C H A P T E R

e101

Handbook of Cannabis and Related Pathologies. http://dx.doi.org/10.1016/B978-0-12-800756-3.00066-1Copyright © 2017 Elsevier Inc. All rights reserved.

e10 Cannabis and the Use of

Amphetamine-Like Substances A. Porcu , M.P. Castelli

Department of Biomedical Sciences, Division of Neuroscience and Clinical Pharmacology, Cittadella Universitaria, Monserrato, CA, Italy

SUMMARY POINTS

• This chapter focuses on coabuse of cannabis and amphetamine-like substances (ALS).

• Cannabis (main psychoactive compound Δ 9 -Tetrahydrocannabinol, Δ 9 -THC) is consumed by 2.9–4.3% of the global population aged 16–64 in the world.

• Cannabis consumption is frequently associated with simultaneous use of other psychoactive compounds such as alcohol, cocaine, and ALS (ie, amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine).

• New psychoactive substances (NPS), such as cathinones and its derivatives, are frequently coabused with cannabis.

• Cannabis + ASL coabuse enhances the subjective effects of the drugs in humans, counteracts the dysphoric symptoms of “coming down” from 3,4-methylenedioxymethamphetamine or methamphetamine (MDMA and METH), and/or improves and mellows the drug experience.

• Both pharmacological and genotype animal studies support the role of the cannabinoid type 1 receptor (CB1R) in the rewarding and addictive properties of MDMA.

• Preclinical and clinical studies investigating the effects of cannabis + ASL and their interaction in METH/MDMA-induced neurotoxicity have reported confl icting fi ndings: cannabis might exacerbate or attenuate METH/MDMA induced neurotoxicity.

KEY FACTS ON THE MONOAMINERGIC TARGET SYSTEM • Monoamines refer to the particular neurotransmitters

dopamine, norepinephrine and serotonin. • These neurotransmitters are involved in mediating a

wide range of physiological and homeostatic functions such as cognition, memory, learning, mood, and behavior.

• These neurotransmitters are synthesized within particular neurons, and exert an effect when they are released into the synapses, where they are able to act on specifi c receptors.

• The dopamine transporter (DAT), serotonin transporter (SERT), and the norepinephrine transporter (NET) transport monoamines in or out of a cell.

• ALS may increase the activity of dopamine, norepinephrine, or serotonin by either increasing release, blocking reuptake, inhibiting metabolism, or acting directly on a receptor.

KEY FACTS ON NEW PSYCHOACTIVE SUBSTANCES (NPS) • NPS are known in the drug market under the names of

“designer drugs,” “legal highs,” “herbal highs,” “bath salts,” or “research chemicals.”

• NPS have become a global phenomenon, and they have affected all regions of the world; 70 (out of 80) countries and territories (88%) examined by UNODC (2014) have reported the emergence of NPS.

• The number of NPS on the global market more than doubled over the period 2009–13. Legislation has not

C0330.indd 101C0330.indd 101 14/12/16 2:43 PM14/12/16 2:43 PM

e102 e10. CANNABIS AND THE USE OF AMPHETAMINE-LIKE SUBSTANCES

IV. CANNABIS, ORGANS, TISSUES AND NON-CNS ASPECTS

LIST OF ABBREVIATIONS

Δ 9 -THC Δ 9 -Tetrahydrocannabinol 5HT Serotonin ADHD Attention-defi cit/hyperactivity disorder AMPH Amphetamine ALS Amphetamine-like substances BDNF Brain-derived neurotrophic factor CB1-KO Cannabinoid type 1 receptor knockout mice CB1R Cannabinoid type 1 receptor CB2-KO Cannabinoid type 2 receptors knockout mice CB2R Cannabinoid type 2 receptor CPP Conditioned place preference DA Dopamine DAT Dopamine transporter DEA Drug Enforcement Administration dUTP 2 � -deoxyuridine 5 � -triphosphate ECS Endocannabinoid system FDA Food and Drug Administration fMRI Functional magnetic resonance technique GFAP Glial fi brillary acidic protein MAO Monoamine oxidase MDMA 3,4-Methylenedioxymethamphetamine METH Methamphetamine MJ Marijuana NE Norepinephrine NET Norepinephrine transporter nNOS Neuronal nitric oxide synthase NO Nitric oxide NPS New psychoactive substances pCREB Phosphorylated cAMP response element–

binding protein PKA Protein kinase A PKC Protein kinase C

RNS Reactive nitrogen species ROS Reactive oxygen species SERT Serotonin transporter TH Tyrosine hydroxylase TTAR1 Activate trace amine associated receptor 1 TUNEL Terminal deoxynucleotidyl transferase VMAT-2 Vesicular monoamine transporter-2

INTRODUCTION

Cannabis is the most widely consumed illicit drug worldwide, with an estimated global use by 2.9– 4.3% of the population aged 16–64 ( UNODC, 2010 ) ( Fig. e10.1 ).

While the prevalence of illicit drugs such as cocaine, amphetamine-like substances (ALS) [ie, amphetamine (AMPH), methamphetamine (METH), and 3,4-methy-lenedioxymethamphetamine (MDMA)] appeared to remain stable between 2009 and 2011, since 2009 the ex-tent of cannabis and opioids use has increased. Cannabis consumption is frequently associated with simultaneous and/or concurrent use of other psychoactive compounds such as alcohol, cocaine, and ALS ( Gouzoulis-Mayfrank & Daumann, 2006 ).

A growing body of clinical and preclinical studies has highlighted the simultaneous use of MDMA, also called ec-stasy, and cannabis ( Parrott, Milani, Gouzoulis-Mayfrank, & Daumann, 2007 ). Strote, Lee, & Wechsler (2002) , survey-ing a sample of over 10,000 US college students, reported a prevalence of ecstasy use of 4.7%, with 92% of consumers also consuming cannabis. Wish, Fitzelle, O’Grady, & Hsu (2006) confi rmed that 98% of recreational MDMA users in a sample of East Coast College students also consume cannabis. Moreover, the presence of a metabolite of the main psychoactive compound Δ 9 -tetrahydrocannabinol ( Δ 9 -THC), 11-nor-9 carboxy-THC, was found in urine sam-ples collected from 198 ecstasy users between 2005 and 2008 ( Black, Cawthon, Robert, & Moser, 2009 ).

In Europe, the prevalence of couse of MDMA + can-nabis ranges from 73% to 100% in different countries ( Sala & Braida, 2005 ), and is higher in males and in regular cannabis users than in women and occasional

been established, making their sale easy and offi cially legal in almost all countries.

