Relationship of marital structure and interactions to opiate abuse relapse

Oxytocin, Tolerance, and the Dark Side of Addiction

Substance use disorders blight the lives of millions of people and inflict a heavy financial burden on society. There is a compelling need for new pharmacological treatments as current drugs have limited efficacy and other major drawbacks. A substantial number of animal and recent clinical studies indicate that the neuropeptide, oxytocin, is a particularly promising therapeutic agent for human addictions, especially alcohol use disorders. In preliminary trials, we found that oxytocin administered by the intranasal route, which produces some neuropeptide penetration into the CNS, potently blocked withdrawal and reduced alcohol consumption in heavy drinkers. A considerable body of earlier animal studies demonstrated that oxytocin inhibits tolerance to alcohol, opioids, and stimulants as well as withdrawal from alcohol and opioids. Based on these preclinical findings and our clinical results, we hypothesize that oxytocin may exert therapeutic effects in substance dependence by the novel mechanism of diminishing established tolerance. A newer wave of studies has almost unanimously found that oxytocin decreases self-administration of a number of addictive substances in several animal models of addiction. Reduction of established tolerance should be included among the potential explanations of oxytocin effects in these studies and changes in tolerance should be examined in future studies in relationship to oxytocin influences on acquisition and reinstatement of self-administration as well as extinction of drug seeking. Oxytocin efficacy in reducing anxiety and stress responses as well as established tolerance suggests it may be uniquely effective in reducing negative reinforcement (Koob's "dark side" of addiction) that maintains chronic substance use.

Neuropeptidergic regulation of pair-bonding and stress buffering: Lessons from voles

This article is part of a Special Issue "SBN 2014". Interpersonal attachment is a critical component of the human experience. Pair-bonding ameliorates the severity of several mental and physical diseases. Thus, a better understanding of how the central nervous system responds to and encodes social-buffering during stress is a valuable research enterprise. The prairie vole (Microtus ochrogaster), as a laboratory animal model, provides the gold standard for the investigation of the neurobiology underlying attachment. Furthermore, emerging research in voles, additional laboratory rodents, transgenic mice, primates, and humans has provided novel insight into the neurochemical mechanisms underlying the therapeutic effects of social bonds reducing anxiety, depression, and drug abuse liability. In the present review, we highlight the work from this burgeoning field and focus on the role(s) of the neuropeptides oxytocin (OT), vasopressin (AVP), and corticotrophin releasing hormone (CRH) mediating stress buffering. Together, the data suggest that OT underlies social bonding to reduce stress-induced psychological illness while AVP and CRH facilitate arousal to enhance autonomic reactivity, increasing susceptibility to adverse mental and physical health.

Oxytocin reverses amphetamine-induced deficits in social bonding: evidence for an interaction with nucleus accumbens dopamine

Drug addiction has devastating consequences on social behaviors and can lead to the impairment of social bonding. Accumulating evidence indicates that alterations in oxytocin (OT) and dopamine (DA) neurotransmission within brain reward circuitry may be involved. We investigated this possibility, as well as the therapeutic potential of OT for drug-induced social deficits, using the prairie vole (Microtus ochrogaster)-a socially monogamous rodent that forms enduring pair bonds between adult mates. We demonstrate that repeated exposure to the commonly abused psychostimulant amphetamine (AMPH) inhibits the formation of partner preferences (an index of pair bonding) in female prairie voles. AMPH exposure also altered OT and DA neurotransmission in regions that mediate partner preference formation: it decreased OT and DA D2 receptor immunoreactivity in the medial prefrontal cortex (mPFC) and nucleus accumbens (NAcc), respectively, and increased NAcc DA levels. Administration of OT directly into the mPFC of AMPH-exposed voles restored partner preferences, and altered NAcc DA levels, and this effect was dependent on OT receptor activation. Together, these data suggest that repeated AMPH exposure impairs pair bonding through an OT-mediated mechanism, and that OT and DA systems within brain reward circuitry may interact to mediate the complex relationship between drug abuse and social bonding. Further, these results provide empirical support for the idea that the central OT system may represent an important target for the treatment of social deficits in addiction.

