Effects of Adolescent Cannabinoid Self-Administration in Rats on Addiction-Related Behaviors and Working Memory

Working Memory Performance Predicts, but Does Not Reduce, Cocaine and Cannabinoid Seeking in Adult Male Rats

BACKGROUND

Cognitive deficits reflecting impaired executive function are commonly associated with psychiatric disorders, including substance use. Cognitive training is proposed to improve treatment outcomes for these disorders by promoting neuroplasticity within the prefrontal cortex, enhancing executive control, and mitigating cognitive decline due to drug use. Additionally, brain derived neurotrophic factor (BDNF) can facilitate plasticity in the prefrontal cortex and reduce drug-seeking behaviors. We investigated whether working memory training could elevate BDNF levels in the prefrontal cortex and if this training would predict or protect against cocaine or cannabinoid seeking.

METHODS

Adult male rats were trained to perform a "simple" or "complex" version of a delayed-match-to-sample working memory task. Rats then self-administered cocaine or the synthetic cannabinoid WIN55,212-2 and were tested for cued drug seeking during abstinence. Tissue from the prefrontal cortex and dorsal hippocampus was analyzed for BDNF protein expression.

RESULTS

Training on the working memory task enhanced endogenous BDNF protein levels in the prelimbic prefrontal cortex but not the dorsal hippocampus. Working memory training did not impact self-administration of either drug but predicted the extent of WIN self-administration and cocaine seeking during abstinence.

CONCLUSIONS

These results suggest that working memory training promotes endogenous BDNF but does not alter drug-seeking or drug-taking behavior. However, individual differences in cognitive performance before drug exposure may predict vulnerability to future drug use.

Adolescent THC impacts on mPFC dopamine-mediated cognitive processes in male and female rats

Rationale

Adolescent cannabis use is linked to later-life changes in cognition, learning, and memory. Rodent experimental studies suggest Δ9-tetrahydrocannabinol (THC) influences development of circuits underlying these processes, especially in the prefrontal cortex, which matures during adolescence.

Objective

We determined how 14 daily THC injections (5mg/kg) during adolescence persistently impacts medial prefrontal cortex (mPFC) dopamine-dependent cognition.

Methods

In adult Long Evans rats treated as adolescents with THC (AdoTHC), we quantify performance on two mPFC dopamine-dependent reward-based tasks-strategy set shifting and probabilistic discounting. We also determined how acute dopamine augmentation with amphetamine (0, 0.25, 0.5 mg/kg), or specific chemogenetic stimulation of ventral tegmental area (VTA) dopamine neurons and their projections to mPFC impacts probabilistic discounting.

Results

AdoTHC sex-dependently impacts acquisition of cue-guided instrumental reward seeking, but has minimal effects on set-shifting or probabilistic discounting in either sex. When we challenged dopamine circuits acutely with amphetamine during probabilistic discounting, we found reduced discounting of improbable reward options, with AdoTHC rats being more sensitive to these effects than controls. In contrast, neither acute chemogenetic stimulation of VTA dopamine neurons nor pathway-specific chemogenetic stimulation of their projection to mPFC impacted probabilistic discounting in control rats, although stimulation of this cortical dopamine projection slightly disrupted choices in AdoTHC rats.

Conclusions

These studies confirm a marked specificity in the cognitive processes impacted by AdoTHC exposure. They also suggest that some persistent AdoTHC effects may alter amphetamine-induced cognitive changes in a manner independent of VTA dopamine neurons or their projections to mPFC.

Working memory performance predicts, but does not reduce, cocaine- and cannabinoid-seeking in adult male rats

Background

Cognitive deficits reflecting impaired executive function are commonly associated with psychiatric disorders, including substance use. Cognitive training is proposed to improve treatment outcomes for these disorders by promoting neuroplasticity within the prefrontal cortex, enhancing executive control, and mitigating cognitive decline due to drug use. Additionally, brain derived neurotrophic factor (BDNF) can facilitate plasticity in the prefrontal cortex and reduce drug-seeking behaviors. We investigated whether working memory training could elevate BDNF levels in the prefrontal cortex and if this training would predict or protect against cocaine or cannabinoid seeking.

Methods

Adult male rats were trained to perform a 'simple' or 'complex' version of a delayed- match-to-sample working memory task. Rats then self-administered cocaine or the synthetic cannabinoid WIN55,212-2 and were tested for cued drug-seeking during abstinence. Tissue from the prefrontal cortex and dorsal hippocampus was analyzed for BDNF protein expression.

Results

Training on the working memory task enhanced endogenous BDNF protein levels in the prelimbic prefrontal cortex but not the dorsal hippocampus. Working memory training did not impact self-administration of either drug but predicted the extent of WIN self-administration and cocaine seeking during abstinence.

Conclusions

These results suggest that working memory training promotes endogenous BDNF but does not alter drug-seeking or drug-taking behavior. However, individual differences in cognitive performance prior to drug exposure may predict vulnerability to future drug use.

Age-dependent memory impairment induced by co-exposure to nicotine and a synthetic cannabinoid in mice

Co-use of marijuana and tobacco products is the second most common drug combination among adolescents. Nicotine (NIC) and cannabinoid use during adolescence induce similar detrimental changes, raising the hypothesis that simultaneous exposure could result in even more severe outcomes. Thus, we investigated whether the co-exposure to NIC and the synthetic cannabinoid WIN 55,212-2 (WIN) in adolescent mice causes behavioral outcomes different from those observed after exposure to a single drug. Male Swiss mice were exposed twice daily to NIC, WIN, or NIC + WIN during adolescence (PND28-47) or adulthood (PND70-89). Drug combination led to a greater reduction in weight gain in adolescent mice, while NIC-induced weight loss was observed in adults. During administration, NIC provoked hypothermia, and WIN produced hyperlocomotion in adolescent and adult mice. Animals exposed to NIC + WIN presented a profile of changes similar to those exposed to NIC. After drug exposure, changes in locomotion, thigmotaxis, social preference, prepulse inhibition, and working and recognition memory were evaluated. Adolescent but not adult mice exposed to NIC showed withdrawal-related hyperlocomotion unaffected by WIN co-administration. An age-specific impairment in object recognition memory was induced only by drug co-exposure during adolescence, which resolved spontaneously before reaching early adulthood. A transient decrease in hippocampal α7 nAChR subunit and CB1 receptor mRNA levels was induced by NIC exposure, which may be involved but is not enough to explain the memory impairment. Our work confirms the potential of NIC and cannabinoids association to aggravate some of the individual drug effects during critical neurodevelopmental periods.