• The most popular of these drugs are based on the substance cathinone (2-amino-1-phenylpropanone) and its synthetic analogs.

• The chemical structure of NPS is similar to that of amphetamine, as well as their physiological and psychological actions.

KEY FACTS ON POLYDRUG USE • Research on polydrugs use is typically done on

relatively small convenient samples (eg, street-based, emergency rooms, and club patrons), where multiple drugs are frequently used consecutively or simultaneously, often for their perceived counteracting or complementary effects.

• It is associated with a higher risk of developing psychiatric and health problems.

FIGURE e10.1 Estimated number of people who used cannabis at least once in the past year, and its prevalence among the population aged 15–64, by region. Source: UNODC (2010) .

C0330.indd 102C0330.indd 102 14/12/16 2:43 PM14/12/16 2:43 PM

AMPHETAMINE-LIKE SUBSTANCES: AMPH, METH, MDMA, AND CATHINONES e103

IV. CANNABIS, ORGANS, TISSUES AND NON-CNS ASPECTS

cannabis consumers ( ESPAD, 2000 ). Due to its low cost, wide availability, and high potential for abuse, METH is the second most frequently abused recreational drug among adolescents, and is often coabused with cannabis ( Gonzalez, Rippeth, Carey, & Heaton, 2004 ).

Several psychosocial and functional reasons can ac-count for the high percentage of concurrent use of Δ 9 -THC and METH or MDMA. Cannabis is often considered a “gateway drug,” and its consumption might predict a signifi cantly higher risk for subsequent use of heavy il-licit drugs such as ALS. However, numerous reports have failed to support this theory, while other studies point to social, environmental, and genetic factors to explain the couse of cannabis and other drugs ( Parrott et al., 2007 ).

MDMA and METH are psychostimulant drugs that induce euphoria, increased sociability, and empathy ( Parrott, 2013 ), while cannabis produces relaxation and feelings of happiness ( Green, Kavanagh, & Young, 2003 ). One of the main reasons for using cannabis in associa-tion with MDMA or METH is that the combination of the two drugs enhances the subjective drug effects, and counteracts the dysphoric symptoms of the ecstasy or METH “coming down” ( Schulz, 2011 ). Indeed, MDMA abusers often consume cannabis in the immediate post-ecstasy period as a symptomatic relief against the nega-tive physiological and emotional states (eg, anhedonia, depression) that follow ecstasy’s “high.” Many ecstasy users also report taking cannabis in the initial acute phase of MDMA to “improve” and “mellow” the experi-ence ( Parrott et al., 2007 ).

In the last few years, many recreational drugs have been synthesized as legal alternatives to scheduled can-nabis and AMPH/METH stimulants. New psychoactive substances (NPS) have been found mostly in Europe and North America, but also in Oceania, South America, and Africa. Because they are new, legislation has not been es-tablished yet, making their sale easy and offi cially legal. Their global market has increased dramatically in recent years: by December 2013, the number of NPS reported to UNODC had reached 348, up from 251 as of July 2012, and 166 in 2009 ( UNODC, 2014 ).

The most popular of these drugs are based on the sub-stance cathinone (2-amino-1-phenylpropanone), an ana-logue of amphetamine, a natural compound of the khat plant ( Paillet-Loilier, Cesbron, Le Boisselier, Bourgine, & Debruyne, 2014 ), which acts on the central dopamine system. Dopaminergic stimulation of the reward system could explain the development of dependence after fre-quent consumption of cathinone derivatives.

Due to the recent discovery of the NPS, only a few survey studies are currently available on their simulta-neous use with cannabis, but no preclinical or clinical studies. On the other hand, despite the high prevalence of cannabis use among MDMA and METH users, the neurobiological interactions between these two drugs

are complex, and data regarding their coadministra-tion in human and animal studies are contradictory ( Mohamed, Ben Hamida, Cassel, & de Vasconcelos, 2011 ; Schulz, 2011 ).

Δ 9 -THC and other cannabis derivatives act via canna-binoid type 1 receptors (CB1R) on the endocannabinoid system (ECS), while the ALS, including MDMA, METH and the cathinones, act by increasing synaptic levels of the monoamines dopamine (DA), serotonin (5HT), and norepinephrine (NE).

For a detailed description of the ECS and the mecha-nism of action of Δ 9 -THC and other cannabinoids, see designated Chapters of this book.

In the following paragraphs, we will briefl y describe the ALS, including cathinones, their molecular pharma-cology, and the pharmacological/neurobiological effects induced by ALS + cannabis.

AMPHETAMINE-LIKE SUBSTANCES: AMPH, METH, MDMA,

AND CATHINONES

Amphetamine (AMPH) is the parent compound of a class of molecules with similar chemical structures and biological properties, referred to as amphetamines ( Fig. e10.2 ) ( Fleckenstein, Volz, Riddle, & Gibb, 2007 ).

In 1935, AMPH was introduced to the market by the pharmaceutical company Smith, Kline and French, with the brand name of “Benzedrine.” for the treat-ment of narcolepsy, mild depression, postencephalitic Parkinsonism, and other disorders. Since 1971, AMPH and METH, a substituted amphetamine, due to their addictive potential, have been inserted in Schedule II of the Controlled Substances Act, and are Food and Drug Administration (FDA)-approved for treatment of attention-defi cit/hyperactivity disorder (ADHD), nar-colepsy, and obesity (DEA Congressional Testimony by Terrance Woodworth; 2000, May 10).

METH is one of the most common ALS; also known as “crystal,” “chalk,” or “ice,” it is taken orally, smoked,

FIGURE e10.2 Chemical structures of amphetamines. Amphet-amine, methamphetamine, and MDMA are the amphetamines most frequently coabused with cannabis.

C0330.indd 103C0330.indd 103 14/12/16 2:43 PM14/12/16 2:43 PM

e104 e10. CANNABIS AND THE USE OF AMPHETAMINE-LIKE SUBSTANCES

IV. CANNABIS, ORGANS, TISSUES AND NON-CNS ASPECTS

snorted, or dissolved in water or alcohol, and injected. The annual prevalence of METH in the United States was 0.5% of the population aged 15–64 in 2012, similar to that estimated between 2009 and 2011 ( SAMHSA, 2013 ).

