Community-dwelling cocaine-dependent men and women respond differently to social stressors versus cocaine cues

Sex differences in hippocampal β-adrenergic receptor subtypes drive retrieval, retention, and learning of cocaine-associated memories

Background

Drug seeking behavior occurs in response to environmental contexts and drug-associated cues. The presence of these pervasive stimuli impedes abstinence success. β-adrenergic receptors (β-ARs) have a long-standing historical implication in driving processes associated with contextual memories, including drug-associated memories in substance use disorders. However, sex differences in the role of β-adrenergic receptors in drug memories remain unknown.

Hypothesis

Prior reports indicate a selective role for β2-ARs in retrieval and retention of contextual drug memories in males, and substantial sex differences exist in the expression of β-ARs of male and female rats. Therefore, we hypothesized that there are sex differences in selective recruitment of β-ARs during different stages of memory encoding and retrieval.

Methods

The role of β-ARs in driving retrieval and learning of contextual cocaine memories was investigated using cocaine conditioned place preference (CPP) in adult male and female Sprague-Dawley rats. Rats were infused directly to the dorsal hippocampus with Propranolol (β1 and β2) or ICI-118,551 (β1) and/or Betaxolol (β2), immediately prior to testing (retrieval), or paired to each cocaine (10 mg/kp, IP) conditioning session (learning).

Results

In males, administration of either β1, β2, or combined β1 and β2-ARs before the initial CPP testing reduced the expression of a CPP compared to vehicle administration. In females, β2-ARs transiently decreased CPP memories, whereas β1 had long lasting but not immediate effects to decrease CPP memories. Additionally, β1 and combined β1 and β2-ARs had immediate and persistent effects to decrease CPP memory expression. DG Fos + neurons predicted cocaine CPP expression in males, whereas CA1 and CA3 Fos + neurons predicted cocaine CPP expression in females.

Conclusion

There are significant sex differences in the role of dorsal hippocampus β-ARs in the encoding and expression of cocaine conditioned place preference. Furthermore, sub regions of the dorsal hippocampus appear to activate differently between male and female rats during CPP. Therefore DG, CA3, and CA1 may have separate region- and sex-specific impacts on driving drug- associated, or context-associated cues.

Role of nucleus accumbens dopamine 2 receptors in motivating cocaine use in male and female rats prior to and following the development of an addiction-like phenotype

A hallmark of cocaine use disorder (CUD) is dysfunction of dopamine signaling in the mesolimbic pathway, including impaired dopamine 2 (D2) receptor signaling. One of the most replicated findings in human imagining studies is decreased striatal D2 receptor binding in individuals with a substance use disorder relative to healthy controls; however, the vast majority of the data is from males, and findings in smokers suggest this molecular shift may not translate to females. The goal of this study was to determine whether there are sex differences in the role of D2 receptors in motivating cocaine use prior to and following the development of an addiction-like phenotype (defined by an enhanced motivation for cocaine relative to the short-access, ShA, group). Here, male and female rats were given ShA (20 infusions/day, 3 days) or extended-access (ExA; 24h/day, 96 infusions/day, 10 days) to cocaine self-administration and then following 14 days of withdrawal, were tested under a progressive-ratio schedule to assess motivation for cocaine use. Once a stable level of motivation was established, the effect of NAc-infusions of the D2 receptor antagonist eticlopride (0-3.0 µg/side) were examined. We found that in males, eticlopride was less effective at decreasing motivation for cocaine following ExA versus ShA self-administration, particularly at low eticlopride doses. In contrast, in females, there were no differences in the effectiveness of eticlopride between ExA and ShA. These findings indicate that males, but not females, become less sensitive to NAc-D2 receptor antagonism with the development of an addiction-like phenotype.

Metabotropic group II glutamate receptors mediate cue-triggered increases in reward-seeking behaviour

RATIONALE

Reward-associated cues can invigorate reward-seeking actions via Pavlovian-to-instrumental transfer (PIT). Glutamatergic neurotransmission mediates the appetitive effects of reward-associated cues. We characterized the expression of PIT and its mediation by metabotropic group II glutamate (mGlu_2/3) receptor activity in female and male rats.

OBJECTIVES

Across the sexes, we used PIT procedures to determine (i) cue-triggered increases in instrumental responding for water reward (experiment 1) and (ii) the respective influences of the mGlu_2/3 receptor agonist LY379268 and thirst satiation on this effect (experiment 2).

METHODS

Water-restricted female and male Sprague-Dawley rats learned to lever press for water. Separately, they learned that one of two auditory stimuli predicts free water (CS + vs CS -). On PIT test days, the CS + and CS - were presented independent of instrumental responding, and we measured effects on lever pressing under extinction (no water). In experiment 1, we characterized PIT across the sexes. In experiment 2, we measured PIT after systemic LY379268 administration (0, 0.3 and 1 mg/kg) and thirst satiation, respectively.

RESULTS

Female and male rats showed similar PIT, with CS + but not CS - presentations potentiating water-seeking behaviour. LY379268 (1 mg/kg) attenuated CS + evoked increases in both water-associated lever pressing and conditioned approach to the water port. Thirst satiation attenuated both water-seeking and CS + evoked conditioned approach behaviour.

CONCLUSIONS

The sexes show similar cue-triggered increases in reward seeking, and thirst satiation suppresses both water-seeking and cue-triggered anticipation of water reward. Finally, across the sexes, mGlu_2/3 receptor activity mediates cue-triggered increases in reward seeking.

Therapeutics for Substance-Using Women: The Need to Elucidate Sex-Specific Targets for Better-Tailored Treatments

In the last decade, alcohol consumption in the US has risen by 84% in women compared with 35% in men. Furthermore, research has shown that sex- and gender-related differences may disadvantage women in terms of developing a range of psychological, cognitive, and medical problems considerably earlier in their drinking history than men, and despite consuming a similar quantity of substances. While this "telescoping" process has been acknowledged in the literature, a concomitant understanding of the underlying biobehavioral mechanisms, and an increase in the development of specific treatments tailored to women, has not occurred. In the current chapter we focus on understanding why the need for personalized, sex-specific medications is imperative, and highlight some of the potential sex-specific gonadal and stress-related adaptations underpinning the accelerated progress from controlled to compulsive drug and alcohol seeking in women. We additionally discuss the efficacy of these mechanisms as novel targets for medications development, using exogenous progesterone and guanfacine as examples. Finally, we assess some of the challenges faced and progress made in terms of developing innovative medications in women. We suggest that agents such as exogenous progesterone and adrenergic medications, such as guanfacine, may provide some efficacy in terms of attenuating stress-induced craving for several substances, as well as improving the ability to emotionally regulate in the face of stress, preferentially in women. However, to fully leverage the potential of these therapeutics in substance-using women, greater focus needs to the placed on reducing barriers to treatment and research by encouraging women into clinical trials.

Corticotropin releasing factor and drug seeking in substance use disorders: Preclinical evidence and translational limitations

The neuropeptide, corticotropin releasing factor (CRF), has been an enigmatic target for the development of medications aimed at treating stress-related disorders. Despite a large body of evidence from preclinical studies in rodents demonstrating that CRF receptor antagonists prevent stressor-induced drug seeking, medications targeting the CRF-R1 have failed in clinical trials. Here, we provide an overview of the abundant findings from preclinical rodent studies suggesting that CRF signaling is involved in stressor-induced relapse. The scientific literature that has defined the receptors, mechanisms and neurocircuits through which CRF contributes to stressor-induced reinstatement of drug seeking following self-administration and conditioned place preference in rodents is reviewed. Evidence that CRF signaling is recruited with repeated drug use in a manner that heightens susceptibility to stressor-induced drug seeking in rodents is presented. Factors that may determine the influence of CRF signaling in substance use disorders, including developmental windows, biological sex, and genetics are examined. Finally, we discuss the translational failure of medications targeting CRF signaling as interventions for substance use disorders and other stress-related conditions. We conclude that new perspectives and research directions are needed to unravel the mysterious role of CRF in substance use disorders.