Impact of Adolescent Cannabis Use on Neurocognitive and Brain Development

Research examining associations between frequent cannabis use in adolescence and brain-behavior outcomes has increased substantially over the past 2 decades. This review attempts to synthesize the state of evidence in this area of research while acknowledging challenges in interpretation. Although there is converging evidence that ongoing, frequent cannabis use in adolescence is associated with small reductions in cognitive functioning, there is still significant debate regarding the persistence of reductions after a period of abstinence. Similarly, there is controversy regarding the replicability of structural and functional neuroimaging findings related to frequent cannabis use in adolescence. Larger studies with informative designs are needed.

Consequences of adolescent drug use

Substance use in adolescence is a known risk factor for the development of neuropsychiatric and substance use disorders in adulthood. This is in part due to the fact that critical aspects of brain development occur during adolescence, which can be altered by drug use. Despite concerted efforts to educate youth about the potential negative consequences of substance use, initiation remains common amongst adolescents world-wide. Additionally, though there has been substantial research on the topic, many questions remain about the predictors and the consequences of adolescent drug use. In the following review, we will highlight some of the most recent literature on the neurobiological and behavioral effects of adolescent drug use in rodents, non-human primates, and humans, with a specific focus on alcohol, cannabis, nicotine, and the interactions between these substances. Overall, consumption of these substances during adolescence can produce long-lasting changes across a variety of structures and networks which can have enduring effects on behavior, emotion, and cognition.

Nicotine Enhances Intravenous Self-administration of Cannabinoids in Adult Rats

INTRODUCTION

Nicotine and cannabis are commonly used together, yet few studies have investigated the effects of concurrent administration. Nicotine exhibits reinforcement enhancing effects by promoting the reinforcing properties of stimuli including other drugs. As many studies of this effect used non-contingent nicotine, we implemented a dual-self-administration model where rats have simultaneous access to two drugs and choose which to self-administer throughout a session. Here, we investigated the effect of self-administered or non-contingently delivered nicotine on cannabinoid self-administration.

METHODS

Adult male rats were allowed to self-administer the synthetic cannabinoid WIN 55,212-2 (WIN) intravenously, with or without subcutaneous nicotine injections before each session. A separate group of animals were allowed to self-administer WIN, nicotine, or saline using a dual-catheter procedure, where each solution was infused independently and associated with a separate operant response. A third group of male and female rats were allowed to self-administer delta-9-tetrahydrocannabinol (THC) with or without pre-session injections of nicotine.

RESULTS

Nicotine injections increased self-administration of WIN and THC. During dual self-administration, nicotine availability increased saline and WIN infusions but nicotine intake was not changed by WIN or saline availability. Rats preferred nicotine over saline, but preferred nicotine and WIN equally when both were available. The effect of nicotine on cannabinoid self-administration was acute and reversible when nicotine was no longer present.

CONCLUSIONS

These results expand our understanding of the ability of nicotine to enhance reinforcement of other drugs and suggest that co-use of nicotine and cannabinoids promotes cannabinoid use beyond what would be taken alone.

IMPLICATIONS

This study utilizes a dual intravenous self-administration model to investigate the ability of nicotine to enhance cannabinoid intake. Our results demonstrate that the reinforcement enhancing properties of nicotine on drug use extend to include cannabinoids, but that this effect occurs specifically when nicotine is administered alongside the cannabinoid. Interestingly, cannabinoid use did not promote nicotine intake, suggesting this mechanism of reinforcement is specific to nicotine.

Impact of Adolescent Cannabis Use on Neurocognitive and Brain Development

Research examining associations between frequent cannabis use in adolescence and brain-behavior outcomes has increased substantially over the past 2 decades. This review attempts to synthesize the state of evidence in this area of research while acknowledging challenges in interpretation. Although there is converging evidence that ongoing, frequent cannabis use in adolescence is associated with small reductions in cognitive functioning, there is still significant debate regarding the persistence of reductions after a period of abstinence. Similarly, there is controversy regarding the replicability of structural and functional neuroimaging findings related to frequent cannabis use in adolescence. Larger studies with informative designs are needed.

Unexpected short- and long-term effects of chronic adolescent HU-210 exposure on emotional behavior

Chronic adolescent cannabinoid receptor agonist exposure has been shown to lead to persistent increases in depressive-like behaviors. This has been a key obstacle to the development of cannabinoid-based therapeutics. However, most of the published work has been performed with only three compounds, namely Δ9-tetrahydrocannabinol, CP55,940 and WIN55,212-2. Hypothesizing that different compounds may lead to distinct outcomes, we herein used the highly potent CB₁R/CB₂R full agonist HU-210, and first aimed at replicating cannabinoid-induced long-lasting effects, by exposing adolescent female Sprague-Dawley rats to increasing doses of HU-210, for 11 days and testing them at adulthood, after a 30-day drug washout. Surprisingly, HU-210 did not significantly impact adult anxious- or depressive-like behaviors. We then tested whether chronic adolescent HU-210 treatment resulted in short-term (24h) alterations in depressive-like behavior. Remarkably, HU-210 treatment simultaneously induced marked antidepressant- and prodepressant-like responses, in the modified forced swim (mFST) and sucrose preference tests (SPT), respectively. Hypothesizing that mFST results were a misleading artifact of HU-210-induced behavioral hyperreactivity to stress, we assessed plasmatic noradrenaline and corticosterone levels, under basal conditions and following an acute swim-stress episode. Notably, we found that while HU-210 did not alter basal noradrenaline or corticosterone levels, it greatly augmented the stress-induced increase in both. Our results show that, contrary to previously studied cannabinoid receptor agonists, HU-210 does not induce persisting depressive-like alterations, despite inducing marked short-term increases in stress-induced reactivity. By showing that not all cannabinoid receptor agonists may induce long-term negative effects, these results hold significant relevance for the development of cannabinoid-based therapeutics.

Endocannabinoid system contributions to sex-specific adolescent neurodevelopment

With an increasing number of countries and states adopting legislation permitting the use of cannabis for medical purposes, there is a growing interest among health and research professionals into the system through which cannabinoids principally act, the endocannabinoid system (ECS). Much of the seminal research into the ECS dates back only 30 years and, although there has been tremendous development within the field during this time, many questions remain. More recently, investigations have emerged examining the contributions of the ECS to normative development and the effect of altering this system during important critical periods. One such period is adolescence, a unique period during which brain and behaviours are maturing and reorganizing in preparation for adulthood, including shifts in endocannabinoid biology. The purpose of this review is to discuss findings to date regarding the maturation of the ECS during adolescence and the consequences of manipulations of the ECS during this period to normative neurodevelopmental processes, as well as highlight sex differences in ECS function, important technical considerations, and future directions. Because most of what we know is derived from preclinical studies on rodents, we provide relevant background of this model and some commentary on the translational relevance of the research in this area.