MDMA, developed and patented in 1918 by Merck for use in synthesis of styptic drugs, was used in the United States by psychotherapists from 1978 to 1985, when, due to its high abuse potential, the DEA (Drug Enforcement Administration) included it in Schedule I. After canna-bis, the second most widely used illegal drugs world-wide are ALS, particularly MDMA ( Parrott, 2013 ). Also known as “ecstasy,” “Molly,” “lover’s speed,” or “the love drug,” MDMA is used by 10.5–25.8 million people worldwide, corresponding to 0.2–0.6% of the adult pop-ulation (16–64 years) ( UNODC, 2010 ). MDMA is mostly consumed at late-night parties (“raves,” “dance clubs,” “techno parties”), where the percentage of users can be up to 95%. The 2009 National Survey on Drug Use and Health reported that the percent consuming MDMA was 1.4% among adolescents (12–17 years old), 3.9% among young adults (18–25 years old) and 0.3% for adults (old-er than 26 years) ( NSDUH, 2010 ).

Among the NPS, the most abused are derivatives of cathinone, which is a β -cheto analogue of AMPH used as a structural template for the discovery of compounds with a wide range of pharmacological activities ( Carroll, Blough, Mascarella, & Navarro, 2010 ).

NPS are usually marketed as tablets of various colors and shapes, or capsules, powders, and crystals, and sold as “bath salts” or “plant fertilizers.” In recent years, sev-eral synthetic analogs of cathinone have emerged on the market, and circulate on the Internet or are sold in smart shops with the misleading indication that they are “not for human consumption” ( Fig. e10.3 ).

The general structure of these substituted compounds shows substitution patterns at four locations on the cathinone molecule, for example, on the carbon atom linked to the carbon in the alpha position (R1), on the

nitrogen atom (R2 and R3), and on the phenyl group (R4) ( Fig. e10.4 ).

ALS Pharmacology

The psychostimulant and rewarding properties of AMPH, METH, and MDMA are due to their ability to enhance neuronal excitability in the brain and, in par-ticular, to increase dopaminergic neuronal activity in the mesolimbic pathway.

Indeed, ALS are historically considered potent indi-rect monoaminergic agonists, raising the synaptic levels of DA, NE, and, to a lesser extent, 5HT through different mechanisms such as inhibition of: (1) the transporters of DA (DAT), NE (NET), and 5HT (SERT); (2) the vesicular monoamine transporter-2 (VMAT-2); and (3) monoamine oxidase (MAO) activity. Specifi cally, although with dif-ferent affi nities, AMPH and its derivatives are substrates of plasmalemma DAT, NET, and SERT, with METH and AMPH having greater affi nity for DAT, and MDMA hav-ing greater affi nity for SERT ( Sulzer, Sonders, Poulsen, & Galli, 2005 ).

According to the “exchange-diffusion model,” the lipophilic AMPH, METH, and MDMA at high concen-trations can diffuse directly across the plasmalemma membrane, while at low concentrations they are trans-ported into the cell by competing with synaptic DA or 5HT at the extracellular site of DAT or SERT. Then, AMPH can disrupt the proton gradient between the in-side and outside of the storage vesicle, resulting in an increased release of DA or 5HT from vesicular compart-ments. At physiological concentrations, AMPH binds to VMAT2, thus inhibiting vesicular monoamine uptake and enhancing cytoplasmic DA levels. As cytoplasmic DA levels rise, DA exits the neuron via reverse transport and/or channel like transport ( Fleckenstein et al., 2007 ).

AMPH can also interact indirectly with DAT. Once entering the neuron, it can bind to and activate trace amine associated receptor 1 (TTAR1), a G-protein

FIGURE e10.3 Representative packaging of NPS products. The indication that this substance is “not for human consumption” makes it automatically legal.

FIGURE e10.4 Chemical structures of cathinones. R1, R2, R3, R4 are the various groups that can be substituted to obtain other synthetic derivatives.

C0330.indd 104C0330.indd 104 14/12/16 2:43 PM14/12/16 2:43 PM

ALS + CANNABIS e105

IV. CANNABIS, ORGANS, TISSUES AND NON-CNS ASPECTS

coupled receptor that is important for the regulation of monoamine transporter function and METH’s action on DAT activity. In particular, AMPH-induced TTAR1 acti-vation via protein kinase A (PKA) and protein kinase C (PKC) signaling determines DAT phosphorylation and internalization, thereby decreasing DAT DA uptake. METH and MDMA also increase glutamate release in the striatum and hippocampus, respectively ( Panenka, Procyshyn, Lecomte, & MacEwan, 2013 ).

Besides its acute actions, moderate to high doses of ALS administered in a “binge pattern” (repeated ad-ministrations at short time intervals) induce long-term effects such as dopaminergic and serotoninergic defi cits, including reductions in expression of the enzymes ty-rosine and tryptophan hydroxylase and DAT and SERT density, as well as decreases in DA and 5HT tissue con-tent ( Marshall & O’Dell, 2012 ). In addition to damage to DA and 5HT terminals, METH and MDMA cause ac-tivation of microglia, and a signifi cant increase in glial fi brillary acidic protein (GFAP), an index of gliosis and central nervous system (CNS) toxicity and cell death. METH increases terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), a marker of apoptotic cell death and DNA damage, and alters expression of the Bcl2 gene and causes apoptosis by increasing caspase-3 activity, and the Fas/Fasl cell death pathways. MDMA exposure in vitro causes an increase in reactive nitrogen species (RNS) and caspase-3 and, in vivo, an enhance-ment in protein levels associated with apoptosis (eg, BAX, cytochrome c, caspase-3) ( Capela, Carmo, Remião, & Bastos, 2009 , Krasnova & Cadet, 2009 ).

Moreover, the increased extracellular glutamate lev-els induced by METH-binging activate N-methyl-D-aspartate (NMDA) receptors, promoting an increase in intracellular Ca 2+ that leads to activation of neuronal ni-tric oxide synthase (nNOS) and subsequent production of nitric oxide (NO), and activation of apoptotic path-ways ( Halpin, Collins, & Yamamoto, 2014 ).

Increasing evidence now suggests the involvement of several interacting mechanisms underlying ALS-induced neurotoxicity, such as hyperthermia, increased produc-tion of reactive oxygen (ROS) and RNS, induction of in-fl ammatory responses, apoptotic pathways, DNA dam-age, and excitotoxic injury. Indeed, ALS-neurotoxicity is associated with long-lasting impairments in mood and cognitive functions in humans and animals ( Marshall & O’Dell, 2012 ).

As concerns synthetic cathinones, data concern-ing their pharmacological and toxicological proper-ties, mechanisms of action and toxic effects are still inconclusive.

