Immune and glial cell alterations in the rat brain after repeated exposure to the synthetic cannabinoid JWH-018.

The use of synthetic cannabinoid receptor agonists (SCRAs) poses major psychiatric risks. We previously showed that repeated exposure to the prototypical SCRA JWH-018 induces alterations in dopamine (DA) transmission, abnormalities in the emotional state, and glial cell activation in the mesocorticolimbic DA circuits of rats. Despite growing evidence suggesting the relationship between substance use disorders (SUD) and neuroinflammation, little is known about the impact of SCRAs on the neuroimmune system. Here, we investigated whether repeated JWH-018 exposure altered neuroimmune signaling, which could be linked with previously reported central effects. Adult male Sprague-Dawley (SD) rats were exposed to JWH-018 (0.25 mg/kg, i.p.) for fourteen consecutive days, and the expression of cytokines, chemokines, and growth factors was measured seven days after treatment discontinuation in the striatum, cortex, and hippocampus. Moreover, microglial (ionized calcium-binding adaptor molecule 1, IBA-1) and astrocyte (glial fibrillary acidic protein, GFAP) activation markers were evaluated in the caudate-putamen (CPu). Repeated JWH-018 exposure induces a perturbation of neuroimmune signaling specifically in the striatum, as shown by increased levels of cytokines [interleukins (IL) -2, -4, -12p70, -13, interferon (IFN) γ], chemokines [macrophage inflammatory protein (MIP) -1α, -3α], and growth factors [macrophage colony-stimulating factor (M-CSF), vascular endothelial growth factor (VEGF)], together with increased IBA-1 and GFAP expression in the CPu. JWH-018 exposure induces persistant brain region-specific immune alterations up to seven days after drug discontinuation, which may contribute to the behavioral and neurochemical dysregulations in striatal areas that play a role in the reward-related processes that are frequently impaired in SUD.

Characterization Of The Neurochemical And Behavioral Effects Of The Phenethylamine 2-Cl-4,5-Mdma In Adolescent And Adult Male Rats.

BACKGROUND: The proliferation of Novel Psychoactive Substances (NPS) in the drug market raises concerns about uncertainty on their pharmacological profile and the health hazard linked to their use. Within the category of synthetic stimulant NPS, the phenethylamine 2-Cl-4,5-methylenedioxymethamphetamine (2-Cl-4,5-MDMA) has been linked to severe intoxication requiring hospitalization. Thereby, the characterization of its pharmacological profile is urgently warranted. METHODS: By in vivo brain microdialysis in adolescent and adult male rats we investigated the effects of 2-Cl-4,5-MDMA on dopamine (DA) and serotonin (5-HT) neurotransmission in two brain areas critical for the motivational and reinforcing properties of drugs, the nucleus accumbens (NAc) shell and the medial prefrontal cortex (mPFC). Moreover, we evaluated the locomotor and stereotyped activity induced by 2-Cl-4,5-MDMA, and the emission of 50-kHz ultrasonic vocalizations (USVs) to characterize its affective properties. RESULTS: 2-Cl-4,5-MDMA increased dialysate DA and 5-HT in a dose-, brain area-, and age-dependent manner. Notably, 2-Cl-4,5-MDMA more markedly increased dialysate DA in the NAc shell and mPFC of adult than adolescent rats, while the opposite was observed on dialysate 5-HT in the NAc shell, with adolescent rats being more responsive. Furthermore, 2-Cl-4,5-MDMA stimulated locomotion and stereotyped activity in both adolescent and adult rats, although to a greater extent in adolescents. Finally, 2-Cl-4,5-MDMA did not stimulate 50-kHz USV emissions. CONCLUSIONS: This is the first pharmacological characterization of 2-Cl-4,5-MDMA demonstrating that its neurochemical and behavioral effects may differ between adolescence and adulthood. These preclinical data could help understanding the central effects of 2-Cl-4,5-MDMA, by increasing awareness on possible health damage in users.

Brief exposure to enriched environment rapidly shapes the glutamate synapses in the rat brain: A metaplastic fingerprint.