Dos(e)Age: Role of Dose and Age in the Long-Term Effect of Cannabinoids on Cognition

Cannabis is still the most widely used illicit drug around the world. While its use has always been prevalent among adolescents, recent evidence suggests that its consumption is also increasing among other population groups, such as pregnant women and aged people. Given the known impact of cannabis on brain development and behavior, it is important to dissect the possible long-term impact of its use across different age groups, especially on measures of cognitive performance. Animal models of cannabinoid exposure have represented a fundamental tool to characterize the long-lasting consequences of cannabinoids on cognitive performance and helped to identify possible factors that could modulate cannabinoids effects in the long term, such as the age of exposure and doses administered. This scoping review was systematically conducted using PubMed and includes papers published from 2015 to December 2021 that examined the effects of cannabinoids, either natural or synthetic, on cognitive performance in animal models where exposure occurred in the prenatal period, during adolescence, or in older animals. Overall, available data clearly point to a crucial role of age in determining the long-term effect of cannabinoid on cognition, highlighting possible detrimental consequences during brain development (prenatal and adolescent exposure) and beneficial outcomes in old age. In contrast, despite the recent advances in the field, it appears difficult to clearly establish a possible role of dosage in the effects of cannabinoids on cognition, especially when the adolescent period is taken into account.

The stoned age: Sex differences in the effects of adolescent cannabinoid exposure on prefrontal cortex structure and function in animal models

Cannabis is the most used drug during adolescence, which is a period of enhanced cortical plasticity and synaptic remodeling that supports behavioral, cognitive, and emotional maturity. In this chapter, we review preclinical studies indicating that adolescent exposure to cannabinoids has lasting effects on the morphology and synaptic organization of the prefrontal cortex and associated circuitry, which may lead to cognitive dysfunction later in life. Additionally, we reviewed sex differences in the effects of adolescent cannabinoid exposure with a focus on brain systems that support cognitive functioning. The body of evidence indicates enduring sex-specific effects in behavior and organization of corticolimbic circuitry, which appears to be influenced by species, strain, drug, route of administration, and window/pattern of drug exposure. Caution should be exercised when extrapolating these results to humans. Adopting models that more closely resemble human cannabis use will provide more translationally relevant data concerning the long-term effects of cannabis use on the adolescent brain.

Animal Models of the Behavioral Symptoms of Substance Use Disorders

To more effectively manage substance use disorders, it is imperative to understand the neural, genetic, and psychological underpinnings of addictive behavior. To contribute to this understanding, considerable efforts have been made to develop translational animal models that capture key behavioral characteristics of addiction on the basis of DSM5 criteria of substance use disorders. In this review, we summarize empirical evidence for the occurrence of addiction-like behavior in animals. These symptoms include escalation of drug use, neurocognitive deficits, resistance to extinction, exaggerated motivation for drugs, increased reinstatement of drug seeking after extinction, preference for drugs over nondrug rewards, and resistance to punishment. The occurrence of addiction-like behavior in laboratory animals has opened the opportunity to investigate the neural, genetic, and psychological background of key aspects of addiction, which may ultimately contribute to the prevention and treatment of substance use disorders.

Effects of repeated adolescent exposure to cannabis smoke on cognitive outcomes in adulthood

BACKGROUND

Cannabis (marijuana) is the most widely used illicit drug in the USA, and consumption among adolescents is rising. Some animal studies show that adolescent exposure to delta 9-tetrahydrocannabinol or synthetic cannabinoid receptor 1 agonists causes alterations in affect and cognition that can persist into adulthood. It is less clear, however, whether similar alterations result from exposure to cannabis via smoke inhalation, which remains the most frequent route of administration in humans.

AIMS

To begin to address these questions, a rat model was used to determine how cannabis smoke exposure during adolescence affects behavioral and cognitive outcomes in adulthood.

METHODS

Adolescent male Long-Evans rats were assigned to clean air, placebo smoke, or cannabis smoke groups. Clean air or smoke exposure sessions were conducted daily during adolescence (from P29-P49 days of age ) for a total of 21 days, and behavioral testing began on P70.

RESULTS

Compared to clean air and placebo smoke conditions, cannabis smoke significantly attenuated the normal developmental increase in body weight, but had no effects on several measures of either affect/motivation (open field activity, elevated plus maze, instrumental responding under a progressive ratio schedule of reinforcement) or cognition (set shifting, reversal learning, intertemporal choice). Surprisingly, however, in comparison to clean air controls rats exposed to either cannabis or placebo smoke in adolescence exhibited enhanced performance on a delayed response working memory task.

CONCLUSIONS

These findings are consistent with a growing body of evidence for limited long-term adverse cognitive and affective consequences of adolescent exposure to relatively low levels of cannabinoids.

Abuse Potential of Synthetic Cannabinoids: AM-1248, CB-13, and PB-22

Currently, the expanding recreational use of synthetic cannabinoids (SCBs) threatens public health. SCBs produce psychoactive effects similar to those of tetrahydrocannabinol, the main component of cannabis, and additionally induce unexpected pharmacological side effects. SCBs are falsely advertised as legal and safe, but in reality, SCB abuse has been reported to cause acute intoxication and addictive disorders. However, because of the lack of scientific evidence to elucidate their dangerous pharmacological effects, SCBs are weakly regulated and continue to circulate in illegal drug markets. In the present study, the intravenous self-administration (IVSA) paradigm was used to evaluate the abuse potential of three SCBs (AM-1248, CB-13, and PB-22) in rats. All three SCBs maintained IVSA with a large number of infusions and active lever presses, demonstrating their reinforcing effects. The increase of active lever presses was particularly significant during the early IVSA sessions, indicating the reinforcementenhancing effects of the SCBs (AM-1248 and CB-13). The number of inactive lever presses was significantly higher in the SCB groups (AM-1248 and CB-13) than that in the vehicle group, indicating their impulsive effects. In summary, these results demonstrated that SCBs have distinct pharmacological properties and abuse potential.