Just as AMPH and cocaine, cathinones in the CNS in-crease synaptic concentrations of catecholamines by in-hibiting their uptake transporters. The meth-cathinone analogs mephedrone and methylone function as

substrates for NET, DAT, and SERT at nanomolar concen-trations, but are nonselective substrates for monoamine transporters in vitro, exhibiting a potency and selectivity comparable to those of MDMA. Mephedrone and meth-ylone produce concurrent elevations in extracellular DA and 5HT in vivo, and high-dose administration produc-es hyperthermia and motor stimulation, but no lasting changes in brain tissue monoamines ( Baumann, Ayestas, Partilla, & Sink, 2012 ).

ALS + CANNABIS

Animal Studies

Pharmacological and genotype studies in animals support the existence of interactions between cannabi-noid and MDMA/METH related to their rewarding ef-fects, and the role played by CB1Rs in these effects ( Sala & Braida, 2005 ). The reinforcing properties elicited by the simultaneous use of MDMA and Δ 9 -THC have been investigated by means of several animal paradigms, such as conditioned place preference (CPP) and intracra-nial and intravenous self-administration. In particular, in rats trained to self-administer MDMA intracerebro-ventricularly, the CB1R agonist CP55940 reduced the amount of lever-pressing to obtain MDMA, while the CB1R antagonist SR141617A (SR) increased MDMA-associated lever-pressing, suggesting an increase and a decrease in MDMA’s reinforcing effects, respectively. SR decreases MDMA-induced CPP in rats, further sup-porting the role of the CB1R in reward processes ( Sala & Braida, 2005 ). Accordingly, CB1-KO mice fail to self-administer MDMA, while MDMA induces CPP and enhances extracellular DA levels in the nucleus ac-cumbens of both wild type and CB1-KO mice ( Touriño et al., 2008 ). This discrepancy might be attributed to the different animal species (rats in the pharmacological studies, and mice in the genetic studies), or to the differ-ent behavioral paradigms utilized (self-administration vs CPP). Indeed, several brain circuits are involved in the self-administration paradigm, such as those regulat-ing motivation, consciousness, arousal, and learning, while CPP is mostly based on conditioning processes. Intriguingly, subthreshold doses of Δ 9 -THC coadmin-istered with a subthreshold dose of MDMA produced CPP in mice, while administration of the same dose of Δ 9 -THC with a rewarding dose of MDMA decreased CPP ( Robledo et al., 2007 ). At low doses, the CB1R agonist WIN55212-2 (WIN) increased the rewarding properties of low doses of MDMA, while MDMA reinstated WIN-induced CPP, although WIN was not able to reinstate MDMA-induced CPP in animals with no prior exposure to cannabinoids ( Manzanedo, Rodríguez-Arias, Daza-Losada, & Maldonado, 2010 ).

C0330.indd 105C0330.indd 105 14/12/16 2:43 PM14/12/16 2:43 PM

e106 e10. CANNABIS AND THE USE OF AMPHETAMINE-LIKE SUBSTANCES

IV. CANNABIS, ORGANS, TISSUES AND NON-CNS ASPECTS

Accumulating evidence supports the role of the ECS in a crucial phase of the addiction cycle, that is, relapse to drug-seeking after a period of abstinence. Animal stud-ies have shown that a priming with CB1R agonists re-instates not only the extinguished cannabinoid-seeking, but also cocaine-, heroin-, and alcohol-seeking, while reinstatement of cannabinoid-, heroin-, nicotine-, and methamphetamine-seeking is prevented by blockade of CB1Rs ( Fattore, Fadda, & Fratta, 2007 ). Notably, a recent study reported that SR, either alone or coadministered with a priming dose of any of the MDMA, reinstated MDMA-induced CPP. Conversely, WIN had no effect on CPP reinstatement, but potentiated the effects of a subthreshold priming dose of MDMA ( Daza-Losada, Miñarro, Aguilar, & Valverde, 2011 ). Collectively, all these fi ndings supported interactions between the ECS and MDMA regulating either drug-taking or drug-seek-ing behaviors.

The rewarding effects of Δ 9 -THC and MDMA/METH are likely mediated through a common neurochemical system, that is, the mesocorticolimbic pathway. In fact, MDMA raises DA levels by different mechanisms, while cannabinoids infl uence the synthesis, release, and turn-over of DA. In addition, cannabinoid and dopamine re-ceptor expression overlaps in some brain areas, includ-ing the nucleus accumbens. Finally, the ECS modulates DAergic transmission by controlling excitatory and in-hibitory inputs on dopaminergic neurons. Both cannabi-noids and MDMA also modify the glutamatergic system in areas involved in reward and addiction ( Maldonado, Valverde, & Berrendero, 2006 ).

A plethora of data obtained from animal models has shown that administration of high or repeated doses of MDMA and METH results in neurotoxicity to the sero-toninergic or dopaminergic system. MDMA neurotoxic-ity is species-dependent, as in rats and monkeys MDMA mostly affects the serotoninergic pathway, while in mice it targets the dopaminergic one. As revealed by biochem-ical, histological and immunohistochemical analyses (see the Section “ALS Pharmacology”), administration of high or repeated doses of MDMA or METH causes long-lasting depletion of 5HT and DA in several brain regions.

In association with these neurotoxic effects on the DAergic and 5HTergic systems, binge METH regimens also cause cognitive and behavioral alterations similar to those observed in METH abusers ( Marshall, Belcher, Feinstein, & O’Dell, 2007 ). Recently, our group demon-strated long-term memory defi cits and startle respon-siveness (index of pathological anxiety) in adult rats, as well as loss of DAergic and 5HTergic brain terminals, following a METH binge neurotoxic regimen ( Bortolato, Frau, Piras, & Luesu, 2009 ). Moreover, the same neu-rotoxic METH treatment upregulated CB1R expres-sion in brain regions that play an important role in the

regulation of emotional and cognitive responses, includ-ing the medial prefrontal cortex, striatum, basolateral amygdala, and hippocampal formation ( Bortolato, Frau, Bini, & Luesu, 2010 ).

MDMA-induced neurotoxicity is associated with functional defi cits, such as the loss of the ability to ther-moregulate, and alterations in locomotor activity in rats ( Capela et al., 2009 ).

The ECS exerts either protective or toxic properties in several in vitro and in vivo models of neuronal injury and neurodegenerative pathologies, including gluta-mate excitotoxicity, hypoxia, ischemic stroke, brain trau-ma, oxidative stress, Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease ( Fernández-Ruiz, García, Sagredo, & Gómez-Ruiz, 2010 ).