Cue-induced cocaine craving enhances psychosocial stress and vice versa in chronic cocaine users

Stress and craving, it has been found, contribute to the development and maintenance of and relapse in cocaine use disorder. Chronic cocaine users (CU), previous research has shown, display altered physiological responses to psychosocial stress and increased vegetative responding to substance-related cues. However, how psychosocial stress and cue-induced craving interact in relation to the CU's physiological responses remains largely unknown. We thus investigated the interaction between acute psychosocial stress and cocaine-cue-related reactivity in 47 CU and 38 controls. In a crossed and balanced design, the participants were randomly exposed to a video-based cocaine-cue paradigm and the Trier Social Stress Test (TSST) or vice versa to investigate possible mutually augmenting effects of both stressors on physiological stress responses. Over the course of the experimental procedure, plasma cortisol, ACTH, noradrenaline, subjective stress, and craving were assessed repeatedly. To estimate the responses during the cocaine-cue paradigm and TSST, growth models and discontinuous growth models were used. Overall, though both groups did not differ in their endocrinological responses to the TSST, CU displayed lower ACTH levels at baseline. The TSST did not elevate craving in CU, but when the cocaine-cue video was shown first, CU displayed an enhanced cortisol response to the subsequent TSST. In CU, cocaine-cues robustly evoked craving but no physiological stress response, while cue-induced craving was intensified after the TSST. Taken together, though CU did not show an altered acute stress response during the TSST, stress and craving together seemed to have mutually augmenting effects on their stress response.

Sex and drug differences in stress, craving and cortisol response to the trier social stress task

RATIONALE

The hypothalamic-pituitary-adrenal (HPA) axis is a critical hormonal system involved in stress response. A number of studies have investigated the HPA axis response of drug-dependent individuals to stressors. Stress-induced vulnerabilities in the HPA axis may differ in response to chronic use of different substances, possibly leading to different target therapies. There has not been a direct comparison of HPA axis and subjective response between individuals with different types of substance use disorders following a laboratory stress intervention.

OBJECTIVES

The primary goal of the current study was to compare subjective and neuroendocrine response to the Trier Social Stress Task (TSST) across multiple primary types of substance use disorders and investigate differential response between males and females.

METHODS

Four hundred participants were drawn from seven studies completed at the Medical University of South Carolina between 2011 and 2021. The TSST was utilized across studies and subjective and neuroendocrine responses measured following completion. Generalized linear mixed effects models and area under the response curve analysis were used to compare both substance type and sex differences.

RESULTS

The study groups involving individuals with cocaine use disorder had blunted stress, craving and cortisol response following the TSST as compared to other substance use groups. Females in the cocaine groups reported higher subjective stress but lower cortisol than males.

CONCLUSIONS

The study results indicate that there may be differential effects of substances on the HPA axis, with cocaine using individuals exhibiting more blunting of the HPA axis response as compared to users of other substances.

Oxytocin moderates corticolimbic social stress reactivity in cocaine use disorder and healthy controls

Social stress can contribute to the development of substance use disorders (SUDs) and increase the likelihood of relapse. Oxytocin (OT) is a potential pharmacotherapy that may buffer the effects of social stress on arousal and reward neurocircuitry. However, more research is needed to understand how OT moderates the brain’s response to social stress in SUDs. The present study examined the effect of intransasal OT (24 IU) versus placebo (PBO) on corticolimbic functional connectivity associated with acute social stress in individuals with cocaine use disorder (CUD; n = 67) and healthy controls (HC; n = 52). Psychophysiological interaction modeling used the left and right amygdala as seed regions with the left and right orbitofrontal and anterior cingulate cortex as a priori regions of interest. Moderators of the OT response included childhood trauma history and biological sex, which were examined in independent analyses. The main finding was that OT normalized corticolimbic connectivity (left amygdala-orbitofrontal and left amygdala-anterior cingulate) as a function of childhood trauma such that connectivity was different between trauma-present and trauma-absent groups on PBO, but not between trauma groups on OT. Effects of OT on corticolimbic connectivity were not different as a function of diagnosis (CUD vs HC) or sex. However, OT reduced subjective anxiety during social stress for CUD participants who reported childhood trauma compared to PBO and normalized craving response as a function of sex in CUD. The present findings add to some prior findings of normalizing effects of OT on corticolimbic circuitry in individuals with trauma histories and provide some initial support that OT can normalize subjective anxiety and craving in CUD.

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Social stress-related corticolimbic connectivity was affected by childhood trauma under placebo.

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Under oxytocin, corticolimbic connectivity differences due to childhood trauma were absent.

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Oxytocin reduced subjective anxiety in cocaine users with childhood trauma.

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Oxytocin reduced subjective craving in male cocaine users.

Consideration of sex and gender differences in addiction medication response

Substance use continues to contribute to significant morbidity and mortality in the United States, for both women and men, more so than another other preventable health condition. To reduce the public health burden attributable to substances, the National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism have identified that medication development for substance use disorder is a high priority research area. Furthermore, both Institutes have stated that research on sex and gender differences in substance use medication development is a critical area. The purpose of the current narrative review is to highlight how sex and gender have been considered (or not) in medication trials for substance use disorders to clarify and summarize what is known regarding sex and gender differences in efficacy and to provide direction to the field to advance medication development that is consistent with current NIH 'sex as a biological variable' (SABV) policy. To that end, we reviewed major classes of abused substances (nicotine, alcohol, cocaine, cannabis, opioids) demonstrating that, sex and gender have not been well-considered in addiction medication development research. However, when adequate data on sex and gender differences have been evaluated (i.e., in tobacco cessation), clinically significant differences in response have been identified between women and men. Across the other drugs of abuse reviewed, data also suggest sex and gender may be predictive of outcome for some agents, although the relatively low representation of women in clinical research samples limits making definitive conclusions. We recommend the incorporation of sex and gender into clinical care guidelines and improved access to publicly available sex-stratified data from medication development investigations.

Sex Differences in Opioid and Psychostimulant Craving and Relapse: A Critical Review

A widely held dogma in the preclinical addiction field is that females are more vulnerable than males to drug craving and relapse. Here, we first review clinical studies on sex differences in psychostimulant and opioid craving and relapse. Next, we review preclinical studies on sex differences in psychostimulant and opioid reinstatement of drug seeking after extinction of drug self-administration, and incubation of drug craving (time-dependent increase in drug seeking during abstinence). We also discuss ovarian hormones' role in relapse and craving in humans and animal models and speculate on brain mechanisms underlying their role in cocaine craving and relapse in rodent models. Finally, we discuss imaging studies on brain responses to cocaine cues and stress in men and women.The results of the clinical studies reviewed do not appear to support the notion that women are more vulnerable to psychostimulant and opioid craving and relapse. However, this conclusion is tentative because most of the studies reviewed were correlational, not sufficiently powered, and not a priori designed to detect sex differences. Additionally, imaging studies suggest sex differences in brain responses to cocaine cues and stress. The results of the preclinical studies reviewed provide evidence for sex differences in stress-induced reinstatement and incubation of cocaine craving but not cue- or cocaine-induced reinstatement of cocaine seeking. These sex differences are modulated in part by ovarian hormones. In contrast, the available data do not support the notion of sex differences in craving and relapse/reinstatement for methamphetamine or opioids in rodent models. SIGNIFICANCE STATEMENT: This systematic review summarizes clinical and preclinical studies on sex differences in psychostimulant and opioid craving and relapse. Results of the clinical studies reviewed do not appear to support the notion that women are more vulnerable to psychostimulant and opioid craving and relapse. Results of preclinical studies reviewed provide evidence for sex differences in reinstatement and incubation of cocaine seeking but not for reinstatement or incubation of methamphetamine or opioid seeking.

