The Association between the Level of Plasma Oxytocin and Craving among Former Heroin Users

Changes in peripheral oxytocin and vasopressin during a silent month-long Insight meditation retreat

Background

Given its putative roles in mediating prosocial behavior, attachment bonds, and stress physiology, oxytocin modulation has been hypothesized to be a biological correlate of the salubrious effects of meditation practice. Here we investigated the effects of a month-long silent meditation retreat on changes in oxytocin, and the related hormone and vasopressin, in relation to psychosocial changes in attachment style, anxiety, personality measures, and feelings of social connectedness with fellow meditators.

Methods

Plasma oxytocin and vasopressin and self-report questionnaires were measured in retreat participants (n = 28) at the beginning of, and 3 weeks into, a residential meditation retreat. Control participants (n = 34), who were similar in age, gender, and meditation experience, were also assessed across a 3-week interval. Linear mixed effects models were used to assess outcomes.

Results

The retreat group showed a small but significant decrease in oxytocin compared to controls who showed no change. In the retreat group, higher openness to experience at Time 1 predicted greater reductions in oxytocin during the retreat, and lower oxytocin at Time 2 was related to stronger feelings of personal connection with fellow meditators. The changes in oxytocin were not related to attachment style or anxiety. Vasopressin decreased over time across both groups, suggesting no specific effect of retreat.

Conclusion

These preliminary findings suggest that meditation training in the context of a silent residential retreat may reduce circulating levels of oxytocin. We interpret this finding from multiple theoretical perspectives, discussing key measurement limitations and proposing future study designs that may help to differentiate the effects of different meditation practices and contexts on oxytocin signaling.

Cocaine use disorder effects on blood oxytocin levels and OXTR DNA methylation

Substance use disorders have been associated with alterations in the oxytocinergic system, but few studies have investigated both the peptide and epigenetic mechanisms potentially implicated in the regulation of oxytocin receptor. In this study, we compared plasma oxytocin and blood DNA methylation in the OXTR gene between people with and without cocaine use disorder (CUD). We measured the oxytocin levels of 51 people with CUD during acute abstinence and of 30 healthy controls using an enzyme immunoassay. The levels of DNA methylation in four CpG sites at exon III of the OXTR gene were evaluated in a subsample using pyrosequencing. The Addiction Severity Index was used to assess clinical characteristics. We found higher oxytocin levels in men with CUD (56.5 pg/mL; 95% CI: 48.2-64.7) than in control men (33.6 pg/mL; 95% CI: 20.7-46.5), while no differences between women with and without CUD were detected. With a moderate effect size, the interaction effect between group and sex remained significant when controlling for height, weight and age data. A positive correlation in the CUD sample was found between oxytocin levels and days of psychological suffering prior to treatment enrollment. No group differences were observed regarding DNA methylation data. This suggests that CUD is associated with higher peripheral oxytocin levels in men during acute abstinence. This finding may be considered in future studies that aim at using exogenous oxytocin as a potential treatment for cocaine addiction.

Paraventricular Nucleus of the Hypothalamus Oxytocin and Incubation of Heroin Seeking

INTRODUCTION

There are numerous pharmacologic treatments for opioid use disorder (OUD), but none that directly target the underlying addictive effects of opioids. Oxytocin, a peptide hormone produced in the paraventricular nucleus (PVN) of the hypothalamus, has been investigated as a potential therapeutic for OUD. Promising preclinical and clinical results have been reported, but the brain region(s) and mechanism(s) by which oxytocin impacts reward processes remain undetermined.

METHODS

Here, we assess peripherally administered oxytocin's impacts on cued reinstatement of heroin seeking following forced abstinence and its effects on neuronal activation in the PVN and key projection regions. We also examine how designer receptors exclusively activated by designer drug (DREADD)-mediated activation or inhibition of oxytocinergic PVN neurons alters cued heroin seeking and social interaction.