Given the frequent coabuse of Δ 9 -THC and MDMA in humans (see Section “Introduction”), their interaction in MDMA-induced neurotoxicity has also been investigat-ed in terms of neurotoxicity.

Coadministration of Δ 9 -THC and CP55940 prevented MDMA-induced hyperthermia, hyperlocomotion, and long-term increase in anxiety measured in the emergence test, but not in the social interaction test in rats ( Morley, Li, Hunt, & Mallet, 2004 ). Accordingly, pretreatment with 3 mg/kg of Δ 9 -THC, considered a dose equivalent to that consumed by moderate cannabis users, prevented MDMA-induced hyperthermia in mice receiving a neu-rotoxic regimen of MDMA ( Touriño et al., 2010 ). This hyperthermic effect was blocked by the CB1R antago-nist AM251 and absent in CB1-KO mice, while neither a CB2R antagonist nor deletion of the CB2R gene abolished Δ 9 -THC’s preventive effect on hyperthermia. Moreover, MDMA-induced microglial and astrocyte activation was abolished by Δ 9 -THC in wild-type mice, and partially at-tenuated in CB2-KO mice, while Δ 9 -THC had no effect in CB1-KO and double CB1/CB2-KO mice. Recently, it was demonstrated that an ultra-low dose of Δ 9 -THC protects mice from various insults, including ecstasy-induced neurotoxicity and cognitive defi cits. This protective effect was long-lasting, and accompanied by increased levels of pCREB (phosphorylated cAMP response element-binding protein) and BDNF (brain-derived neurotroph-ic factor) in some brain areas ( Fishbein, Gov, Assaf, & Gafni, 2012 ). Altogether, these fi ndings suggest that Δ 9 -THC protects an animal from MDMA-neurotoxicity by lowering body temperature and neuroinfl ammation through both CB1 and CB2Rs.

Chronic administration of Δ 9 -THC during adolescence attenuated MDMA-induced hyperthermia, and blunted some behavioral MDMA-induced effects ( Shen, Ali, & Meyer, 2011 ). Additionally, Δ 9 -THC prevented MDMA-induced decreases in exploratory behavior, and reduc-tions in 5HT and SERT levels in the striatum, frontal, and parietal cortex, suggesting that chronic coadministra-tion during adolescence might provide some protection

C0330.indd 106C0330.indd 106 14/12/16 2:43 PM14/12/16 2:43 PM

ALS + CANNABIS e107

IV. CANNABIS, ORGANS, TISSUES AND NON-CNS ASPECTS

against MDMA-neurotoxicity. Indeed, chronic treatment with Δ 9 -THC and MDMA during adolescence produced sex-dependent long-lasting molecular, behavioral, and endocrine-effects, along with modifi cations of astrocytes, microglia reactive markers, CB1R, and SERT expression. Specifi cally, coadministration of Δ 9 -THC and MDMA im-paired working memory in female rats, and attentional capabilities in both sexes, more severely than when ad-ministered alone. Moreover, both drugs—either sepa-rately or in combination—induced increases in reactive microglia cells, suggesting that chronic administration of these drugs might account for persistent modifi cations of microglia reactivity.

As regards the METH + cannabis association, only two groups, including ours, have investigated the abil-ity of the ECS to prevent METH-induced neurotoxicity in rats and mice ( Castelli et al., 2014 ; Nader, Rapino, Gennequin, & Chavant, 2014 ). Specifi cally, pre- and posttreatment with Δ 9 -THC reduced overexpression of nNOS and astrogliosis in the caudate-putamen and pre-frontal cortex, respectively, in rats exposed to a neuro-toxic regimen of METH. SR reversed the neuroprotective effects of Δ 9 -THC on METH-induced nNOS expression, while it failed to counteract the effect of Δ 9 -THC on de-creasing METH-induced astrogliosis. Our fi ndings indi-cate that Δ 9 -THC prevents METH-induced neurotoxicity through inhibition of nNOS and astrogliosis via both CB1 receptor-dependent and -independent mechanisms ( Castelli et al., 2014 ). According to this, it has been re-ported that Δ 9 -THC, URB597, and JZL184 (inhibitors of degradation of anandamide and 2-arachidonoyl glycer-ol, respectively) attenuated the decrease in TH levels in the striatum, demonstrating that, in mice, stimulation of the ECS reduced METH neurotoxicity to dopaminergic terminals ( Nader et al., 2014 ).

As concerns cathinone derivatives, no animal stud-ies are currently available on the concomitant use of cannabis.

Human Studies

In contrast to basic research, human studies investi-gating acute and long-term effects of the consumption of cannabis + MDMA are limited and often contradic-tory. When consumed acutely, cannabis can enhance MDMA-induced subjective effects and counteract ad-verse MDMA effects, such as fatigue, insomnia, reduced appetite, irritability, panic attacks, visual hallucinations, and paranoid delusions that appear when “coming off” MDMA. As previously demonstrated in animals ( Morley et al., 2004 ), cannabis can also acutely attenuate body temperature in dance club recreational ecstasy us-ers ( Parrott et al., 2007 ).

Both drugs taken alone may have detrimental ef-fects on memory and cognition ( Parrott, 2013 ; Solowij,

Stephens, Roffman, & Babor, 2002 ), and when taken to-gether can determine neurocognitive defi cits in several domains. Noteworthy, while in animal studies MDMA increases oxidative stress, cannabinoids have antioxida-tive and antiinfl ammatory properties, supporting the idea that cannabinoids might also have neuroprotective effects against MDMA-neurotoxicity in humans.

The literature on the long-term effects of each sub-stance and/or their combination on cognitive functions, memory, mood, and impulsivity is inconsistent. Indeed, several reports demonstrated that defi cits in memory, learning, or verbal fl uency, as well as self-reported psy-chopathological problems such as depression, anxiety, paranoid ideation, and obsessive-compulsive behavior are mainly associated with cannabis use, rather than with ecstasy ( Gouzoulis-Mayfrank & Daumann, 2006 ).

However, other studies revealed a clear relationship between neuropsychobiological defi cits and MDMA use, rather than cannabis use, that is, memory/cognitive defi cits were related to ecstasy, but not to cannabis use. Indeed, higher self-rated psychiatric symptoms were reported in both light and heavy ecstasy polydrug us-ers than in the control group that included cannabis us-ers ( Parrott, 2006 ). Several factors might explain these confl icting fi ndings, including the relative use of can-nabis and ecstasy, the amount of each drug used (heavy versus light users), and the psychobiological function examined. MDMA and cannabis may also infl uence dif-ferent cognitive aspects, that is, cannabis use has been associated with everyday memory problems, while MDMA use accentuates prospective memory problems ( Parrott, 2006 ).