Common and gender-specific associations with cocaine use on gray matter volume: Data from the ENIGMA addiction working group

Gray matter volume (GMV) in frontal cortical and limbic regions is susceptible to cocaine-associated reductions in cocaine-dependent individuals (CD) and is negatively associated with duration of cocaine use. Gender differences in CD individuals have been reported clinically and in the context of neural responses to cue-induced craving and stress reactivity. The variability of GMV in select brain areas between men and women (e.g., limbic regions) underscores the importance of exploring interaction effects between gender and cocaine dependence on brain structure. Therefore, voxel-based morphometry data derived from the ENIGMA Addiction Consortium were used to investigate potential gender differences in GMV in CD individuals compared to matched controls (CTL). T1-weighted MRI scans and clinical data were pooled from seven sites yielding 420 gender- and age-matched participants: CD men (CDM, n = 140); CD women (CDW, n = 70); control men (CTLM, n = 140); and control women (CTLW, n = 70). Differences in GMV were assessed using a 2 × 2 ANCOVA, and voxelwise whole-brain linear regressions were conducted to explore relationships between GMV and duration of cocaine use. All analyses were corrected for age, total intracranial volume, and site. Diagnostic differences were predominantly found in frontal regions (CD < CTL). Interestingly, gender × diagnosis interactions in the left anterior insula and left lingual gyrus were also documented, driven by differences in women (CDW < CTLW). Further, lower right hippocampal GMV was associated with greater cocaine duration in CDM. Given the importance of the anterior insula to interoception and the hippocampus to learning contextual associations, results may point to gender-specific mechanisms in cocaine addiction.

BDNF and Cortisol in the Diagnosis of Cocaine-Induced Depression

BACKGROUND

Major depressive disorder (MDD) and cocaine use disorder (CUD) are related with disability and high mortality rates. The assessment and treatment of psychiatric comorbidity is challenging due to its high prevalence and its clinical severity, mostly due to suicide rates and the presence of medical comorbidities. The aim of this study is to investigate differences in brain derived neurotrophic factor (BDNF) and cortisol plasmatic levels in patients diagnosed with CUD-primary-MDD and CUD-induced-MDD and also to compare them to a sample of MDD patients (without cocaine use), a sample of CUD (without MDD), and a group of healthy controls (HC) after a stress challenge.

METHODS

A total of 46 subjects were included: MDD (n = 6), CUD (n = 15), CUD-primary-MDD (n = 16), CUD-induced-MDD (n = 9), and 21 HC. Psychiatric comorbidity was assessed with the Spanish version of the Psychiatric Research Interview for Substance and Mental Disorders IV (PRISM-IV), and depression severity was measured with the Hamilton Depression Rating Scale (HDRS). Patients were administered the Trier Social Stress Test (TSST) before and after the biological measures, including BDNF, and cortisol levels were obtained.

RESULTS

After the TSST, Cohen's d values between CUD-primary-MDD and CUD-induced-MDD increased in each assessment from 0.19 post-TSST to 2.04 post-90-TSST. Pairwise differences among CUD-induced-MDD and both MDD and HC groups had also a large effect size value in post-30-TSST and post-90-TSST. In the case of the BDNF concentrations, CUD-primary-MDD and CUD-induced-MDD in post-90-TSST (12,627.27 ± 5488.09 vs.17,144.84 ± 6581.06, respectively) had a large effect size (0.77).

CONCLUSION

Results suggest a different pathogenesis for CUD-induced-MDD with higher levels of cortisol and BDNF compared with CUD-primary-MDD. Such variations should imply different approaches in treatment.

Neurochemical mechanisms and neurocircuitry underlying the contribution of stress to cocaine seeking

In individuals with substance use disorders, stress is a critical determinant of relapse susceptibility. In some cases, stressors directly trigger cocaine use. In others, stressors interact with other stimuli to promote drug seeking, thereby setting the stage for relapse. Here, we review the mechanisms and neurocircuitry that mediate stress-triggered and stress-potentiated cocaine seeking. Stressors trigger cocaine seeking by activating noradrenergic projections originating in the lateral tegmentum that innervate the bed nucleus of the stria terminalis to produce beta adrenergic receptor-dependent regulation of neurons that release corticotropin releasing factor (CRF) into the ventral tegmental area (VTA). CRF promotes the activation of VTA dopamine neurons that innervate the prelimbic prefrontal cortex resulting in D1 receptor-dependent excitation of a pathway to the nucleus accumbens core that mediates cocaine seeking. The stage-setting effects of stress require glucocorticoids, which exert rapid non-canonical effects at several sites within the mesocorticolimbic system. In the nucleus accumbens, corticosterone attenuates dopamine clearance via the organic cation transporter 3 to promote dopamine signaling. In the prelimbic cortex, corticosterone mobilizes the endocannabinoid, 2-arachidonoylglycerol (2-AG), which produces CB1 receptor-dependent reductions in inhibitory transmission, thereby increasing excitability of neurons which comprise output pathways responsible for cocaine seeking. Factors that influence the role of stress in cocaine seeking, including prior history of drug use, biological sex, chronic stress/co-morbid stress-related disorders, adolescence, social variables, and genetics are discussed. Better understanding when and how stress contributes to drug seeking should guide the development of more effective interventions, particularly for those whose drug use is stress related.

Daily associations among craving, affect, and social interactions in the lives of patients during residential opioid use disorder treatment

OBJECTIVE

This study captured the interrelationships among craving, negative affect, and positive and negative social exchanges in the daily lives of patients in residential treatment for opioid use disorders (OUDs).

METHOD

Participants were 73 patients (77% male), age 19 to 61 (Mage = 30.10, SDage = 10.13) in residential treatment for OUD. Participants completed a smartphone-based survey 4 times per day for 12 consecutive days that measured positive and negative social exchanges (Test of Negative Social Exchange), negative affect (PA-NA scales), and craving (frequency and intensity). Within-person, day-level associations among daily positive and negative social exchanges, negative affect, and craving were examined using multilevel modeling.

RESULTS

Daily negative social exchanges (M = 1.44, SD = 2.27) were much less frequent than positive social exchanges (M = 6.59, SD = 4.00) during residential treatment. Whereas negative social exchanges had a direct association with same-day craving (β = 0.08; 95% CI = 0.01, 0.16, ΔR2 = 0.01), positive social exchanges related to craving indirectly via moderation of the within-person negative affect-craving link (β = -0.01; 95% CI = -0.01, -0.001, ΔR2 = 0.002). Positive social exchanges decoupled the same-day linkage between negative affect and craving on days when individuals had at least four more positive social exchanges than usual.

CONCLUSIONS

These results indicate that both negative affect and negative social exchanges are uniquely related to craving on a daily basis, and that extra positive social interactions can reduce the intraindividual coupling of negative affect and craving during residential treatment for OUD. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The effect of oxytocin, gender, and ovarian hormones on stress reactivity in individuals with cocaine use disorder

RATIONALE

Cocaine use disorder (CUD) is associated with dysregulation of the hypothalamic-pituitary-adrenal axis, which plays a critical role in the human stress response. Men and women with CUD differ in reactivity to social stressors. The hypothalamic neuropeptide oxytocin is involved in anxiolytic and natural reward processes, and has shown therapeutic potential for addictive disorders and stress reduction.

OBJECTIVES

To examine the impact of oxytocin (oxytocin (OXY) vs. placebo (PBO)) and gender (female (F) vs. male (M)) on response to a social stress task in individuals with CUD. To explore whether ovarian hormones moderate this stress response.

