nocebo effects among diverse patient populations; and describes placebo/nocebo influences in research related to psychopharmacology, including the relevance of endogenous opioids to new lines of research on antidepressant pharmacotherapies.

Simple Coumarins from Peucedanum luxurians Fruits: Evaluation of Anxiolytic Activity and Influence on Gene Expression Related to Anxiety in Zebrafish Model

Anxiety is one of the most common central nervous system disorders, affecting at least one-quarter of the worldwide population. The medications routinely used for the treatment of anxiety (mainly benzodiazepines) are a cause of addiction and are characterized by many undesirable side effects. Thus, there is an important and urgent need for screening and finding novel drug candidates that can be used in the prevention or treatment of anxiety. Simple coumarins usually do not show side effects, or these effects are much lower than in the case of synthetic drugs acting on the central nervous system (CNS). This study aimed to evaluate the anxiolytic activity of three simple coumarins from Peucedanum luxurians Tamamsch, namely officinalin, stenocarpin isobutyrate, and officinalin isobutyrate, in a 5 dpf larval zebrafish model. Moreover, the influence of the tested coumarins on the expression of genes involved in the neural activity (c-fos, bdnf) or dopaminergic (th1), serotoninergic (htr1Aa, htr1b, htr2b), GABA-ergic (gabarapa, gabarapb), enkephalinergic (penka, penkb), and galaninergic (galn) neurotransmission was assessed by quantitative PCR. All tested coumarins showed significant anxiolytic activity, with officinalin as the most potent compound. The presence of a free hydroxyl group at position C-7 and the lack of methoxy moiety at position C-8 might be key structural features responsible for the observed effects. In addition, officinalin and its isobutyrate upregulated the expression of genes involved in neurotransmission and decreased the expression of genes connected with neural activity. Therefore, the coumarins from P. luxurians might be considered as promising drug candidates for the therapy of anxiety and related disorders.

Risk Factors for Prolonged Opioid Use Following Total Hip Arthroplasty and Total Knee Arthroplasty: A Narrative Review of Recent Literature

Objective:

To provide pharmacists and other health care professionals with the knowledge required to minimize the risk of prolonged opioid use following total hip arthroplasty (THA) and total knee arthroplasty (TKA).

Data Sources:

A literature search of PubMed and Embase was performed, and included the search terms: (opioid OR opiate OR opium) AND (risk factor OR predict*) AND (arthroplasty OR replacement) NOT shoulder.

Study Selection and Data Extraction:

Randomized control trials, cohort studies (both prospective and retrospective), systematic reviews, and meta-analyses were included if risk ratios (RRs) or odds ratios (ORs) were reported and published within the last 5 years.

Data Synthesis:

]Twenty studies met inclusion criteria, including 2 meta-analyses and 2 prospective studies. There were several risk factors that overlapped between studies and presented clinically significant risks for prolonged opioid use following THA and TKA surgery. Of these, age < 65 (RRs: 1.15-9.36), preoperative opioid use (RRs: 1.09-7.81), larger quantities of opioids prescribed at discharge (RRs: 1.26-8.81), and TKA surgery (RRs: 1.73-6.07) were the most significant. Several risk factors were recently described, including migraines (RRs: 1.14-5.11) and fibromyalgia (RRs: 1.1-2.3) that may be of interest for further research.

Relevance to Patient Care and Clinical Practice:

This review presents a discussion of the factors associated with prolonged opioid use following THA and TKA surgeries, which are among the most common orthopedic surgeries.

Conclusions:

Prescribers should carefully consider patient-specific factors when prescribing opioids as there are several factors, including age, surgery type, and medical conditions that can predispose patients to prolonged opioid use.

Effects of acute pain medications on posttraumatic stress symptoms in early aftermath of trauma

Posttraumatic stress symptoms (PTSS) develop as sequelae from traumatic injuries. Limited studies suggest that using opioids to reduce acute pain immediately after trauma may also reduce subsequent PTSS, but other pain medications rarely have been examined for preventing acute PTSS. The current study examined the effects of commonly used pain medications, opioid and nonsteroidal anti-inflammatory drugs (NSAIDs), on PTSS after acute traumatic injuries. Participants ( n = 71) were categorized into opioid or NSAID group according to their medical records and self-reported medication use. Their PTSS were assessed using posttraumatic stress disorder checklist twice within 2 weeks after trauma. Participants' pain levels reduced from pretreatment to follow-up in both groups, F (1, 55) = 6.696, P = 0.012, partial η 2 = 0.109. Interestingly, a significant interaction between time and medication group on PTSS reached statistical significance, F (1, 69) = 6.014, P = 0.017, partial η 2 = 0.080. Follow-up analyses revealed that this interaction was driven by a significant PTSS reduction only in opioid but not in NSAID group. These findings suggested that pain reduction alone is not sufficient to reduce acute PTSS in the NSAID group, highlighting the need to continue further investigations into the mechanisms by which opioids reduce PTSS in the early posttrauma period.

Case Report: De Novo and Persistent Psychosis After Withdrawal From Chronic Opioid Therapy

Psychiatric illness is associated with both chronic pain syndromes and opioid use disorder, further complicating how we care for patients with psychiatric issues. We report a unique case of a de novo and persistent psychotic disorder after complicated opioid withdrawal in a patient without any psychiatric history. The patient developed persistent auditory hallucinations after discontinuation of chronic opioid therapy that responded only to atypical antipsychotic (olanzapine) treatment. This case illustrates the neuropsychiatric effects of chronic opioid exposure, as well as layered clinical management dimensions related to opioid detoxification and psychosis treatment. Long-term opioid therapy may have lasting neuropsychiatric effects, including playing a role in the development and/or expression of psychotic disorders. Here we review the limited literature on the effects of opioids on psychosis. This complex case also demonstrates a clinical approach for effectively co-managing psychiatric symptoms in the context of chronic pain and chronic opioid therapy.

Anxiety and Depression: What Do We Know of Neuropeptides?

