Effects of intravenous cocaine on plasma cortisol and prolactin in human cocaine abusers

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.

Involvement of the ghrelin system in the maintenance and reinstatement of cocaine-motivated behaviors: a role of adrenergic action at peripheral β1 receptors

Cocaine addiction is a significant medical and public concern. Despite decades of research effort, development of pharmacotherapy for cocaine use disorder remains largely unsuccessful. This may be partially due to insufficient understanding of the complex biological mechanisms involved in the pathophysiology of this disorder. In the present study, we show that: (1) elevation of ghrelin by cocaine plays a critical role in maintenance of cocaine self-administration and cocaine-seeking motivated by cocaine-conditioned stimuli; (2) acquisition of cocaine-taking behavior is associated with the acquisition of stimulatory effects of cocaine by cocaine-conditioned stimuli on ghrelin secretion, and with an upregulation of ghrelin receptor mRNA levels in the ventral tegmental area (VTA); (3) blockade of ghrelin signaling by pretreatment with JMV2959, a selective ghrelin receptor antagonist, dose-dependently inhibits reinstatement of cocaine-seeking triggered by either cocaine or yohimbine in behaviorally extinguished animals with a history of cocaine self-administration; (4) JMV2959 pretreatment also inhibits brain stimulation reward (BSR) and cocaine-potentiated BSR maintained by optogenetic stimulation of VTA dopamine neurons in DAT-Cre mice; (5) blockade of peripheral adrenergic β1 receptors by atenolol potently attenuates the elevation in circulating ghrelin induced by cocaine and inhibits cocaine self-administration and cocaine reinstatement triggered by cocaine. These findings demonstrate that the endogenous ghrelin system plays an important role in cocaine-related addictive behaviors and suggest that manipulating and targeting this system may be viable for mitigating cocaine use disorder.

Alterations of Stress-Related Glucocorticoids and Endocannabinoids in Hair of Chronic Cocaine Users

BACKGROUND

Previous research in animals and humans has demonstrated a potential role of stress regulatory systems, such as the hypothalamic-pituitary-adrenal (HPA) axis and the endocannabinoid (eCB) system, in the development of substance use disorders. We thus investigated alterations of HPA and eCB markers in individuals with chronic cocaine use disorder by using an advanced hair analysis technique.

METHODS

We compared hair concentrations of glucocorticoids (cortisone, cortisol) and the eCBs 2-arachidonylglycerol, anandamide (AEA), oleoylethanolamide (OEA), and palmitoylethanolamide (PEA) between 48 recreational cocaine users (RCU), 25 dependent cocaine users (DCU), and 67 stimulant-naïve controls. Self-reported substance use and hair concentrations of substances were also assessed.

RESULTS

Significantly higher concentrations of hair cortisone were found in RCU and DCU compared with controls. Hair concentrations of OEA and PEA were significantly lower in DCU compared with RCU and controls. Additionally, within cocaine users, elevated cocaine hair concentration was a significant predictor for increased glucocorticoid and decreased OEA hair levels. Moreover, higher 3,4-methyl​enedioxymethamphetamine hair concentration was correlated with elevated cortisone and AEA, OEA, and PEA levels in hair within cocaine users, whereas more self-reported cannabis use was associated with lower eCBs levels in hair across the total sample.

CONCLUSION

Our findings support the hypothesis that the HPA axis and eCB system might be important regulators for substance use disorders. The mechanistic understanding of changes in glucocorticoid and eCB levels in future research might be a promising pharmacological target to reduce stress-induced craving and relapse specifically in cocaine use disorder.

Psychiatric symptoms and expression of glucocorticoid receptor gene in cocaine users: A longitudinal study

BACKGROUND

Chronic cocaine users (CU) display reduced peripheral expression of the glucocorticoid receptor gene (NR3C1), which is potentially involved in stress-related psychiatric symptoms frequently occurring in CU. However, it is unknown whether psychiatric symptoms and lower NR3C1 expression are related to each other and whether reduction of drug consumption reverse them.

METHOD

At baseline, NR3C1 mRNA expression was measured in 68 recreational CU, 30 dependent CU, and 68 stimulant-naïve controls. Additionally, the Revised Symptom Checklist (SCL-90R) and the Barratt Impulsiveness Scale (BIS) were assessed. At a one-year follow-up, the association between change in NR3C1 expression and psychiatric symptoms was examined in 48 stimulant-naïve controls, 19 CU who increased and 19 CU who decreased their consumption. At both test sessions, cocaine concentrations in hair samples were determined. Mixed-effects models were used to investigate how changes in drug use intensity affect severity of psychiatric symptoms and NR3C1 expression over time.

RESULTS

At baseline, recreational and dependent CU displayed elevated impulsivity and considerable symptom burden across most of the SCL-90R subscales. Time-group interaction effects were found for several impulsivity scores, SCL-90R Global Severity Index, Paranoid Thoughts, and Depression subscales as well as for NR3C1 expression. Pairwise comparisons showed that decreasing CU specifically improved in these SCL-90R subscales, while their NR3C1 expression was adapted. Finally, changes in NR3C1 expression were negatively correlated with changes in impulsivity but not SCL-90R scores.

CONCLUSION

Our findings suggest that NR3C1 expression changes and some psychiatric symptoms are reversible upon reduction of cocaine intake, thus favouring abstinence-oriented treatment approaches.

Glucocorticoid receptor gene variants and lower expression of NR3C1 are associated with cocaine use

Animal and cross-sectional human studies suggest that chronic cocaine use is associated with altered responsivity of the hypothalamic-pituitary-adrenal axis to stress. Moreover, increased susceptibility to stress has been proposed as an important factor for development, maintenance and relapse of cocaine addiction. As the glucocorticoid receptor gene (NR3C1) mediates genomic effects of the stress hormone cortisol, we investigated NR3C1 expression and the association of NR3C1 genotypes with cocaine use, addiction and comorbid psychiatric symptoms in 126 chronic cocaine users and 98 stimulant-naïve healthy controls. A comprehensive psychiatric assessment was performed including severity of depressive symptoms and current psychological distress. Whole blood NR3C1 mRNA levels were determined and six NR3C1 polymorphisms (rs10482605, rs41423247, rs10052957, rs6189, rs56149945 and rs6198) were genotyped. Compared to controls, cocaine users showed significantly lower NR3C1 expression (P < 0.001), which was not affected by NR3C1 genotypes. In controls, rs41423247 [P < 0.01, false discovery rate (FDR)-corrected], haplotype 2 and haplotype 3 (both P < 0.05, FDR-corrected) were associated with altered NR3C1 gene expression. Haplotype 3 (including minor alleles of rs10052957 and rs41423247) was associated with an increased risk for cocaine addiction (odds ratio = 2.74, P < 0.05, uncorrected). Moreover, addicted cocaine users carrying haplotype 3 showed higher depression scores (P < 0.01, FDR-corrected) than noncarriers. Considering possible confounding effects of alcohol and/or depression, we conclude that chronic cocaine use is associated with lower NR3C1 gene expression suggesting possible direct effects of the drug on the biological adaptation of stress-related genes. Finally, we postulate that haplotype 3 of NR3C1 might serve as a potential risk factor for stimulant addiction and associated psychiatric symptoms.

Peripheral blood microRNA levels in females with cocaine use disorder

BACKGROUND

There is growing emphasis in the field of psychiatry on the need to identify candidate biomarkers to aid in diagnosis and clinical management of addictive disorders. MicroRNAs (miRNAs) are small nucleotide sequences with the ability to regulate gene expression at the transcriptomic level. However, the role of miRNAs as potential biomarkers for addiction is still underexplored. Based on translational and clinical findings, we compared the expression levels of microRNA-124 (miR-124), microRNA-181 (miR-181), and microRNA-212 (miR-212) between a group of females with cocaine use disorder (CUD; n = 30) and a group of healthy female controls (HC; n = 20).

