Intranasal Oxytocin Does Not Modulate Responses to Alcohol in Social Drinkers

The Relationship Between Oxytocin and Alcohol Dependence

The hypothalamic neuropeptide oxytocin (OT) is well known for its prosocial, anxiolytic, and ameliorating effects on various psychiatric conditions, including alcohol use disorder (AUD). In this chapter, we will first introduce the basic neurophysiology of the OT system and its interaction with other neuromodulatory and neurotransmitter systems in the brain. Next, we provide an overview over the current state of research examining the effects of acute and chronic alcohol exposure on the OT system as well as the effects of OT system manipulation on alcohol-related behaviors in rodents and humans. In rodent models of AUD, OT has been repeatedly shown to reduce ethanol consumption, particularly in models of acute alcohol exposure. In humans however, the results of OT administration on alcohol-related behaviors are promising but not yet conclusive. Therefore, we further discuss several physiological and methodological limitations to the effective application of OT in the clinic and how they may be mitigated by the application of synthetic OT receptor (OTR) agonists. Finally, we discuss the potential efficacy of cutting-edge pharmacology and gene therapies designed to specifically enhance endogenous OT release and thereby rescue deficient expression of OT in the brains of patients with severe forms of AUD and other incurable mental disorders.

Oxytocin Reduces Sensitized Stress-Induced Alcohol Relapse in a Model of Posttraumatic Stress Disorder and Alcohol Use Disorder Comorbidity

BACKGROUND

There is high comorbidity of posttraumatic stress disorder (PTSD) and alcohol use disorder with few effective treatment options. Animal models of PTSD have shown increases in alcohol drinking, but effects of stress history on subsequent vulnerability to alcohol relapse have not been examined. Here we present a mouse model of PTSD involving chronic multimodal stress exposure that resulted in long-lasting sensitization to stress-induced alcohol relapse, and this sensitized stress response was blocked by oxytocin (OT) administration.

METHODS

Male and female mice trained to self-administer alcohol were exposed to predator odor (TMT) + yohimbine over 5 consecutive days or left undisturbed. After reestablishing stable alcohol responding/intake, mice were tested under extinction conditions, and then all mice were exposed to TMT or context cues previously associated with TMT before a reinstatement test session. Separate studies examined messenger RNA expression of Oxt and Oxtr in hypothalamus following chronic stress exposure. A final study examined the effects of systemic administration of OT on stress-induced alcohol relapse in mice with and without a history of chronic stress experience.

RESULTS

Chronic stress exposure produced long-lasting sensitization to subsequent stress-induced alcohol relapse that also generalized to stress-related context cues and transcriptional changes in hypothalamic OT system. OT injected before the reinstatement test session completely blocked the sensitized stress-induced alcohol relapse effect.

CONCLUSIONS

Collectively, these results provide support for the therapeutic potential of OT, along with highlighting the value of utilizing this model in evaluating other pharmacological interventions for treatment of PTSD/alcohol use disorder comorbidity.

A randomized controlled trial examining the effects of intranasal oxytocin on alcohol craving and intimate partner aggression among couples

BACKGROUND

While alcohol use disorder (AUD) is a well-established risk factor for intimate partner aggression (IPA), effective treatments for co-occurring AUD and IPA (AUD/IPA) are lacking. Oxytocin is one promising pharmacological candidate for AUD/IPA given its potential to modulate social behavior and attenuate alcohol use. However, emerging data suggests that oxytocin's prosocial effects are inconsistent, and a small number of studies have also found that oxytocin might have the potential to be aggressogenic. No studies have directly examined the impact of oxytocin on alcohol- or IPA-related outcomes in a dyadic context.

METHODS

The goal of this double-blind, randomized, and placebo-controlled trial was to examine the effects of a single dose of intranasal oxytocin (40 international units) on cue-induced alcohol craving, subjective aggression, laboratory task-based IPA, and cortisol reactivity in a sample of 100 couples (N = 200 individuals) with AUD and physical IPA in their current relationship.