RESULTS

As predicted, peripheral oxytocin administration successfully decreased cued heroin seeking on days 1 and 30 of abstinence. Oxytocin administration also led to increased neuronal activity within the PVN and the central amygdala (CeA). Activation of oxytocinergic PVN neurons with an excitatory (Gq) DREADD did not impact cued reinstatement or social interaction. In contrast, suppression with an inhibitory (Gi) DREADD reduced heroin seeking on abstinence day 30 and decreased time spent interacting with a novel conspecific.

DISCUSSION

These findings reinforce oxytocin's therapeutic potential for OUD, the basis for which may be driven in part by increased PVN-CeA circuit activity. Our results also suggest that oxytocin has distinct signaling and/or other mechanisms of action to produce these effects, as inhibition, but not activation, of oxytocinergic PVN neurons did not recapitulate the suppression in heroin seeking.

Oxytocin as an adolescent treatment for methamphetamine addiction after early life stress in male and female rats

Early life stress (ELS) is associated with perturbed neural development and augmented vulnerability to mental health disorders, including addiction. How ELS changes the brain to increase addiction risk is poorly understood, and there are no therapies which target this ELS-induced vulnerability. ELS disrupts the oxytocin system, which can modulate addiction susceptibility, suggesting that targeting the oxytocin system may be therapeutic in this ELS-addiction comorbidity. Therefore, we determined whether adolescent oxytocin treatment after ELS could: (1) reduce vulnerability to anxiety, social deficits, and methamphetamine-taking and reinstatement; and (2) restore hypothalamic oxytocin and corticotropin-releasing factor expressing neurons and peripheral oxytocin and corticosterone levels. Long Evans pups underwent maternal separation (MS) for either 15 min or 360 min on postnatal days (PND) 1-21. During adolescence (PNDs 28-42), rats received a daily injection of either oxytocin or saline. In Experiment 1, adult rats were assessed using the elevated plus-maze, social interaction procedure, and methamphetamine self-administration procedure, including extinction, and cue-, methamphetamine- and yohimbine-induced reinstatement. In Experiment 2, plasma for enzyme immunoassays and brain tissue for immunofluorescence were collected from adult rats after acute stress exposure. Adolescent oxytocin treatment ameliorated ELS-induced anxiety and reduced methamphetamine- and yohimbine-induced reinstatement in both sexes, and suppressed methamphetamine intake and facilitated extinction in males only. Additionally, adolescent oxytocin treatment after ELS restored oxytocin-immunoreactive cells and stress-induced oxytocin levels in males, and attenuated stress-induced corticosterone levels in both sexes. Adolescent oxytocin treatment reverses some of the ELS effects on later-life psychopathology and vulnerability to addiction.

The Effects of Oxytocin on Craving, Mental Health Parameters, and Stress Hormones in Methamphetamine-Dependent Patients Undergoing Matrix Treatment Model: A Randomized, Double-Blind Clinical Trial

BACKGROUND

Methamphetamine (METH) dependence is an increasing public health problem with a wide range of mental and physical adverse effects. Recent studies report that oxytocin (OXT) has potential therapeutic properties in drug dependence. Hence, the present study was designed to evaluate the effects of OXT on craving, mental health (depression and anxiety), and stress hormones (ACTH and cortisol) in METH-dependent patients undergoing matrix treatment model (MTM), an intensive outpatient approach for stimulant abuse treatment.

METHODS

This randomized placebo-controlled clinical trial was conducted in 42 METH-dependent patients undergoing MTM to receive either intranasal OXT 40 IU (n = 21) or normal saline as placebo (n = 21) for 4 weeks. Clinical and biochemical parameters were measured at baseline and end of trials in METH-dependent patients.

RESULTS

Our findings indicated that OXT administration for 4 weeks is associated with a significant improvement in the craving and depression scores, respectively (p < 0.001 and p < 0.001), but there was no significant difference for anxiety scores compared with the placebo group. In addition, OXT administration significantly decreased cortisol (p < 0.001) and ACTH levels (p < 0.002).