METHODS

Blood expression levels of miR-124, miR-181, and miR-212 in the HC and CUD group were determined by qPCR, using two miRNAs as endogenous controls (miR-24 and miR-126). Substance use behavior was assessed by self-report using the Addiction Severity Index (ASI-6) and depressive symptoms severity was measured using the Beck Depressive Inventory (BDI-II). Urine screen test was performed to detect cocaine metabolites.

RESULTS

Mir-124 and miR-181 were upregulated in the CUD group (p > 0.01). Furthermore, increased cognitive/affective depression symptoms were identified among a CUD subgroup with the higher miR-181 expression levels (p > 0.05). No significant difference in expression levels was found for miR-212.

CONCLUSIONS

MiR-124 and miR-181 show promise as biomarkers for CUD when assessed in the peripheral blood. Further investigation is needed to elucidate the molecular mechanisms underlying these associations and to validate target genes regulated by these miRNAs.

Animal Models of the Impact of Social Stress on Cocaine Use Disorders

Cocaine use disorders are strongly influenced by the social conditions prior, during, and after exposure to cocaine. In this chapter, we discuss how social factors such as early life stress, social rank stress, and environmental stress impact vulnerability and resilience to cocaine. The discussion of each animal model begins with a brief review of examples from the human literature, which provide the psychosocial background these models attempt to capture. We then discuss preclinical findings from use of each model, with emphasis on how social factors influence cocaine-related behaviors and how sex and age influence the behaviors and neurobiology. Models discussed include (1) early life social stress, such as maternal separation and neonatal isolation, (2) social defeat stress, (3) social hierarchies, and (4) social isolation and environmental enrichment. The cocaine-related behaviors reviewed for each of these animal models include cocaine-induced conditioned place preference, behavioral sensitization, and self-administration. Together, our review suggests that the degree of psychosocial stress experienced yields robust effects on cocaine-related behaviors and neurobiology, and these preclinical findings have translational impact for the future of cocaine use disorder treatment.

Modified single prolonged stress reduces cocaine self-administration during acquisition regardless of rearing environment

Until recently, there were few rodent models available to study the interaction of post-traumatic stress disorder (PTSD) and drug taking. Like PTSD, single prolonged stress (SPS) produces hypothalamic-pituitary-adrenal (HPA) axis dysfunction and alters psychostimulant self-administration. Other stressors, such as isolation stress, also alter psychostimulant self-administration. However, it is currently unknown if isolation housing combined with SPS can alter the acquisition or maintenance of cocaine self-administration. The current study applied modified SPS (modSPS; two hours restraint immediately followed by cold swim stress) to rats raised in an isolation condition (Iso), enrichment condition (Enr), or standard condition (Std) to measure changes in cocaine self-administration and HPA markers. Regardless of rearing condition, rats exposed to modSPS had greater corticosterone (CORT) release and reduced cocaine self-administration during initial acquisition compared to non-stressed controls. In addition, during initial acquisition, rats that received both Iso rearing and modSPS showed a more rapid increase in cocaine self-administration across sessions compared to Enr and Std rats exposed to modSPS. Following initial acquisition, a dose response analysis showed that Iso rats were overall most sensitive to changes in cocaine unit dose; however, modSPS had no effect on the cocaine dose response curve. Further, there was no effect of either modSPS or differential rearing on expression of glucocorticoid receptor (GR) in hypothalamus, medial prefrontal cortex, amygdala, or nucleus accumbens. By using modSPS in combination with Iso housing, this study identified unique contributions of each stressor to acquisition of cocaine self-administration.

HPA Axis Interactions with Behavioral Systems

Perhaps the most salient behaviors that individuals engage in involve the avoidance of aversive experiences and the pursuit of pleasurable experiences. Engagement in these behaviors is regulated to a significant extent by an individual's hormonal milieu. For example, glucocorticoid hormones are produced by the hypothalamic-pituitary-adrenocortical (HPA) axis, and influence most aspects of behavior. In turn, many behaviors can influence HPA axis activity. These bidirectional interactions not only coordinate an individual's physiological and behavioral states to each other, but can also tune them to environmental conditions thereby optimizing survival. The present review details the influence of the HPA axis on many types of behavior, including appetitively-motivated behaviors (e.g., food intake and drug use), aversively-motivated behaviors (e.g., anxiety-related and depressive-like) and cognitive behaviors (e.g., learning and memory). Conversely, the manuscript also describes how engaging in various behaviors influences HPA axis activity. Our current understanding of the neuronal and/or hormonal mechanisms that underlie these interactions is also summarized. © 2016 American Physiological Society. Compr Physiol 6:1897-1934, 2016.

Female Japanese quail with high levels of estradiol demonstrate cocaine-induced conditioned place preference

Preclinical research has indicated that females may be more sensitive to the rewarding properties of cocaine. However, the majority of this research has been done in rodent species. Environmental cues associated with human drug-taking behavior tend to be visual. Because rodents do not rely on the visual system as their primary sense modality, the use of a visually oriented species may add to our understanding of cue-elicited drug cravings and relapse. The present study examined the potential role of the steroid hormone, estradiol, in the rewarding properties of cocaine in female Japanese quail using a conditioned place preference (CPP) procedure. In the current experiment, female quail were housed on either an 8L:16D (light:dark) or 16L:8D (light:dark) cycle for 21 days to induce photoregression or photostimulation, respectively. They then received 10, 20, or 30 mg/kg cocaine, or saline during conditioning. Conditioning trials were carried out for 8 days, once per day for 30 min, for a total of 4 cocaine and 4 saline alternating conditioning trials. Results indicated that female quail housed in long-light conditions (16L:8D) had significantly higher levels of estradiol than short-cycle females. Additionally, photostimulated female quail developed a CPP to 10 and 20 mg/kg cocaine. Short-cycle females did not show cocaine-induced CPP to any dose tested. Results indicate that cocaine is dose-dependently rewarding to photostimulated female Japanese quail. Furthermore, the current findings suggest that estradiol may enhance the rewarding properties of cocaine in female quail. (PsycINFO Database Record

Regulation of dopamine system responsivity and its adaptive and pathological response to stress

Although, historically, the norepinephrine system has attracted the majority of attention in the study of the stress response, the dopamine system has also been consistently implicated. It has long been established that stress plays a crucial role in the pathogenesis of psychiatric disorders. However, the neurobiological mechanisms that mediate the stress response and its effect in psychiatric diseases are not well understood. The dopamine system can play distinct roles in stress and psychiatric disorders. It is hypothesized that, even though the dopamine (DA) system forms the basis for a number of psychiatric disorders, the pathology is likely to originate in the afferent structures that are inducing dysregulation of the DA system. This review explores the current knowledge of afferent modulation of the stress/DA circuitry, and presents recent data focusing on the effect of stress on the DA system and its relevance to psychiatric disorders.

