Udi E. Ghitza

Role of BDNF and GDNF in drug reward and relapse: a review.

Brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) are neurotrophic factors that are critical for the growth, survival, and differentiation of developing neurons. These neurotrophic factors also play important roles in the survival and function of adult neurons, learning and memory, and synaptic plasticity. Since the mid-1990s, investigators have studied the role of BDNF and GDNF in the behavioral effects of abused drugs and in the neuroadaptations induced by repeated exposure to drugs in the mesocorticolimbic dopamine system. Here, we review rodent studies on the role of BDNF and GDNF in drug reward, as assessed in the drug self-administration and the conditioned place preference procedures, and in drug relapse, as assessed in extinction and reinstatement procedures. Our main conclusion is that whether BDNF or GDNF would facilitate or inhibit drug-taking behaviors depends on the drug type, the brain site, the addiction phase (initiation, maintenance, or abstinence/relapse), and the time interval between site-specific BDNF or GDNF injections and the reward- and relapse-related behavioral assessments.

The anxiogenic drug yohimbine reinstates palatable food seeking in a rat relapse model: a role of CRF1 receptors.

The major problem in treating excessive eating is high rates of relapse to maladaptive eating habits during diet treatments; this relapse is often induced by stress or anxiety states. Preclinical studies have not explored this clinical problem. Here, we adapted a reinstatement model (commonly used to study relapse to abused drugs) to examine the role of stress and anxiety in relapse to palatable food seeking during dieting. Rats were placed on restricted diet (75–80% of daily standard food) and for 12 intermittent training days (9 h/day, every other day) lever-pressed for palatable food pellets (25% fat, 48% carbohydrate) under a fixed ratio 1 (20-s timeout) reinforcement schedule. Subsequently, the rats were given 10 daily extinction sessions during which lever presses were not reinforced, and were then injected with yohimbine (an α-2 adrenoceptor antagonist that induces stress and anxiety in humans and non-humans) or given a single food pellet to assess reinstatement of food seeking. The rats rapidly learned to lever press for the palatable pellets and across the training days the ratio of timeout nonreinforced lever presses to reinforced lever presses progressively increased more than three-fold, suggesting the development of compulsive eating behavior. After extinction, yohimbine injections and pellet priming reliably reinstated food seeking. The corticotropin-releasing factor1 (CRF1) receptor antagonist antalarmin attenuated the reinstatement induced by yohimbine, but not pellet priming. Antalarmin also reversed yohimbines anxiogenic effects in the social interaction test. These data suggest that CRF is involved in stress-induced relapse to palatable food seeking, and that CRF1 antagonists should be considered for the treatment of maladaptive eating habits.

Stress impairs reconsolidation of drug memory via glucocorticoid receptors in the basolateral amygdala.

Relapse to drug taking induced by exposure to cues associated with drugs of abuse is a major challenge to the treatment of drug addiction. Previous studies indicate that drug seeking can be inhibited by disrupting the reconsolidation of a drug-related memory. Stress plays an important role in modulating different stages of memory including reconsolidation, but its role in the reconsolidation of a drug-related memory has not been investigated. Here, we examined the effects of stress and corticosterone on reconsolidation of a drug-related memory using a conditioned place preference (CPP) procedure. We also determined the role of glucocorticoid receptors (GRs) in the basolateral amygdala (BLA) in modulating the effects of stress on reconsolidation of this memory. We found that rats acquired morphine CPP after conditioning, and that this CPP was inhibited by stress given immediately after re-exposure to a previously morphine-paired chamber (a reconsolidation procedure). The disruptive effect of stress on reconsolidation of morphine related memory was prevented by inhibition of corticosterone synthesis with metyrapone or BLA, but not central amygdala (CeA), injections of the glucocorticoid (GR) antagonist RU38486 [(11,17)-11-[4-(dimethylamino)phenyl]-17-hydroxy-17-(1-propynyl)estra-4,9-dien-3-one]. Finally, the effect of stress on drug related memory reconsolidation was mimicked by systemic injections of corticosterone or injections of RU28362 [11,17-dihydroxy-6-methyl-17-(1-propynyl)androsta-1,4,6-triene-3-one] (a GR agonist) into BLA, but not the CeA. These results show that stress blocks reconsolidation of a drug-related memory, and this effect is mediated by activation of GRs in the BLA.

The mGluR2/3 agonist LY379268 attenuates context- and discrete cue-induced reinstatement of sucrose seeking but not sucrose self-administration in rats.

We recently reported that systemic injections of the mGluR(2/3) agonist LY379268, which decreases evoked glutamate release, attenuate context- and discrete cue-induced reinstatement of heroin seeking, but not heroin self-administration. Here, we report that systemic injections of LY379268 attenuate context- and discrete cue-induced reinstatement of sucrose seeking, but not sucrose self-administration. These results suggest that similar neuronal mechanisms mediate cue-induced relapse to opiate- and palatable food seeking.