RESULTS

There were no statistically significant differences between the oxytocin and placebo conditions for any of the primary outcomes.

CONCLUSIONS

Findings suggest that a single dose of intranasal oxytocin was not efficacious in mitigating alcohol craving or aggression in this sample. Although hypotheses were not supported, the findings provide important evidence that oxytocin was not aggressogenic in this high-risk sample. Future research investigating dispositional and contextual moderators of oxytocin response in addition to the therapeutic effects of more intensive oxytocin dosing or administration strategies on alcohol craving and aggression is warranted.

Barriers and Breakthroughs in Targeting the Oxytocin System to Treat Alcohol Use Disorder

Development of better treatments for alcohol use disorder (AUD) is urgently needed. One promising opportunity for this development is the potential of targeting the oxytocin peptide system. Preclinical studies showed that administration of exogenous oxytocin or, more recently, stimulation of neurons expressing endogenous oxytocin lead to a decreased alcohol consumption across several rodent models. Initial clinical studies also showed that administration of oxytocin decreased craving for alcohol and heavy alcohol drinking. However, several more recent clinical studies were not able to replicate these effects. Thus, although targeting the oxytocin system holds promise for the treatment of AUD, more nuanced approaches toward development and application of these treatments are needed. In this mini-review we discuss potential caveats resulting in differential success of attempts to use oxytocin for modulating alcohol use disorder-related behaviors in clinical studies and evaluate three directions in which targeting the oxytocin system could be improved: (1) increasing potency of exogenously administered oxytocin, (2) developing oxytocin receptor agonists, and (3) stimulating components of the endogenous oxytocin system. Both advances and potential pitfalls of these directions are discussed.

Alcohol and oxytocin: Scrutinizing the relationship

The initial enthusiasm towards oxytocin (OXT) as a potential treatment for alcohol use disorder has been recently tempered by recognizing existing gaps in literature and the recent appearance of a relatively small number of clinical studies with negative outcomes. On the other hand, several new studies continue to support the OXT system's potential for such treatment. In this review, we thoroughly analyze existing literature assessing both alcohol's effects on the OXT system and OXT's effects on alcohol-related behaviors. Both rodent and clinical research is discussed. We identify areas that have been studied extensively and those that have been undeservingly understudied. OXT's potential effects on tolerance, withdrawal, craving, anxiety and social behaviors, and how these processes ultimately affect alcohol consumption, are critically explored. We conclude that while OXT can affect alcohol consumption in males and females, more comprehensive studies on OXT's effects on alcohol-related tolerance, withdrawal, craving, anxiety and social affiliations in subjects of both sexes and across several levels of analyses are needed.

Effect of early life social adversity on drug abuse vulnerability: Focus on corticotropin-releasing factor and oxytocin

Early life adversity can set the trajectory for later psychiatric disorders, including substance use disorders. There are a host of neurobiological factors that may play a role in the negative trajectory. The current review examines preclinical evidence suggesting that early life adversity specifically involving social factors (maternal separation, adolescent social isolation and adolescent social defeat) may influence drug abuse vulnerability by strengthening corticotropin-releasing factor (CRF) systems and weakening oxytocin (OT) systems. In adulthood, pharmacological and genetic evidence indicates that both CRF and OT systems are directly involved in drug reward processes. With early life adversity, numerous studies show an increase in drug abuse vulnerability measured in adulthood, along a concomitant strengthening of CRF systems and a weakening of OT systems. Mechanistic studies, while relatively few in number, are generally consistent with the theme that strengthened CRF systems and weakened OT systems mediate, at least in part, the link between early life adversity and drug abuse vulnerability. Establishing a direct role of CRF and OT in mediating the relation between early life social stressors and drug abuse vulnerability will inform clinical researchers and practitioners toward the development of intervention strategies to reduce risk among those suffering from early life adversities. This article is part of the special issue on 'Vulnerabilities to Substance Abuse'.