As regards the potential neuroprotective effect of can-nabis on ecstasy users, cannabis + MDMA users were found to have fewer psychobiological problems (ie, lower rates of anger, hostility, depression, and nega-tive symptoms) than noncannabis users ( Gouzoulis-Mayfrank & Daumann, 2006 ). Moreover, altered brain activation and poor working performance were detected in MDMA users, and the concomitant use of cannabis was suggested to improve the MDMA-induced altera-tions ( Parrott, 2006 ). Notably, coadministration of these two drugs did not worsen cognitive impairments in-duced by either drug ( Dumont, van Hasselt, de Kam, & Van Gerven, 2011 ).

Despite the wide consumption of METH + cannabis, only a few clinical studies have investigated the interac-tions between these two drugs, and their acute and long-lasting effects.

A positron emission tomography study showed that the combined use of these two drugs caused reduced re-gional cerebral glucose metabolism in the frontal, tem-poral, and striatal brain areas of METH + marijuana (MJ) users during completion of a continuous performance task, in comparison to individuals that abused METH

C0330.indd 107C0330.indd 107 14/12/16 2:43 PM14/12/16 2:43 PM

e108 e10. CANNABIS AND THE USE OF AMPHETAMINE-LIKE SUBSTANCES

IV. CANNABIS, ORGANS, TISSUES AND NON-CNS ASPECTS

alone, but no differences were observed in continuous performance task accuracy between the two groups ( Gouzoulis-MayFrank & Daumann, 2006 ). Accordingly, cognitive functioning in several ability areas (ie, verbal fl uency, abstraction/executive functioning, attention/working memory, learning, and delayed recall/retention) in METH + MJ were found not to differ signif-icantly from the control group, or METH users without a history of MJ dependence ( Gonzalez et al., 2004 ). Re-cently, decreased frontal N-acetylaspartyl glutamate lev-els, an indicator of intact neuronal integrity, were found in adolescents using METH + MJ, compared to healthy controls and METH groups, supporting the idea that concomitant heavy cannabis and METH use may induce neurotoxicity in the adolescent brain ( Sung, Carey, Stein, & Ferrett, 2013 ).

Further clinical and preclinical studies are needed to clarify if concurrent use of cannabis and MDMA/METH worsens or improves neurocognitive functions.

Finally, a paucity of clinical data are available on the effects of cathinone derivatives given alone or in combi-nation with cannabis. In humans, cathinones induce pri-marily stimulant effects such as euphoria, elevated mood, mental stimulation, intensifi cation of sensory sensations, increased energy and sociability, empathy connection, and decreased inhibition ( Prosser & Nelson, 2012 ). How-ever, high doses of cathinones lead to hallucinations, paranoia, agitation, self-mutilation, psychosis, tachycar-dia, increased blood pressure, and hemorrhage.

Chronic khat use is associated with impaired inhibito-ry control, and long-term use of cathinone is associated with dysfunctions in the prefrontal cortex, and reduced DA levels in the striatum ( Colzato, Ruiz, van den Wildenberg, & Bajo, 2011 ). Even before clubbing (and af-ter recent drug use), mephedrone users performed worse than nonusers on cognitive tasks and, contrary to con-trols, showed decreased performance in verbal learning and fl uency ( Herzig, Brooks, & Mohr, 2013 ). Yet, when subjects were analyzed for their use of other drugs or preexisting factors, it turned out that prior polydrug use (cannabis + alcohol in particular, but also AMPH) and related psychological traits (depression) were likely to affect cognitive functioning in the sample studied.

The presence of some of these substances was de-tected through surveys/questionnaires, studies on drug samples and biological fl uids, and case reports. In one in-stance, a driver stopped by offi cers of the Massachusetts State Police and subjected to blood sample analysis re-vealed the presence of clonazepam, 7-aminoclonazepam, carboxy-THC, diphenhydramine, and MDMA ( Elian & Hackett, 2014 ). The analysis of fl uid body samples ob-tained from suspected NPS intoxication cases detected synthetic cannabinoids of the JHW series and cathinones (methylone, butylone, mephedrone, fl ephedrone, and

methcathinone), often present in combinations of two or more drugs ( Papaseit, Farrè, Schifano, & Torrens, 2014 ). Most worrisome, the recent trend seems to be to mix different types of designer drugs like cathinones (stim-ulants) or tryptamines (hallucinogens) with synthetic cannabinoids.

MINI-DICTIONARY

Amphetamine-like substances Although there are a variety of amphetamines, in this chapter, amphetamine-like substances (ALS) stands for amphetamine (AMPH), methamphetamine (METH), 3,4-methylenedioxymethamphetamine (MDMA), and cathinones. The fi rst three compounds are frequently coabused with cannabis, while cathinones are the most popular new psychoactive substances (NPS). Chatinone 2-amino-1-phenylpropanone, a natural compound of the khat plant. Drug addiction A chronic, relapsing brain disease that causes compulsive drug-seeking and use, despite harmful consequences to the drug addict and those around them. Dopamine A monoamine neurotransmitter. In particular, the mesolimbic dopamine system that projects from the ventral tegmental area to the nucleus accumbens has been implicated in the rewarding effects of drugs of abuse. Ecstasy or MDMA This drug is a phenylethylamine, a molecule that belongs to the group of synthetic derivatives of methamphetamine. It is an illegal drug, synthesized for the fi rst time in 1912, with a prevailing action on the serotonergic system. NPS A new psychoactive substance is defi ned as a new narcotic or psychotropic drug, in pure form or in preparation. Polydrug use A common phenomenon defi ned as the consumption of more than one drug during a specifi c time period. Reward system The brain circuit that controls an individual’s response to natural rewarding stimuli, such as food, sex, and social interaction.

References Baumann , M. H. , Ayestas , M. A. , Jr. , Partilla , J. S. , Sink , J. R. , et al. ( 2012 ) .

The designer methcathinone analogs, mephedrone and methylone, are substrates for monoamine transporters in brain tissue . Neuro-psychopharmacology , 37 , 1192 – 1203 .