The Contingency of Cocaine Administration Accounts for Structural and Functional Medial Prefrontal Deficits and Increased Adrenocortical Activation

The prelimbic region (PL) of the medial prefrontal cortex (mPFC) is implicated in the relapse of drug-seeking behavior. Optimal mPFC functioning relies on synaptic connections involving dendritic spines in pyramidal neurons, whereas prefrontal dysfunction resulting from elevated glucocorticoids, stress, aging, and mental illness are each linked to decreased apical dendritic branching and spine density in pyramidal neurons in these cortical fields. The fact that cocaine use induces activation of the stress-responsive hypothalamo-pituitary-adrenal axis raises the possibility that cocaine-related impairments in mPFC functioning may be manifested by similar changes in neuronal architecture in mPFC. Nevertheless, previous studies have generally identified increases, rather than decreases, in structural plasticity in mPFC after cocaine self-administration. Here, we use 3D imaging and analysis of dendritic spine morphometry to show that chronic cocaine self-administration leads to mild decreases of apical dendritic branching, prominent dendritic spine attrition in PL pyramidal neurons, and working memory deficits. Importantly, these impairments were largely accounted for in groups of rats that self-administered cocaine compared with yoked-cocaine- and saline-matched counterparts. Follow-up experiments failed to demonstrate any effects of either experimenter-administered cocaine or food self-administration on structural alterations in PL neurons. Finally, we verified that the cocaine self-administration group was distinguished by more protracted increases in adrenocortical activity compared with yoked-cocaine- and saline-matched controls. These studies suggest a mechanism whereby increased adrenocortical activity resulting from chronic cocaine self-administration may contribute to regressive prefrontal structural and functional plasticity.

SIGNIFICANCE STATEMENT

Stress, aging, and mental illness are each linked to decreased prefrontal plasticity. Here, we show that chronic cocaine self-administration in rats leads to decrements in medial prefrontal structural and functional plasticity. Notably, these impairments were largely accounted for in rats that self-administered cocaine compared with yoked counterparts. Moreover, we verified previous reports showing that adrenocortical output is augmented by cocaine administration and is more protracted in rats that were permitted to receive the drug contingently instead of passively. These studies suggest that increased adrenocortical activity resulting from cocaine self-administration may contribute to regressive prefrontal structural and functional plasticity.

Activation of physiological stress responses by a natural reward: Novel vs. repeated sucrose intake

Pharmacological rewards, such as drugs of abuse, evoke physiological stress responses, including increased heart rate and blood pressure, and activation of the hypothalamic-pituitary-adrenal (HPA) axis. It is not clear to what extent the natural reward of palatable foods elicits similar physiological responses. In order to address this question, HPA axis hormones, heart rate, blood pressure and brain pCREB immunolabeling were assessed following novel and repeated sucrose exposure. Briefly, adult, male rats with ad libitum food and water were given either a single (day 1) or repeated (twice-daily for 14 days) brief (up to 30 min) exposure to a second drink bottle containing 4 ml of 30% sucrose drink vs. water (as a control for bottle presentation). Sucrose-fed rats drank more than water-fed on all days of exposure, as expected. On day 1 of exposure, heart rate, blood pressure, plasma corticosterone, and locomotion were markedly increased by presentation of the second drink bottle regardless of drink type. After repeated exposure (day 14), these responses habituated to similar extents regardless of drink type and pCREB immunolabeling in the hypothalamic paraventricular nucleus (PVN) also did not vary with drink type, whereas basolateral amygdala pCREB was increased by sucrose intake. Taken together, these data suggest that while sucrose is highly palatable, physiological stress responses were evoked principally by the drink presentation itself (e.g., an unfamiliar intervention by the investigators), as opposed to the palatability of the offered drink.

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.

Association of leukocytosis with amphetamine and cocaine use

OBJECTIVE

Determining the etiology of unexplained leukocytosis in asymptomatic patients may incur unnecessary testing, cost, and prolonged emergency department stay. The objective was to delineate if use of amphetamines and/or cocaine is a factor.

METHODS

For two years we reviewed all psychiatric patients presenting for medical clearance with exclusions for infection, epilepsy, trauma, or other nonpsychiatric medical conditions.

RESULTS

With a total of 1,206 patients, 877 (72.7%) amphetamines/cocaine-negative drug screen controls had mean WBC 8.4 ± 2.6 × 10³/µL. The 240 (19.9%) amphetamines-positive, cocaine-negative, patients had WBC 9.4 ± 3.3 × 10³/µL (P < 0.0001). The 72 (6.0%) amphetamines-negative, cocaine-positive, patients had WBC 7.1 ± 1.8 × 10³/µL (P < 0.0001). The remaining 17 (1.4%) amphetamines/cocaine-positive patients had WBC 10.0 ± 4.2 × 10³/µL (P = 0.01). Amphetamines-positive patients had a supranormal WBC ratio significantly higher than controls (23.8% versus 14.8%, P = 0.001), whereas only one cocaine-positive patient had a supranormal WBC count, with significantly lower ratio (1.4%, P = 0.0003).

CONCLUSION

Use of amphetamines, not cocaine, may be associated with idiopathic leukocytosis. This may be explained by unique pharmacologic, neuroendocrine, and immunomodulatory differences.

The combination of metyrapone and oxazepam for the treatment of cocaine and other drug addictions

Although scientists have been investigating the neurobiology of psychomotor stimulant reward for many decades, there is still no FDA-approved treatment for cocaine or methamphetamine abuse. Research in our laboratory has focused on the relationship between stress, the subsequent activation of the hypothalamic-pituitary-adrenal (HPA) axis, and psychomotor stimulant reinforcement for almost 30 years. This research has led to the development of a combination of low doses of the cortisol synthesis inhibitor, metyrapone, and the benzodiazepine, oxazepam, as a potential pharmacological treatment for cocaine and other substance use disorders. In fact, we have conducted a pilot clinical trial that demonstrated that this combination can reduce cocaine craving and cocaine use. Our initial hypothesis underlying this effect was that the combination of metyrapone and oxazepam reduced cocaine seeking and taking by decreasing activity within the HPA axis. Even so, doses of the metyrapone and oxazepam combination that consistently reduced cocaine taking and seeking did not reliably alter plasma corticosterone (or cortisol in the pilot clinical trial). Furthermore, subsequent research has demonstrated that this drug combination is effective in adrenalectomized rats, suggesting that these effects must be mediated above the level of the adrenal gland. Our evolving hypothesis is that the combination of metyrapone and oxazepam produces its effects by increasing the levels of neuroactive steroids, most notably tetrahydrodeoxycorticosterone, in the medial prefrontal cortex and amygdala. Additional research will be necessary to confirm this hypothesis and may lead to the development of improved and specific pharmacotherapies for the treatment of psychomotor stimulant use.

Physiological and subjective effects of acute intranasal methamphetamine during extended-release alprazolam maintenance

BACKGROUND

Medications development for methamphetamine dependence is ongoing, but no widely accepted, effective pharmacotherapy has been identified. Previous studies have demonstrated neurobiological perturbations to central GABA(A) activity following chronic stimulant use, and that positive modulation of GABA(A) receptors attenuates the neurochemical and behavioral response to stimulant drugs such as methamphetamine. Therefore, GABA(A) modulators could be useful as pharmacotherapies for stimulant-use disorders.

METHODS

This study tested the hypothesis that intranasal methamphetamine would be safe and well tolerated during maintenance on extended-release alprazolam (XR), and that the effects of methamphetamine would be attenuated. Eight non-treatment-seeking, stimulant-dependent individuals completed an inpatient experiment in which ascending doses of intranasal methamphetamine (0, 5, 10, 20 and 30 mg) were administered after four days of alprazolam XR maintenance (0 and 1mg/day).

RESULTS

Intranasal methamphetamine produced prototypical effects (e.g., increased positive subjective ratings and elevated cardiovascular signs). The combination of intranasal methamphetamine and alprazolam XR was safe and well tolerated. Alprazolam XR produced small, but orderly, reductions in some of the subjective effects of methamphetamine, and performance impairment.