Cannabinoid-Induced Conditioned Place Preference, Intravenous Self-Administration, and Behavioral Stimulation Influenced by Ghrelin Receptor Antagonism in Rats

Cannabis/cannabinoids are widely used for recreational and therapy purposes, but their risks are largely disregarded. However, cannabinoid-associated use disorders and dependence are alarmingly increasing and an effective treatment is lacking. Recently, the growth hormone secretagogue receptor (GHSR1A) antagonism was proposed as a promising mechanism for drug addiction therapy. However, the role of GHS-R1A and its endogenous ligand ghrelin in cannabinoid abuse remains unclear. Therefore, the aim of our study was to investigate whether the GHS-R1A antagonist JMV2959 could reduce the tetrahydrocannabinol (THC)-induced conditioned place preference (CPP) and behavioral stimulation, the WIN55,212-2 intravenous self-administration (IVSA), and the tendency to relapse. Following an ongoing WIN55,212-2 self-administration, JMV2959 3 mg/kg was administered intraperitoneally 20 min before three consequent daily 120-min IVSA sessions under a fixed ratio FR1, which significantly reduced the number of the active lever-pressing, the number of infusions, and the cannabinoid intake. Pretreatment with JMV2959 suggested reduction of the WIN55,212-2-seeking/relapse-like behavior tested in rats on the twelfth day of the forced abstinence period. On the contrary, pretreatment with ghrelin significantly increased the cannabinoid IVSA as well as enhanced the relapse-like behavior. Co-administration of ghrelin with JMV2959 abolished/reduced the significant efficacy of the GHS-R1A antagonist in the cannabinoid IVSA. Pretreatment with JMV2959 significantly and dose-dependently reduced the manifestation of THC-induced CPP. The THC-CPP development was reduced after the simultaneous administration of JMV2959 with THC during conditioning. JMV2959 also significantly reduced the THC-induced behavioral stimulation in the LABORAS cage. Our findings suggest that GHS-R1A importantly participates in the rewarding/reinforcing effects of cannabinoids.

Early-life stress exacerbates the effects of WIN55,212-2 and modulates the cannabinoid receptor type 1 expression

Early-life stress induces an abnormal brain development and increases the risk of psychiatric diseases, including depression, anxiety and substance use disorders. We have developed a reliable model for maternal neglect, named maternal separation with early weaning (MSEW) in CD1 mice. In the present study, we evaluated the long-term effects on anxiety-like behaviours, nociception as well as the Iba1-positive microglial cells in this model in comparison to standard nest (SN) mice. Moreover, we investigated whether MSEW alters the cannabinoid agonist WIN55,212-2 effects regarding reward, spatial and emotional memories, tolerance to different cannabinoid responses, and physical dependence. Adult male offspring of MSEW group showed impaired responses on spatial and emotional memories after a repeated WIN55,212-2 treatment. These behavioural impairments were associated with an increase in basolateral amygdala and hippocampal CB1-expressing fibres and higher number of CB1-containing cells in cerebellum. Additionally, MSEW promotes a higher number of Iba1-positive microglial cells in basolateral amygdala and cerebellum. As for the cannabinoid-induced effects, rearing conditions did not influence the rewarding effects of WIN55,212-2 in the conditioned place preference paradigm. However, MSEW mice showed a delay in the development of tolerance to the cannabinoid effects. Moreover, CB1-positive fibres were reduced in limbic areas in MSEW mice after cannabinoid withdrawal precipitated with the CB1 antagonist SR141617A. These findings support that early-life stress promotes behavioural and molecular changes in the sensitivity to cannabinoids, which are mediated by alterations in CB1 signalling in limbic areas and it induces an increased Iba1-microglial marker which could interfere in emotional memories formation.

Disentangling the lasting effects of adolescent cannabinoid exposure

Cannabis is the most widely used illicit substance among adolescents, and adolescent cannabis use is associated with various neurocognitive deficits that can extend into adulthood. A growing body of evidence supports the hypothesis that adolescence encompasses a vulnerable period of development where exposure to exogenous cannabinoids can alter the normative trajectory of brain maturation. In this review, we present an overview of studies of human and rodent models that examine lasting effects of adolescent exposure. We include evidence from meta-analyses, longitudinal, or cross-sectional studies in humans that consider age of onset as a factor that contributes to the behavioral dysregulation and altered structural or functional development in cannabis users. We also discuss evidence from preclinical rodent models utilizing well-characterized or innovative routes of exposure, investigating the effects of dose and timing to produce behavioral deficits or alterations on a neuronal and behavioral level. Multiple studies from both humans and animals provide contrasting results regarding the magnitude of residual effects. Combined evidence suggests that exposure to psychoactive cannabinoids during adolescence has the potential to produce subtle, but lasting, alterations in neurobiology and behavior.

Dorsolateral striatum dopamine-dependent cocaine seeking is resistant to pavlovian cue extinction in male and female rats

Cue exposure therapy (CET) reduces craving induced by drug-associated cues in individuals with substance use disorders. A preclinical model of CET, cue extinction, similarly reduces cue-induced cocaine seeking in rodent self-administration models; however, those models may not capture the habitual or compulsive aspects of drug use. Thus, the effectiveness of cue extinction was tested in male and female rats trained to self-administer cocaine using second-order (SO) or fixed-ratio (FR) schedules of reinforcement to facilitate dorsolateral striatum (DLS) dopamine-dependent or -independent response strategies, respectively. Cue extinction significantly reduced drug seeking in FR-trained rats, replicating prior results, but was ineffective in SO-trained rats. SO-trained rats also showed increased indices of glutamate signaling in the DLS relative to FR-trained rats, despite comparable levels of cocaine intake. Furthermore, in SO-trained rats, antagonism of AMPA receptors in the DLS rescued the efficacy of cue extinction to reduce drug seeking. Finally, the effectiveness of cue extinction was also revealed in SO-trained rats when they were taught to perform a new, non-habitual response for cocaine cue presentation. Overall, our findings indicate that habit-like drug seeking leads to plasticity in the DLS and behavior that is resistant to cue extinction, but that the effects of cue extinction are restored when DLS glutamatergic signaling is blocked. These results have implications for the effectiveness of clinical cue exposure therapy.

Intravenous self-administration of delta-9-THC in adolescent rats produces long-lasting alterations in behavior and receptor protein expression

RATIONALE

Initial exposure to cannabinoids, including Δ-9-tetrahydrocannabinol (THC), often occurs during adolescence. Considerable neurodevelopmental alterations occur throughout adolescence, and the environmental insult posed by exogenous cannabinoid exposure may alter natural developmental trajectories. Multiple studies suggest that long-lasting deficits in cognitive function occur as a result of adolescent cannabis use, but considerable variability exists in the magnitude of these effects.