Environmental enrichment (EE) has been shown to produce beneficial effects in addiction disorders; however, due to its configurational complexity, the underlying mechanisms are not yet fully elucidated. Recent evidence suggests that EE, acting as a metaplastic agent, may affect glutamatergic mechanisms underlying appetitive memory and, in turn, modulate reward-seeking behaviours: here, we have investigated such a possibility following a brief EE exposure. Adult male Sprague-Dawley rats were exposed to EE for 22 h and the expression of critical elements of the glutamate synapse was measured 2 h after the end of EE in the medial prefrontal cortex (mPFC), nucleus accumbens (NAc) and hippocampus (Hipp) brain areas, which are critical for reward and memory. We focused our investigation on the expression of NMDA and AMPA receptor subunits, their scaffolding proteins SAP102 and SAP97, vesicular and membrane glutamate transporters vGluT1 and GLT-1, and critical structural components such as proteins involved in morphology and function of glutamatergic synapses, PSD95 and Arc/Arg3.1. Our findings demonstrate that a brief EE exposure induces metaplastic changes in glutamatergic mPFC, NAc and Hipp. Such changes are area-specific and involve postsynaptic NMDA/AMPA receptor subunit composition, as well as changes in the expression of their main scaffolding proteins, thus influencing the retention of such receptors at synaptic sites. Our data indicate that brief EE exposure is sufficient to dynamically modulate the glutamatergic synapses in mPFC-NAc-Hipp circuits, which may modulate rewarding and memory processes.

THC and CBD: Villain versus Hero? Insights into Adolescent Exposure.

Cannabis is the most used drug of abuse worldwide. It is well established that the most abundant phytocannabinoids in this plant are Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD). These two compounds have remarkably similar chemical structures yet vastly different effects in the brain. By binding to the same receptors, THC is psychoactive, while CBD has anxiolytic and antipsychotic properties. Lately, a variety of hemp-based products, including CBD and THC, have become widely available in the food and health industry, and medical and recreational use of cannabis has been legalized in many states/countries. As a result, people, including youths, are consuming CBD because it is considered "safe". An extensive literature exists evaluating the harmful effects of THC in both adults and adolescents, but little is known about the long-term effects of CBD exposure, especially in adolescence. The aim of this review is to collect preclinical and clinical evidence about the effects of cannabidiol.

3-[3-(Phenalkylamino)cyclohexyl]phenols: Synthesis, biological activity, and in silico investigation of a naltrexone-derived novel class of MOR-antagonists.

The development of novel µ-opioid receptor (MOR) antagonists is one of the main objectives of drug discovery and development. Based on a simplified version of the morphinan scaffold, 3-[3-(phenalkylamino)cyclohexyl]phenol analogs were designed, synthesized, and evaluated for their MOR antagonist activity in vitro and in silico. At the highest concentrations, the compounds decreased by 52% to 75% DAMGO-induced GTPγS stimulation, suggesting that they acted as antagonists. Moreover, Extra-Precision Glide and Generalized-Born Surface Area experiments provided useful information on the nature of the ligand-receptor interactions, indicating a peculiar combination of C-1 stereochemistry and N-substitutions as feasibly essential for MOR-ligand complex stability. Interestingly, compound 9 showed the best experimental binding affinity, the highest antagonist activity, and the finest MOR-ligand complex stability. In silico experiments also revealed that the most promising stereoisomer (1R, 3R, 5S) 9 retained 1,3-cis configuration with phenol ring equatorial oriented. Further studies are needed to better characterize the pharmacodynamics and pharmacokinetic properties of these compounds.

Pharmacological characterization of novel synthetic opioids: Isotonitazene, metonitazene, and piperidylthiambutene as potent µ-opioid receptor agonists.

Recent trends of opioid abuse and related fatalities have highlighted the critical role of Novel Synthetic Opioids (NSOs). We studied the µ-opioid-like properties of isotonitazene (ITZ), metonitazene (MTZ), and piperidylthiambutene (PTB) using different approaches. In vitro studies showed that ITZ and MTZ displayed a higher potency in both rat membrane homogenates (EC50:0.99 and 19.1 nM, respectively) and CHO-MOR (EC50:0.71 and 10.0 nM, respectively) than [D-Ala2, NMe-Phe4, Gly-ol5]-enkephalin (DAMGO), with no difference in maximal efficacy (Emax) between DAMGO and NSOs. ITZ also has higher affinity (Ki:0.06 and 0.05 nM) at the MOR than DAMGO in both systems, whilst MTZ has higher affinity in CHO-MOR (Ki=0.23 nM) and similar affinity in rat cerebral cortex (Ki = 0.22 nM). PTB showed lower affinity and potency than DAMGO. In vivo, ITZ displayed higher analgesic potency than fentanyl and morphine (ED50:0.00156, 0.00578, 2.35 mg/kg iv, respectively); ITZ (0.01 mg/kg iv) and MTZ (0.03 mg/kg iv) reduced behavioral activity and increased dialysate dopamine (DA) in the NAc shell (max. about 200% and 170% over basal value, respectively. Notably, ITZ elicited an increase in DA comparable to that of higher dose of morphine (1 mg/kg iv), but higher than the same dose of fentanyl (0.01 mg/kg iv). In silico, induced fit docking (IFD) and metadynamic simulations (MTD) showed that binding modes and structural changes at the receptor, ligand stability, and the overall energy score of NSOs were consistent with the results of the biological assays.

