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

Endocannabinoids and related lipids linked to social exclusion in individuals with chronic non-medical prescription opioid use

Opioid-related overdose deaths are still on the rise in North America, emphasizing the need to better understand the underlying neurobiological mechanisms regarding the development of opioid use disorder (OUD). Recent evidence from preclinical and clinical studies indicate that the endocannabinoid system (ECS) may play a crucial role in stress and reward, both involved in the development and maintenance of substance use disorders. Animal models demonstrate a specific crosstalk between the ECS and the endogenous opioid system. However, translational studies in humans are scarce. Here, we investigated basal plasma levels of the endocannabinoids anandamide (AEA) and 2-arachidonoyglycerol (2-AG), and eight endocannabinoid-related lipids, including oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), as well as whole blood fatty acid amide hydrolase (FAAH) activity in chronic non-medical prescription opioid users (NMPOU; n = 21) compared to opioid-naïve healthy controls (n = 29) considering age, sex, and cannabis use as potential confounders. Additionally, the association of endocannabinoids and related lipids with the participants' response to experimentally induced social exclusion was examined. We found significantly elevated basal AEA, OEA, and PEA levels in NMPOU compared to controls, but no differences in FAAH activity, 2-AG, or other endocannabinoid-related lipids. Within NMPOU, higher AEA levels were associated with lower perception of social exclusion. Robust positive correlations within N-acylethanolamines (i.e., AEA, OEA, and PEA) indicate strong metabolic associations. Together with our recent findings of elevated basal 2-AG levels in dependent cocaine users, present results indicate substance-specific alterations of the ECS that may have implications in the search for novel therapeutic interventions for these populations.

Associations of psychoactive substances and steroid hormones in hair: Findings relevant to stress research from a large cohort of young adults

OBJECTIVE

Epidemiological studies increasingly use hair samples to assess people's cumulative exposure to steroid hormones, but how the use of different psychoactive substances may affect steroid hormone levels in hair is, so far, largely unknown. The current study addresses this gap by establishing the substance exposure correlates of cortisol, cortisone, and testosterone in hair, while also accounting for a number of relevant covariates.

METHOD

Data came from a large urban community-sample of young adults with a high prevalence of substance use (N = 1002, mean age=20.6 years, 50.2% female), who provided 3 cm of hair samples. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) quantified cortisol, cortisone, and testosterone, as well as delta-9-tetrahydrocannabinol (THC), 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy"), cocaine, several opioids, and their respective metabolites. Multiple linear regression models with covariates were used to predict steroid hormone levels from substance exposure in a four-step approach: In the full sample, low and high substance hair concentrations (median split) were first tested against no use for each substance individually (step 1) and for all substances together (step 2). Then, within the participants with any substance in hair only, the continuous hair concentration of each substance in pg/mg (step 3) and finally of all substances together, were regressed (step 4).

RESULTS

Low, high, and continuous levels of THC in hair were robustly associated with higher levels of cortisol (sig. in step 1 low THC: β = 0.29, p = .021; high THC: β = 0.42, p = .001; step 2: low THC: β = 0.27, p = 0.036, and high THC: β = 0.40, p = .004, and step 4: β = 0.12, p = .041). Participants with high MDMA levels had higher levels of cortisone without adjusting for other substances (step 1: β = 0.34, p = .026), but this effect was not significant in the other models. While high THC levels were associated with lower levels of testosterone in step 2 (β = -0.35, p = .018), MDMA concentration was positively related to testosterone concentration with and without adjusting for other substances (step 3: β = 0.24, p = .041; step 4: β = 0.17, 95%, p = .015) in male participants.

CONCLUSION

The use of psychoactive substances, especially of cannabis and ecstasy, should be considered in studies investigating steroid hormones in hair.

Repeated footshock stress induces an escalation of cocaine self-administration in male and female rats: Role of the cannabinoid receptor 1

Stress is a significant contributor to the development and progression of substance use disorders (SUDs) and is problematic as it is unavoidable in daily life. Therefore, it is important to understand the neurobiological mechanisms that underlie the influence of stress on drug use. We have previously developed a model to examine the contribution of stress to drug-related behavior by administering a stressor, electric footshock stress, daily at the time of cocaine self-administration in rats resulting in an escalation of cocaine intake. This stress-induced escalation of cocaine intake involves neurobiological mediators of stress and reward such as cannabinoid signaling. However, all of this work has been conducted in male rats. Here we test the hypothesis that repeated daily stress can produce an escalation of cocaine in both male and female rats. We further hypothesize that cannabinoid receptor 1 (CB1R) signaling is recruited by repeated stress to influence cocaine intake in both male and female rats. Male and female Sprague-Dawley rats self-administered cocaine (0.5 mg/kg/inf, i.v.) during a modified short-access paradigm wherein the 2-hr access was separated into 4-30 min self-administration blocks separated by 4-5 min drug free period. Footshock stress produced a significant escalation of cocaine intake similarly in both male and female rats. Female stress-escalated rats did display greater time-out non-reinforced responding and greater "front-loading" behavior. In males, systemic administration of a CB1R inverse agonist/antagonist Rimonabant only attenuated cocaine intake in rats with a history of combined repeated stress and cocaine self-administration. However, in females, Rimonabant attenuated cocaine intake in the no stress control group but only at the highest dose of Rimonabant (3 mg/kg, i.p.) suggesting that females show a greater sensitivity to CB1R antagonism. However, female rats with a history of stress showed even greater sensitivity to CB1R antagonism as both doses of Rimonabant (1, 3 mg/kg) attenuated cocaine intake in stress-escalated rats similar to males. Altogether these data demonstrate that stress can produce significant changes in cocaine self-administration and suggests that repeated stress at the time of cocaine self-administration recruits CB1Rs to regulate cocaine-taking behavior across sexes.