METHODS

One hundred twelve adults with CUD were randomized to receive 40 IU intranasal oxytocin (n = 56) or matching placebo (n = 56). Forty minutes after drug administration, participants were exposed to a social stressor. Generalized linear mixed models were used to examine neuroendocrine (cortisol) and subjective (craving, stress) response at pre-stressor, stressor + 0, + 10, + 30, + 60 min.

RESULTS

Gender moderated the effect of oxytocin on neuroendocrine response (p = 0.048); women receiving oxytocin (F + OXY) showed blunted cortisol response compared to the other three groups (F + PBO; M + OXY; M + PBO). There was a main effect of gender on subjective stress response; women reported greater stress following the stressor compared to men (p = 0.016). Oxytocin had no significant effect on craving or stress, and gender did not moderate the effect of oxytocin on either measure. Higher endogenous progesterone was associated with lower craving response in women (p = 0.033).

CONCLUSIONS

Oxytocin may have differential effects in men and women with CUD. Women may be at greater risk for relapse in response to social stressors, but ovarian hormones may attenuate this effect.

Neural correlates of oxytocin and cue reactivity in cocaine-dependent men and women with and without childhood trauma

RATIONALE

Women with cocaine use disorder have worse treatment outcomes compared with men. Sex differences in cocaine addiction may be driven by differences in neurobiology or stress reactivity. Oxytocin is a potential therapeutic for stress reduction in substance use disorders, but no studies have examined the effect of oxytocin on neural response to drug cues in individuals with cocaine use disorders or potential sex differences in this response.

OBJECTIVES

The goal of this study was to examine the effect of intranasal oxytocin on cocaine cue reactivity in cocaine dependence, modulated by gender and history of childhood trauma.

METHODS

Cocaine-dependent men with (n = 24) or without (n = 19) a history of childhood trauma and cocaine-dependent women with (n = 16) or without (n = 8) a history of childhood trauma completed an fMRI cocaine cue reactivity task under intranasal placebo or oxytocin (40 IU) on two different days. fMRI response was measured in the right amygdala and dorsomedial prefrontal cortex (DMPFC).

RESULTS

In the DMPFC, oxytocin reduced fMRI response to cocaine cues across all subject groups. However, in the amygdala, only men with a history of childhood trauma showed a significantly reduced fMRI response to cocaine cues on oxytocin versus placebo, while women with a history of childhood trauma showed an enhanced amygdala response to cocaine cues following oxytocin administration. Cocaine-dependent subjects with no history of childhood trauma showed no effect of oxytocin on amygdala response.

CONCLUSIONS

Oxytocin can reduce cue reactivity in cocaine dependence, but its effect is modified by sex and childhood trauma history. Whereas men with cocaine dependence may benefit from oxytocin administration, additional studies are needed to determine whether oxytocin can be an effective therapeutic for cocaine-dependent women.

Brain activity associated with social exclusion overlaps with drug-related frontal-striatal circuitry in cocaine users: A pilot study

Background

Exposure to various types of stress can elevate craving for cocaine and hasten relapse among substance dependent individuals. This investigation evaluated the effects of social exclusion on brain activity in cocaine dependent individuals.

Method

Forty three individuals (18 crack-cocaine users, 25 controls) were recruited from the community to participate in functional neuroimaging study in which they performed a simulated 3 person ball-tossing game (Cyberball). Each participant was told that the other 2 players were in nearby MRI scanners. Task blocks included: Inclusion (likelihood of our participant receiving the ball = 50%), Exclusion (likelihood gradually decreases to 0%), and Rest. Self-worth variables (e.g self-esteem, locus of control) were measured before and after the ball-tossing game. General linear model-based statistics were used to measure the brain response to inclusion and exclusion within and between the groups with respect to rest.

Results

Relative to controls, cocaine users had significantly more activity during Exclusion versus Inclusion in 3 areas: the right medial frontal gyrus (Brodmann Area 9,10), left ventral lateral frontal gyrus (Brodmann Area 10,47) and right caudate. This was driven by a higher response to social exclusion in the cocaine users. There was no difference between groups in the brain reactivity to social inclusion.

Conclusion

Cocaine dependent individuals have an amplified brain response to social exclusion stress in cortical regions associated with emotional regulation, arousal, craving and perception of physical pain. These data suggest that there may be a neurological basis for the well-established relationship between social stress and addiction.

Social defeat stress and escalation of cocaine and alcohol consumption: Focus on CRF

Both the ostensibly aversive effects of unpredictable episodes of social stress and the intensely rewarding effects of drugs of abuse activate the mesocorticolimbic dopamine systems. Significant neuroadaptations in interacting stress and reward neurocircuitry may underlie the striking connection between stress and substance use disorders. In rodent models, recurring intermittent exposure to social defeat stress appears to produce a distinct profile of neuroadaptations that translates most readily to the repercussions of social stress in humans. In the present review, preclinical rodent models of social defeat stress and subsequent alcohol, cocaine or opioid consumption are discussed with regard to: (1) the temporal pattern of social defeat stress, (2) male and female protocols of social stress-escalated drug consumption, and (3) the neuroplastic effects of social stress, which may contribute to escalated drug-taking. Neuroadaptations in corticotropin-releasing factor (CRF) and CRF modulation of monoamines in the ventral tegmental area and the bed nucleus of the stria terminalis are highlighted as potential mechanisms underlying stress-escalated drug consumption. However, the specific mechanisms that drive CRF-mediated increases in dopamine require additional investigation as do the stress-induced neuroadaptations that may contribute to the development of compulsive patterns of drug-taking.

Effects of alcohol and psychostimulants on the vasopressin system: behavioral implications

Drug addiction is a chronic brain disease characterized by a compulsion to seek drugs, a loss of control with respect to drug consumption, and negative emotional states, including increased anxiety and irritability during withdrawal. Central vasopressin (AVP) and its receptors are involved in controlling social behavior, anxiety and reward, all of which are altered by drugs of abuse. Hypothalamic AVP neurons influence the stress response by modulating the hypothalamic-pituitary-adrenal (HPA) axis. The extrahypothalamic AVP system, however, is commonly associated with social recognition, motivational and anxiety responses. The specific relationship between AVP and drugs of abuse has been rarely reviewed. Here, we provide an overview of the interaction between the brain AVP system and psychostimulants and alcohol. We focus on the effects of alcohol and psychostimulants on AVP regulation of the HPA axis, their effect on the brain AVP system and their behavioral implications, the influence of the AVP system on addictive behaviors, AVP's organizational effects on the brain and consequently on behavior, and we highlight clinical studies on the relation between the AVP system and drug addiction. Finally, we discuss the data to address areas that need further research to support clinical trials and prevent drug-related disorders. This article is protected by copyright. All rights reserved.

Resting State Functional Connectivity of the Lateral and Medial Hypothalamus in Cocaine Dependence: An Exploratory Study

The role of dopamine in cocaine misuse has been extensively documented for the mesocorticolimbic circuit. Preclinical work from earlier lesion studies to recent multidisciplinary investigations has suggested that the hypothalamus is critically involved in motivated behavior, with the lateral and medial hypothalamus each involved in waking/feeding and resting/satiety. However, little is known of hypothalamus function and dysfunction in cocaine misuse. Here, we examined resting state functional connectivity of the lateral and medial hypothalamus in 70 individuals with cocaine dependence (CD) and 70 age as well as gender matched healthy controls (HC). Image pre-processing and analyses followed published work. Compared to HC, CD showed increased lateral hypothalamic connectivity with dorsolateral prefrontal cortex and decreased functional connectivity with the ventral precuneus. CD showed increased medial hypothalamic connectivity with the inferior parietal lobule and decreased connectivity with the ventromedial prefrontal cortex, temporal gyrus, fusiform gyrus, and ventral striatum. Further, at trend level significance, the connectivity strength between lateral hypothalamus and dorsolateral prefrontal cortex was positively correlated with total amount of cocaine use in the past month (p = 0.004, r = 0.35) and the connectivity strength between medial hypothalamus and ventral striatum was negatively correlated with cocaine craving as assessed by the Tiffany Cocaine Craving Questionnaire (p = 0.008, r = -0.33). Together, the findings demonstrated altered resting state functional connectivity of the hypothalamus and may provide new insight on circuit level deficits in cocaine dependence.

