Smoked cocaine self-administration in females

Estradiol and Mu opioid-mediated reward: The role of estrogen receptors in opioid use

Opioid use and opioid use disorder are characterized by sex and gender differences, and some of these differences may be mediated by differences in the hormonal milieu within and across individuals. This review focuses on the role of ovarian hormones, and particularly estradiol, on the endogenous mu opioid receptor system. There is an abundance of data indicating that estradiol influences the activity of endogenous mu opioid peptides, the activation of mu opioid receptors, and the internalization and desensitization of mu opioid receptors. These effects have functional consequences on behaviors mediated by endogenous mu opioid receptor activity and on sensitivity to mu opioid agonists and antagonists. Recent behavioral data suggest these consequences extend to mu opioid reward, and preclinical studies report that estradiol decreases self-administration of mu opioid receptor agonists across a range of experimental conditions. Data collected in human laboratory studies suggest that estradiol may have functionally similar effects in clinical populations, and thus estrogen receptors may be a potential target in the development of novel therapeutics. This review summarizes data from cellular assays to clinical trials to explore how estradiol influences mu opioid receptor activity, as well as potential ways in which estrogen receptors may be targeted to address the problems of opioid use.

Hormones, nicotine, and cocaine: clinical studies

Nicotine and cocaine each stimulate hypothalamic-pituitary-adrenal and -gonadal axis hormones, and there is increasing evidence that the hormonal milieu may modulate the abuse-related effects of these drugs. This review summarizes some clinical studies of the acute effects of cigarette smoking or IV cocaine on plasma drug and hormone levels and subjective effects ratings. The temporal covariance between these dependent measures was assessed with a rapid (2 min) sampling procedure in nicotine-dependent volunteers or current cocaine users. Cigarette smoking and IV cocaine each stimulated a rapid increase in LH and ACTH, followed by gradual increases in cortisol and DHEA. Positive subjective effects ratings increased immediately after initiation of cigarette smoking or IV cocaine administration. However, in contrast to cocaine's sustained positive effects (<20 min), ratings of "high" and "rush" began to decrease within one or two puffs of a high-nicotine cigarette while nicotine levels were increasing. Peak nicotine levels increased progressively after each of three successive cigarettes smoked at 60 min intervals, but the magnitude of the subjective effects ratings and peak ACTH and cortisol levels diminished. Only DHEA increased consistently after successive cigarettes. The possible influence of neuroactive hormones on nicotine dependence and cocaine abuse and the implications for treatment of these addictive disorders are discussed.

Self-administration of cocaine, cannabis and heroin in the human laboratory: benefits and pitfalls

The objective of this review is to describe self-administration procedures for modeling addiction to cocaine, cannabis and heroin in the human laboratory, the benefits and pitfalls of the approach, and the methodological issues unique to each drug. In addition, the predictive validity of the model for testing treatment medications will be addressed. The results show that all three drugs of abuse are reliably and robustly self-administered by non-treatment-seeking research volunteers. In terms of pharmacotherapies, cocaine use is extraordinarily difficult to disrupt either in the laboratory or in the clinic. A range of medications has been shown to significantly decrease cocaine's subjective effects and craving without decreasing either cocaine self-administration or cocaine abuse by patients. These negative data combined with recent positive findings with modafinil suggest that self-administration procedures are an important intermediary step between pre-clinical and clinical studies. In terms of cannabis, a recent study suggests that medications that improve sleep and mood during cannabis withdrawal decrease the resumption of marijuana self-administration in abstinent volunteers. Clinical data on patients seeking treatment for their marijuana use are needed to validate these laboratory findings. Finally, in contrast to cannabis or cocaine dependence, there are three efficacious Food and Drug Administration-approved medications to treat opioid dependence, all of which decrease both heroin self-administration and subjective effects in the human laboratory. In summary, self-administration procedures provide meaningful behavioral data in a small number of individuals. These studies contribute to our understanding of the variables maintaining cocaine, marijuana and heroin intake, and are important in guiding the development of more effective drug treatment programs.