OBJECTIVES

We sought to establish a novel procedure for achieving intravenous THC self-administration in adolescent rats in order to determine if volitional THC intake in adolescence produced indices of addiction-related behavior, altered working memory performance in adulthood, or altered the expression of proteins associated with these behaviors across several brain regions.

METHODS

Male and female adolescent rats learned to operantly self-administer escalating doses of THC intravenously from PD 32-51. Upon reaching adulthood they were tested in abstinence for cued reinstatement of THC-seeking and working memory performance on a delayed-match-to-sample task. In a separate cohort, glutamatergic, GABAergic, and cannabinoid receptor protein expression was measured in multiple brain regions.

RESULTS

Both male and female adolescents self-administered THC and exhibited cue-induced lever pressing throughout abstinence. THC-exposed males exhibited slightly enhanced working memory performance in adulthood, and better performance positively correlated with total THC self-administered during adolescence. Adolescent THC-exposed rats exhibited reductions in CB1, GABA, and glutamate receptor protein, primarily in the prefrontal cortex, dorsal hippocampus, and ventral tegmental area.

CONCLUSIONS

These results suggest that THC exposure at self-administered doses can produce moderate behavioral and molecular alterations, including sex-dependent effects on working memory performance in adulthood.

Adolescent Cannabinoid and Nicotine Exposure Differentially Alters Adult Nicotine Self-Administration in Males and Females

INTRODUCTION

During adolescence, exposure to nicotine or cannabis independently induces effects on neuromaturation and later cognitive function. However, the potential effect of both drugs under co-use conditions has become of increasing concern given the prevalence of e-cigarettes, legalization of cannabis, and availability of synthetic "spice" cannabinoid agonists.

AIMS AND METHODS

The current studies investigated the effects of exposure to a cannabinoid receptor agonist (WIN55,212-2) and/or nicotine over a discrete time period in mid-adolescence on later intravenous nicotine self-administration in adult male and female mice. We further examined whether cannabinoid agonist administration in adulthood would alter nicotine reinforcement, with either acute or chronic pairing across 7 days.

RESULTS

We found that adult males exhibited increased nicotine self-administration at a lower, rewarding nicotine dose following adolescent cannabinoid exposure, either alone or with nicotine coadministration. In contrast, adult females demonstrated an opposing effect in which adolescent cannabinoid and nicotine coexposure resulted in decreased nicotine intake compared with the nicotine only and control groups. Furthermore, after maintaining nicotine self-administration across sessions, pretreatment with a low dose of the cannabinoid agonist decreased nicotine intake in both male and female control mice, and this lowering effect was evidenced after both acute and chronic treatment. However, the cannabinoid agonist was ineffective in altering nicotine intake in mice previously exposed to nicotine, cannabinoid agonist, or both during adolescence.

CONCLUSIONS

These data provide evidence that adolescent drug exposure can alter later nicotine reinforcement in a sex-specific manner and can further modulate the effectiveness of interventions in reducing nicotine intake during adulthood.

IMPLICATIONS

These studies demonstrate a significant impact of nicotine, cannabinoids, or coexposure on developmental processes during adolescence. Differential effects were observed within each sex, with opposing results found for cannabinoid exposure on nicotine intake in males and females. Intriguingly, we also evidenced resistance to the lowering effects of a cannabinoid agonist on nicotine intake in adulthood based on adolescent drug exposure. Thus, these findings have important implications for our understanding of the impact of nicotine and cannabinoids (eg, Δ9-tetrahydrocannabinol (THC) and synthetic "spice" cannabinoids) during development, with further implications for the effectiveness of therapeutic interventions based on prior drug exposure in youth.

Comparative analysis of the modulation of perineuronal nets in the prefrontal cortex of rats during protracted withdrawal from cocaine, heroin and sucrose self-administration

Relapse into drug use is a significant problem for people recovering from addiction. The ability that conditioned cues have to reinstate and reinvigorate drug-seeking is potentiated over time (incubation of seeking), posing an additional difficulty for maintaining abstinence. While the prefrontal cortex has been involved in the incubation phenomenon and the extracellular matrix, perineuronal nets (PNNs) in particular, may play a vital role in brain plasticity associated to drug relapse, there are no comparative analyses between different drug classes and natural reinforcers. Here, we compare the effects of early (1 day) and protracted (30 days) withdrawal from to cocaine, heroin and sucrose self-administration on the total density and density per intensity range of PNNs of different territories of the prefrontal cortex of male Lewis rats. Our results show that cocaine self-administration increases the density of PNNs in the dorsal prelimbic, infralimbic and ventral orbitofrontal cortices, while protracted withdrawal reversesthis effect in the dorsal prelimbic cortex. Also, heroin self-administration increases the density of PNNs in the infralimbic cortex and ventral orbitofrontal cortices, but this effect is lost after 30 days of withdrawal in the infralimbic cortex. Finally, the self-administration of sucrose-sweetened water or the protracted withdrawal from this powerful reinforcer does not affect any of the PNN parameters analysed. Our results show that two different drugs of abuse (but not a natural reward) with specific pharmacological and physiological actions, differentially modulate PNNs in specific areas of the rodent prefrontal cortex with potential implications for the incubation of seeking phenomenon.

Neural substrates underlying the negative impact of cannabinoid exposure during adolescence

As cannabinoid use among the adolescent population becomes widespread with recent legalizations, understanding more about its effects on the developing brain becomes increasingly important. Adolescent cannabinoid use has been shown to elicit both short and long lasting effects on cortical function, in part due to its impact on maturing brain regions including the prefrontal cortex and associated inputs. This paper provides an overview of current state of knowledge on the lasting impact of repeated cannabinoid exposure on behavior and associated neural circuits in adolescents compared to other age groups. Data obtained from human and rodent literature are integrated to discuss potential neural mechanisms underpinning the enduring negative impact of cannabinoid exposure during this sensitive period of brain development.

THC exposure during adolescence does not modify nicotine reinforcing effects and relapse in adult male mice

RATIONALE

Cannabis use is typically initiated during adolescence, and different studies suggest that adolescent cannabinoid exposure may increase the risk for drug addiction in adulthood.

OBJECTIVES

This study investigated the effects of adolescent exposure to the main psychoactive component of cannabis, ∆⁹-tetrahydrocannabinol (THC), in the reinforcing properties of nicotine in adult male mice. Possible alterations in relapse to nicotine-seeking behaviour in adult animals due to THC adolescent exposure were also evaluated.