Adolescent self-administration of the synthetic cannabinoid receptor agonist JWH-018 induces neurobiological and behavioral alterations in adult male mice.

RATIONALE: The use of synthetic cannabinoid receptor agonists (SCRAs) is growing among adolescents, posing major medical and psychiatric risks. JWH-018 represents the reference compound of SCRA-containing products. OBJECTIVES: This study was performed to evaluate the enduring consequences of adolescent voluntary consumption of JWH-018. METHODS: The reinforcing properties of JWH-018 were characterized in male CD1 adolescent mice by intravenous self-administration (IVSA). Afterwards, behavioral, neurochemical, and molecular evaluations were performed at adulthood. RESULTS: Adolescent mice acquired operant behavior (lever pressing, Fixed Ratio 1-3; 7.5 µg/kg/inf); this behavior was specifically directed at obtaining JWH-018 since it increased under Progressive Ratio schedule of reinforcement, and was absent in vehicle mice. JWH-018 IVSA was reduced by pretreatment of the CB1-antagonist/inverse agonist AM251. Adolescent exposure to JWH-018 by IVSA increased, at adulthood, both nestlet shredding and marble burying phenotypes, suggesting long-lasting repetitive/compulsive-like behavioral effects. JWH-018 did not affect risk proclivity in the wire-beam bridge task. In adult brains, there was an increase of ionized calcium binding adaptor molecule 1 (IBA-1) positive cells in the caudate-putamen (CPu) and nucleus accumbens (NAc), along with a decrease of glial fibrillary acidic protein (GFAP) immunoreactivity in the CPu. These glial alterations in adult brains were coupled with an increase of the chemokine RANTES and a decrease of the cytokines IL2 and IL13 in the cortex, and an increase of the chemokine MPC1 in the striatum. CONCLUSIONS: This study suggests for the first time that male mice self-administer the prototypical SCRA JWH-018 during adolescence. The adolescent voluntary consumption of JWH-018 leads to long-lasting behavioral and neurochemical aberrations along with glia-mediated inflammatory responses in adult brains.

Repeated exposure to JWH-018 induces adaptive changes in the mesolimbic and mesocortical dopaminergic pathways, glial cells alterations, and behavioural correlates.

BACKGROUND AND PURPOSE: Spice/K2 herbal mixtures, containing synthetic cannabinoids such as JWH-018, have been marketed as marijuana surrogates since 2004. JWH-018 has cannabinoid CB1 receptor-dependent reinforcing properties and acutely increases dopaminergic transmission selectively in the NAc shell. Here, we tested the hypothesis that repeated administration of JWH-018 (i) modulates behaviour, (ii) affects dopaminergic transmission and its responsiveness to motivational stimuli, and (iii) is associated with a neuroinflammatory phenotype. EXPERIMENTAL APPROACH: Rats were administered with JWH-018 once a day for 14 consecutive days. We then performed behavioural, electrophysiological, and neurochemical evaluation at multiple time points after drug discontinuation. KEY RESULTS: Repeated JWH-018 exposure (i) induced anxious and aversive behaviours, transitory attentional deficits, and withdrawal signs; (ii) decreased spontaneous activity and number of dopamine neurons in the VTA; and (iii) reduced stimulation of dopaminergic transmission in the NAc shell while potentiating that in the NAc core, in response to acute JWH-018 challenge. Moreover, (iv) we observed a decreased dopamine sensitivity in the NAc shell and core, but not in the mPFC, to a first chocolate exposure; conversely, after a second exposure, dialysate dopamine fully increased in the NAc shell and core but not in the mPFC. Finally, selected dopamine brain areas showed (v) astrogliosis (mPFC, NAc shell and core, VTA), microgliosis (NAc shell and core), and downregulation of CB1 receptors (mPFC, NAc shell and core). CONCLUSION AND IMPLICATIONS: Repeated exposure to JWH-018 may provide a useful model to clarify the detrimental effects of recurring use of Spice/K2 drugs.