In modern society, there has been a rising trend of depression and anxiety. This trend heavily impacts the population's mental health and thus contributes significantly to morbidity and, in the worst case, to suicides. Modern medicine, with many antidepressants and anxiolytics at hand, is still unable to achieve remission in many patients. The pathophysiology of depression and anxiety is still only marginally understood, which encouraged researchers to focus on neuropeptides, as they are a vast group of signaling molecules in the nervous system. Neuropeptides are involved in the regulation of many physiological functions. Some act as neuromodulators and are often co-released with neurotransmitters that allow for reciprocal communication between the brain and the body. Most studied in the past were the antidepressant and anxiolytic effects of oxytocin, vasopressin or neuropeptide Y and S, or Substance P. However, in recent years, more and more novel neuropeptides have been added to the list, with implications for the research and development of new targets, diagnostic elements, and even therapies to treat anxiety and depressive disorders. In this review, we take a close look at all currently studied neuropeptides, their related pathways, their roles in stress adaptation, and the etiology of anxiety and depression in humans and animal models. We will focus on the latest research and information regarding these associated neuropeptides and thus picture their potential uses in the future.

Brain systems in cocaine abstinence-induced anxiety-like behavior in rodents: A review

Cocaine use disorder (CUD) is a significant public health issue that generates substantial personal, familial, and economic burdens. Still, there are no FDA-approved pharmacotherapies for CUD. Cocaine-dependent individuals report anxiety during withdrawal, and alleviation of anxiety and other negative affective states may be critical for maintaining drug abstinence. However, the neurobiological mechanisms underlying abstinence-related anxiety in humans or anxiety-like behavior in rodents are not fully understood. This review summarizes investigations regarding anxiety-like behavior in mice and rats undergoing cocaine abstinence, as assessed using four of the most common anxiety-related assays: the elevated plus (or its derivative, the elevated zero) maze, open field test, light-dark transition test, and defensive burying task. We first summarize available evidence that cocaine abstinence generates anxiety-like behavior that persists throughout protracted abstinence. Then, we examine investigations concerning neuropeptide, neurotransmitter, and neuromodulator systems in cocaine abstinence-induced anxiety-like behavior. Throughout, we discuss how differences in sex, rodent strain, cocaine dose and dosing strategy and abstinence duration interact to generate anxiety-like behavior.

Goofballing of Opioid and Methamphetamine: The Science Behind the Deadly Cocktail

Globally, millions of people suffer from various substance use disorders (SUD), including mono-and polydrug use of opioids and methamphetamine. Brain regions such as the cingulate cortex, infralimbic cortex, dorsal striatum, nucleus accumbens, basolateral and central amygdala have been shown to play important roles in addiction-related behavioral changes. Clinical and pre-clinical studies have characterized these brain regions and their corresponding neurochemical changes in numerous phases of drug dependence such as acute drug use, intoxication, craving, withdrawal, and relapse. At present, many studies have reported the individual effects of opioids and methamphetamine. However, little is known about their combined effects. Co-use of these drugs produces effects greater than either drug alone, where one decreases the side effects of the other, and the combination produces a prolonged intoxication period or a more desirable intoxication effect. An increasing number of studies have associated polydrug abuse with poorer treatment outcomes, drug-related deaths, and more severe psychopathologies. To date, the pharmacological treatment efficacy for polydrug abuse is vague, and still at the experimental stage. This present review discusses the human and animal behavioral, neuroanatomical, and neurochemical changes underlying both morphine and methamphetamine dependence separately, as well as its combination. This narrative review also delineates the recent advances in the pharmacotherapy of mono- and poly drug-use of opioids and methamphetamine at clinical and preclinical stages.

Unconventional anxiety pharmacology in zebrafish: Drugs beyond traditional anxiogenic and anxiolytic spectra

Anxiety is the most prevalent brain disorder and a common cause of human disability. Animal models are critical for understanding anxiety pathogenesis and its pharmacotherapy. The zebrafish (Danio rerio) is increasingly utilized as a powerful model organism in anxiety research and anxiolytic drug screening. High similarity between human, rodent and zebrafish molecular targets implies shared signaling pathways involved in anxiety pathogenesis. However, mounting evidence shows that zebrafish behavior can be modulated by drugs beyond conventional anxiolytics or anxiogenics. Furthermore, these effects may differ from human and/or rodent responses, as such 'unconventional' drugs may affect zebrafish behavior despite having no such profiles (or exerting opposite effects) in humans or rodents. Here, we discuss the effects of several putative unconventional anxiotropic drugs (aspirin, lysergic acid diethylamide (LSD), nicotine, naloxone and naltrexone) and their potential mechanisms of action in zebrafish. Emphasizing the growing utility of zebrafish models in CNS drug discovery, such unconventional anxiety pharmacology may provide important, evolutionarily relevant insights into complex regulation of anxiety in biological systems. Albeit seemingly complicating direct translation from zebrafish into clinical phenotypes, this knowledge may instead foster the development of novel CNS drugs, eventually facilitating innovative treatment of patients based on novel 'unconventional' targets identified in fish models.

Associations between baseline opioid use disorder severity, mental health and biopsychosocial functioning, with clinical responses to computer-assisted therapy treatment

Background: Increasing rates of opioid-related overdose have been identified globally. Treatment for opioid use disorders (OUD) includes medications for opioid use disorder (MOUD) alongside behavioral support. Novel approaches to behavioral support should be explored, including computer-assisted therapy (CAT) programs.Objectives: Examine differences between baseline and post-treatment measures of opioid use and biopsychosocial functioning for individuals with OUD engaging with the CAT program 'Breaking Free Online,' and the extent to which participant characteristics may be associated with post-treatment measures.Methods: 1107 individuals engaged with CAT and provided baseline and post-treatment data - 724 (65.4%) were male, 383 (34.6%) were female.Results: Significant differences between baseline and post-treatment measures were identified (all p <.0001, effect sizes range:15 -.50). Participant characteristics were associated with post-treatment measures of opioid use, opioid dependence, mental health issues, quality of life, and biopsychosocial impairment (all p <.0001). An aggregated consensus measure of clinical impairment was found to be associated with changes in opioid use and post-treatment biopsychosocial functioning measures, with those participants with greater baseline clinical impairment demonstrating a greater magnitude of improvement from baseline to post-treatment than those with lower clinical impairment.Conclusion: CAT may reduce opioid use and improve biopsychosocial functioning in individuals with OUD. CAT could therefore provide a solution to the global opioid crisis if delivered as combination behavioral support alongside MOUD. Findings also indicate that it may be important for treatment systems to identify individuals with psychosocial complexity who might require behavioral support and MOUD.