Individual predictors of the subjective effects of intravenous cocaine

The subjective and reinforcing effects of addictive substances can vary greatly between individuals. This study compared the relative contributions of baseline drug use, craving, stressful life events, and social factors in determining the subjective effects of cocaine in individual participants. Twelve veterans meeting criteria for cocaine dependence were evaluated in a laboratory setting. Self-report of the subjective effects of intravenous cocaine was recorded following single- and double-blind, placebo-controlled injections. Increased positive subjective effects of cocaine, including drug-induced 'good' effects and the value of intravenous injections, were most strongly correlated with greater family and social dysfunction measured through the Addiction Severity Index (ASI). Social dysfunction was the strongest predictor of cocaine-induced euphoria, accounting for approximately one-half of its variability. Participants who were dissatisfied with their current marital status reported almost no 'bad' effects of cocaine but instead reported increased drug-induced 'high', euphoria, and injection value. Although further research is required to determine the generalizability of this association, our findings are parallel to recent preclinical results showing that social interaction can attenuate psychostimulant reward. Effects of substance abuse treatment that rely on improved social function may be mediated through changes in the brain's reinforcement system that modify the rewarding effects of cocaine.

Salubrious effects of oxytocin on social stress-induced deficits

Social relationships are a fundamental aspect of life, affecting social, psychological, physiological, and behavioral functions. While positive social interactions can attenuate stress and promote health, the social environment can also be a major source of stress when it includes social disruption, confrontation, isolation, or neglect. Social stress can impair the basal function and stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis, impairing function of multiple biological systems and posing a risk to mental and physical health. In contrast, social support can ameliorate stress-induced physiological and immunological deficits, reducing the risk of subsequent psychological distress and improving an individual's overall well-being. For better clinical treatment of these physiological and mental pathologies, it is necessary to understand the regulatory mechanisms of stress-induced pathologies as well as determine the underlying biological mechanisms that regulate social buffering of the stress system. A number of ethologically relevant animal models of social stress and species that form strong adult social bonds have been utilized to study the etiology, treatment, and prevention of stress-related disorders. While undoubtedly a number of biological pathways contribute to the social buffering of the stress response, the convergence of evidence denotes the regulatory effects of oxytocin in facilitating social bond-promoting behaviors and their effect on the stress response. Thus, oxytocin may be perceived as a common regulatory element of the social environment, stress response, and stress-induced risks on mental and physical health. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.

Social bonding decreases the rewarding properties of amphetamine through a dopamine D1 receptor-mediated mechanism

Although the protective effects of social bonds on drug use/abuse have been well documented, we know little about the underlying neural mechanisms. Using the prairie vole (Microtus ochrogaster)--a socially monogamous rodent that forms long-term pair bonds after mating--we demonstrate that amphetamine (AMPH) conditioning induced a conditioned place preference (CPP) in sexually naive (SN), but not pair-bonded (PB), males. Although AMPH treatment induced a similar magnitude of dopamine release in the nucleus accumbens (NAcc) of SN and PB males, it had differential effects on NAcc D1 receptor (D1R) binding. Specifically, AMPH treatment increased D1R binding in SN, but decreased D1R binding in PB males. NAcc D1R, but not D2 receptor, antagonism blocked AMPH-induced CPP in SN males and NAcc D1R activation before AMPH conditioning enabled AMPH-induced CPP in PB males. Together, our data demonstrate that pair-bonding experience decreases the rewarding properties of AMPH through a D1R-mediated mechanism.

The role of mesocorticolimbic dopamine in regulating interactions between drugs of abuse and social behavior

The use of addictive drugs can have profound short- and long-term consequences on social behaviors. Similarly, social experiences and the presence or absence of social attachments during early development and throughout life can greatly influence drug intake and the susceptibility to drug abuse. The following review details this reciprocal interaction, focusing on common drugs of abuse (e.g., psychostimulants, opiates, alcohol and nicotine) and social behaviors (e.g., maternal, sexual, play, aggressive and bonding behaviors). The neural mechanisms underlying this interaction are discussed, with a particular emphasis on the involvement of the mesocorticolimbic dopamine system.