Impact of gender on corticotropin-releasing factor and noradrenergic sensitivity in cocaine use disorder

Responses to stress may be important in understanding gender differences in substance use disorders and may also be a target for development of treatment interventions. A growing body of both preclinical and clinical research supports important underlying gender differences in the corticotropin-releasing factor (CRF) and noradrenergic systems, which may contribute to drug use. Preclinical models have demonstrated increased sensitivity of females to CRF and noradrenergic-induced drug reinstatement compared with males, and, consistent with these findings, human laboratory studies have demonstrated greater sensitivity to corticotropin-releasing hormone (CRH) and noradrenergic stimulation in cocaine-dependent women compared with men. Furthermore, neuroimaging studies have demonstrated increased neural response to stressful stimuli in cocaine-dependent women compared with men as well as showing significant sex differences in the sensitivity of brain regions responsible for regulating the response to CRH. Development of interventions targeting the noradrenergic system and stress response in drug-dependent individuals could have important clinical implications for both women and men. © 2016 Wiley Periodicals, Inc.

Parameters for abolishing conditioned place preference for cocaine from running and environmental enrichment in male C57BL/6J mice

RATIONALE

Evidence suggests that 4 weeks of voluntary wheel running abolishes conditioned place preference (CPP) for cocaine in male C57BL/6J mice.

OBJECTIVES

To determine the duration and timing of exposure to running wheels necessary to reduce CPP, and the extent to which the running per se influences CPP as compared to environmental enrichment without running.

METHODS

A total of 239 males were conditioned for 4days twice daily with cocaine (10mg/kg) and then split into 7 intervention groups prior to 4days of CPP testing. Experiment 1 consisted of two groups housed as follows: short sedentary group (SS; n=20) in normal cages for 1 week; the short running group (SR; n=20) with running wheels for 1 week. Experiment 2 consisted of five groups housed as follows; short 1 week of running followed by a 3 week sedentary period (SRS; n=20); a 3 week sedentary period followed by 1 week of running (SSR; n=20); long sedentary group (LS; n=66) in normal cages for 4 weeks; long running group (LR; n=66) with running wheels for 4 weeks; and long environmental enrichment group (EE; n=27) with toys for 4 weeks.

RESULTS

Levels of running were similar in all running groups. Both running and environmental enrichment reduced CPP relative to sedentary groups.

CONCLUSIONS

Results suggest that the abolishment of cocaine CPP from running is robust and occurs with as low as 1 week of intervention but may be related to enrichment component of running rather than physical activity.

CP-154,526 Modifies CREB Phosphorylation and Thioredoxin-1 Expression in the Dentate Gyrus following Morphine-Induced Conditioned Place Preference

Corticotropin-releasing factor (CRF) acts as neuro-regulator of the behavioral and emotional integration of environmental and endogenous stimuli associated with drug dependence. Thioredoxin-1 (Trx-1) is a functional protein controlling the redox status of several proteins, which is involved in addictive processes. In the present study, we have evaluated the role of CRF1 receptor (CRF1R) in the rewarding properties of morphine by using the conditioned place preference (CPP) paradigm. We also investigate the effects of the CRF1R antagonist, CP-154,526, on the morphine CPP-induced activation of CRF neurons, CREB phosphorylation and Trx expression in paraventricular nucleus (PVN) and dentate gyrus (DG) of the mice brain. CP-154,526 abolished the acquisition of morphine CPP and the increase of CRF/pCREB positive neurons in PVN. Moreover, this CRF1R antagonist prevented morphine-induced CRF-immunoreactive fibers in DG, as well as the increase in pCREB expression in both the PVN and DG. In addition, morphine exposure induced an increase in Trx-1 expression in DG without any alterations in PVN. We also observed that the majority of pCREB positive neurons in DG co-expressed Trx-1, suggesting that Trx-1 could activate CREB in the DG, a brain region involved in memory consolidation. Altogether, these results support the idea that CRF1R antagonist blocked Trx-1 expression and pCREB/Trx-1 co-localization, indicating a critical role of CRF, through CRF1R, in molecular changes involved in morphine associated behaviors.

Yohimbine administration and cue-reactivity in cocaine-dependent individuals

RATIONALE

Preclinical studies suggest that stress potentiates cue-induced cocaine seeking and that this effect is more pronounced in females. These findings have not been characterized in clinical populations.

OBJECTIVES

The objectives of this study were to examine the impact a pharmacological stressor, alpha-2 adrenergic receptor antagonist yohimbine, on the subjective, endocrine, and physiologic responses to drug-paired cues cocaine-dependent men and women.

METHODS

In a double-blind placebo-controlled cross-over study, cocaine-dependent men (n = 32), cocaine-dependent women (n = 30), control men (n = 32), and control women (n = 25) received either yohimbine or placebo prior to two cocaine cue exposure sessions.

RESULTS

Yohimbine increased ratings of anxiety both before (p < 0.001) and after (p = 0.035) cues, and the post-cue increase in anxiety was more pronounced in women (p = 0.001). Yohimbine also significantly increased craving, compared with placebo (p < 0.05), following the cue presentation, and this effect was greater in women than men (gender by treatment interaction; p = 0.006). Yohimbine also increased salivary cortisol (p < 0.001) and dehydroepiandrosterone (p = 0.003) levels, regardless of diagnostic group. Women had a significantly greater heart rate response following yohimbine as compared with men (p < 0.001).

CONCLUSIONS

Stress may increase the salience of cocaine cues for cocaine-dependent women as compared with men. This suggests gender differences in vulnerability to craving and relapse under stressful conditions.

Fos expression induced by cocaine-conditioned cues in male and female rats

Previous studies have shown that female rats exhibit different patterns of drug seeking during multiple phases of cocaine addiction when compared with males. However, the underlying mechanisms for these sex differences remain largely unknown. Here, we used a cocaine self-administration/reinstatement model to examine neuronal activation, as determined by Fos expression, following cue-induced reinstatement of cocaine seeking in male and female rats. Fos expression revealed both similarities between sexes in some brain regions, as well as selective sexually dimorphic patterns. As compared to no cue control subjects, conditioned cues induced higher Fos expression in the Cg1 region of the anterior cingulate cortex, but lower expression in the nucleus accumbens in both males and females. Females exhibited higher Fos expression than males in multiple brain regions, including the agranular insular cortex, dorsal medial caudate-putamen, nucleus accumbens shell, ventral tegmental area, dorsal subiculum, and ventral CA1 and CA3 regions of the hippocampus. Notably, only Fos expression in the prelimbic cortex, nucleus accumbens shell, basolateral amygdala, and ventral subiculum correlated positively with lever responding in response to conditioned cues across males and females. These findings indicate that while sexually dimorphic Fos activation does occur, the relationship between cue-induced cocaine seeking and neuronal activation may be similar for males and females in key brain regions of the relapse circuit.

Impact of acute guanfacine administration on stress and cue reactivity in cocaine-dependent individuals

BACKGROUND

Stress and drug-paired cues increase drug craving and noradrenergic activity in cocaine-dependent individuals. Thus, medications that attenuate noradrenergic activity may be effective therapeutic treatment options for cocaine-dependent individuals.