CONCLUSIONS

The present results demonstrate that methamphetamine use during alprazolam XR treatment would not pose a significant safety risk. Given the potential of GABA(A) positive modulators to manage certain aspects of stimulant abuse and dependence (i.e., drug-induced seizures, anxiety and stress), but the relatively small impact on the acute abuse-related effects of methamphetamine observed here, additional research with GABA(A) positive modulators is warranted, but should consider their use as an adjunct component of combination behavioral and/or drug treatment.

Involvement of tissue plasminogen activator in stress responsivity during acute cocaine withdrawal in mice

There is evidence that increased release of corticotropin-releasing factor (CRF) in the central nucleus of the amygdala (CeA) contributes to stress responsivity during cocaine withdrawal (WD). Recent studies suggest that tissue plasminogen activator (tPA) in the CeA is a downstream effector protein for CRF after acute "binge" cocaine administration. The purpose of this study was to determine if tPA modulates cocaine WD-induced stress responsivity. Wild-type (WT) and tPA-deficient (tPA - / - ) mice were subjected to chronic (14 days) "binge" cocaine (45 mg/kg per day) or its acute (1 day) WD. Extracellular tPA activity, CRF mRNA levels, and plasma corticosterone (CORT) levels were measured in tPA - / -  and WT mice. Extracellular tPA activity was reduced by 50% in the CeA and medial amygdala of WT mice after chronic cocaine and returned to basal levels after acute WD. Unlike WT mice, tPA - / -  mice did not display elevated amygdalar CRF mRNA levels during cocaine WD. In comparison to WT mice, tPA - / -  mice showed a blunted plasma CORT response during acute WD. These results demonstrate that tPA activity in the amygdala (Amy) is altered by chronic cocaine exposure, and further suggest an involvement of tPA in modulating amygdalar CRF stress responsive system and hypothalamic-pituitary-adrenal axis in response to acute cocaine WD.

Cocaine administration increases CD4/CD8 lymphocyte ratio in peripheral blood despite lymphopenia and elevated corticosterone

The CD4/CD8 lymphocyte ratio in peripheral blood is used in the diagnosis of HIV infection, autoimmune disorders or susceptibility to infections. The present experiment aimed to evaluate the lymphocyte subsets, their distribution and CD4/CD8 ratio in blood after repeated, intravenous administration of cocaine. Adult male Wistar rats received three daily, in 30 min intervals, intravenous infusions of cocaine hydrochloride (5 mg/kg) or saline for 14 consecutive days. After each infusion the locomotor-activating effects of cocaine were assessed. Blood samples were collected 30 min after the last daily infusion on the 1st, 7th and 14th day of treatment. Total leukocyte numbers, percentages of leukocyte subpopulations, and T, B, NK, T CD4+, and T CD8+ lymphocyte subsets, IFN-γ, and plasma corticosterone were determined. Repeated cocaine treatment resulted in an increase in neutrophil numbers and a significant decrease in total leukocyte and lymphocyte numbers involving a significant reduction in numbers of T, B, and NK lymphocyte subsets. T CD4+ and T CD8+ lymphocyte numbers were reduced but with a considerably smaller decrease in T CD4+ number. Cocaine treatment altered proportions between the lymphocyte subsets by decreasing the percentages of T CD8+, B, and NK cells but increasing a percentage of T CD4+ cells. Destabilization in proportions between T CD4+ and T CD8+ was manifested as an elevated CD4/CD8 ratio that occurred despite increased plasma corticosterone and the lymphocytopenia. Cocaine did not affect the concentration of IFN-γ. The results suggest that although cocaine induced lymphopenia, it did not suppress the overall immune activity in terms of the CD4/CD8 ratio.

Individual differences in cocaine-induced locomotor activity of male Sprague-Dawley rats are not explained by plasma corticosterone levels

Humans differ in their initial response to, and subsequent abuse of, addictive drugs like cocaine. Rodents also exhibit marked individual differences in responsiveness to cocaine. Previously, we classified male Sprague-Dawley rats as either low or high cocaine responders (LCRs or HCRs, respectively), based on their acute low-dose cocaine-induced locomotor activity, and found that with repeated drug exposure LCRs exhibit greater cocaine locomotor sensitization, reward and reinforcement than HCRs. Differential cocaine-induced increases in striatal dopamine help to explain the LCR/HCR phenotypes. Differential levels of stress and/or anxiety could also contribute but have not been explored. Here we measured open-field activity and plasma corticosterone levels both pre- and post-cocaine treatment in LCRs, HCRs, and saline-treated controls. The three groups did not differ in baseline locomotor activity or corticosterone levels. Importantly, LCR/HCR differences in corticosterone levels were also not observed following acute cocaine (10mg/kg, i.p.), when cocaine induced approximately 3.5-fold greater locomotor activity in HCRs than LCRs. Additionally, there were no LCR/HCR differences in plasma corticosterone levels following 5 days of once-daily cocaine, during which time LCRs developed locomotor sensitization such that their cocaine-induced locomotor activity no longer differed from that of HCRs. Likewise, there were no group activity differences in any of four concentric zones within the open-field chamber. In summary, neither plasma corticosterone levels nor thigmotaxis-type anxiety appears to be a factor that contributes to the observed cocaine-induced LCR/HCR behavioral differences.

Stress, alcohol and drug interaction: an update of human research

A challenging question that continues unanswered in the field of addiction is why some individuals are more vulnerable to substance use disorders than others. Numerous risk factors for alcohol and other drugs of abuse, including exposure to various forms of stress, have been identified in clinical studies. However, the neurobiological mechanisms that underlie this relationship remain unclear. Critical neurotransmitters, hormones and neurobiological sites have been recognized, which may provide the substrates that convey individual differences in vulnerability to addiction. With the advent of more sophisticated measures of brain function in humans, such as functional imaging technology, the mechanisms and neural pathways involved in the interactions between drugs of abuse, the mesocorticolimbic dopamine system and stress systems are beginning to be characterized. This review provides a neuroadaptive perspective regarding the role of the hormonal and brain stress systems in drug addiction with a focus on the changes that occur during the transition from occasional drug use to drug dependence. We also review factors that contribute to different levels of hormonal/brain stress activation, which has implications for understanding individual vulnerability to drug dependence. Ultimately, these efforts may improve our chances of designing treatment strategies that target addiction at the core of the disorder.

Chronic stress, drug use, and vulnerability to addiction

Stress is a well-known risk factor in the development of addiction and in addiction relapse vulnerability. A series of population-based and epidemiological studies have identified specific stressors and individual-level variables that are predictive of substance use and abuse. Preclinical research also shows that stress exposure enhances drug self-administration and reinstates drug seeking in drug-experienced animals. The deleterious effects of early life stress, child maltreatment, and accumulated adversity on alterations in the corticotropin releasing factor and hypothalamic-pituitary-adrenal axis (CRF/HPA), the extrahypothalamic CRF, the autonomic arousal, and the central noradrenergic systems are also presented. The effects of these alterations on the corticostriatal-limbic motivational, learning, and adaptation systems that include mesolimbic dopamine, glutamate, and gamma-amino-butyric acid (GABA) pathways are discussed as the underlying pathophysiology associated with stress-related risk of addiction. The effects of regular and chronic drug use on alterations in these stress and motivational systems are also reviewed, with specific attention to the impact of these adaptations on stress regulation, impulse control, and perpetuation of compulsive drug seeking and relapse susceptibility. Finally, research gaps in furthering our understanding of the association between stress and addiction are presented, with the hope that addressing these unanswered questions will significantly influence new prevention and treatment strategies to address vulnerability to addiction.