Personality differences in brain network mechanisms for placebo analgesia and nocebo hyperalgesia in experimental pain: a functional magnetic resonance imaging study

Background

Placebo and nocebo responses have been increasingly gaining the attention of clinical and scientific researchers. Inconsistent conclusions from current studies indicate that different factors potentially affect both placebo and nocebo responses. Increasing evidence suggests that personality differences may affect the mechanisms of both two responses. In the present work, we explored the characteristics of neural signals of placebo and nocebo responses based on functional connectivity (FC) analysis and Granger causality analysis (GCA).

Methods

A total of 34 healthy participants received conditional induction training to establish placebo and nocebo responses. Every participant completed the following experimental workflow, including scanning of baseline, experimental low back pain model establishment, scanning of acute pain status, and scanning of placebo response or nocebo response. We collect visual analogue scale (VAS) data after each scanning. Functional magnetic resonance imaging (fMRI) data from different personality groups were subjected to FC analysis and multivariate GCA (mGCA).

Results

Pain scores for placebo and nocebo responses were statistically different across different personality. There are also statistically differences in the neural signals of two responses across different personality.

Conclusions

The findings of the present study indicated that extroverted and introverted participants are likely to experience placebo analgesic effects and nocebo hyperalgesia effects, respectively. Both extroverted and introverted participants showed significant changes in brain networks under placebo response. Variation in emotional control and ventromedial prefrontal cortex inactivity may constitute the bulk of the personality differences in placebo analgesia. Differences in the regulation of the sensory conduction system (SCS) and release of the emotional circuit could be important factors affecting personality differences in nocebo hyperalgesia.

Anxiety, depression, and opioid misuse among adults with chronic pain: the role of emotion dysregulation

The opioid epidemic is a significant public health concern in the United States, particularly among adults with chronic pain. Considerable research suggests that people with mental health problems, including anxiety and depression, may experience more opioid-related problems in the context of chronic pain. Yet, little work has examined potential mechanisms underyling these relations. Emotion dysregulation is one mechanistic factor that may link anxiety and depression and opioid-related problems among persons with chronic pain. Therefore, the current study examined the explanatory role of emotion dysregulation in the cross-sectional relationship between anxiety and depression problems and current opioid misuse and severity of opioid dependence among 431 adults with chronic pain who reported currently using opioid medications (74% female, Mage=38.32 years, SD = 11.11). Results indicated that emotion dysregulation explained, in part, the relationship between anxiety and depression symptoms and opioid-related problems. These findings highlight the need to further consider the role of emotion dysregulation among adults with chronic pain who use prescription opioids and experience symptoms of anxiety or depression. Future prospective research will be needed to further establish emotion dysregulation as a mechanism in anxiety/depression-opioid misuse/dependence processes.

An Argument for Reconsidering the Role of Social Support in Treating Anxiety Disorders

Reminders of loved ones have long been avoided during extinction-based treatments because of their assumed status as safety signals, which, by inhibiting fear in the moment, impair the long-term outcomes of fear extinction. Yet, recent work has demonstrated that in contrast to standard safety signals, social support reminders actually enhance fear extinction and lead to lasting reduction of fear, suggesting that they may have beneficial effects during exposure therapy that have before-now been overlooked. Here, we argue for a revision of the assumption that social support is detrimental to fear extinction processes and propose that future work should focus on the potential of social support reminders to improve treatment outcomes in those with anxiety disorders.

CRHCeA→VTA inputs inhibit the positive ensembles to induce negative effect of opiate withdrawal

Plasticity of neurons in the ventral tegmental area (VTA) is critical for establishment of drug dependence. However, the remodeling of the circuits mediating the transition between positive and negative effect remains unclear. Here, we used neuronal activity-dependent labeling technique to characterize and temporarily control the VTA neuronal ensembles recruited by the initial morphine exposure (morphine-positive ensembles, Mor-Ens). Mor-Ens preferentially projected to NAc, and induced dopamine-dependent positive reinforcement. Electrophysiology and rabies viral tracing revealed the preferential connections between the VTA-projective corticotrophin-releasing hormone (CRH) neurons of central amygdala (CRH^CeA→VTA) and Mor-Ens, which was enhanced after escalating morphine exposure and mediated the negative effect during opiate withdrawal. Pharmacologic intervention or CRISPR-mediated repression of CRHR1 in Mor-Ens weakened the inhibitory CRH^CeA→VTA inputs, and alleviated the negative effect during opiate withdrawal. These data suggest that neurons encoding opioid reward experience are inhibited by enhanced CRH^CeA→VTA inputs induced by chronic morphine exposure, leading to negative effect during opiate withdrawal, and provide new insight into the pathological changes in VTA plasticity after drug abuse and mechanism of opiate dependence.

A mu-opioid feedback model of human social behavior

Since the discovery of pain relieving and rewarding properties of opiates such as morphine or heroin, the human mu-opioid system has been a target for medical research on pain processing and addiction. Indeed, pain and pleasure act mutually inhibitory on each other and the mu-opioid system has been suggested as an underlying common neurobiological mechanism. Recently, research interest extended the role of the endogenous mu-opioid system beyond the hedonic value of pain and pleasure towards human social-emotional behavior. Here we propose a mu-opioid feedback model of social behavior. This model is based upon recent findings of opioid modulation of human social learning, bonding and empathy in relation to affiliative and protective tendencies. Fundamental to the model is that the mu-opioid system reinforces socially affiliative or protective behavior in response to positive and negative social experiences with long-term consequences for social behavior and health. The functional implications for stress, anxiety, depression and attachment behaviors are discussed.