Effects of smoking successive low- and high-nicotine cigarettes on hypothalamic-pituitary-adrenal axis hormones and mood in men

Smoking one cigarette produces rapid nicotine dose-related increases in hypothalamic-pituitary-adrenal (HPA) axis hormones, mood, and heart rate, but relatively little is known about the effects of smoking several cigarettes successively. Twenty-four healthy adult men who met Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria for nicotine dependence provided informed consent. After overnight abstinence from smoking, men smoked three low- or high-nicotine cigarettes for 4 min each at 60 min intervals. Samples for nicotine and hormone analysis, Visual Analog Scale (VAS) ratings of subjective effects and heart rate were collected at 4, 8, 12, 16, 20, 30, 40, and 50 min after each cigarette. After low-nicotine cigarettes, nicotine levels, adrenocorticotropin hormone, and heart rate did not increase significantly, cortisol and dehydroepiandrosterone decreased significantly, and positive VAS ratings were lower but parallel to ratings after high-nicotine cigarette smoking. After high-nicotine cigarettes, peak nicotine levels increased monotonically. HPA axis hormones increased after smoking, but peak levels did not differ significantly after successive high-nicotine cigarettes. Positive VAS ratings and heart rate increased after each high-nicotine cigarette, but peak levels were lower after smoking the second and third cigarette. 'Craving' decreased significantly after smoking both low- and high-nicotine cigarettes, then gradually increased during the 60 min interval between cigarettes. These data are consistent with clinical reports that the first cigarette after overnight nicotine abstinence is most salient. Tolerance to the subjective and cardiovascular effects of nicotine developed rapidly during repeated cigarette smoking, but nicotine-stimulated increases in HPA axis hormones did not change significantly.

Neural correlates of high and craving during cocaine self-administration using BOLD fMRI

Modern theories of drug dependence hold the hedonic effects of drug-taking central to understanding the motivation for compulsive drug use. Previous neuroimaging studies have begun to identify brain regions associated with acute drug effects after passive delivery. In this study, a more naturalistic model of cocaine self-administration (SA) was employed in order to identify those sites associated with drug-induced high and craving as measures of reward and motivation. Non-treatment seeking cocaine-dependent subjects chose both when and how often i.v. cocaine administration occurred within a medically supervised SA procedure. Both functional magnetic resonance imaging (fMRI) data and real-time behavioral ratings were acquired during the 1-h SA period. Drug-induced HIGH was found to correlate negatively with activity in limbic, paralimbic, and mesocortical regions including the nucleus accumbens (NAc), inferior frontal/orbitofrontal gyrus (OFC), and anterior cingulate (AC), while CRAVING correlated positively with activity in these regions. This study provides the first evidence in humans that changes in subjective state surrounding cocaine self-administration reflect neural activity of the endogenous reward system.

Opioid-, cannabis- and alcohol-dependent women show more rapid progression to substance abuse treatment

Alcohol-dependent women progress faster from onset of alcohol drinking to entry into treatment, experiencing an earlier onset (i.e., "telescoping") of alcohol-related complications. This phenomenon also appears to be evident in drug-dependent women, though the data available to support telescoping in drug dependence is less abundant.

OBJECTIVE

To evaluate gender effects on progression to treatment entry and on the frequency, severity and related complications of DSM-III-R drug and alcohol dependence among 271 substance-dependent patients (mean age: 32.6 years; 156 women).

METHOD

Multivariate and univariate ANCOVA was used to compare age at onset of regular use of cocaine, opioids, cannabis and alcohol and time elapsed between initiation of regular use of each substance and entry into an index or current substance abuse treatment. Scores on the Addiction Severity Index (ASI) were also examined.

RESULTS

There was no gender difference among patients in the age at onset of regular use of any substance. Women experienced fewer years of regular use of opioids and cannabis, and fewer years of regular alcohol drinking before entering treatment. Although the severity of drug and alcohol dependence did not differ by gender, women reported more severe psychiatric, medical and employment complications.