Effects of acute systemic cocaine administration on the cortisol, ACTH and prolactin levels of black tufted-ear marmosets

The effect of acute systemic cocaine administration on total circulating cortisol, adrenocorticotropin hormone (ACTH) and prolactin levels of nine adult black tufted-ear marmoset monkeys (Callithrix penicillata) was investigated. For each subject, two blood samples were obtained after an i.p. injection of 10 and 20mg/kg of cocaine: one sample was drawn 30-min post-injection, while the second was following a 60-min interval. Blood samples were also obtained 0, 30 and 60 min following a saline injection. The 20 mg/kg dose of cocaine induced a significant decrease in ACTH levels 60 min after being administered. Circulating levels of cortisol, on the other hand, increased significantly 60 min after the 20 mg/kg dose. Prolactin concentrations decreased significantly 30 and 60 min after both doses of cocaine had been administered (10 and 20 mg/kg). Finally, the content of the three hormones analyzed remained constant 0, 30 and 60 min post-saline administrations. Therefore, an acute systemic cocaine challenge alters the basal circulating levels of ACTH, cortisol and prolactin of marmoset monkeys. A distinct response pattern was observed for each hormone analyzed, possibly related to specific negative feedback mechanisms and/or this species glucocorticoid-resistance. The use of this small neotropical primate may thus provide a unique opportunity to investigate cocaine-induced neuroendocrine effects.

Making a bad thing worse: adverse effects of stress on drug addiction

Sustained exposure to various psychological stressors can exacerbate neuropsychiatric disorders, including drug addiction. Addiction is a chronic brain disease in which individuals cannot control their need for drugs, despite negative health and social consequences. The brains of addicted individuals are altered and respond very differently to stress than those of individuals who are not addicted. In this Review, we highlight some of the common effects of stress and drugs of abuse throughout the addiction cycle. We also discuss both animal and human studies that suggest treating the stress-related aspects of drug addiction is likely to be an important contributing factor to a long-lasting recovery from this disorder.

Daily cocaine self-administration under long-access conditions augments restraint-induced increases in plasma corticosterone and impairs glucocorticoid receptor-mediated negative feedback in rats

Cocaine addiction appears to be associated with a drug-induced dysregulation of stressor responsiveness that may contribute to further cocaine use. The present study examined alterations in stressor-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis in rats provided daily access to cocaine for self-administration (SA) under long-access conditions (1.0 mg/kg/infusion; 6 hx14 days). Cocaine self-administering rats displayed reduced basal plasma corticosterone (CORT) levels but showed an augmented restraint-induced percent increase response from baseline compared to saline self-administering controls when measured 24 days after SA testing. This augmented CORT response may have been attributable to impaired glucocorticoid receptor (GR)-mediated feedback regulation of HPA function, since cocaine self-administering rats were also less susceptible to dexamethasone (0.01 mg/kg, i.p.) suppression of plasma CORT levels. GR protein expression measured using Western blot analysis was significantly reduced in the dorsomedial hypothalamus (including the paraventricular nucleus [PVN]) but not in the pituitary gland, ventromedial hypothalamus, dorsal hippocampus, ventral subiculum, medial prefrontal cortex or amygdala in cocaine self-administering rats. Surprisingly, basal corticotropin-releasing hormone (CRH) mRNA or post-restraint increases in CRH mRNA measured at a single (90 min) time-point in the PVN using in situ hybridization did not differ between groups. The findings suggest that cocaine use produces persistent changes in individual responsiveness to stressors that may contribute to the addiction process.

The neurobiology and genetics of impulse control disorders: relationships to drug addictions

Impulse control disorders (ICDs), including pathological gambling, trichotillomania, kleptomania and others, have been conceptualized to lie along an impulsive-compulsive spectrum. Recent data have suggested that these disorders may be considered addictions. Here, we review the genetic and neuropathological bases of the impulse control disorders and consider the disorders within these non-mutually exclusive frameworks.

Relationship of prolactin response to meta-chlorophenylpiperazine with severity of drug use in cocaine dependence

RATIONALE

Serotonergic (5-HT) mechanisms appear to mediate central effects of cocaine. Therefore 5-HT disturbances could be associated with drug severity.

OBJECTIVES

We investigated whether prolactin (PRL) response to meta-chlorophenylpiperazine (m-CPP), a mixed 5-HT agonist/antagonist were associated with severity of cocaine use.

METHODS

Thirty-six cocaine-dependent subjects and 33 controls underwent a challenge with 0.5 mg/kg of oral m-CPP. Severity of drug use was assessed using the Addiction Severity Index (ASI).

RESULTS

The PRL response to m-CPP was significantly blunted in cocaine patients compared to controls (F = 21.86, p < 0.001). DeltaPRL (peak PRL-baseline PRL) was negatively correlated with ASI-drug (r = -0.45, p < 0.01), ASI-alcohol (r = -0.32, p < 0.05), and ASI-psychological (r = -0.41, p < 0.01) composite scores, and with the quantity, frequency and duration of drug use (r ranged from - 0.41 to - 0.32, p ranged from < 0.01 to 0.05). Hierarchical regressions showed that ASI-drug composite scores significantly predicted the variance in DeltaPRL after controlling for behavioral and demographic variables (F = 4.27, p < 0.05).

CONCLUSIONS

The results indicate that disturbances in 5-HT function as reflected by a blunted response to m-CPP seem to be primarily associated with severity of drug use and to a lesser, although significant extent with behavioral traits in cocaine-dependent patients.

Decreased cell proliferation in the dentate gyrus of rats after repeated administration of cocaine

Cell proliferation in the dentate gyrus of hippocampus was assessed using in vivo labeling with 5-bromo-2'-deoxyuridine (BrdU) in adult rats that were administered cocaine (20 mg/kg) for 14 consecutive days. Rats showed increased stereotypy at a challenge dose of cocaine after 1 week of withdrawal, suggesting the acquisition of behavioral sensitization. Twenty-four hours after final injection of repetitive cocaine administration, a 26% decrease in BrdU-positive cells was observed, compared with control rats. However, this returned to control level within 1 week. No differences were observed in rats that received a single injection of cocaine. Differentiation of newly formed cells was not influenced. These data imply that the regulation of hippocampal cell proliferation by cocaine may be involved in the development of certain symptoms of addiction, such as cognitive impairment and acquisition of behavioral sensitization.

Glucocorticoid negative feedback in methadone-maintained former heroin addicts with ongoing cocaine dependence: dose-response to dexamethasone suppression

Combined cocaine and illicit opiate use is common. This study aimed to test the hypothesis that cocaine dependence in former heroin-addicted patients maintained on methadone treatment is associated with enhanced glucocorticoid negative feedback. Multiple dose dexamethasone suppression tests, using a conventional 2.0 mg dose, and two lower doses, 0.5 mg and 0.125 mg, were performed in 10 methadone-maintained former heroin addicts with ongoing cocaine dependence (C-MM), 10 stabilized methadone-maintained former heroin addicts with no ongoing drug or alcohol use (MM), and 22 normal volunteers (NV). At 9 hours, there was no difference in plasma adrenocorticotropin hormone (ACTH) and/or cortisol levels among groups on the baseline day, as well as after the two lower doses of dexamethasone. At 17 hours, C-MM and MM had significantly lower plasma ACTH and/or cortisol levels than NV. However, C-MM did not significantly differ from MM in their hormonal levels. When the hormonal responses to dexamethasone are expressed as magnitude of lowering from baseline, there was no significant difference at any dose among groups. Therefore, C-MM exhibited a normal glucocorticoid negative feedback in the morning. Using the standard interpretation of dexamethasone suppression testing based on the examination of the actual hormonal levels rather than the difference from baseline condition, C-MM appear to have glucocorticoid effects similar to MM, yet were both greater than NV in the late afternoon. Thus, further studies are needed to know whether altered glucocorticoid negative feedback is related to chronic cocaine exposure, or is the result of former heroin addiction and/or its long-term treatment with methadone.