The µ-opioid system in midline thalamic nuclei modulates defence strategies towards a conditioned fear stimulus in male mice

BACKGROUND

Nuclei located in the dorsal midline thalamus, such as the paraventricular nucleus of the thalamus (PVT), are crucial to modulate fear and aversive behaviour. In addition, the PVT shows a dense expression of µ-opioid receptors (MORs) and could mediate the anxiolytic effects of opioids.

METHODS

We analysed the contribution of MORs in the dorsal midline thalamus (i.e. the PVT) to the performance of mice in a classical fear conditioning paradigm. We locally injected a specific agonist (DAMGO), an antagonist (CTAP) of MOR or saline as a control into the dorsal midline thalamus of male mice, prior to fear extinction training. We assessed freezing as a typical measure of fear and extended our analysis by evaluation of aversive, non-aversive and neutral behavioural features using compositional data analysis.

RESULTS

Pharmacological blockade of MORs through CTAP in the dorsal midline thalamus induced a fear memory extinction deficit, as evidenced by maintained freezing during extinction sessions. Stimulation of MORs by DAMGO resulted in an overall increase in locomotor activity, associated with decreased freezing during recall of extinction. Compositional data analysis confirmed the freezing-related pharmacological effects and revealed specific differences in basic behavioural states. CTAP-treated mice remained in an aversive state, whereas DAMGO-treated mice displayed predominantly neutral behaviour.

CONCLUSIONS

Fear extinction requires the integrity of the µ-opioid system in the dorsal midline thalamus. Pharmacological stimulation of MOR and associated facilitation of fear extinction recall suggest a potential therapeutic avenue for stress-related or anxiety disorders.

Morphine in the Setting of Acute Heart Failure: Do the Risks Outweigh the Benefits?

The use of opioids in acute pulmonary oedema is considered standard therapy by many physicians. The immediate relieving effect of morphine on the key symptomatic discomfort associated with acute heart failure, dyspnoea, facilitated the categorisation of morphine as a beneficial treatment in this setting. During the last decade, several retrospective studies raised concerns regarding the safety and efficacy of morphine in the setting of acute heart failure. In this article, the physiological effects of morphine on the cardiovascular and respiratory systems are summarised, as well as the potential clinical benefits and risks associated with morphine therapy. Finally, the reported clinical outcomes and adverse event profiles from recent observational studies are discussed, as well as future perspectives and potential alternatives to morphine in the setting of acute heart failure.

Clinical characteristics distinguishing tramadol-using adolescents from other substance-using adolescents in an out-patient treatment setting

BACKGROUND

Non-medical Prescription Opioid Use (NMPOU) has increased worldwide during the last decades, and specifically, tramadol misuse may represent a novel pattern of substance use among adolescents. The present study aims to analyze characteristics distinguishing tramadol-using adolescents from other substance-using adolescents seeking out-patient treatment.

METHODS

This is a cross-sectional study of treatment-seeking patients between 13 and 24 years of age in an out-patient facility for substance use problems in Malmö, Sweden. A total of 526 treatment-seeking adolescents at an out-patient treatment center were included. Data on substance use, treatment history and socio-demographic variables were extracted through a semi-structured interview method aimed specifically for adolescents with alcohol or drug problems (Ung-DOK). Lifetime tramadol users were compared to non-users, and also, primary tramadol users were compared to remaining subjects.

RESULTS

Thirty-one percent (n = 162) were tramadol users (lifetime prevalence). In logistic regression, the tramadol group showed a significantly increased risk of tobacco use, problematic lifetime cocaine, benzodiazepine and amphetamine use, and were more likely to report contacts with the judicial system, and less likely to report contacts with child or adult psychiatry, and more likely to have parents born outside the Scandinavian countries. In logistic regression, primary tramadol use was negatively associated with frequent cannabis use.

CONCLUSIONS

Tramadol use appears to be a novel pattern among treatment-seeking adolescents. They showed a significantly increased risk of initiation of other illicit drugs and criminal behaviour, despite less contact with psychiatric care. More attention may be needed to this relatively novel pattern of opioid use.

Opioid receptor blockade inhibits self-disclosure during a closeness-building social interaction

Social ties are critical to human health and well-being; thus, it is important to gain a better understanding of the neurobiological mechanisms involved in the development of interpersonal closeness. Prior research indicates that endogenous opioids may play a role in social affiliation by elaborating feelings of social connection and warmth; however, it is not currently known whether opioids mediate affiliative behavior and emerging feelings of closeness in humans at the relationship initiation stage. This randomized, double-blind study examined opioidergic processes in the context of a naturalistic, face-to-face social interaction. Eighty pairs of unacquainted participants (final N = 159 due to removal of one dyad member from analysis) received either 50 mg of the opioid receptor antagonist naltrexone or placebo prior to completing a closeness-building exercise centered on escalating self-disclosure (sharing of personal information about the self). Compared to the placebo group, naltrexone participants held lower social reward expectations prior to the interaction, engaged in less intimacy-fostering behavior (self-disclosure) during the interaction, and reported wanting less closeness with their partner. Feelings of social connection were not significantly lower in the naltrexone group. However, placebo participants experienced improvements in mood after the closeness-building task whereas naltrexone participants did not. These findings suggest that endogenous opioids may contribute to behavioral, affective, and motivational processes related to the development of initial closeness.