OBJECTIVES

To examine the impact of acute administration of the α2 adrenergic receptor agonist guanfacine on responses to multiple risk factors for relapse in cocaine-dependent individuals.

METHODS

In a double-blind, placebo-controlled study, cocaine-dependent individuals (n = 84), were randomized to receive either 2 mg guanfacine (n = 50) or placebo (n = 34). Within each treatment arm, subjects were randomized to either a stress (guanfacine n = 26; placebo n = 15) or a no-stress (guanfacine n = 24; placebo n = 19) group. Participants in the stress group performed the Trier Social Stress Test. Subjects in each group were exposed to a neutral cue and then to cocaine-related cues. Plasma cortisol and subjective responses were compared between the four groups.

RESULTS

The no-stress guanfacine group reported greater craving in response to cocaine cues as compared to the neutral cue (p < 0.001). The guanfacine stress group reported greater subjective stress at the neutral cue than at baseline (p = 0.032). The cocaine cue increased subjective stress in the guanfacine (p < 0.001) no-stress group. There were no effects of guanfacine on cortisol levels in either the stress or no stress groups (all p > 0.70).

CONCLUSION

This study found no effects of a single 2 mg dose of guanfacine on reactivity to stress and cues alone or on the interaction of stress and drug cues. In cocaine-dependent individuals an acute 2 mg dose of guanfacine may not be an effective therapeutic treatment strategy.

Effects of cocaine on the hypothalamic-pituitary-adrenal axis

INTRODUCTION

Cocaine hydrochloride is a psychoactive substance extracted from the leaves of plants called Erythroxylum coca. Cocaine is the second most commonly used drug in the world after cannabis; 20 % of cocaine users will become long-term cocaine-dependent patients. Different routes of administration may be recognized: smokable modality, intranasal and intravenous. Cocaine is a potent stimulant of the sympathetic nervous system and causes structural changes on the brain, heart, lung, liver and kidney. It has long been known that use of cocaine may produce alterations to the endocrine system. Research on behavioral and neuroendocrine effects of cocaine dates back several years ago and has increasingly focused on alterations of the hypothalamic-pituitary-adrenal (HPA) axis, which appears to be the chief target of cocaine effects.

STUDIES

Animal (mainly rats and monkeys) and human studies have clearly shown a close relation between cocaine consumption and overdrive of the HPA axis. Such activation is likely involved, though via a still undefined mechanism, in the behavioral and cardiovascular changes of drug abusers as well as in the reinforcement/relapse phenomena. Further studies of the pathophysiology of cocaine addicts will help to devise new therapeutic strategies for these patients.

Stress modulates illness-course of substance use disorders: a translational review

Childhood trauma and post-childhood chronic/repeated stress could increase the risk of a substance use disorder by affecting five stages of addiction illness-course: (a) initial experimentation with substances; (b) shifting from experimental to regular use; (c) escalation from regular use to abuse or dependence; (d) motivation to quit; and (e) risk of (re-)lapse. We reviewed the human literature on relationships between stress and addiction illness-course. We explored per illness-course stage: (i) whether childhood trauma and post-childhood chronic/repeated stress have comparable effects and (ii) whether effects cut across classes of substances of abuse. We further discuss potential underlying mechanisms by which stressors may affect illness-course stages for which we relied on evidence from studies in animals and humans. Stress and substances of abuse both activate stress and dopaminergic motivation systems, and childhood trauma and post-childhood stressful events are more chronic and occur more frequently in people who use substances. Stressors increase risk to initiate early use potentially by affecting trait-like factors of risk-taking, decision making, and behavioral control. Stressors also accelerate transition to regular use potentially due to prior effects of stress on sensitization of dopaminergic motivation systems, cross-sensitizing with substances of abuse, especially in people with high trait impulsivity who are more prone to sensitization. Finally, stressors increase risk for abuse and dependence, attenuate motivation to quit, and increase relapse risk potentially by intensified sensitization of motivational systems, by a shift from positive to negative reinforcement due to sensitization of the amygdala by corticotropin releasing factor, and by increased sensitization of noradrenergic systems. Stress generally affects addiction illness-course across stressor types and across classes of substances of abuse.

The role of guanfacine as a therapeutic agent to address stress-related pathophysiology in cocaine-dependent individuals

The pathophysiology of cocaine addiction is linked to changes within neural systems and brain regions that are critical mediators of stress system sensitivity and behavioral processes associated with the regulation of adaptive goal-directed behavior. This is characterized by the upregulation of core adrenergic and corticotropin-releasing factor mechanisms that subserve negative affect and anxiety and impinge upon intracellular pathways in the prefrontal cortex underlying cognitive regulation of stress and negative emotional state. Not only are these mechanisms essential to the severity of cocaine withdrawal symptoms, and hence the trajectory of clinical outcome, but also they may be particularly pertinent to the demography of cocaine dependence. The ability of guanfacine to target overlapping stress, reward, and anxiety pathophysiology suggests that it may be a useful agent for attenuating the stress- and cue-induced craving state not only in women but also in men. This is supported by recent research findings from our own laboratory. Additionally, the ability of guanfacine to improve regulatory mechanisms that are key to exerting cognitive and emotional control over drug-seeking behavior also suggests that guanfacine may be an effective medication for reducing craving and relapse vulnerability in many drugs of abuse. As cocaine-dependent individuals are typically polydrug abusers and women may be at a greater disadvantage for compulsive drug use than men, it is plausible that medications that target catecholaminergic frontostriatal inhibitory circuits and simultaneously reduce stress system arousal may provide added benefits for attenuating cocaine dependence.

Brain stress system response after morphine-conditioned place preference

This study examined the involvement of the brain stress system in the reinforcing effects of morphine. One group of mice was conditioned to morphine using the conditioned place preference (CPP) paradigm and the other group received morphine in a home-cage (non-conditioned). Adrenocorticotropic hormone and corticosterone levels were measured by radioimmunoassay; phospho (p) CREB expression and the number of corticotropin-releasing factor (CRF) neurons and fibres were measured by immunohistochemistry in different brain areas. We observed that the number of CRF neurons in the paraventricular nucleus (PVN) was increased after morphine-induced CPP, which was paralleled with enhanced CRF-immunoreactivity fibres in the nucleus tractus solitarius (NTS) and ventral tegmental area (VTA) vs. home-cage group injected with morphine. Morphine exposure induced an increase in CREB phosphorylated at Ser133 in the PVN and central amygdale (CeA), whereas mice exhibiting morphine CPP had higher levels of pCREB in the PVN, CeA and bed nucleus of the stria terminalis (BNST). We also found that most of the CRF-positive neurons in the PVN, CeA and BNST co-express pCREB after morphine CPP expression, suggesting that the drug-associated environmental contexts can elicit neuronal activity in the brain stress system. From the present results it is clear that exposure to a drug-associated context remains a potent activator of signalling pathways leading to CRF activation in the brain stress system.

The effects of exogenous progesterone on drug craving and stress arousal in cocaine dependence: impact of gender and cue type

AIMS

Exogenous progesterone has been shown to attenuate the rewarding effects of cocaine. However, its effects on provoked drug craving, stress arousal and cognitive performance has not been systematically investigated in cocaine dependent men and women. Thus, we conducted a double-blind placebo-controlled study assessing the efficacy of progesterone in reducing provoked drug craving, stress system arousal and improving cognitive performance in cocaine dependent men and women.