Black , D. L. , Cawthon , B. , Robert , T. , Moser , F. , et al. ( 2009 ) . Multiple drug ingestion by ecstasy abusers in the United States . Journal of Analytical Toxicology , 33 , 143 – 147 .

Bortolato , M. , Frau , R. , Piras , A. P. , Luesu , W. , et al. ( 2009 ) . Metham-phetamine induces long-term alterations in reactivity to environ-mental stimuli: correlation with dopaminergic and serotonergic toxicity . Neurotoxicity Research , 15 , 232 – 245 .

Bortolato , M. , Frau , R. , Bini , V. , Luesu , W. , et al. ( 2010 ) . Methamphet-amine neurotoxicity increases brain expression and alters behav-ioral functions of CB 1 cannabinoid receptors . Journal of Psychiatric Research , 44 , 944 – 955 .

Capela , J. P. , Carmo , H. , Remião , F. , Bastos , M. L. , et al. ( 2009 ) . Molecu-lar and cellular mechanisms of ecstasy-induced neurotoxicity: an overview . Molecular Neurobiology , 39 , 210 – 271 .

Carroll , F. I. , Blough , B. E. , Mascarella , S. W. , Navarro , H. A. , et al. ( 2010 ) . Synthesis and biological evaluation of bupropion analogues as potential pharmacotherapies for smoking cessation . Journal of Medicinal Chemistry , 53 , 2204 – 2214 .

C0330.indd 108C0330.indd 108 14/12/16 2:43 PM14/12/16 2:43 PM

IV. CANNABIS, ORGANS, TISSUES AND NON-CNS ASPECTS

REFERENCES e109

Castelli, M.P., Madeddu, C., Casti, A., Casu, A., et al. (2014) Δ 9-tetrahydrocannabinol prevents methamphetamine-induced neurotoxicity. PLoS One . 20, 9(5):e98079.

Colzato , S. L. , Ruiz , M. J. , van den Wildenberg , W. P. M. , Bajo , M. T. , et al. ( 2011 ) . Long-term effects of chronic khat use: impaired inhibi-tory control . Frontiers in Psychology , 219 , 1 – 5 .

Daza-Losada , M. , Miñarro , J. , Aguilar , M. A. , Valverde , O. , et al. ( 2011 ) . Acute blockade of CB1 receptor leads to reinstatement of MDMA-induced conditioned place preference . Pharmacology Biochemistry and Behavior , 100 , 33 – 39 .

Dumont , G. J. , van Hasselt , J. G. , de Kam , M. , Van Gerven , J. M. , et al. ( 2011 ) . Acute psychomotor, memory and subjective effects of MDMA and THC co-administration over time in healthy volun-teers . Journal of Psychopharmacology , 25 , 478 – 489 .

Elian , A. A. , & Hackett , J. ( 2014 ) . A polydrug intoxication involving methoxetamine in a drugs and driving case . Journal of Forensic Sci-ences , 59 , 854 – 858 .

ESPAD (2000). The 1999 alcohol and other drug use among students in 30 Eruropean countries, Swedish council for information on al-cohol and other drugs (CAN). The Pompidou group of the Council of Europe.

Fattore , L. , Fadda , P. , & Fratta , W. ( 2007 ) . Endocannabinoid regulation of relapse mechanisms . Pharmacological Research , 5 , 418 – 427 .

Fernández-Ruiz , J. , García , C. , Sagredo , O. , Gómez-Ruiz , M. , et al. ( 2010 ) . The endocannabinoid system as a target for the treatment of neuronal damage . Expert Opinion in Therapeutic Targets , 14 , 387 – 404 .

Fishbein , M. , Gov , S. , Assaf , F. , Gafni , M. , et al. ( 2012 ) . Long-term behavioral and biochemical effects of an ultra-low dose of Δ 9-tetrahydrocannabinol (THC): neuroprotection and ERK signal-ing . Experimental Brain Research , 221 , 437 – 448 .

Fleckenstein , A. E. , Volz , T. J. , Riddle , E. L. , Gibb , J. W. , et al. ( 2007 ) . New insights into the mechanism of action of amphetamines . An-nual Reviews of Pharmacology and Toxicology , 47 , 681 – 698 .

Gonzalez , R. , Rippeth , J. D. , Carey , C. L. , Heaton , R. K. , et al. ( 2004 ) . Neurocognitive performance of methamphetamine users discor-dant for history of marijuana exposure . Drug and Alcohol Depen-dence , 76 , 181 – 190 .

Gouzoulis-Mayfrank , E. , & Daumann , J. ( 2006 ) . The confounding prob-lem of polydrug use in recreational ecstasy/MDMA users: a brief overview . Journal of Psychopharmacology , 20 , 188 – 193 .

Green , B. , Kavanagh , D. , & Young , R. ( 2003 ) . Being stoned: a review of self-reported cannabis effects . Drug and Alcohol Reviews , 22 , 453 – 460 .

Halpin , L. E. , Collins , S. A. , & Yamamoto , B. K. ( 2014 ) . Neurotoxicity of methamphetamine and 3,4-methylenedioxymethamphetamine . Life Sciences , 97 , 37 – 44 .

Herzig , D. A. , Brooks , R. , & Mohr , C. ( 2013 ) . Inferring about individual drug and schizotypy effects on cognitive functioning in polydrug using mephedrone users before and after clubbing . Human Psycho-pharmacology , 28 , 168 – 182 .

Krasnova , I. N. , & Cadet , J. L. ( 2009 ) . Methamphetamine toxicity and messengers of death . Brain Research Reviews , 60 , 379 – 407 .

Maldonado , R. , Valverde , O. , & Berrendero , F. ( 2006 ) . Involvement of the endocannabinoid system in drug addiction . Trends in Neurosci-ence , 29 , 225 – 232 .

Manzanedo , C. , Rodríguez-Arias , M. , Daza-Losada , M. , Maldonado , C. , et al. ( 2010 ) . Effect of the CB1 cannabinoid agonist WIN 55212-2 on the acquisition and reinstatement of MDMA-induced conditioned place preference in mice . Behavior and Brain Function , 22 , 6 – 19 .

Marshall , J. F. , & O’Dell , S. J. ( 2012 ) . Methamphetamine infl uences on brain and behavior: unsafe at any speed? Trends in Neuroscience , 35 , 536 – 545 .

Marshall , J. F. , Belcher , A. M. , Feinstein , E. M. , & O’Dell , S. J. ( 2007 ) . Methamphetamine-induced neural and cognitive changes in ro-dents . Addiction , 102 , 61 – 69 .