CONCLUSIONS

These findings suggest that OXT can be considered as a new potential therapeutic for the treatment of METH-dependent patients undergoing MTM. Further studies are required to explore the effectiveness and safety of OXT.

The potential role of oxytocin in addiction: What is the target process?

Oxytocin regulates a variety of centrally-mediated functions, ranging from socio-sexual behavior, maternal care, and affiliation to fear, stress, anxiety. In the past years, both clinical and preclinical studies characterized oxytocin for its modulatory role on reward-related neural substrates mainly involving the interplay with the mesolimbic and mesocortical dopaminergic pathways. This suggests a role of this nonapeptide on the neurobiology of addiction raising the possibility of its therapeutic use. Although far from a precise knowledge of the underlying mechanisms, the putative role of the bed nucleus of the stria terminalis as a key structure where oxytocin may rebalance altered neurochemical processes and neuroplasticity involved in dependence and relapse has been highlighted. This view opens new opportunities to address the health problems related to drug misuse.

Descended Social Anxiety Disorder and Craving in Women Heroin Dependence Through Exercise Alerts Plasma Oxytocin Levels

Purpose: This study explored the association between peripheral blood oxytocin (OT) and social anxiety disorder (SAD) and cue-induced cravings in female heroin addicts. The effect of exercise on alleviation of SAD and OT levels was also explored. Methods: A total of 72 females with heroin dependence were assigned to three groups based on SAD severity. The three groups were Non-SAD control, SAD control, and SAD exercise groups. Subjects in the SAD exercise group underwent aerobic exercise and resistance training for 8 weeks (60 min/day, 5 days/week). Enzyme-linked immunosorbent assay analysis and Liebowitz Social Anxiety Scale (LSAS) scores were used to determine plasma OT concentration and SAD, respectively. Cue-induced craving was assessed using Visual Analog Scale (VAS) and Desires for Drug Questionnaire (DDQ). Mixed-effect analysis of variance and Pearson correlation analysis were used to explore the effect and correlation between different parameters. Results: OT levels in the SAD exercise group were significantly high after exercise (p < 0.01). LSAS, VAS, and DDQ ("Desire and Intention" and "Negative reinforcement") scores in the SAD exercise group were significantly lower after exercise (p < 0.01). Plasma OT level was negatively correlated with LSAS score (r = -0.534, p < 0.001), VAS score (r = -0.609, p < 0.001), "Desire and Intention" score (r = -0.555, p < 0.001), and "Negative reinforcement" score (r = -0.332, p < 0.01) and positively correlated with the "control" score (r = 0.258, p < 0.05). LSAS was positively correlated with VAS score (r = 0.588, p < 0.001) and "Desire and Intention" score (r = 0.282, p < 0.05). Conclusions: The findings of the present study indicate that plasma OT is a potential peripheral biomarker for prediction of the severity of social anxiety in female heroin withdrawal patients. Aerobic exercise combined with resistance training plus incremental load for 8 weeks can increase plasma OT levels and significantly reduce severity of SAD and cue-induced cravings in female heroin addicts.

Craving and opioid use disorder: A scoping review

INTRODUCTION

The subjective experience of drug craving is a prominent and common clinical phenomenon for many individuals diagnosed with opioid use disorder (OUD), and could be a valuable clinical endpoint in medication development studies. The purpose of this scoping review is to provide an overview and critical analysis of opioid craving assessments located in the published literature examining OUD.

METHOD

Studies were identified through a search of PubMed, Embase, and PsychInfo databases and included for review if opioid craving was the focus and participants were diagnosed with or in treatment for OUD.

RESULTS

Fifteen opioid craving assessment instruments were identified across the 87 studies included for review. The most common were the Visual Analog Scale (VAS, 41 studies), Desires for Drug Questionnaire (DDQ, 12 studies), Heroin Craving Questionnaire (HCQ, 10 studies), and Obsessive-Compulsive Drug Use Scale (OCDUS, 10 studies). Craving assessments varied considerably in their format, content, time frame, and underlying subscales, and only 6 of 15 had been psychometrically evaluated.