METHODS

Forty-two early abstinent treatment-seeking cocaine dependent individuals were randomly assigned to either daily doses of placebo (12M/9F) or micronized progesterone (12M/9F) (400 mg/day), for 7 days. Under experimental conditions, all subjects were exposed to three 5-min personalized guided imagery conditions (stress, cocaine cue, relaxing), one per day, consecutively in a random, counterbalanced order. Subjective craving, mood, hypothalamic-pituitary-adrenal (HPA) and cardiovascular output, and a cognitive measure of inhibitory control (Stroop Color Word Task) were assessed pre- and post imagery.

RESULTS

Progesterone relative to placebo significantly decreased cue-induced craving and cortisol responses and increased cue-induced ACTH. In addition, women but not men receiving progesterone reported lower ratings of negative emotion and higher ratings of relaxed mood following stress exposure. Improved Stroop performance was observed in all participants receiving progesterone, across all conditions.

CONCLUSIONS

Progesterone was selectively effective in reducing cocaine cue-induced but not stress-related cocaine craving as well as specific measures of the provoked arousal state. Findings suggest that progesterone's effects on drug craving and arousal are moderated by both the type of environmental cue exposure and gender.

"White Box" Epidemiology and the Social Neuroscience of Health Behaviors: The Environmental Affordances Model

Crucial advances have been made in our knowledge of the social determinants of health and health behaviors. Existing research on health disparities, however, generally fails to address a known paradox in the literature: While blacks have higher risk of medical morbidity relative to non-Hispanic whites, blacks have lower rates of common stress-related forms of psychopathology such as major depression and anxiety disorders. In this article we propose a new theoretical approach, the Environmental Affordances Model, as an integrative framework for the origins of both physical and mental health disparities. We highlight early empirical support and a growing body of experimental animal and human research on self-regulatory health behaviors and stress coping that is consistent with the proposed framework. We conclude that transdisciplinary approaches, such as the Environmental Affordances Model, are needed to understand the origins of group-based disparities to implement effective solutions to racial and ethnic group inequalities in physical and mental health.

Association of elevated cytokines with childhood adversity in a sample of healthy adults

OBJECTIVE

Childhood trauma has been associated adult stress-related disorders. However, little is known about physiologic alterations in adults with a history of early life trauma that do not have current psychiatric or medical diagnoses. In this study, the relationships between childhood adversity and cytokine and C-reactive protein (CRP) levels in healthy adults were examined.

METHOD

Participants included men (n = 18) and women (n = 20) who did not meet DSM-IV criteria for Axis I psychiatric disorders or any major medical illness. Cytokine and CRP levels were obtained from baseline blood samples. Subjects completed the Early Trauma Inventory Self Report (ETI-SR). The primary outcomes included serum interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-1β (IL1-β), and CRP levels. In addition, the mean numbers of traumatic experiences (sexual, physical, emotional, general, and the summed total) were measured.

RESULTS

Significant positive associations were found between the total ETI score and IL-6 (p = 0.05), IL1-β (p < 0.05), and TNF-α (p = 0.01). Significant positive correlations were found between the number of general traumas and IL1-β (p < 0.05), TNF-α (p < 0.05), and IL-6 (p < 0.01). Neither the total number of traumas nor any of the trauma subscales were significantly associated with CRP levels.

CONCLUSIONS

The positive association between childhood trauma and basal cytokine levels supports the extant literature demonstrating the long-term impact of childhood trauma and stress on homeostatic systems. Importantly, this association was found in healthy adults, suggesting that these alterations may precede the development of significant stress-related psychiatric disorder or disease.

Addiction and corticotropin-releasing hormone type 1 receptor antagonist medications

Derangements in corticotropin-releasing hormone (CRH) through its type 1 receptor (CRHR1) have been identified in many pathologic conditions. Preclinical models of addiction find that small-molecule antagonists of CRHR1 can limit induction, maintenance, and relapse to drugs of abuse. Neuropsychiatric clinical trials of CRHR1 antagonists have shown mixed efficacy; treatment of addictive disorders has not been established, but finding effective treatments for addictive disorders is critical. Establishing effectiveness for substance abuse treatment will require a different design approach than was used for depression and anxiety trials. Focusing on active versus passive outcome measures, such as resilience to external stressful stimuli, may provide signals in curbing craving and relapse. Study design should include measures of abstinence and drug exposure, but additional elements of stress prevention should also be incorporated. Agents that could provide preemptive protection from drug use and relapse are novel and untested. An understanding of the evolutionary significance of the stress system and preclinical models suggests that these agents may provide protection in this manner. Investigators designing future trials might refocus their understanding of addiction and treatment in this new direction.

Stress system changes associated with marijuana dependence may increase craving for alcohol and cocaine

OBJECTIVE

To date, little research exists defining bio-behavioral adaptations associated with both marijuana abuse and risk of craving and relapse to other drugs of abuse during early abstinence.

METHOD

Fifty-nine treatment-seeking individuals dependent on alcohol and cocaine were recruited. Thirty of these individuals were also marijuana (MJ) dependent; 29 were not. Twenty-six socially drinking healthy controls were also recruited. All participants were exposed to three 5-min guided imagery conditions (stress, alcohol/cocaine cue and relaxing), presented randomly, one per day across three consecutive days. Measures of craving, anxiety, heart rate, blood pressure, plasma adrenocorticotrophic hormone and cortisol were collected at baseline and subsequent recovery time points.

RESULTS

The MJ-dependent group showed increased basal anxiety ratings and cardiovascular output alongside enhanced alcohol craving and cocaine craving, and dampened cardiovascular response to stress and cue. They also demonstrated elevated cue-induced anxiety and stress-induced cortisol and adrenocorticotrophic hormone levels, which were not observed in the non-MJ-dependent group or controls. Cue-related alcohol craving and anxiety were both predictive of a shorter number of days to marijuana relapse following discharge from inpatient treatment.

CONCLUSIONS

Findings provide some support for drug cross-sensitization in terms of motivational processes associated with stress-related and cue-related craving and relapse.

Cue-induced reactivity, cortisol response and substance use outcome in treated heroin dependent individuals

BACKGROUND

Environmental stimuli associated with drug taking have been known to elicit drug craving and physiologic arousal, as well as hypothalamic-pituitary-adrenal axis activation. However, the relationship between these responses and substance use outcomes in heroin-dependent subjects has not been previously studied. We investigated the relationship among subjective and physiologic reactivity, biological stress response evoked in the laboratory, and relapse to substance use in treated opiate-dependent individuals.

METHODS

Eighteen opiate-abstinent methadone- or buprenorphine-treated patients and 13 control subjects were exposed to neutral- and drug-cue exposure laboratory sessions with a 3-month follow-up period. Exposure to cues involved both videotapes and handling during a 100-min session. Subjective craving, agonistic effects, withdrawal feelings, galvanic skin resistance, and salivary cortisol were assessed. Substance use outcome among patients was examined during the follow-up phase. Differences between relapsers, nonrelapsers, and controls were analyzed with respect to the data on drug-cue responsivity and on cortisol responses using repeated-measures analysis of variance. The association with substance use outcome was assessed using a nominal logistic model.

RESULTS

Relapsers experienced greater drug-cue induced subjective responses and an increased cortisol response compared with both nonrelapsers and control subjects. After adjusting on covariates, cue-induced cortisol response was associated with the relapser group and was highly correlated with self-reports of "high."

CONCLUSIONS

Subjects defined as relapsers presented a higher cue-induced reactivity during the drug-cue exposure as well as an increased cortisol response to drug cues. Higher cortisol response to drug cues may increase relapse vulnerability in stable-dose buprenorphine or methadone-maintained subjects.