CONCLUSIONS

These findings support the notion of an accelerated progression to treatment entry among opioid-, cannabis- and alcohol-dependent women, and suggest that there exists a gender-based vulnerability to the adverse consequences of these disorders.

Clinical Implications of Reinforcement as a Determinant of Substance Use Disorders

Extensive scientific evidence indicates that reinforcement plays an important role in the genesis, maintenance, and recovery from substance use disorders. In this chapter, we review recent clinical research from laboratory, clinic, and naturalistic settings examining the role of reinforcement in substance use disorders. Well-controlled human laboratory studies are reviewed characterizing orderly interactions between the reinforcing effects of drugs and environmental context that have important implications for understanding risk factors for substance use disorders and for the development of efficacious interventions. Recent treatment-outcome studies on voucher-based contingency management and community reinforcement therapy are reviewed demonstrating how reinforcement and related principles can be used to improve outcomes across a wide range of different substance use disorders and populations. Overall, the chapter characterizes a vigorous area of clinical research that has much to contribute to a scientific analysis of substance use disorders.

Die neuropsychologischen Effekte von Kokain

Zusammenfassung: Kokainkonsumenten sind in der Regel entweder Gelegenheitskonsumenten mit geringem und relativ gut kontrollierbarem Kokainkonsum oder Kokainabhängige, die exzessiv große Mengen Kokain einnehmen (Binge-Taking). Neuropsychologische Untersuchungen bei Gelegenheitskonsumenten mit kleinen bis mittleren Kokaindosen, die geeignet sind, “Euphorie” und “Hochgefühle” auszulösen, ergaben bisher keine Hinweise auf neuropsychologische Funktionsbeeinträchtigungen in der akuten Phase. Vielmehr wurden in der akuten Kokainphase verbesserte Aufmerksamkeitsleistungen und schnellere Reaktionszeiten gemessen, die bis zum Beginn der postakuten Phase anhielten. Explizite Untersuchungen zur postakuten Phase oder Studien über die Effekte von Kokain in einem hohen Dosisbereich liegen derzeit nicht vor. Kokainabhängige weisen in einem Abstinenzzeitraum von bis zu mindestens 3 Monaten neuropsychologische, neurologische und unter Umständen auch psychiatrische Defizite auf. Deutliche Defizite abstinenter Kokainabhängiger wurden bei der Aufmerksamkeitsleistung, der Konzentration, der inhibitorischen Kontrolle und im Gedächtnis gefunden, wobei die verschiedenen Gedächtnistypen unterschiedlich betroffen sind. Kommt es bei Kokainabhängigen zu einer erneuten Kokaineinnahme, d.h. zu einer Binge-Phase, so ist unmittelbar danach in der so genannten Crash-Phase noch zusätzlich mit zum Teil schweren emotional-motivationalen Beeinträchtigungen zu rechnen.

The pharmacokinetic determinants of the frequency and pattern of intravenous cocaine self-administration in rats by pharmacokinetic modeling

We investigated the pharmacokinetic determinants of the frequency of intravenous cocaine self-administration in 2.5-h sessions. Two groups of rats were implanted with dual catheters that permitted cocaine infusion and blood sampling via the femoral and jugular vein catheters, respectively. Half of the animals in each group self-administered one of the two cocaine unit doses (0.5 and 1 mg/kg/infusion) by pressing a lever under a continuous schedule of reinforcement. To monitor serum cocaine concentrations, the remaining animals received concurrent, response-independent infusions whenever the matched animals self-administered cocaine infusions. Multiple concentration-time data in two successive self-administrations were determined to monitor the extent of fluctuation in concentrations by pharmacokinetic modeling. Behavioral analyses revealed the higher unit dose (1 mg/kg) resulted in less frequent cocaine self-administration, and a longer interinfusion interval, whereas the total doses were similar for the two groups (24.5-27.0 mg/kg/2.5 h). Cocaine decayed biexponentially. Both the values of clearance and terminal elimination rate constant for the self-administration paradigm were significantly greater than those after the bolus cocaine dosing series (0.5 and 1 mg/kg, separated by 3 days). The regularity in cocaine self-administration produced relatively stable serum cocaine concentrations that oscillated between maximum (C(max)) and minimum (C(min)) values regardless of dose size and interinfusion interval. Although the C(max) for the 1-mg/kg unit dose (1.47 microg/ml) was significantly higher than that for the 0.5-mg/kg dose (0.82 microg/ml), the C(min) values between the groups approximated each other (0.28, and 0.34 microg/ml, respectively). Hence, the C(min) is the determinant of the initiation of the next drug-taking behavior.