DISCUSSION

This review identified a variety of opioid craving assessments, but few had been evaluated for their psychometric properties making it difficult to ascertain whether craving is being assessed optimally in studies of OUD. Thus, the development of a reliable and valid opioid craving assessment would be worthwhile and could be guided by recently published Food and Drug Administration Clinical Outcome Assessment (COA) guidelines. Importantly, a COA focused on opioid craving could be a valuable addition to research studies designed to evaluate novel treatments for OUD.

Oxytocin modulates alcohol-cue induced functional connectivity in the nucleus accumbens of social drinkers

The brain oxytocin system is involved in a wide range of addictive behaviors, inhibiting prime- and cue-induced relapse in preclinical models of substance use disorders. Especially the ability of oxytocin to modulate connectivity between the nucleus accumbens (NAc) and cortical regions has been identified as a factor likely to be critical to its effects on relapse. We thus investigated the effect of oxytocin on NAc functional connectivity during an alcohol cue-reactivity task. Thirteen male social drinkers participated in a randomized double-blind placebo-controlled cross-over functional magnetic resonance imaging (fMRI) alcohol cue-reactivity task with and without prior intranasal application of 24 IU oxytocin. Effects of oxytocin and functional connectivity during presentation of alcohol cues were assessed using ROI-to-ROI generalized psychophysiological interaction analyses. Oxytocin application significantly reduced NAc connectivity with the cuneus and thalamo-occipital connectivity, while enhancing connectivity between the paracingulate gyrus and precentral gyrus. This effect was specific to the alcohol presentation and was not found during processing of neutral pictures. In addition, the NAc-cuneus connectivity significantly correlated with alcohol cue-induced craving during the scanning session. For the first time, we could show that oxytocin selectively attenuates NAc connectivity during an alcohol cue-reactivity task which was related to changes in subjective craving for alcohol. This might reflect an attenuation of alcohol-cue saliency by oxytocin, which improves inhibitory control over craving and cue reactivity.

Opioids and the hormone oxytocin

The neuropeptide Oxytocin (ΟΤ) is involved as a neurohormone, a neurotransmitter, or a neuromodulator in an extensive range of central and peripheral effects, complex emotional and social human behaviors, memory and learning processes. It is implicated in homeostatic, neuroadaptive processes associated with stress responses and substance use via interactions with the hypothalamic-pituitary-adrenal (HPA) axis and the dopamine mesolimbic reward stress system. This chapter reviews the preclinical and clinical literature on the complicated relationships between endogenous and exogenous opioids and ΟΤ systems and attempts to highlight key findings to date on the effectiveness of intranasal OT administration to treat opioid use disorders. OΤ seems to attenuate, even inhibit, the development of opioid use disorders in preclinical models but is still under clinical research as a promising pharmacological agent in the treatment of opioid use related behaviors. Evidence suggests a role for OT as an adjunctive or stand-alone treatment of behavioral, cognitive and emotional deficits associated with substance use, which may be responsible for seeking behavior and relapse. The mechanisms by which oxytocin acts to reverse the neural substrates of these deficits, partially due to substance induced alterations of the endogenous OT system, and thus modify the behavioral response to substance use are discussed. Other clinically relevant issues are also discussed.

The impact of early life stress on the central oxytocin system and susceptibility for drug addiction: Applicability of oxytocin as a pharmacotherapy

Early life trauma is strongly associated with an increased vulnerability to abuse illicit drugs and the impairment of neural development. This includes alterations to the development of the oxytocin system, which plays a pivotal role in the regulation of social behaviours and emotion. Dysregulation of this important system also contributes to increased susceptibility to develop drug addiction. In this review, we provide an overview of the animal models of early life stress that are widely used, and discuss the impact that early life stress has on drug-taking behaviour in adolescence and adulthood in both sexes. We link this to the changes that early life stress has on the endogenous oxytocin system, and how exogenously administered oxytocin may help to re-establish functioning of the system, and in turn, reduce drug-taking behaviour.