METHODS

Adolescent mice were exposed to escalating doses of THC from PND35 to PND49. When mice reached adulthood (PND70), surgical procedures were applied for further behavioural evaluation. Nicotine self-administration sessions were conducted consecutively for 10 days. Following extinction, mice were tested for cue- and stress-induced reinstatement of nicotine-seeking behaviour.

RESULTS

Adolescent THC treatment did not modify acquisition and extinction of nicotine self-administration in adulthood. Moreover, THC exposure did not alter relapse to nicotine seeking induced by stress or nicotine-associated cues.

CONCLUSIONS

These results suggest that a history of exposure to THC during adolescence under these particular conditions does not modify the reinforcing effects and seeking behaviour of nicotine in the adult period.

A Systematic Review of Human Neuroimaging Evidence of Memory-Related Functional Alterations Associated with Cannabis Use Complemented with Preclinical and Human Evidence of Memory Performance Alterations

Cannabis has been associated with deficits in memory performance. However, the neural correlates that may underpin impairments remain unclear. We carried out a systematic review of functional magnetic resonance imaging (fMRI) studies investigating brain functional alterations in cannabis users (CU) compared to nonusing controls while performing memory tasks, complemented with focused narrative reviews of relevant preclinical and human studies. Twelve studies employing fMRI were identified finding functional brain activation during memory tasks altered in CU. Memory performance studies showed CU performed worse particularly during verbal memory tasks. Longitudinal studies suggest that cannabis use may have a causal role in memory deficits. Preclinical studies have not provided conclusive evidence of memory deficits following cannabinoid exposure, although they have shown evidence of cannabinoid-induced structural and histological alteration. Memory performance deficits may be related to cannabis use, with lower performance possibly underpinned by altered functional activation. Memory impairments may be associated with the level of cannabis exposure and use of cannabis during developmentally sensitive periods, with possible improvement following cessation of cannabis use.

Adolescent drug exposure: A review of evidence for the development of persistent changes in brain function

Over the past decade, many studies have indicated that adolescence is a critical period of brain development and maturation. The refinement and maturation of the central nervous system over this prolonged period, however, makes the adolescent brain highly susceptible to perturbations from acute and chronic drug exposure. Here we review the preclinical literature addressing the long-term consequences of adolescent exposure to common recreational drugs and drugs-of-abuse. These studies on adolescent exposure to alcohol, nicotine, opioids, cannabinoids and psychostimulant drugs, such as cocaine and amphetamine, reveal a variety of long-lasting behavioral and neurobiological consequences. These agents can affect development of the prefrontal cortex and mesolimbic dopamine pathways and modify the reward systems, socio-emotional processing and cognition. Other consequences include disruption in working memory, anxiety disorders and an increased risk of subsequent drug abuse in adult life. Although preventive and control policies are a valuable approach to reduce the detrimental effects of drugs-of-abuse on the adolescent brain, a more profound understanding of their neurobiological impact can lead to improved strategies for the treatment and attenuation of the detrimental neuropsychiatric sequelae.

Adolescent Δ9-Tetrahydrocannabinol Exposure Selectively Impairs Working Memory but Not Several Other mPFC-Mediated Behaviors

As the frequency of cannabis use by 14-16-year-olds increases, it becomes increasingly important to understand the effect of cannabis on the developing central nervous system. Using mice as a model system, we treated adolescent (28 day old) C57BL6/J mice of both sexes for 3 weeks with 3 mg/kg tetrahydrocannabinol (THC). Starting a week after the last treatment, several cognitive behaviors were analyzed. Mice treated with THC as adolescents acquired proficiency in a working memory task more slowly than vehicle-treated mice. Working memory recall in both sexes of THC-treated mice was also deficient during increasing cognitive load compared to vehicle-treated mice. Our adolescent THC treatment did not strongly affect social preference, anxiety behaviors, or decision-making behaviors on the elevated T maze task. In summary, under the conditions of this study, adolescent THC treatment of mice markedly affected the establishment, and persistence of working memory, while having little effect on decision-making, social preference or anxiety behaviors. This study provides further support that adolescent THC affects specific behavioral domains.

Adolescent neurodevelopment and substance use: Receptor expression and behavioral consequences

Adolescence is the transitional period between childhood and adulthood, during which extensive brain development occurs. Since this period also overlaps with the initiation of drug use, it is important to consider how substance use during this time might produce long-term neurobiological alterations, especially against the backdrop of developmental changes in neurotransmission. Alcohol, cannabis, nicotine, and opioids all produce marked changes in the expression and function of the neurotransmitter and receptor systems with which they interact. These acute and chronic alterations also contribute to behavioral consequences ranging from increased addiction risk to cognitive or neuropsychiatric behavioral dysfunctions. The current review provides an in-depth overview and update of the developmental changes in neurotransmission during adolescence, as well as the impact of drug exposure during this neurodevelopmental window. While most of these factors have been studied in animal models, which are the focus of this review, future longitudinal studies in humans that assess neural function and behavior will help to confirm pre-clinical findings. Furthermore, the neural changes induced by each drug should also be considered in the context of other contributing factors, such as sex. Further understanding of these consequences can help in the identification of novel approaches for preventing and reversing the neurobiological effects of adolescent substance use.

Cannabinoid and nicotine exposure during adolescence induces sex-specific effects on anxiety- and reward-related behaviors during adulthood

Nicotine and cannabis use during adolescence has the potential to induce long lasting changes on affective and cognitive function. Here, we examined whether adolescent exposure to nicotine, the cannabinoid agonist WIN55-212,2 (WIN), or co-exposure to both would alter operant learning, locomotion, and anxiety- and reward-related behaviors in male and female mice during adulthood. Males exposed to a moderate dose of WIN (2 mg/kg) or co-exposed to nicotine and the moderate dose of WIN exhibited decreased anxiety-associated behaviors and increased cognitive flexibility, but did not differ in operant learning or generalized locomotion. In contrast, differences were not found among the females in these measures at the moderate WIN dose or in both sexes with exposure to a low WIN dose (0.2 mg/kg). Furthermore, a sex-dependent dissociative effect was found in natural reward consumption. Males exposed to the moderate dose of WIN or co-exposed to nicotine and the moderate dose of WIN demonstrated increased sucrose consumption. In contrast, females exposed to the moderate dose of WIN exhibited a decrease in sucrose consumption, which was ameliorated with co-administration of nicotine. Together, these novel findings demonstrate that adolescent exposure to cannabinoids in the presence or absence of nicotine results in altered affective and reward-related behaviors during adulthood.