Pharmacokinetics of repeated doses of intravenous cocaine across the menstrual cycle in rhesus monkeys

Numerous studies in rodents suggest that there are sex differences in response to cocaine that are related to fluctuations in the ovarian hormones of females. Given that female rhesus monkeys have menstrual cycles that are remarkably similar to those of humans, they provide an ideal laboratory animal model for assessing the effects of cocaine across the menstrual cycle. The present study assessed the effects of 4 injections of intravenous (i.v.) cocaine (0.00, 0.25 or 0.50 mg/kg), spaced 15 min apart, in 4 female rhesus monkeys. Each monkey was tested with each dose during 4 phases of the menstrual cycle: menses, midfollicular, periovulatory and midluteal. Estradiol and progesterone levels were measured each session before cocaine administration to verify phase of the menstrual cycle. Cocaine and cocaine metabolite levels were measured 5 min after each cocaine dose and 5, 15, 30, 45, 60 and 120 min after the last cocaine dose. Similarly, levels of luteinizing hormone (LH) and prolactin levels were measured before, 5, 15, 30, 45, 60 and 120 min after the last cocaine dose. Cocaine and metabolite levels increased as a function of dose, but there were minimal differences across the menstrual cycle following repeated injections of cocaine. With a few exceptions, LH levels decreased as a function of time within the session, with no differences as a function of cocaine dose. Cocaine produced transient increases in LH levels during the luteal phase, with maximal levels occurring after the second cocaine injection. Lastly, cocaine substantially decreased prolactin levels across all menstrual cycle phases. Taken together, these data indicate that any behavioral differences observed either across the menstrual cycle or between males and females, are probably not related to alterations in the pharmacokinetics of cocaine across the menstrual cycle.

Bioscience-bioethics and life factors affecting reproduction with special reference to the Indigenous Australian population

The demand for equality of recognition or respect is the dominant passion of modernity. The 20th century experienced a giant leap in technological inventiveness and ruthless use of technological power. In the 21st century, human welfare and environmental wellbeing demand fundamental political appraisal. We have the means, if we choose, to eradicate poverty and to responsibly protect the global environment. However, economic, political and cultural systems act to differentially allocate the benefits and risks for growth between socioeconomic groups. For example, it is a matter of pride that the neonatal mortality rate in affluent societies has dropped substantially since the late 1970s. However, the level of infant mortality (three times the national average) and low birthweight (13%) among the Indigenous Australian population is the highest in the country. With hindsight we now know that is the inevitable legacy of Australia's colonial history. Chronic physical and psychological stress is recognized as an important etiological factor in many lifestyle diseases of the cardiovascular, immune and reproductive systems. Diseases of adaptation are further advanced by non-adaptive lifestyle choices, depression, alcoholism and other drug dependencies. This review describes the principles of bioscience ethics and targets equity issues as they affect human reproduction across generations with particular reference to the Indigenous population of Australia. The review also considers ways we may advance global and cultural maturity from the Indigenous Australian perspective and proposes an ecologically based model of preventative care. If we are to embrace fundamental social change and protect future children without threatening parents' basic freedoms, then new beliefs and priorities--based on a compassionate understanding of biological systems--must evolve from the general public. Belief in human rights arising from a sense of human dignity is a collective outcome originating from individual commitment. The golden rule; that is, Nature's principle of reciprocity, is fundamental in bridging the gap between knowledge and effective action.

Relationship of serum prolactin with severity of drug use and treatment outcome in cocaine dependence

RATIONALE

Alteration in serum prolactin (PRL) levels may reflect changes in central dopamine activity, which modulates the behavioral effects of cocaine. Therefore, serum PRL may have a potential role as a biological marker of drug severity and treatment outcome in cocaine dependence.

OBJECTIVE

We investigated whether serum PRL levels differed between cocaine-dependent (CD) subjects and controls, and whether PRL levels were associated with severity of drug use and treatment outcome in CD subjects.

METHODS

Basal PRL concentrations were assayed in 141 African-American (AA) CD patients attending an outpatient treatment program and 60 AA controls. Severity of drug use was assessed using the Addiction Severity Index (ASI). Measures of abstinence and retention during 12 weeks of treatment and at 6-month follow-up were employed as outcome variables.

RESULTS

The basal PRL (ng/ml) in CD patients (9.28+/-4.13) was significantly higher than controls (7.33+/-2.94) (t=3.77, P<0.01). At baseline, PRL was positively correlated with ASI-drug (r=0.38, P<0.01), ASI-alcohol (r=0.19, P<0.05), and ASI-psychological (r=0.25, P<0.01) composite scores, and with the quantity of cocaine use (r=0.18, P<0.05). However, PRL levels were not significantly associated with number of negative urine screens, days in treatment, number of sessions attended, dropout rate or changes in ASI scores during treatment and at follow-up. Also, basal PRL did not significantly contribute toward the variance in predicting any of the outcome measures.

CONCLUSION

Although cocaine use seems to influence PRL levels, it does not appear that PRL is a predictor of treatment outcome in cocaine dependence.

Short-term cocaine treatment causes neuroadaptive changes in Galphaq and Galpha11 proteins in rats undergoing withdrawal

One of the characteristics of drug dependence is that a drug has to be administered repeatedly before withdrawal effects can be observed. We have previously shown that withdrawal after 14 days of cocaine treatment produces a supersensitivity of hypothalamic 5-hydroxytryptamine (serotonin) 2A (5-HT(2A)) receptors, which is accompanied by increases in the levels of Galpha(q) and Galpha(11) proteins. Unfortunately, the exact duration of cocaine treatment necessary to induce alterations in G protein levels during cocaine withdrawal is unknown. The present study investigated the minimum cocaine treatment period required to produce changes in protein levels of membrane- and cytosol-associated Galpha(q) and Galpha(11) proteins in the hypothalamic paraventricular nucleus, amygdala, and frontal cortex. Rats were injected with cocaine (15 mg/kg i.p., b.i.d.) for 0, 1, 3, 5, and 7 days and tested after 2 days of withdrawal. The levels of Galpha(q) and Galpha(11) proteins were increased in the paraventricular nucleus and the amygdala but not in the frontal cortex. Although 1 and 3 days of cocaine treatment were sufficient to maximally elevate the protein levels of Galpha(11) and Galpha(q) proteins in the amygdala, 5 days of treatment were required to maximally increase the levels of Galpha(11) and Galpha(q) proteins in the paraventricular nucleus. The data suggest that the amygdala shows a faster neuroadaptation to the effects of cocaine than the hypothalamic paraventricular nucleus. These findings provide insight into the relative importance of individual components of 5-HT(2A) receptor signal transduction system in regulating the overall sensitivity of this signaling in cocaine-treated rats.

Participants receiving dehydroepiandrosterone during treatment for cocaine dependence show high rates of cocaine use in a placebo-controlled pilot study

Twenty-three cocaine-dependent participants were randomly assigned to receive either dehydroepiandrosterone (DHEA; n = 11; 100 mg/day) or placebo (n = 12) in the context of 12 weeks of thrice weekly cognitive-behavioral group counseling. Outcomes were retention, urine drug screening, cocaine craving, adverse experiences, and medication compliance. DHEA-treated participants averaged 45.8 (SD = 28.8) days in treatment, compared with 70.7 (SD = 20.6) days for placebo, r(21) = -2.4, p =.03, and provided 26.8% (SD = 29.3) of urine samples free of cocaine metabolite compared with 70.6% (SD = 39.9) for the placebo condition, r(21) = -3.0, p =.01. No differences were detected between conditions for cocaine craving or adverse experiences. High levels of medication compliance were documented. Results argue against using high doses of DHEA as a pharmacotherapy for cocaine dependence.