Behavioral, neurobiological, and neurochemical mechanisms of ethanol self-administration: A translational review

Alcohol use disorder has multiple characteristics including excessive ethanol consumption, impaired control over drinking behaviors, craving and withdrawal symptoms, compulsive seeking behaviors, and is considered a chronic condition. Relapse is common. Determining the neurobiological targets of ethanol and the adaptations induced by chronic ethanol exposure is critical to understanding the clinical manifestation of alcohol use disorders, the mechanisms underlying the various features of the disorder, and for informing medication development. In the present review, we discuss ethanol's interactions with a variety of neurotransmitter systems, summarizing findings from preclinical and translational studies to highlight recent progress in the field. We then describe animal models of ethanol self-administration, emphasizing the value, limitations, and validity of commonly used models. Lastly, we summarize the behavioral changes induced by chronic ethanol self-administration, with an emphasis on cue-elicited behavior, the role of ethanol-related memories, and the emergence of habitual ethanol seeking behavior.

Effect of alcohol on blood pressure

BACKGROUND

Alcohol is consumed by over 2 billion people worldwide. It is a common substance of abuse and its use can lead to more than 200 disorders including hypertension. Alcohol has both acute and chronic effects on blood pressure. This review aimed to quantify the acute effects of different doses of alcohol over time on blood pressure and heart rate in an adult population.

OBJECTIVES

Primary objective To determine short-term dose-related effects of alcohol versus placebo on systolic blood pressure and diastolic blood pressure in healthy and hypertensive adults over 18 years of age. Secondary objective To determine short-term dose-related effects of alcohol versus placebo on heart rate in healthy and hypertensive adults over 18 years of age.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomised controlled trials up to March 2019: the Cochrane Hypertension Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 2), in the Cochrane Library; MEDLINE (from 1946); Embase (from 1974); the World Health Organization International Clinical Trials Registry Platform; and ClinicalTrials.gov. We also contacted authors of relevant articles regarding further published and unpublished work. These searches had no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing effects of a single dose of alcohol versus placebo on blood pressure (BP) or heart rate (HR) in adults (≥ 18 years of age).

DATA COLLECTION AND ANALYSIS

Two review authors (ST and CT) independently extracted data and assessed the quality of included studies. We also contacted trial authors for missing or unclear information. Mean difference (MD) from placebo with 95% confidence interval (CI) was the outcome measure, and a fixed-effect model was used to combine effect sizes across studies.  MAIN RESULTS: We included 32 RCTs involving 767 participants. Most of the study participants were male (N = 642) and were healthy. The mean age of participants was 33 years, and mean body weight was 78 kilograms. Low-dose alcohol (< 14 g) within six hours (2 RCTs, N = 28) did not affect BP but did increase HR by 5.1 bpm (95% CI 1.9 to 8.2) (moderate-certainty evidence). Medium-dose alcohol (14 to 28 g) within six hours (10 RCTs, N = 149) decreased systolic blood pressure (SBP) by 5.6 mmHg (95% CI -8.3 to -3.0) and diastolic blood pressure (DBP) by 4.0 mmHg (95% CI -6.0 to -2.0) and increased HR by 4.6 bpm (95% CI 3.1 to 6.1) (moderate-certainty evidence for all).  Medium-dose alcohol within 7 to 12 hours (4 RCTs, N = 54) did not affect BP or HR. Medium-dose alcohol > 13 hours after consumption (4 RCTs, N = 66) did not affect BP or HR. High-dose alcohol (> 30 g) within six hours (16 RCTs, N = 418) decreased SBP by 3.5 mmHg (95% CI -6.0 to -1.0), decreased DBP by 1.9 mmHg (95% CI-3.9 to 0.04), and increased HR by 5.8 bpm (95% CI 4.0 to 7.5). The certainty of evidence was moderate for SBP and HR, and was low for DBP. High-dose alcohol within 7 to 12 hours of consumption (3 RCTs, N = 54) decreased SBP by 3.7 mmHg (95% CI -7.0 to -0.5) and DBP by 1.7 mmHg (95% CI -4.6 to 1.8) and increased HR by 6.2 bpm (95% CI 3.0 to 9.3). The certainty of evidence was moderate for SBP and HR, and low for DBP. High-dose alcohol ≥ 13 hours after consumption (4 RCTs, N = 154) increased SBP by 3.7 mmHg (95% CI 2.3 to 5.1), DBP by 2.4 mmHg (95% CI 0.2 to 4.5), and HR by 2.7 bpm (95% CI 0.8 to 4.6) (moderate-certainty evidence for all).  AUTHORS' CONCLUSIONS: High-dose alcohol has a biphasic effect on BP; it decreases BP up to 12 hours after consumption and increases BP > 13 hours after consumption. High-dose alcohol increases HR at all times up to 24 hours. Findings of this review are relevant mainly to healthy males, as only small numbers of women were included in the included trials.