Synergistic effect between citalopram and citicoline on anxiolytic effect in non-sensitized and morphine-sensitized mice: An isobologram analysis

In the present study, the effects of intraperitoneal (i.p.) injections of citalopram and citicoline on morphine-induced anxiolytic effects were investigated in non-sensitized and morphine-sensitized mice using elevated plus-maze (EPM). Subcutaneous (s.c.) administration morphine (5 mg/kg) increased the percentage of open arm time (%OAT, in morphine-sensitized mice), and open arm entries (%OAE, in non-sensitized mice), but not a locomotor activity, indicating an anxiolytic response to morphine. On the other hand, i.p. administration of naloxone decreased %OAT (morphine-sensitized mice), and %OAE (non-sensitized and morphine-sensitized mice), but not a locomotor activity, showing an anxiogenic effect to naloxone. Moreover, i.p.co-administration of citalopram (5 and 10 mg/kg) and citicoline (75 mg/kg) induced the anxiolytic effect. Interestingly, i.p. co-administration of low doses of citalopram (0.5, 1 and 2.5 mg/kg) and citicoline (25 mg/kg) significantly increased %OAT and %OAE in non-sensitized as well as %OAT in morphine-sensitized mice, indicating an anxiolytic effect. An isobolographic analysis of data was performed, presenting a synergistic interaction between citalopram and citicoline upon the production of anxiolytic effect in non-sensitized and morphine-sensitized mice. In conclusion, it seems that (1) morphine sensitization affects the anxiety behavior in the EPM, (2) μ-opioid receptors play an important role in morphine anxiolytic effect, (3) citalopram and citicoline induced anti-anxiety effect, (4) a synergistic effect of citalopram and citicoline upon induction of anti-anxiety behavior in non-sensitized and morphine-sensitized mice.

Negative Affect-Related Factors Have the Strongest Association with Prescription Opioid Misuse in a Cross-Sectional Cohort of Patients with Chronic Pain

OBJECTIVE

Increased opioid prescription to relieve pain among patients with chronic pain is associated with increased risk for misuse, potentially leading to substance use disorders and overdose death. We aimed to characterize the relative importance and identify the most significant of several potential risk factors for the severity of self-reported prescribed opioid misuse behaviors.

METHODS

A sample of 1,193 patients (mean age ± SD = 50.72 ± 14.97 years, 64.04% female) with various chronic pain conditions completed a multidimensional registry assessing four pain severity measures and 14 physical, mental, and social health status factors using the National Institutes of Health's Patient-Reported Outcomes Measurement Information System (PROMIS). A validated PROMIS measure of medication misuse was completed by 692 patients who endorsed currently taking opioid medication. Patients taking opioid medications were compared across all measures with those who do not take opioid medications. Subsequently, a data-driven regression analysis was used to determine which measures best explained variability in severity of misuse. We hypothesized that negative affect-related factors, namely anxiety, anger, and/or depression, would be key predictors of misuse severity due to their crucial role in chronic pain and substance use disorders.

RESULTS

Patients taking opioid medications had significantly greater impairment across most measures. Above and beyond demographic variables, the only and most significant predictors of prescribed opioid misuse severity were as follows: anxiety (β = 0.15, P = 0.01), anger (β = 0.13, P = 0.02), Pain Intensity-worst (β = 0.09, P = 0.02), and depression (β = 0.13, P = 0.04).

CONCLUSIONS

Findings suggest that anxiety, anger, and depression are key factors associated with prescribed opioid misuse tendencies in patients with chronic pain and that they are potential targets for therapeutic intervention.

Interaction of Cannabis Use and Aging: From Molecule to Mind

Given the aging Baby Boomer generation, changes in cannabis legislation, and the growing acknowledgment of cannabis for its therapeutic potential, it is predicted that cannabis use in the older population will escalate. It is, therefore, important to determine the interaction between the effects of cannabis and aging. The aim of this report is to describe the link between cannabis use and the aging brain. Our review of the literature found few and inconsistent empirical studies that directly address the impact of cannabis use on the aging brain. However, research focused on long-term cannabis use points toward cumulative effects on multimodal systems in the brain that are similarly affected during aging. Specifically, the effects of cannabis and aging converge on overlapping networks in the endocannabinoid, opioid, and dopamine systems that may affect functional decline particularly in the hippocampus and prefrontal cortex, which are critical areas for memory and executive functioning. To conclude, despite the limited current knowledge on the potential interactive effects between cannabis and aging, evidence from the literature suggests that cannabis and aging effects are concurrently present across several neurotransmitter systems. There is a great need for future research to directly test the interactions between cannabis and aging.

Review: Exteroceptive Sensory Abnormalities in Childhood and Adolescent Anxiety and Obsessive-Compulsive Disorder: A Critical Review

OBJECTIVE

Childhood anxiety and obsessive-compulsive disorder (OCD) are defined by fear, worry, and uncertainty, but there is also evidence that affected children possess exteroceptive sensory abnormalities. These sensory features may often instigate symptoms and cause significant distress and functional impairment. In addition, a purported class of conditions known as "sensory processing disorders" may significantly overlap with childhood anxiety and OCD, which provides further support for a connection between abnormal sensation and fear-based psychopathology.

METHOD

The current review was conducted to synthesize and to critically evaluate the existing research on exteroceptive sensory abnormalities in childhood anxiety and OCD. Because of the paucity of research in this area, studies with adult populations were also briefly reviewed.

RESULTS

The review found significant support for the notion that sensory abnormalities are common in children with anxiety disorders and OCD, but there are significant limitations to research in this area that prevent firm conclusions.

CONCLUSION

Potential avenues for future research on sensory features of pediatric anxiety and OCD are discussed.

Examination of pain threshold and neuropeptides in patients with acute suicide risk

INTRODUCTION

One of the main challenges in suicide prevention is the limited understanding of the biological mechanisms underlying suicide. Recent findings suggest impairments in pain processing in acutely suicidal patients. However, little is known about the biological factors that may drive these discrete physiological abnormalities. In this study, we examined plasma peptides involved in analgesic and inflammatory responses and physical pain threshold in acutely suicidal patients.

METHODS

Thirty-seven depressed patients of both sexes hospitalized for severe suicidal ideation or a recent suicide attempt were characterized clinically including history of suicidal ideation and behavior. Psychological and physical pain, and pressure pain threshold was also measured. Plasma levels of β-endorphin, neurotensin, agouti-related protein (AgRP), C-reactive protein (CRP), adrenocorticotropic hormone (ACTH), and brain-derived neurotrophic factor (BDNF) were run in Milliplex multiplex assays.