Immune cell activity during the initial stages of withdrawal from chronic exposure to cocaine or morphine

The immunosuppression accompanying illicit drug use has been shown to contribute to a decreased resistance to a variety of pathogens; however, there is relatively little information on how long these effects persist following withdrawal from chronic drug exposure. To begin to address this question, Sprague-Dawley male rats were administered either cocaine (10 mg/kg, i.p., b.i.d.) for 7 days or morphine (escalating doses up to 40 mg/kg, s.c., b.i.d.) for a 10-day period. Control groups of animals received similar saline injections for equivalent time periods. Drug administration was abruptly discontinued and animals were sacrificed at 2, 24, 72 or 96 h following the last dose. At these time points, proliferation responses of peripheral blood T-lymphocytes stimulated by concanavalin A (Con A) and plasma levels of corticosterone were measured. Plasma corticosterone levels of cocaine- or morphine-treated animals were found to be significantly elevated 24 h following drug cessation as compared to saline animals. At this time, proliferation responses were significantly decreased and were further suppressed during cocaine and morphine withdrawal at 96 and 72 h, respectively. These results suggest that abrupt cessation of cocaine or morphine administration leads to activation of stress-related pathways that may contribute to an increased susceptibility of infection during the initial withdrawal phase.

Neuroendocrine alterations in a high-dose, extended-access rat self-administration model of escalating cocaine use

One approach for studying cocaine addiction has been to permit escalating patterns of self-administration (SA) by rats by prolonging daily drug availability. Rats provided long access (LgA) to high cocaine doses, but not rats provided shorter cocaine access (ShA), progressively escalate their cocaine intake and display characteristics of human addiction. The purpose of the present study was to investigate the effects of 14 days of ShA or LgA, high-dose cocaine SA on plasma corticosterone (CORT), prolactin (PRL), and related mRNAs. Acutely, cocaine SA increased plasma CORT and reduced plasma PRL levels. SA training produced circadian increases in CORT that appeared to occur in anticipation of cocaine availability. With repeated LgA, high-dose SA, the daily CORT area under the curve (AUC) progressively decreased, apparently due to tolerance to cocaine's effects on CORT and a reduction in basal CORT levels. In contrast, the daily CORT AUC in ShA rats increased across testing despite constant rates of SA. When measured 12 days after SA testing, pro-opioimelanocortin and glucocorticoid receptor mRNA levels in the anterior pituitary were lower in LgA rats than in ShA rats. The effects of SA on PRL remained constant across SA testing in LgA rats, but increased in duration in ShA rats. Anterior pituitary dopamine D2 receptor mRNA levels were lower in LgA rats than in ShA rats. These findings indicate that the transition to escalating patterns of SA may be associated with altered levels of hormones and gene expression within neuroendocrine systems. Such changes may underlie the onset of human addictive disease.

Hypothalamic-pituitary-adrenal axis and sympatho-adreno-medullary responses during stress-induced and drug cue-induced cocaine craving states

RATIONALE

Environmental stimuli associated with cocaine are known to elicit drug craving and increase the likelihood of relapse. However, the psychobiological changes that occur with exposure to these stimuli and in episodes of drug craving are not well understood. This study examined the response of brain stress circuits to environmental stimuli that are known to increase cocaine craving in cocaine dependent individuals.

METHODS

Fifty-four treatment seeking cocaine dependent individuals, who were admitted to an inpatient treatment research unit for 2-4 weeks, participated in three laboratory sessions. Subjects were exposed to a brief 5-min guided imagery procedure that involved imagining a recent personal stressful situation, a drug-related situation and a neutral-relaxing situation, one imagery per session presented in random order. Subjective ratings of craving and anxiety, cardiovascular measures, and plasma levels of adrenocorticotrophic hormone (ACTH), cortisol, prolactin, norepinephrine (NE) and epinephrine (EPI) were assessed.

RESULTS

Exposure to stress and to drug cues each resulted in significant increases in cocaine craving and subjective anxiety, pulse rate, systolic blood pressure, ACTH, cortisol, prolactin and NE as compared to the response to neutral imagery. In addition, stress imagery also increased diastolic blood pressure and plasma EPI as compared to responses to the drug cue imagery and neutral-relaxing imagery.

CONCLUSIONS

The findings indicate a significant activation of the CRF-HPA axis and noradrenergic/sympatho-adreno-medullary (SAM) system response during stress-induced and drug cue induced cocaine craving states in cocaine dependent individuals. The role of stress system activation in cocaine craving and in cocaine use is discussed.

Treatment-seeking inpatient cocaine abusers show hypothalamic dysregulation of both basal prolactin and cortisol secretion

Cocaine causes neuroendocrine aberrations in cocaine abusers with pituitary stress hormone secretion providing a window to the stress system in the brain. Substance abusers and control participants were hormonally profiled for 3 weeks. Abusers showed significant basal elevations in prolactin in week 1 with normalization over the 3 weeks. No differences in prolactin secretion were seen with either thyrotropin-releasing hormone stimulation or L-dopa suppression testing. Basal afternoon cortisol secretion was significantly elevated during weeks 1 and 2 comparing abusers to controls. Elevated afternoon cortisol secretion is a sensitive indicator of central stress activation. These results point to the hypothalamus, not the pituitary gland, as being primarily altered in cocaine withdrawal. The data demonstrate that both the dopamine-prolactin and hypothalamic-pituitary-adrenal (HPA) axes are affected during cocaine cessation. As medications are developed to modulate activation of a dysfunctional stress system, future therapeutic studies of substance abuse, withdrawal, craving and relapse should employ more sophisticated tests of hypothalamic pituitary function, especially the HPA axis, as this information may be a guide in the diagnosis and predict clinical responses.

Biological markers of cocaine addiction: implications for medications development

The search for effective medications for cocaine addiction has been elusive. The failure to find such medications so far could be due to poor understanding of the underlying biology both in the premorbid condition and following the disease state of chronic cocaine use. Population heterogeneity could be a major factor in response to medications. In an attempt to highlight the issue of biomarkers we reviewed physiological, neuroendocrine and neuroimaging studies to identify specific biological changes/markers that could be used to characterize subgroups among chronic cocaine users. Merging the biology within medications studies of cocaine abusers could prove useful for targeting specific pharmacological agents to subgroups of patients, prediction of response to medication and relapse to use.

Stress-induced suppression of the immune system after withdrawal from chronic cocaine

Recent evidence suggests that withdrawal from cocaine shares similarities to the stress response. Here, we examine whether withdrawal from chronic cocaine produces immune system alterations and whether the hypothalamic-pituitary-adrenal axis is involved. Sprague-Dawley male rats received cocaine (10 mg/kg i.p., b.i.d.) or saline, followed by 2 h, 1, 2, 4, 6, and 14 days of withdrawal. Proliferation responses of peripheral blood lymphocytes to concanavalin A were significantly suppressed at the 2-h, 1- and 2-day time points, and persisted for up to 6 days during withdrawal from chronic cocaine. Flow cytometric analysis revealed no significant differences in the immunophenotype of blood lymphocytic populations of T cells, B cells, or monocytes at 2 or 6 days of withdrawal from cocaine. Consistent with the suppression in cellular immunity observed in the in vitro response, the in vivo delayed-type hypersensitivity response was also significantly decreased in cocaine withdrawing animals. Plasma corticosterone levels were significantly elevated 2 and 24 h after cessation of cocaine but returned to basal values by 2 days of withdrawal. The suppressive effects of cocaine withdrawal were no longer observed in either adrenalectomized animals or those treated with the glucocorticoid receptor antagonist mifepristone (RU486), when administered during the first 2 days of withdrawal. These data argue that repeated exposure to cocaine followed by withdrawal leads to an activation of the neuroendocrine stress response, which alters cellular immunity during the initial withdrawal phase and may contribute to an increased susceptibility to infection.