Mohamed , W. M. , Ben Hamida , S. , Cassel , J. C. , de Vasconcelos , A. P. , et al. ( 2011 ) . MDMA: interactions with other psychoactive drugs . Pharmacology Biochemistry and Behavior , 99 , 759 – 774 .

Morley , K. C. , Li , K. M. , Hunt , G. E. , Mallet , P. E. , et al. ( 2004 ) . Cannabinoids prevent the acute hyperthermia and partially protect against the 5HT depleting effects of MDMA(“Ecstasy”) in rats . Neu-ropharmacology , 46 , 954 – 965 .

Nader , J. , Rapino , C. , Gennequin , B. , Chavant , F. , et al. ( 2014 ) . Prior stimulation of the endocannabinoid system prevents methamphetamine-induced dopaminergic neurotoxicity in the striatum through activation of CB(2) receptors . Neuropharmacology , 5 , pii: S0028-3908 .

NSDUH (2010). Results from the 2009 National Survey on Drug use and Health. Summary of National Findings, volume 1, n2010 (september 2010). http://www.oas.samhsa.gov/NSDUH

Paillet-Loilier , M. , Cesbron , A. , Le Boisselier , R. , Bourgine , et al. ( 2014 ) . Emerging drugs of abuse: current perspectives on substituted cathi-nones . Substance Abuse and Rehabilitation , 5 , 37 – 52 .

Panenka , W. J. , Procyshyn , R. M. , Lecomte , T. , MacEwan , G. W. , et al. ( 2013 ) . Methamphetamine use: a comprehensive review of molecu-lar, preclinical and clinical fi ndings . Drug and Alcohol Dependence , 129 , 167 – 179 .

Papaseit , E. , Farrè , M. , Schifano , F. , & Torrens , M. ( 2014 ) . Emerging drugs in Europe . Current Opinion in Psychiatry , 27 , 243 – 250 .

Parrott , A. C. ( 2006 ) . MDMA in humans: factors which affect the neu-ropsychobiological profi les of recreational ecstasy users, the inte-grative role of bioenergetic stress . Journal of Psychopharmacology , 20 , 147 – 163 .

Parrott , A. C. ( 2013 ) . Human psychobiology of MDMA or ‘Ecstasy’: an overview of 25 years of empirical research . Human Psychopharmacol-ogy, Clinical and Experimental , 28 , 289 – 307 .

Parrott , A. C. , Milani , R. M. , Gouzoulis-Mayfrank , E. , & Daumann , J. ( 2007 ) . Cannabis and Ecstasy/MDMA (3,4-methylenedioxymeth-amphetamine): an analysis of their neuropsychobiological inter-actions in recreational users . Journal of Neural Transmission , 114 , 959 – 968 .

Prosser , J. M. , & Nelson , L. S. ( 2012 ) . The toxicology of bath salts: a review of synthetic cathinones . Journal of Medical Toxicology , 8 , 33 – 42 .

Robledo , P. , Trigo , J. M. , Panayi , F. , de la Torre , R. , et al. ( 2007 ) . Be-havioural and neurochemical effects of combined MDMA and THC administration in mice . Psychopharmacology , 195 , 255 – 264 .

Sala , M. , & Braida , D. ( 2005 ) . Endocannabinoids and 3,4-methylene-dioxymethamphetamine (MDMA) interaction . Pharmacology Bio-chemistry and Behavior , 81 , 407 – 416 .

SAMHSA . ( 2013 ) . Substance Abuse and Mental Health Services Adminis-tration, Results from the 2012 National Survey on Drug Use and Health: Summary of National Findings, NSDUH Series H-46, HHS Publication No. (SMA) 13-4795 . Rockville, MD : Substance Abuse and Mental Health Services Administration .

Schulz , S. ( 2011 ) . MDMA & cannabis: a mini-review of cognitive, be-havioral, and neurobiological effects of co-consumption . Current Drug Abuse Reviews , 4 , 81 – 86 .

Shen , E. Y. , Ali , S. F. , & Meyer , J. S. ( 2011 ) . Chronic administration of THC prevents the behavioral effects of intermittent adoles-cent MDMA administration and attenuates MDMA-induced hyperthermia and neurotoxicity in rats . Neuropharmacology , 61 , 1183 – 1192 .

Solowij , N. , Stephens , R. , Roffman , R. A. , & Babor , T. ( 2002 ) . Does marijuana use cause long-term cognitive defi cits? JAMA , 287 , 2653 – 2654 .

Strote , J. , Lee , J. E. , & Wechsler , H. ( 2002 ) . Increasing MDMA use among college students: results of a national survey . Journal of Adolescent Health , 30 , 64 – 72 .

C0330.indd 109C0330.indd 109 14/12/16 2:43 PM14/12/16 2:43 PM

e110 e10. CANNABIS AND THE USE OF AMPHETAMINE-LIKE SUBSTANCES

IV. CANNABIS, ORGANS, TISSUES AND NON-CNS ASPECTS

Sulzer , D. , Sonders , M. S. , Poulsen , N. W. , & Galli , A. ( 2005 ) . Mecha-nisms of neurotransmitter release by amphetamines: a review . Prog-ress in Neurobiology , 75 , 406 – 433 .

Sung , Y. H. , Carey , P. D. , Stein , D. J. , Ferrett , H. L. , et al. ( 2013 ) . De-creased frontal N-acetylaspartate levels in adolescents concurrently using both methamphetamine and marijuana . Behavior and Brain Research , 246 , 154 – 161 .

Touriño , C. , Ledent , C. , Maldonado , R. , & Valverde , O. ( 2008 ) . CB1 can-nabinoid receptor modulates 3,4-methylenedioxymethamphetamine acute responses and reinforcement . Biological Psychiatry , 63 , 1030 – 1038 .

Touriño , C. , Zimmer , A. , & Valverde , O. ( 2010 ) . THC Prevents MDMA neurotoxicity in mice . PLoS One , 5 , 9143 .

United Nations Offi ce on Drugs and Crime, UNODC (2010). World Drug Report. United Nations Publication.

United Nations Offi ce on Drugs and Crime, UNODC (2014). World Drug Report. United Nations Publication.

Wish , E. D. , Fitzelle , D. B. , O’Grady , K. E. , Hsu , M. H. , et al. ( 2006 ) . Evidence for significant polydrug use among ecstasy-using college students . Journal of the American College Health , 55 , 99 – 104 .

C0330.indd 110C0330.indd 110 14/12/16 2:43 PM14/12/16 2:43 PM