RESULTS

The number of lifetime suicide attempts was positively correlated with β-endorphin (r = 0.702; p = 0.007), and neurotensin (r = 0.728, p = 0.007) plasma levels. Higher pain threshold was measured in the suicide attempt group as compared to the suicidal ideation group. Pain threshold was strongly and negatively associated with CRP plasma levels (r = -0.548; p < 0.001). In patients reporting chronic pain, lower AgRP levels and lower pain threshold were observed (t = 4.472; p = 0.001).

CONCLUSION

Our results suggest that abnormalities in the opioid and neurotensin systems may underlie the increase in pain threshold found in suicide attempters, and possibly risk for suicidal behavior. Targeting pain circuits and systems may provide therapeutic mechanisms for suicide prevention.

[Anxiety in the elderly]

Anxiety occurs in about one third of people over 65 years of age. However, its identification in this age has significant difficulties. The clinical manifestations, pathogenetic mechanisms, approaches to the diagnosis and treatment of various types of anxiety are described in the article. Particular attention is paid to the comorbidity of anxiety disorders in elderly patients. A comprehensive approach to the treatment of elderly patients with anxiety includes psychotherapeutic and pharmacotherapeutic approaches. Special attention should be paid to the efficacy and safety of the drugs, which is especially important in this category of patients.

Panicolytic-like effect of µ1-opioid receptor blockade in the inferior colliculus of prey threatened by Crotalus durissus terrificus pit vipers

BACKGROUND

The endogenous opioid peptide system has been implicated in the neural modulation of fear and anxiety organised by the dorsal midbrain. Furthermore, previous results indicate a fundamental role played by inferior colliculus (IC) opioid mechanisms during the expression of defensive behaviours, but the involvement of the IC µ₁-opioid receptor in the modulation of anxiety- and panic attack-related behaviours remains unclear. Using a prey-versus-snake confrontation paradigm, we sought to investigate the effects of µ₁-opioid receptor blockade in the IC on the defensive behaviour displayed by rats in a dangerous situation.

METHODS

Specific pathogen-free Wistar rats were treated with microinjection of the selective µ₁-opioid receptor antagonist naloxonazine into the IC at different concentrations (1.0, 3.0 and 5.0 µg/0.2 µL) and then confronted with rattlesnakes ( Crotalus durissus terrificus). The defensive behavioural repertoire, such as defensive attention, flat back approach (FBA), startle, defensive immobility, escape or active avoidance, displayed by rats either during the confrontations with wild snakes or during re-exposure to the experimental context without the predator was analysed.

RESULTS

The blockade of µ₁-opioid receptors in the IC decreased the expression of both anxiety-related behaviours (defensive attention, FBA) and panic attack-related responses (startle, defensive immobility and escape) during the confrontation with rattlesnakes. A significant decrease in defensive attention was also recorded during re-exposure of the prey to the experimental apparatus context without the predator.

CONCLUSION

Taken together, these results suggest that a decrease in µ_1-opioid receptor signalling activity within the IC modulates anxiety- and panic attack-related behaviours in dangerous environments.

Enkephalinase inhibitors, potential therapeutics for the future treatment of diarrhea predominant functional gastrointestinal disorders

The endogenous opioid system (EOS) is considered being a crucial element involved in the pathophysiology of irritable bowel syndrome (IBS) as it regulates gastrointestinal (GI) homeostasis through modulation of motility and water and ion secretion/absorption. Along with opioid receptors (ORs), the following components of EOS can be distinguished: 1. endogenous opioid peptides (EOPs), namely enkephalins, endorphins, endomorphins and dynorphins, and 2. peptidases, which regulate the metabolism (synthesis and degradation) of EOPs. Enkephalins, which are δ-opioid receptors agonists, induce significant effects in the GI tract as they act as potent pro-absorptive neurotransmitters. The action of enkephalins and other EOPs is limited, since EOPs are easily and rapidly inactivated by a natural metalloendopeptidase (enkephalinase/neprilysin) and aminopeptidase N. Studies show that the activity of EOPs can be enhanced by inhibition of these enzymes. In this review, we discuss the antidiarrheal and antinociceptive potential of enkephalinase inhibitors. Furthermore, our review is to answer the question whether enkephalinase inhibitors may be helpful in the future treatment of diarrhea predominant functional GI disorders.

Effects of chronic fentanyl administration on behavioral characteristics of mice

Background

Fentanyl, a synthetic opioid categorized as a narcotic analgesic, has a 100‐ to 200‐fold stronger effect than most opioids, such as morphine. Fatal accidents due to chronic use and abuse of fentanyl are a worldwide social problem. One reason for the abuse of fentanyl is its psychostimulant effects that could induce behavioral changes. The effects of chronic fentanyl administration on behavior, however, are unclear.

Methods

Adult male C57BL/6J mice were chronically administered fentanyl (0.03 or 0.3 mg/kg/d i.p.), and various behaviors were assessed using a behavioral test battery.

Results

Mice chronically administered a high dose of fentanyl (0.3 mg/kg/d) exhibited decreased anxiety‐like behavior as assessed by the open field and elevated plus maze tests. On the other hand, interruption of fentanyl administration led to increased anxiety‐like behavior as observed in the light and dark transition test. The hot plate test revealed that chronic administration of fentanyl reduced pain sensitivity. High‐dose chronic fentanyl administration reduced the locomotor stimulatory effects of cocaine. The results, however, failed to reach the threshold for study‐wide statistical significance.

Conclusion

Chronic fentanyl administration induces some behavioral changes in mice. Although further studies are needed to clarify the underlying mechanisms of the behavioral effects of chronic fentanyl administration, our findings suggest that fentanyl is safe under properly controlled conditions.

To investigate the effects of long‐term fentanyl use on brain function, adult male C57BL/6J mice were chronically administered fentanyl (0.03 or 0.3 mg/kg/d ip) and analyzed in a behavioral test battery. Chronic fentanyl administration reduced anxiety‐like behavior, pain sensitivity, and the locomotor stimulatory effects of cocaine in mice. The results, however, failed to reach the threshold for study‐wide statistical significance.