Corticotrophin releasing factor (CRF) induced reinstatement of cocaine seeking in male and female rats

Significant sex differences have been demonstrated in clinical and preclinical studies of cocaine addiction, with some of the most consistent differences noted in regard to the role of stress and craving. The current study examined stress-induced reinstatement of cocaine seeking in male and female rats in an animal model of relapse using corticotropin-releasing factor (CRF) administration. Both male and female rats demonstrated increased cocaine seeking in response to CRF. CRF-induced reinstatement was highly variable across both male and female rats, and further analysis revealed a subpopulation that was particularly sensitive to CRF (high responders). Female high responders displayed significantly increased responding to CRF compared to males. Individual differences in stress responsivity could thus contribute to the likelihood of relapse, with females showing greater heterogeneity to stress-induced relapse.

Psychoticism and neuroticism predict cocaine dependence and future cocaine use via different mechanisms

BACKGROUND

Personality characteristics have been associated with cocaine use. However, little is known about the mechanisms through which personality could impact drug use. The present study investigated the cross-sectional and prospective relationships between personality dimensions (i.e., impulsivity, neuroticism) and problematic cocaine use. Reactivity to a pharmacological stressor as a potential mediator of the relationship between neuroticism and future cocaine use was also examined.

METHODS

Participants were 53 cocaine-dependent individuals and 47 non-dependent controls. Subjects completed the Eysenck Personality Questionnaire (EPQ) at baseline and were administered i.v. corticotrophin releasing hormone (CRH; 1 μg/kg). Cocaine use in the 30 days following CRH administration was measured.

RESULTS

Cocaine-dependent individuals had higher scores on the psychoticism (i.e., impulsivity, aggression; p=0.02) and neuroticism (p<0.01) scales of the EPQ than non-dependent controls. Cocaine-dependent individuals also had a greater subjective stress response to CRH than controls (p<0.01). Cocaine-dependent individuals with elevated psychoticism used significantly more cocaine over the follow-up period (p<0.05), whereas individuals with elevated neuroticism trended towards using cocaine more frequently over the follow-up (p=0.07). Finally, there was a trend for an indirect effect of neuroticism on frequency of cocaine use through subjective reactivity to CRH.

CONCLUSIONS

The findings extend past research on the association between personality and cocaine use, and suggest that motives for cocaine use may systematically vary across personality characteristics. Moreover, tailoring therapeutic interventions to individuals' personalities may be an area that warrants further investigation.

Reduced metabolism in brain "control networks" following cocaine-cues exposure in female cocaine abusers

Objective

Gender differences in vulnerability for cocaine addiction have been reported. Though the mechanisms are not understood, here we hypothesize that gender differences in reactivity to conditioned-cues, which contributes to relapse, are involved.

Method

To test this we compared brain metabolism (using PET and ¹⁸FDG) between female (n = 10) and male (n = 16) active cocaine abusers when they watched a neutral video (nature scenes) versus a cocaine-cues video.

Results

Self-reports of craving increased with the cocaine-cue video but responses did not differ between genders. In contrast, changes in whole brain metabolism with cocaine-cues differed by gender (p<0.05); females significantly decreased metabolism (−8.6%±10) whereas males tended to increase it (+5.5%±18). SPM analysis (Cocaine-cues vs Neutral) in females revealed decreases in frontal, cingulate and parietal cortices, thalamus and midbrain (p<0.001) whereas males showed increases in right inferior frontal gyrus (BA 44/45) (only at p<0.005). The gender-cue interaction showed greater decrements with Cocaine-cues in females than males (p<0.001) in frontal (BA 8, 9, 10), anterior cingulate (BA 24, 32), posterior cingulate (BA 23, 31), inferior parietal (BA 40) and thalamus (dorsomedial nucleus).

Conclusions

Females showed greater brain reactivity to cocaine-cues than males but no differences in craving, suggesting that there may be gender differences in response to cues that are not linked with craving but could affect subsequent drug use. Specifically deactivation of brain regions from “control networks” (prefrontal, cingulate, inferior parietal, thalamus) in females could increase their vulnerability to relapse since it would interfere with executive function (cognitive inhibition). This highlights the importance of gender tailored interventions for cocaine addiction.

Influence of cocaine dependence and early life stress on pituitary-adrenal axis responses to CRH and the Trier social stressor

Long-term changes in the hypothalamic-pituitary-adrenal (HPA) axis as a result of early life stress could be related to the development of substance use disorders during adulthood. In this study, the neuroendocrine, physiologic (HR), and subjective responses to corticotropin releasing hormone (CRH) and the Trier Social Stress Task (TSST) in individuals with cocaine dependence, with (n=21)/without early life stress (n=21), non-dependent individuals with early life stress (n=22), and a control group were examined (n=21). CRH increased cortisol and ACTH levels in all groups. However, a significant effect of early life stress on ACTH was observed indicating that the increase in ACTH was greatest in subjects with a history of childhood stress. Post hoc analysis indicated the early life stress/non-cocaine dependent individuals exhibited significantly higher levels of ACTH as compared to the early life stress/cocaine-dependent group. Despite the elevated ACTH response there was no difference between the groups in the cortisol response to CRH. The TSST produced a significant elevation in ACTH and cortisol all study groups. No significant group differences were observed. The subjective stress and peak heart rate responses to the TSST were greatest in cocaine-dependent subjects without early life stress. In response to CRH, subjective stress and craving were positively correlated in cocaine-dependent subjects regardless of early life stress history, while stress and craving following the TSST were correlated only in cocaine-dependent subjects without a history of early life stress. Findings support previous studies demonstrating that subjects with a history of childhood adversity exhibit elevated ACTH and blunted cortisol levels in response to stress. In contrast, HR and subjective stress in response to the TSST were greatest in cocaine-dependent subjects without a history of early life stress, suggesting that childhood adversity may desensitize autonomic and subjective responding to social stress in adults with cocaine dependence.

Testosterone is essential for cocaine sensitization in male rats

Most studies agree that males and females respond differently to drugs of abuse. In females, estradiol enhances the behavioral response to cocaine. However, studies on the role of testosterone and the locomotor response to psychostimulants in the male rat are inconclusive. Our study was designed to determine the behavioral effects of testosterone on the development and persistence of cocaine sensitization in male rats. We tested different doses of cocaine (10, 15 and 30mg/kg) to determine which dose induced locomotor sensitization in intact (INT) and gonadectomized (GDX) animals. We also investigated if GDX males with testosterone replacement (GDX-T) showed a similar locomotor response to cocaine as INT males. Our data showed that gonadectomy enhanced the locomotor response to a single cocaine injection. This effect was not observed in gonadectomized rats that received testosterone replacement. However, GDX rats did not show a progressive increase in their locomotor response to repeated cocaine administration (15 and 30mg/kg) (sensitization) as did INT and GDX-T animals. It is possible that in GDX males, the initial high locomotor response to cocaine creates a ceiling effect that limits further increase in cocaine-induced hyperactivity. These findings indicate that testosterone not only modulates the behavioral response to a single and to repeated cocaine injections, but is also essential for male rats to become sensitized to cocaine.

Extinction of drug cue reactivity in methamphetamine-dependent individuals

Conditioned responses to drug-related environmental cues (such as craving) play a critical role in relapse to drug use. Animal models demonstrate that repeated exposure to drug-associated cues in the absence of drug administration leads to the extinction of conditioned responses, but the few existing clinical trials focused on extinction of conditioned responses to drug-related cues in drug-dependent individuals show equivocal results. The current study examined drug-related cue reactivity and response extinction in a laboratory setting in methamphetamine-dependent individuals. Methamphetamine cue-elicited craving was extinguished during two sessions of repeated (3) within-session exposures to multi-modal (picture, video, and in-vivo) cues, with no evidence of spontaneous recovery between sessions. A trend was noted for a greater attenuation of response in participants with longer (4-7 day) inter-session intervals. These results indicate that extinction of drug cue conditioned responding occurs in methamphetamine-dependent individuals, offering promise for the development of extinction- based treatment strategies.