Enhancing effects of acute exposure to cannabis smoke on working memory performance

Numerous preclinical studies show that acute cannabinoid administration impairs cognitive performance. Almost all of this research has employed cannabinoid injections, however, whereas smoking is the preferred route of cannabis administration in humans. The goal of these experiments was to systematically determine how acute exposure to cannabis smoke affects working memory performance in a rat model. Adult male (n = 15) and female (n = 16) Long-Evans rats were trained in a food-motivated delayed response working memory task. Prior to test sessions, rats were exposed to smoke generated by burning different numbers of cannabis or placebo cigarettes, using a within-subjects design. Exposure to cannabis smoke had no effect on male rats' performance, but surprisingly, enhanced working memory accuracy in females, which tended to perform less accurately than males under baseline conditions. In addition, cannabis smoke enhanced working memory accuracy in a subgroup of male rats that performed comparably to the worst-performing females. Exposure to placebo smoke had no effect on performance, suggesting that the cannabinoid content of cannabis smoke was critical for its effects on working memory. Follow-up experiments showed that acute administration of either Δ9-tetrahydrocannabinol (0.0, 0.3, 1.0, 3.0 mg/kg) or the cannabinoid receptor type 1 antagonist rimonabant (0.0, 0.2, 0.6, 2.0 mg/kg) impaired working memory performance. These results indicate that differences in the route, timing, or dose of cannabinoid administration can yield distinct cognitive outcomes, and highlight the need for further investigation of this topic.

Development of working memory in the male adolescent rat

Working memory develops over the course of adolescence, and neuroimaging studies find development-associated changes in the activity of prefrontal cortical brain regions. Establishment of a rodent model of working memory development would permit more comprehensive studies of the molecular and circuit basis for working memory development in health and disease. Thus, in this study, working memory performance was compared between adolescent and adult male Sprague-Dawley rats using an operant-based, delay-match-to-sample working memory task. Adolescent and adult rats showed similar rates of learning the task and similar performance at a low cognitive load (delays ≤ 6 s). However, when the cognitive load increased, adolescents exhibited impaired working memory performance relative to adults, until postnatal day 50 when performance was not significantly different. Despite evidence that cannabinoids disrupt working memory, we found no effect of acute treatment with the cannabinoid receptor agonist, WIN55212,2, at either age. Moreover, expression of glutamate and GABA receptor subunits was examined in the prelimbic and infralimbic prefrontal cortex across development. NMDA receptor subunit GluN2B expression significantly decreased with age in parallel with improvements in working memory. Thus, we show evidence that rats can be used as a model to study the molecular underpinnings of working memory development.

Animal models in addiction research: A dimensional approach

Drug addiction affects approximately 10% of the population and these numbers are rising. Treatment and prevention of addiction are impeded by current diagnostic systems, such as DSM-5, which are based on outcomes rather than processes. Here, we review the importance of adopting a dimensional framework, specifically the Research Domain Criteria (RDoC), to identify protective and vulnerability mechanisms in addiction. We discuss how preclinical researchers should work within this framework to develop animal models based on domains of function. We highlight RDoC paradigms related to addiction and discuss how these can be used to investigate the biological underpinnings of an addiction cycle (i.e., binge/intoxication, negative affect, and craving). Using this information, we then outline the critical role of animal research in ongoing revisions to the RDoC matrix (specifically the functional significance of domains, constructs and subconstructs) and its contribution to the development and refinement of addiction theories. We conclude with an overview of the contribution that animal research has made to the development of pharmacological and behavioural treatments for addiction.

The ongoing challenge of novel psychoactive drugs of abuse. Part I. Synthetic cannabinoids (IUPAC Technical Report)

In the past decade, the world has experienced a large increase in the number of novel compounds appearing on the illicit drug market for recreational purposes. Such substances are designed to circumvent governmental regulations; the illegal drug manufacturers take a known psychoactive compound reported in the scientific literature and slightly modify its chemical structure in order to produce analogues that will mimic the pharmacological activity of the original substance. Many of these novel substances are sold via the Internet. Among the various chemical classes, synthetic cannabinoid receptor modulators, commonly referred to as “synthetic cannabinoids” have been at the forefront, as demonstrated by the frequency of drug seizures, numerous severe toxic effects, and fatalities associated with some of these substances. This review presents the chemical structures of relevant synthetic cannabinoids and describes their mechanism of action, pharmacological features, metabolic pathways, and structure-activity relationships. It illustrates the approaches used in forensic testing, both for bulk analysis (drug seizures) and for analytical toxicology (biological matrices) and discusses aspects of regulation surrounding this drug class. This report is intended to provide pertinent information for the purposes of informing scientific, medical, social, and governmental bodies about this ever-evolving recreational drug class and the challenges it poses worldwide.

Impact of Sleep and Circadian Rhythms on Addiction Vulnerability in Adolescents

Sleep homeostasis and circadian function are important maintaining factors for optimal health and well-being. Conversely, sleep and circadian disruptions are implicated in a variety of adverse health outcomes, including substance use disorders. These risks are particularly salient during adolescence. Adolescents require 8 to 10 hours of sleep per night, although few consistently achieve these durations. A mismatch between developmental changes and social/environmental demands contributes to inadequate sleep. Homeostatic sleep drive takes longer to build, circadian rhythms naturally become delayed, and sensitivity to the phase-shifting effects of light increases, all of which lead to an evening preference (i.e., chronotype) during adolescence. In addition, school start times are often earlier in adolescence and the use of electronic devices at night increases, leading to disrupted sleep and circadian misalignment (i.e., social jet lag). Social factors (e.g., peer influence) and school demands further impact sleep and circadian rhythms. To cope with sleepiness, many teens regularly consume highly caffeinated energy drinks and other stimulants, creating further disruptions in sleep. Chronic sleep loss and circadian misalignment enhance developmental tendencies toward increased reward sensitivity and impulsivity, increasing the likelihood of engaging in risky behaviors and exacerbating the vulnerability to substance use and substance use disorders. We review the neurobiology of brain reward systems and the impact of sleep and circadian rhythms changes on addiction vulnerability in adolescence and suggest areas that warrant additional research.