Opioidergic Regulation of Emotional Arousal: A Combined PET–fMRI Study

Emotions can be characterized by dimensions of arousal and valence (pleasantness). While the functional brain bases of emotional arousal and valence have been actively investigated, the neuromolecular underpinnings remain poorly understood. We tested whether the opioid and dopamine systems involved in reward and motivational processes would be associated with emotional arousal and valence. We used in vivo positron emission tomography to quantify μ-opioid receptor and type 2 dopamine receptor (MOR and D2R, respectively) availability in brains of 35 healthy adult females. During subsequent functional magnetic resonance imaging carried out to monitor hemodynamic activity, the subjects viewed movie scenes of varying emotional content. Arousal and valence were associated with hemodynamic activity in brain regions involved in emotional processing, including amygdala, thalamus, and superior temporal sulcus. Cerebral MOR availability correlated negatively with the hemodynamic responses to arousing scenes in amygdala, hippocampus, thalamus, and hypothalamus, whereas no positive correlations were observed in any brain region. D2R availability—here reliably quantified only in striatum—was not associated with either arousal or valence. These results suggest that emotional arousal is regulated by the MOR system, and that cerebral MOR availability influences brain activity elicited by arousing stimuli.

Relationship of anxiety with joint pain and its management: A population survey

OBJECTIVES

The aims of the present study was to examine the associations between the severity of pain and anxiety in a community population reporting joint pain, and to investigate the management of joint pain in the presence of comorbid anxiety.

METHODS

A population survey was carried out of people aged ≥45 years, registered with eight general practices in Cheshire, Shropshire and Staffordshire, UK. Respondents were asked to report pain intensity in their hands, hips, knees and feet (on a numerical rating scale), anxiety symptoms (Generalized Anxiety Disorder seven-item [GAD-7] scale) and guideline-recommended treatments used to manage pain. Clinical anxiety was defined by a GAD-7 score of 10 or more.

RESULTS

A total of 11,222 respondents with joint pain were included in the analysis, with 1,802 (16.1%) reporting clinical anxiety. Respondents reporting more severe pain were more likely to report clinical anxiety (severe versus mild pain, odds ratio [OR] 5.36, 95% confidence interval [CI] 4.56 to 6.31). The number of pain sites was also positively associated with clinical anxiety (four versus one site; OR 3.64, 95% CI 3.09 to 4.30). Those with clinical anxiety were less likely to undertake general fitness exercises (OR 0.60, 95% CI 0.52 to 0.70), but more likely to diet (OR 1.43, 95% CI 1.21 to 1.69), use walking aids (OR 1.53, 95% CI 1.32 to 1.77) and assistive devices (OR 1.24, 95% CI 1.04 to 1.49), and more likely to use opioids (OR 1.34, 95% CI 1.18 to1.52).

CONCLUSIONS

Anxiety is common among patients presenting to primary care with joint pain. Patients with anxiety are likely to manage their joint pain differently to those without. Case-finding to identify and treat anxiety would be appropriate in this population, with caution about opioid prescribing and consideration of exercise as an intervention.

Zebrafish models relevant to studying central opioid and endocannabinoid systems

The endocannabinoid and opioid systems are two interplaying neurotransmitter systems that modulate drug abuse, anxiety, pain, cognition, neurogenesis and immune activity. Although they are involved in such critical functions, our understanding of endocannabinoid and opioid physiology remains limited, necessitating further studies, novel models and new model organisms in this field. Zebrafish (Danio rerio) is rapidly emerging as one of the most effective translational models in neuroscience and biological psychiatry. Due to their high physiological and genetic homology to humans, zebrafish may be effectively used to study the endocannabinoid and opioid systems. Here, we discuss current models used to target the endocannabinoid and opioid systems in zebrafish, and their potential use in future translational research and high-throughput drug screening. Emphasizing the high degree of conservation of the endocannabinoid and opioid systems in zebrafish and mammals, we suggest zebrafish as an excellent model organism to study these systems and to search for the new drugs and therapies targeting their evolutionarily conserved mechanisms.

Optimizing Placebo and Minimizing Nocebo to Reduce Pain, Catastrophizing, and Opioid Use: A Review of the Science and an Evidence-Informed Clinical Toolkit

Pain, a noxious psychosensory experience, motivates escape behavior to assure protection and survival. Psychological factors alter the experience and trajectory of pain, as well as behavior and treatment response. In the context of pain, the placebo effect (expectation for pain relief) releases endogenous opioids and facilitates analgesia from exogenously administered opioids. Nocebo hyperalgesia (expectation for persistent or worsening pain) opposes endogenous opioid analgesia and patient engagement in prescription opioid tapering. Reductions in nocebo hyperalgesia and pain catastrophizing may enhance descending modulation of pain, mediate adaptive structural brain changes and promote patient engagement in opioid tapering. Interventions that minimize nocebo and optimize placebo may adaptively shape the central nervous system toward pain relief and potentially opioid reduction. Here we provide a critical description of catastrophizing and its impact on pain, placebo and nocebo effects. We also consider the importance of minimizing nocebo and optimizing placebo effects during prescription opioid tapering, and offer a clinical toolkit of resources to accomplish these goals clinically.

Opioid system and human emotions

Emotions are states of vigilant readiness that guide human and animal behaviour during survival-salient situations. Categorical models of emotions posit neurally and physiologically distinct basic human emotions (anger, fear, disgust, happiness, sadness and surprise) that govern different survival functions. Opioid receptors are expressed abundantly in the mammalian emotion circuit, and the opioid system modulates a variety of functions related to arousal and motivation. Yet, its specific contribution to different basic emotions has remained poorly understood. Here, we review how the endogenous opioid system and particularly the μ receptor contribute to emotional processing in humans. Activation of the endogenous opioid system is consistently associated with both pleasant and unpleasant emotions. In general, exogenous opioid agonists facilitate approach-oriented emotions (anger, pleasure) and inhibit avoidance-oriented emotions (fear, sadness). Opioids also modulate social bonding and affiliative behaviour, and prolonged opioid abuse may render both social bonding and emotion recognition circuits dysfunctional. However, there is no clear evidence that the opioid system is able to affect the emotions associated with surprise and disgust. Taken together, the opioid systems contribute to a wide array of positive and negative emotions through their general ability to modulate the approach versus avoidance motivation associated with specific emotions. Because of the protective effects of opioid system-mediated prosociality and positive mood, the opioid system may constitute an important factor contributing to psychological and psychosomatic resilience.