Depressive symptoms modulate the subjective and physiological response to cocaine in humans

The goal of this study was to examine the relationship between the presence of subclinical depressive symptoms and physiological and subjective responses to smoked cocaine in humans. Cocaine users without major depression, who participated in various inpatient studies, received a single 0.4 mg/kg of smoked cocaine. When the relationship between the Beck Depression Inventory (BDI) scores and various subjective and physiological responses to cocaine was examined, similar trends were found. Low BDI scores of 0-7 were associated with a smaller physiological and subjective cocaine response. In contrast, BDI ranges of 8-13 were associated with enhanced cocaine response which plateaued or declined in the higher (> 14) BDI group. These group differences were not explained by sex or body weight differences among groups. The implication of these results is that the presence of depressive symptoms may affect cocaine use behavior partly by being associated with an enhanced response to cocaine.

Sex differences in self-reported and physiological response to oral cocaine and placebo in humans

Self-report and physiological data from 27 male and 8 female cocaine-abusing volunteers exposed to cocaine (80 mg/70 kg p.o.) and placebo were examined for sex differences in their responses. Females reported significantly greater baseline ratings on the Pentobarbital-Chlorpromazine-Alcohol Group (PCAG) (sedation) and Lysergic Acid Diethylamide (LSD) (dysphoria) subscales of the Addiction Research Center Inventory-Short Form (ARCI) relative to males. In addition, females reported significantly greater ratings on the Visual Analogs Scales (VAS) Bad Drug Effects and Anxious/Nervous scales relative to males, regardless of drug. Cocaine produced greater increase in systolic blood pressure in males following cocaine, whereas females showed greater increases following placebo. These results suggest that a placebo control is necessary to determine sex differences in response to an active drug.

Individual differences in the subjective response to smoked cocaine in humans

The individual variables that determine the effects of cocaine in humans are not well understood. In this study, we examined the relationship between the subjective response to cocaine and selected individual variables in cocaine-dependent participants. A single 0.4-mg/kg dose of smoked cocaine was received by 75 smoked cocaine users. The variables associated with increased subjective response to cocaine were male sex, presence of alcohol use, higher baseline Beck Depression Inventory (BDI) scores, and duration of cocaine use. The change in heart rate and diastolic blood pressure in response to cocaine delivery were also positively associated with the subjective response to cocaine. In contrast, body weight, years of schooling, and the change in the heart rate with the expectation of cocaine delivery were associated with a diminished subjective response to cocaine. The importance of these variables in maintaining the cocaine use behavior needs to be studied further.

Predictors of cardiovascular response to smoked cocaine in humans

The purpose of this study was to examine the predictors of heart rate and blood pressure changes following cocaine administration. Sixty-two smoked cocaine users received a single 0.4 mg/kg dose of smoked cocaine. Male sex, African American race, higher body weight and current marijuana use predicted a greater cardiovascular response to cocaine. In contrast, higher baseline blood pressure, heart rate, amount and frequency of current cocaine use and presence of current cocaine snorting predicted a diminished cardiovascular response to cocaine. Whether these predictors of the cardiovascular response to smoked cocaine in the laboratory also predict cardiovascular complications from long-term cocaine use needs to be studied further.