The Effects of Cannabinoids on Executive Functions: Evidence from Cannabis and Synthetic Cannabinoids-A Systematic Review

Background—Cannabis is the most popular illicit drug in the Western world. Repeated cannabis use has been associated with short and long-term range of adverse effects. Recently, new types of designer-drugs containing synthetic cannabinoids have been widespread. These synthetic cannabinoid drugs are associated with undesired adverse effects similar to those seen with cannabis use, yet, in more severe and long-lasting forms. Method—A literature search was conducted using electronic bibliographic databases up to 31 December 2017. Specific search strategies were employed using multiple keywords (e.g., “synthetic cannabinoids AND cognition,” “cannabis AND cognition” and “cannabinoids AND cognition”). Results—The search has yielded 160 eligible studies including 37 preclinical studies (5 attention, 25 short-term memory, 7 cognitive flexibility) and 44 human studies (16 attention, 15 working memory, 13 cognitive flexibility). Both pre-clinical and clinical studies demonstrated an association between synthetic cannabinoids and executive-function impairment either after acute or repeated consumptions. These deficits differ in severity depending on several factors including the type of drug, dose of use, quantity, age of onset and duration of use. Conclusions—Understanding the nature of the impaired executive function following consumption of synthetic cannabinoids is crucial in view of the increasing use of these drugs.

High times for cannabis: Epigenetic imprint and its legacy on brain and behavior

Extensive debates continue regarding marijuana (Cannabis spp), the most commonly used illicit substance in many countries worldwide. There has been an exponential increase of cannabis studies over the past two decades but the drug's long-term effects still lack in-depth scientific data. The epigenome is a critical molecular machinery with the capacity to maintain persistent alterations of gene expression and behaviors induced by cannabinoids that have been observed across the individual's lifespan and even into the subsequent generation. Though mechanistic investigations regarding the consequences of developmental cannabis exposure remain sparse, human and animal studies have begun to reveal specific epigenetic disruptions in the brain and the periphery. In this article, we focus attention on long-term disturbances in epigenetic regulation in relation to prenatal, adolescent and parental germline cannabinoid exposure. Expanding knowledge about the protracted molecular memory could help to identify novel targets to develop preventive strategies and treatments for behaviors relevant to neuropsychiatric risks associated with developmental cannabis exposure.

Preclinical Studies of Cannabinoid Reward, Treatments for Cannabis Use Disorder, and Addiction-Related Effects of Cannabinoid Exposure

Cannabis use has become increasingly accepted socially and legally, for both recreational and medicinal purposes. Without reliable information about the effects of cannabis, people cannot make informed decisions regarding its use. Like alcohol and tobacco, cannabis can have serious adverse effects on health, and some people have difficulty discontinuing their use of the drug. Many cannabis users progress to using and becoming addicted to other drugs, but the reasons for this progression are unclear. The natural cannabinoid system of the brain is complex and involved in many functions, including brain development, reward, emotion, and cognition. Animal research provides an objective and controlled means of obtaining information about: (1) how cannabis affects the brain and behavior, (2) whether medications can be developed to treat cannabis use disorder, and (3) whether cannabis might produce lasting changes in the brain that increase the likelihood of becoming addicted to other drugs. This review explains the tactics used to address these issues, evaluates the progress that has been made, and offers some directions for future research.

Consequences of Adolescent Exposure to the Cannabinoid Receptor Agonist WIN55,212-2 on Working Memory in Female Rats

Marijuana is a prevalent illicit substance used by adolescents, and several studies have indicated that adolescent use can lead to long-term cognitive deficits including problems with attention and memory. However, preclinical animal studies that observe cognitive deficits after cannabinoid exposure during adolescence utilize experimenter administration of doses of cannabinoids that may exceed what an organism would choose to take, suggesting that contingency and dose are critical factors that need to be addressed in translational models of consequences of cannabinoid exposure. Indeed, we recently developed an adolescent cannabinoid self-administration paradigm in male rats, and found that prior adolescent self-administration of the cannabinoid receptor agonist WIN55,212-2 (WIN) resulted in improved working memory performance in adulthood. In addition, the doses self-administered were not as high as those that are found to produce memory deficits. However, given known sex differences in both drug self-administration and learning and memory processes, it is possible that cannabinoid self-administration could have different cognitive consequences in females. Therefore, we aimed to explore the effects of self-administered vs. experimenter-administered WIN in adolescent female rats on adult cognitive function. Female rats were trained to self-administer WIN daily throughout adolescence (postnatal day 34–59). A control group self-administered vehicle solution. The acute effects of adolescent WIN self-administration on memory were determined using a short-term spatial memory test 24 h after final SA session; and the long-term effects on cognitive performance were assessed during protracted abstinence in adulthood using a delayed-match-to-sample working memory task. In a separate experiment, females were given daily intraperitoneal (IP) injections of a low or high dose of WIN, corresponding to self-administered and typical experimenter-administered doses, respectively, or its vehicle during adolescence and working memory was assessed under drug-free conditions in adulthood. While self-administration of WIN in adolescence had no significant effects on short-term spatial memory or adult working memory, experimenter administration of WIN resulted in improved adult working memory performance that was more pronounced in the low dose group. Thus, low-dose adolescent WIN exposure, whether self-administered or experimenter-administered, results in either improvements or no change in adult working memory performance in female rats, similar to previous results found in males.

Adolescent Exposure to the Synthetic Cannabinoid WIN 55212-2 Modifies Cocaine Withdrawal Symptoms in Adult Mice

Chronic cannabinoid consumption is an increasingly common behavior among teenagers and has been shown to cause long-lasting neurobehavioral alterations. Besides, it has been demonstrated that cocaine addiction in adulthood is highly correlated with cannabis abuse during adolescence. Cocaine consumption and subsequent abstinence from it can cause psychiatric symptoms, such as psychosis, cognitive impairment, anxiety, and depression. The aim of the present research was to study the consequences of adolescent exposure to cannabis on the psychiatric-like effects promoted by cocaine withdrawal in adult mice. We pre-treated juvenile mice with the cannabinoid CB1 receptor agonist WIN 55212-2 (WIN) and then subjected them to a chronic cocaine treatment during adulthood. Following these treatments, animals were tested under cocaine withdrawal in the following paradigms: pre-pulse inhibition, object recognition, elevated plus maze, and tail suspension. The long-term psychotic-like actions induced by WIN were not modified after cocaine cessation. Moreover, the memory impairments induced by cocaine withdrawal were not altered by previous adolescent WIN intake. However, WIN pre-treatment prevented the anxiogenic effects observed after cocaine abstinence, and led to greater depressive-like symptoms following cocaine removal in adulthood. This study is the first to show the long-lasting behavioral consequences of juvenile exposure to WIN on cocaine withdrawal in adult mice.