LINKED ARTICLES

This article is part of a themed section on Emerging Areas of Opioid Pharmacology. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.14/issuetoc.

Expectancy Modulation of Opioid Neurotransmission

Expectancies are powerful modulators of cognitive and emotional experiences, as well as the neurobiological responses linked to these processes. In medicine, placebo effects are a clear example of how expectancies activate opioid neurotransmission in a treatment context, leading to the experience of analgesia and the improvement of emotional states, among other symptoms. Molecular neuroimaging techniques using positron emission tomography (PET) and the selective μ-opioid receptor tracer [11C]carfentanil have significantly contributed to our understanding of the neurobiological systems involved in the formation of placebo effects. This line of research has described neural and neurotransmitter networks implicated in placebo effects and provided the technical tools to examine inter-individual differences in the function of placebo responsive mechanisms. As a consequence, the capacity to activate endogenous opioid networks during the administration of placebos has been linked to the concept of resiliency mechanisms, partially determined by genetic factors, and uncovered by the cognitive emotional integration of the expectations created by the therapeutic environment and its maintenance through learning mechanisms. This evidence has contributed to the understanding of the biological bases of the cognitive and psychological mechanisms implicated in the response to treatments, and opened up new opportunities for drug development and the enhancement of treatment responses. Further, delineation of these processes within and across diseases is critical to understand neural systems that could be enhanced to promote symptomatic improvement and modify disease progression.

Women on the Edge: Opioids, Benzodiazepines, and the Social Anxieties Surrounding Women's Reproduction in the U.S. "Opioid Epidemic"

The current "opioid epidemic" provides an opportunity to identify age-old social anxieties about drug use while opening up new lines of inquiry about how and why drug use epidemics become gendered. This paper reflects on the intertwined phenomena of opioid and benzodiazepine prescribing to U.S. women to examine how gender, race, and class inform social anxieties about reproduction and parenting. Multiple discourses abound about the relationship between women and the "opioid epidemic." Epidemiological reports attribute premature death among White women to the deadly combination of opioids and antianxiety medications. The National Institute on Drug Abuse reports that "every 25 minutes a baby is born suffering from opioid withdrawal," leading to costly hospital stays for infants and the potential for mother-child separation and other forms of family adjudication postpartum. Primary care providers are reluctant to distinguish diagnoses of chronic noncancer pain from anxiety among their female patients. Taken together, these discourses beg the question: What exactly are we worried about? I compare and contrast the narratives of two anxious women on opioids to raise larger structural questions about pregnancy, parenting, and drug use and to interrogate the public narrative that women on opioids threaten the American family and thwart the American Dream.

The effect of post-traumatic stress disorder on the risk of developing prescription opioid use disorder: Results from the National Epidemiologic Survey on Alcohol and Related Conditions III

OBJECTIVE

To evaluate the effect of baseline post-traumatic stress disorder (PTSD) and each symptoms cluster on the risk of developing opioid use disorder (OUD) in those exposed to opioid painkillers and to assess the effect of comorbid PTSD and OUD on functioning, OUD severity, and treatment seeking compared with individuals with OUD only.

METHODS

We obtained data from 4025 individuals exposed to opioid painkillers from the National Epidemiologic Survey on Alcohol and Related Conditions III. We matched individuals with baseline PTSD with individuals without PTSD on demographics, developmental background, family history, personalities, and exposure to stressful life events with propensity score methodology. We controlled for clinical diagnoses and other risk factors that may have occurred after PTSD onset. Quality of life was assessed with the SF-12; the number of diagnostic criteria met indicated OUD severity.

RESULTS

Baseline PTSD predicted OUD after controlling for matching variables and other risk factors, including baseline mood/anxiety disorders and other substance use disorders (odds ratio[OR]: 1.58; 95% confidence interval[CI]: 1.14-2.17; p=0.02). Among individuals with PTSD, arousal/reactivity cluster predicted OUD. Individuals with comorbid PTSD and OUD had lower mean scores on the SF-12 scale and greater severity of OUD than individuals with OUD. There were no differences in help-seeking.

CONCLUSION

Baseline PTSD increases the risk of developing OUD after exposure to opioid painkillers. Clinicians should screen for PTSD diagnosis and arousal/reactivity symptoms prior to prescribing painkillers. Integrated treatments are strongly recommended for patients with this dual diagnosis.

Therapeutical strategies for anxiety and anxiety-like disorders using plant-derived natural compounds and plant extracts

Anxiety and anxiety-like disorders describe many mental disorders, yet fear is a common overwhelming symptom often leading to depression. Currently two basic strategies are discussed to treat anxiety: pharmacotherapy or psychotherapy. In the pharmacotherapeutical clinical approach, several conventional synthetic anxiolytic drugs are being used with several adverse effects. Therefore, studies to find suitable safe medicines from natural sources are being sought by researchers. The results of a plethora experimental studies demonstrated that dietary phytochemicals like alkaloids, terpenes, flavonoids, phenolic acids, lignans, cinnamates, and saponins or various plant extracts with the mixture of different phytochemicals possess anxiolytic effects in a wide range of animal models of anxiety. The involved mechanisms of anxiolytics action include interaction with γ-aminobutyric acid A receptors at benzodiazepine (BZD) and non-BZD sites with various affinity to different subunits, serotonergic 5-hydrodytryptamine receptors, noradrenergic and dopaminergic systems, glutamate receptors, and cannabinoid receptors. This review focuses on the use of both plant-derived natural compounds and plant extracts with anxiolytic effects, describing their biological effects and clinical application.