Smoked cocaine self-administration in females and voucher incentives for abstinence

There are three purposes for this study: (1) To extend the laboratory study of heavy smoked cocaine use to women, (2) to assess cocaine withdrawal symptoms and (3) to assess the utility of voucher incentives for achieving and maintaining cocaine and other drug abstinence in female cocaine abusers.

METHODS

Ten non-treatment seeking female cocaine smokers resided inpatient for 4-5 days and could smoke up to 6 doses of cocaine base (50 mg each) twice a day (at 1200 h and again at 1600 h) for 2 consecutive days. During the following 2-week outpatient phase, women were given US $40 in merchandise vouchers if urinalysis indicated lower drug levels from the previous day.

RESULTS

Women self-administered 20.4 out of 24 possible doses. Compared to the 1200 session, heart rate and blood pressure, but not subjective effects, were still significantly increased prior to the 1600 session. Nine women completed the outpatient phase, attending 98% of their appointments. Using the One-Half Rule, 56% of urines indicated no new cocaine or other drug use.

IMPLICATIONS

Although a US $40 voucher incentive for a "clean" urine was not sufficient to eliminate cocaine use, the possibility of earning the voucher was sufficient to maintain nearly perfect attendance.

Dissociation between subjective and behavioral responses after cocaine stimuli presentations

This study was designed to explore the relationship between craving and cocaine-seeking behavior with the use of both subjective and behavioral measures. Five males and five females who have used crack at least two times a week for 6 months, and who reported using 0.5 g of crack within 24 h on at least one occasion, participated in an inpatient study. Subjects underwent a total of four experimental sessions, during which they were exposed to either neutral (Neutral Stimuli Condition) or cocaine-related (Cocaine Stimuli Condition) external and internal stimuli. Subjects were exposed to each stimuli condition twice, on separate days, in randomized order. External stimuli comprised neutral or cocaine-related videotapes and paraphernalia, and the internal stimulus was either a 5-mg ('placebo') or 0.4 mg/kg delivery of cocaine. At baseline and after each stimulus exposure, subjects completed a composite cocaine craving questionnaire. Subjects next worked on concurrently-available fixed-ratio tasks either for tokens that could be exchanged for money ($2) or for tokens that were exchangeable for deliveries of cocaine (0.4 mg/kg). The results show that subjects reported significantly greater cocaine craving after exposure to cocaine-related vs. neutral stimuli, indicating that craving for cocaine can be successfully modeled in a laboratory setting. However, this change in subjective response did not predict drug-seeking behavior. The number of cocaine tokens earned following exposure to the cocaine-related vs neutral stimuli was similar. These results suggest that in a laboratory setting, craving may be unrelated to cocaine-seeking behavior in non-treatment-seeking cocaine users.

Gender differences in crack users who are research volunteers

This study compared gender differences in a non-treatment sample of crack cocaine users interested in participating in a research study on addiction. Data was collected from initial telephone screening interviews of women and men responding to cocaine research recruitment in a midwest urban environment over a two-year period. Female respondents (n = 88) were age- and race-matched with men interviewed over the same time period, for a total sample size of 176. Mean age of the female sample was 33 years and the majority were African-American. Basic demographics were similar for both genders. Respondents had first used cocaine at 24 years of age and currently smoked 2 g cocaine/day for 5 days/week, a rate higher than that found in many treatment samples. Women were found to have significantly higher rates of cigarette smoking, headaches and history of suicidal ideation, and significantly more women reported emergency room visits following crack use than did men. Equal numbers of men and women had been convicted of a crime (56%), with significantly fewer women reporting having committed a crime involving violence. Nearly all respondents (94%) reported that crack use had negative effects on their value systems, and significant numbers of both genders reported involvement with bartering crack and sex. Two-thirds of women able to become pregnant used no method of birth control and the use of barrier methods was infrequent. Forty-two percent admitted to using cocaine during pregnancy. These data indicate that while patterns of crack use per se do not differ between women and men in this sample, community outreach programs may benefit from focusing on other associated behaviors that do show differences between genders.