Internet-Delivered Treatment for Substance Abuse: A Multisite Randomized Controlled Trial

OBJECTIVE Computer-delivered interventions have the potential to improve access to quality addiction treatment care. The objective of this study was to evaluate the effectiveness of the Therapeutic Education System (TES), an Internet-delivered behavioral intervention that includes motivational incentives, as a clinician-extender in the treatment of substance use disorders. METHOD Adult men and women (N=507) entering 10 outpatient addiction treatment programs were randomly assigned to receive 12 weeks of either treatment as usual (N=252) or treatment as usual plus TES, with the intervention substituting for about 2 hours of standard care per week (N=255). TES consists of 62 computerized interactive modules covering skills for achieving and maintaining abstinence, plus prize-based motivational incentives contingent on abstinence and treatment adherence. Treatment as usual consisted of individual and group counseling at the participating programs. The primary outcome measures were abstinence from drugs and heavy drinking (measured by twice-weekly urine drug screens and self-report) and time to dropout from treatment. RESULTS Compared with patients in the treatment-as-usual group, those in the TES group had a lower dropout rate (hazard ratio=0.72, 95% CI=0.57, 0.92) and a greater abstinence rate (odds ratio=1.62, 95% CI=1.12, 2.35). This effect was more pronounced among patients who had a positive urine drug or breath alcohol screen at study entry (N=228) (odds ratio=2.18, 95% CI=1.30, 3.68). CONCLUSIONS Internet-delivered interventions such as TES have the potential to expand access and improve addiction treatment outcomes. Additional research is needed to assess effectiveness in non-specialty clinical settings and to differentiate the effects of the community reinforcement approach and contingency management components of TES.

Brain mu-opioid receptor binding predicts treatment outcome in cocaine-abusing outpatients

BACKGROUND Cocaine users not seeking treatment have increased regional brain mu-opioid receptor (mOR) binding that correlates with cocaine craving and tendency to relapse. In cocaine-abusing outpatients in treatment, the relationship of mOR binding and treatment outcome is unknown. METHODS We determined whether regional brain mOR binding before treatment correlates with outcome and compared it with standard clinical predictors of outcome. Twenty-five individuals seeking outpatient treatment for cocaine abuse or dependence (DSM-IV) received up to 12 weeks of cognitive-behavioral therapy and cocaine abstinence reinforcement, whereby each cocaine-free urine was reinforced with vouchers redeemable for goods. Regional brain mOR binding was measured before treatment using positron emission tomography with [¹¹C]]-carfentanil (a selective mOR agonist). Main outcome measures were: 1) overall percentage of urines positive for cocaine during first month of treatment; and 2) longest duration (weeks) of abstinence from cocaine during treatment, all verified by urine toxicology. RESULTS Elevated mOR binding in the medial frontal and middle frontal gyri before treatment correlated with greater cocaine use during treatment. Elevated mOR binding in the anterior cingulate, medial frontal, middle frontal, middle temporal, and sublobar insular gyri correlated with shorter duration of cocaine abstinence during treatment. Regional mOR binding contributed significant predictive power for treatment outcome beyond that of standard clinical variables such as baseline drug and alcohol use. CONCLUSIONS Elevated mOR binding in brain regions associated with reward sensitivity is a significant independent predictor of treatment outcome in cocaine-abusing outpatients, suggesting a key role for the brain endogenous opioid system in cocaine addiction.

Peptide YY3-36 Decreases Reinstatement of High-Fat Food Seeking during Dieting in a Rat Relapse Model

A major problem in treating obesity is high rates of relapse to maladaptive food-taking habits during dieting. This relapse is often provoked by acute re-exposure to palatable food, food-associated cues, or stress. We used a reinstatement model, commonly used to study relapse to abused drugs, to explore the effect of peptide YY3-36 (PYY3-36) on reinstatement of high-fat (35%, 45 mg pellets) food seeking induced by acute exposure to the pellets (pellet priming), a cue previously associated with pellet delivery (pellet cue), or yohimbine (2 mg/kg, a pharmacological stressor). Rats were placed on a restricted diet (16 g of chow per day) and lever-pressed for the pellets for 9–12 sessions (6 h/d, every 48 h); pellet delivery was paired with a tone–light cue. They were then given 10–20 extinction sessions wherein lever presses were not reinforced with the pellets and subsequently tested for reinstatement of food seeking. Systemic PYY3-36 injections (100–200 μg/kg) decreased pellet priming- and pellet cue-induced reinstatement of food seeking but not yohimbine-induced reinstatement. Arcuate nucleus (Arc) injections of PYY3-36 (0.4 μg per side) decreased pellet priming-induced reinstatement. The attenuation of pellet priming-induced reinstatement by systemic PYY3-36 was reversed by systemic (2 mg/kg) but not Arc (0.5 μg per side) injections of the Y2 receptor antagonist BIIE0246. Arc PYY3-36 injections did not decrease pellet cue-induced reinstatement. Finally, systemic PYY3-36 injections had minimal effects on ongoing food self-administration or heroin priming- or heroin cue-induced reinstatement of heroin seeking. These data identify an effect of systemic PYY3-36 on relapse to food seeking that is independent of Y2 receptor activation in Arc and suggest that PYY3-36 should be considered for the treatment of relapse to maladaptive food-taking habits during dieting.