Alterations in hypothalamic-pituitary-adrenal axis activity and in levels of proopiomelanocortin and corticotropin-releasing hormone-receptor 1 mRNAs in the pituitary and hypothalamus of the rat during chronic 'binge' cocaine and withdrawal

Tolerance to the stimulatory effects of cocaine on the hypothalamic-pituitary-adrenal (HPA) axis develops after chronic 'binge' cocaine exposure in the rat. This blunting of HPA axis activity in response to cocaine is associated with a cocaine-induced reduction of corticotropin-releasing hormone (CRH) mRNA level in the hypothalamus. There is limited information about the effects of withdrawal from chronic cocaine on HPA activity. The present studies were undertaken to determine levels of the HPA hormones adrenocorticotropic hormone (ACTH) and corticosterone across 10 days of withdrawal following chronic 'binge' pattern cocaine administration (3 x 15 mg/kg/day at hourly intervals) for 14 days. Male Fischer rats showed a significantly attenuated HPA axis response to chronic 'binge' pattern cocaine administration 30 min after the last injection on the 14th day, as measured by both plasma ACTH and corticosterone levels at the nadir time point. Twenty-four hours following the final administration of 'binge' cocaine (the 1st day of withdrawal), a significant elevation of plasma ACTH levels and a modest, but significant, elevation of plasma corticosterone levels were found at the nadir time point. This acute withdrawal-related activation of the hormones of the HPA axis was no longer found on the 10th day of withdrawal. In the anterior pituitary, levels of both proopiomelanocortin (POMC) and CRH-receptor 1 (R1) mRNAs were significantly higher than saline controls on the 14th day of chronic 'binge' cocaine and were at control levels on the 4th day of withdrawal. In the neurointermediate lobe of the pituitary, a sustained reduction in POMC mRNA levels was observed on the 3rd, 7th and 14th day of chronic 'binge' cocaine, but POMC mRNA was at control levels by the 4th day of withdrawal. In the hypothalamus, POMC mRNA levels showed a transient decrease on the 1st day of 'binge' cocaine with no change during chronic 'binge' cocaine or its withdrawal. CRH mRNA levels in the hypothalamus were not different from saline controls on the 1st and 4th days of withdrawal. Taken together, the present results show that after development of adaptation or tolerance to chronic 'binge' cocaine there is an increase in HPA activity during acute cocaine withdrawal. In addition to being associated with CRH input from the hypothalamus, the activation of the HPA axis by cocaine withdrawal may be, at least in part, due to the increased POMC and/or CRH-R1 gene expression observed in the anterior pituitary after chronic 'binge' cocaine.

Interaction between glucocorticoid hormones, stress and psychostimulant drugs

In this review we summarize data obtained from animal studies showing that glucocorticoid hormones have a facilitatory role on behavioural responses to psychostimulant drugs such as locomotor activity, self-administration and relapse. These behavioural effects of glucocorticoids involve an action on the meso-accumbens dopamine system, one of the major systems mediating the addictive properties of drugs of abuse. The effects of glucocorticoids in the nucleus accumbens are site-specific; these hormones modify dopamine transmission in only the shell of this nucleus without modifying it in the core. Studies with corticosteroid receptor antagonists suggest that the dopaminergic effects of these hormones depend mostly on glucocorticoid, not on mineralocorticoid receptors. These data suggest that an increase in glucocorticoid hormones, through an action on mesolimbic dopamine neurons, could increase vulnerability to drug abuse. We also discuss the implications of this finding with respect to the physiological role of glucocorticoids. It is proposed that an increase in glucocorticoids, by activating the reward pathway, could counteract the aversive effects of stress. During chronic stress, repeated increases in glucocorticoids and dopamine would result in sensitization of the reward system. This sensitized state, which can persist after the end of the stress, would render the subject more responsive to drugs of abuse and consequently more vulnerable to the development of addiction.

Abdominal pain in patients with hyperglycemic crises

BACKGROUND

The aim of the study was to evaluate the incidence and prognosis of abdominal pain in patients with diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar nonketotic state (HHS). Abdominal pain, sometimes mimicking an acute abdomen, is a frequent manifestation in patients with DKA. The prevalence and clinical significance of gastrointestinal symptoms including abdominal pain in HHS have not been prospectively evaluated.

MATERIALS AND METHODS

This is a prospectively collected evaluation of 200 consecutive patients with hyperglycemic crises admitted to a large inner-city teaching hospital in Atlanta, GA.We analyzed the admission clinical characteristics, laboratory studies, and hospital course of 189 consecutive episodes of DKA and 11 cases of HHS during a 13-month period starting in October 1995.

RESULTS

Abdominal pain occurred in 86 of 189 patients with DKA (46%). In 30 patients, the cause of abdominal pain was considered to be secondary to the precipitating cause of metabolic decompensation. Five of them required surgical intervention including 1 patient with Fournier's necrotizing fasciitis, 1 with cholecystitis, 1 with acute appendicitis, and 2 patients with perineal abscess. The presence of abdominal pain was not related to the severity of hyperglycemia or dehydration; however, a strong association was observed between abdominal pain and metabolic acidosis. In DKA patients with abdominal pain, the mean serum bicarbonate (9 +/- 1 mmol/L) and blood pH (7.12 +/- 0.02) were lower than in patients without pain (15 +/- 1 mmol/L and 7.24 +/- 0.09, respectively, both P <.001). Abdominal pain was present in 86% of patients with serum bicarbonate less than 5 mmol/L, in 66% of patients with levels of 5 to less than 10 mmol/L, in 36% of patients with levels 10 to less than 15 mmol/L, and in 13% of patients with bicarbonate levels 15 to 18 mmol/L. Patients with DKA and abdominal pain had a more frequent history of alcohol (51%) and cocaine abuse (13%) than those without abdominal pain (24% and 2%, respectively, both P <.001). One patient with HHS reported nausea and vomiting on admission, but abdominal pain was not reported in any patient with HHS.

CONCLUSIONS

Gastrointestinal manifestations including abdominal pain are common in patients with DKA and are associated with severe metabolic acidosis and with a history of alcohol or cocaine abuse, but not with the severity of hyperglycemia or dehydration. Our study indicates that investigation of the etiology of abdominal pain in DKA should be reserved for patients without severe metabolic acidosis or if the pain persists after the resolution of ketoacidosis.

The HPA axis in cocaine use: implications for pharmacotherapy

The role of the hypothalamic-pituitary-adrenal (HPA) axis in cocaine use is reviewed within the context of two approaches to developing pharmacological treatments in humans: (1) reducing the reinforcing effects of cocaine and (2) reducing cocaine addict's susceptibility to stress-induced relapse. This review suggests that HPA-axis-suppressing medications are unlikely to block cocaine's reinforcing effects completely but may be useful in decreasing the frequency of use by increasing the addicted individual's resistance to stress-induced relapse. Implications for designing inpatient studies to test the safety and efficacy of candidate pharmacological agents are discussed.