Inhibitory and disinhibitory effects of psychomotor stimulants and depressants on the sexual behavior of male and female rats

Drugs of abuse comprise several pharmacological classes, including psychomotor stimulants, such as amphetamine and cocaine, and CNS depressants, such as morphine and alcohol. Few studies have examined the effects of those drugs systematically on human sexual behavior, although substantial clinical and epidemiological literatures suggest that drugs in both classes either inhibit sexual responding or can be "prosexual" in certain situations, thereby increasing the potential of risky sexual activity and the spread of sexually transmitted diseases. This paper reviews original data in rats showing that both classes of drug inhibit or disinhibit sexual behavior depending on the animal's baseline level of sexual responding, hormonal status, whether the drug is given acutely or chronically, and whether the animal has learned to inhibit sexual responding toward nonreceptive partners or in the presence of conditioned olfactory cues that predict sexual nonreward.

Characteristics, retention and readmissions of opioid-dependent clients treated with oral naltrexone

The aims of this study were to examine the retention rates of opioid-dependent clients treated with oral naltrexone and identify factors that influence retention in treatment of 981 opioid-dependent clients at a public out-patient clinic in Perth, Western Australia. The average retention period for all clients was 9.0 weeks. The factors associated with longer retention were being employed and referral source. Clients who were employed stayed significantly longer in treatment than unemployed clients. Clients referred from a private clinic were retained in treatment significantly longer than those referred from other sources (X = 10.3 vs. 5.9 weeks). While the majority (80.8%) had one admission to naltrexone treatment, 19.2% presented for readmission, some on three or more occasions in the study period. The median period between the end of the first episode of treatment and commencement of the second was 15.6 weeks. The median period between the end of the second episode of treatment and commencement of the third was 11.4 weeks. Those employed had a higher probability of being retained longer in treatment than those who were unemployed in subsequent treatment episodes. Clinicians should expect that initial retention in naltrexone is likely to be relatively short, and that a substantial proportion of clients will represent for further treatment.

The role of spouses of substance abusers in treatment: gender differences

Studies exploring gender differences among substance abusers in treatment have been fairly consistent in finding that females who enter treatment express more severe psychological and psychosocial disturbances than males, despite presenting with shorter and less intense substance abuse histories. However, strands of evidence suggest that the presence of a spouse, generally perceived as an asset in the treatment of the substance abuser, may have different implications for females than for males. In order to clarify this issue, 67 male and 18 female married substance abusers in treatment and their spouses were questioned on their substance use and psychological and social functioning. Similar to other studies, the female substance abusers reported greater disturbance on dimensions of employment and psychological functioning, but less severity of alcohol abuse. Comparison of male and female spouses, however, revealed that male spouses were likely to present with the following characteristics: (1) more symptoms of substance abuse and depression, (2) less overall physical well-being, and (3) to be less inclined to help others or be involved with their children than the female spouses. These findings are consistent with the view that the process of substance abuse is telescoped in females and is associated with more disturbed functioning in women on admission to treatment than in men. However, contextual differences--specifically in terms of availability of spousal support--may contribute significantly both to the understanding of differences in female versus male substance abusers in treatment as well as to the development of guidelines for adapting treatment based on gender.

The efficacy of naltrexone in preventing reabuse of heroin after detoxification

The efficacy of Naltrexone in preventing reabuse of heroin among heroin addicts in Israel was studied in a double-blind, controlled design. Naltrexone (or placebo) treatment was given as part of a general treatment plan that continued for 12 weeks. Thirty-two addicts who successfully completed a detoxification program and met research criteria, were included in the study. Fifty milligrams of Naltrexone were taken orally three times a week (25 mg twice a week for the first 2 weeks). The follow-up procedure included an interview, urine tests, and screening for possible adverse effects. In addition, social and psychological parameters were evaluated. Fewer heroin-positive urine tests were found the Naltrexone group than in the placebo group. Throughout the entire study, the number of drug-free patients in the Naltrexone group was higher than in the placebo group. The Naltrexone group showed a significant improvement in most psychological parameters as compared with the placebo group. No differences were found in compliance or ratio of adverse effects between the Naltrexone and placebo groups. The concept "heroin abuse load" based on daily heroin consumption and duration of addiction enabled us to predict which addicts would complete the treatment program. The results suggest that heroin addicts in Israel may benefit from treatment with Naltrexone.