Potential for limited reinforcing and abuse-related subjective effects of intranasal oxytocin

BACKGROUND

There has been growing interest in using oxytocin as a pharmacotherapy for psychiatric disorders, including substance use disorder. Limited data exist regarding oxytocin's reinforcing efficacy, which is a necessary consideration for novel pharmacotherapies, especially in substance-using populations.

AIMS

This study aimed to determine the potential reinforcing effects of intranasally administered oxytocin by assessing behavioral economic demand and subjective effects.

METHODS

Healthy adults (n = 23) participated in a double-blind, repeated-measures, laboratory study wherein they received intranasal oxytocin (40 IU) or placebo in a randomized order across two sessions. Participants completed drug purchasing tasks at the conclusion of both sessions. Throughout both sessions, subjective and physiological effects were assessed.

RESULTS

Demand-curve analysis of purchasing tasks revealed greater median purchasing for oxytocin relative to placebo. Physiological and subjective effects did not significantly differ between oxytocin and placebo. However, a nonsignificant trend was observed for moderately greater drug liking for oxytocin relative to placebo. There was a significant, positive correlation between the difference in drug liking (between oxytocin and placebo) and the difference in lowest-price purchasing (between oxytocin and placebo).

CONCLUSIONS

These data suggest the potential for limited reinforcing and abuse-related subjective effects of intranasal oxytocin. Given the small sample, the greater drug liking of oxytocin compared to placebo, and the positive relation between demand and drug liking, it is possible that oxytocin may produce reinforcing effects in some participants. Therefore, additional studies of oxytocin reinforcement are warranted.

Effects of Oxytocin Administration on Cue-Induced Craving in Co-occurring Alcohol Use Disorder and PTSD: A Within-Participant Randomized Clinical Trial

BACKGROUND

Individuals with alcohol use disorder (AUD) are much more likely to meet criteria for posttraumatic stress disorder (PTSD) than the general population. Compared to AUD alone, those with comorbid AUD-PTSD experience worse outcomes. Prior literature suggests that oxytocin, a hypothalamic neuropeptide, may be effective in the treatment of both AUD and PTSD when administered intranasally, although specific mechanisms remain elusive.

METHODS

Forty-seven male patients with comorbid AUD-PTSD were administered intranasal oxytocin in a randomized, double-blind, dose-ranging (20 IU, 40 IU, and matched placebo), within-participant design with study visits at least 1 week apart. A cue-induced craving paradigm was conducted using each participant's preferred alcoholic beverage versus a neutral water cue. Self-reported alcohol craving and heart rate (HR) were recorded and analyzed using linear mixed-effect models.

RESULTS

While alcohol cues significantly induced self-reported craving and increased HR compared to neutral water cues, neither dosage of oxytocin compared to placebo reduced self-reported cue-induced alcohol craving nor cue-induced changes in HR in patients with PTSD-AUD.

CONCLUSIONS

These preliminary findings suggest that oxytocin does not affect cue-induced craving. Our results contribute to an ever-growing field of research investigating the effects of intranasal oxytocin on the symptoms of substance use disorders and will help further refine methodology and streamline future inquiries in this area.