Design and Methodological Considerations of an Effectiveness Trial of a Computer-assisted Intervention: An Example from the NIDA Clinical Trials Network

Computer-assisted interventions hold the promise of minimizing two problems that are ubiquitous in substance abuse treatment: the lack of ready access to treatment and the challenges to providing empirically-supported treatments. Reviews of research on computer-assisted treatments for mental health and substance abuse report promising findings, but study quality and methodological limitations remain an issue. In addition, relatively few computer-assisted treatments have been tested among illicit substance users. This manuscript describes the methodological considerations of a multi-site effectiveness trial conducted within the National Institute on Drug Abuses (NIDAs) National Drug Abuse Treatment Clinical Trials Network (CTN). The study is evaluating a web-based version of the Community Reinforcement Approach, in addition to prize-based contingency management, among 500 participants enrolled in 10 outpatient substance abuse treatment programs. Several potential effectiveness trial designs were considered and the rationale for the choice of design in this study is described. The study uses a randomized controlled design (with independent treatment arm allocation), intention-to-treat primary outcome analysis, biological markers for the primary outcome of abstinence, long-term follow-up assessments, precise measurement of intervention dose, and a cost-effectiveness analysis. Input from community providers during protocol development highlighted potential concerns and helped to address issues of practicality and feasibility. Collaboration between providers and investigators supports the utility of infrastructures that enhance research partnerships to facilitate effectiveness trials and dissemination of promising, technologically innovative treatments. Outcomes from this study will further the empirical knowledge base on the effectiveness and cost-effectiveness of computer-assisted treatment in clinical treatment settings.

Role of food-type in yohimbine- and pellet-priming-induced reinstatement of food-seeking

We have recently adapted a reinstatement model, commonly used to study relapse to drugs of abuse, to study the role of stress and anxiety in relapse to palatable food seeking [Ghitza UE, Gray SM, Epstein DH, Rice KC, Shaham Y. The anxiogenic drug yohimbine reinstates palatable food seeking in a rat relapse model: a role of CRF(1) receptors. Neuropsychopharmacology [in press]]. We found that the anxiogenic drug yohimbine, as well as pellet-priming, reinstate food seeking in food restricted rats previously trained to lever press for palatable food pellets (25% fat, 48% carbohydrate). Here, we studied the generality of the effect of yohimbine and pellet priming on reinstatement of food seeking by using three distinct pellet types: non-sucrose carbohydrate (NSC) (5.5% fat, 60% carbohydrate, 4.5% fiber), fiber (0% fat, 0% carbohydrate, 91% fiber) and sucrose (0% fat, 91% carbohydrate, 4% fiber). Rats were placed on a restricted diet (75-80% of daily standard food) and for 9-12 intermittent training days (9 h/day, every other day) lever-pressed for the food pellets under a fixed ratio-1 (20-s timeout) reinforcement schedule. Subsequently, the rats were given 9-10 daily extinction sessions during which lever-presses were not reinforced, and were then injected with yohimbine (0, 0.5, 1.0, 2.0 mg/kg, i.p.) or given a single food pellet to induce reinstatement of food seeking. Yohimbine reinstated food seeking previously reinforced by NSC and sucrose pellets, but had a minimal effect on food seeking in rats previously trained to lever press for fiber pellets. Pellet priming produced a greater degree of reinstatement of lever pressing in rats previously trained on NSC pellets than in rats trained on fiber or sucrose pellets. Results suggest that the magnitude of the effect of yohimbine and pellet priming on reinstatement of food seeking depends in part on the composition of the food pellets used during training.

Challenges and Opportunities for Integrating Preventive Substance-Use-Care Services in Primary Care through the Affordable Care Act

Undertreated or untreated substance use disorders (SUD) remain a pervasive, medically-harmful public health problem in the United States, particularly in medically underserved and low-income populations lacking access to appropriate treatment. The need for greater access to SUD treatment was expressed as policy in the Final Rule on standards related to essential health benefits, required to be covered through the 2010 Affordable Care Act (ACA) health insurance exchanges. SUD treatment services have been included as an essential health benefit, in a manner that complies with the Mental Health Parity and Addiction Equity Act (MHPAEA) of 2008. Consequently, with the ACA, a vast expansion of SUD-care services in primary care is looming. This commentary discusses challenges and opportunities under the ACA for equipping health care professionals with appropriate workforce training, infrastructure, and resources to support and guide science-based Screening, Brief Intervention, and Referral to Treatment (SBIRT) for SUD in primary care.