Metaplastic Effects of Ketamine and MK-801 on Glutamate Receptors Expression in Rat Medial Prefrontal Cortex and Hippocampus.

Ketamine and MK-801 by blocking NMDA receptors may induce reinforcing effects as well as schizophrenia-like symptoms. Recent results showed that ketamine can also effectively reverse depressive signs in patients' refractory to standard therapies. This evidence clearly points to the need of characterization of effects of these NMDARs antagonists on relevant brain areas for mood disorders. The aim of the present study was to investigate the molecular changes occurring at glutamatergic synapses 24 h after ketamine or MK-801 treatment in the rat medial prefrontal cortex (mPFC) and hippocampus (Hipp). In particular, we analyzed the levels of the glutamate transporter-1 (GLT-1), NMDA receptors, AMPA receptors subunits, and related scaffolding proteins. In the homogenate, we found a general decrease of protein levels, whereas their changes in the post-synaptic density were more complex. In fact, ketamine in the mPFC decreased the level of GLT-1 and increased the level of GluN2B, GluA1, GluA2, and scaffolding proteins, likely indicating a pattern of enhanced excitability. On the other hand, MK-801 only induced sparse changes with apparently no correlation to functional modification. Differently from mPFC, in Hipp, both substances reduced or caused no changes of glutamate receptors and scaffolding proteins expression. Ketamine decreased NMDA receptors while increased AMPA receptors subunit ratios, an effect indicative of permissive metaplastic modulation; conversely, MK-801 only decreased the latter, possibly representing a blockade of further synaptic plasticity. Taken together, these findings indicate a fine tuning of glutamatergic synapses by ketamine compared to MK-801 both in the mPFC and Hipp.

Protocols for instrumental memory reconsolidation in rodents: A methodological review.

BACKGROUND: Memory reconsolidation enables the update of a previously consolidated memory trace after its reactivation. Although Pavlovian memory reconsolidation has been widely demonstrated, instrumental memory reconsolidation is still debated. Early studies suggested that instrumental memories did not undergo reconsolidation and therefore could not be disrupted, whereas other authors suggested that these memories are just more resistant to destabilization and reconsolidation in comparison to Pavlovian memories. AIM AND RESULTS: The present paper reviews the behavioral protocols used to investigate appetitive instrumental memory reconsolidation in rodents and describes in detail the specific methods used for memory retrieval, with a critical analysis of the different experimental parameters. CONCLUSIONS: The modalities under which the reconsolidation of appetitive (sucrose or drugs of abuse) instrumental memories occurs have been explored and partially elucidated. Further investigations are recommended on the boundary conditions that constrain instrumental memory reactivation.

Neurophysiological and Neurochemical Effects of the Putative Cognitive Enhancer (S)-CE-123 on Mesocorticolimbic Dopamine System.

Treatments for cognitive impairments associated with neuropsychiatric disorders, such as attention deficit hyperactivity disorder or narcolepsy, aim at modulating extracellular dopamine levels in the brain. CE-123 (5-((benzhydrylsulfinyl)methyl) thiazole) is a novel modafinil analog with improved specificity and efficacy for dopamine transporter inhibition that improves cognitive and motivational processes in experimental animals. We studied the neuropharmacological and behavioral effects of the S-enantiomer of CE-123 ((S)-CE-123) and R-modafinil in cognitive- and reward-related brain areas of adult male rats. In vivo single unit recordings in anesthetized animals showed that (S)-CE-123, but not R-modafinil, dose-dependently (1.25 to 10 mg/kg i.v.) reduced firing of pyramidal neurons in the infralimbic/prelimbic (IL/PrL) cortex. Neither compound the affected firing activity of ventral tegmental area dopamine cells. In freely moving animals, (S)-CE-123 (10 mg/kg i.p.) increased extracellular dopamine levels in the IL/PrL, with different patterns when compared to R-modafinil (10 mg/kg i.p.); in the nucleus accumbens shell, a low and transitory increase of dopamine was observed only after (S)-CE-123. Neither (S)-CE-123 nor R-modafinil initiated the emission of 50-kHz ultrasonic vocalizations, a behavioral marker of positive affect and drug-mediated reward. Our data support previous reports of the procognitive effects of (S)-CE-123, and show a minor impact on reward-related dopaminergic areas.

The metaplastic effects of ketamine on sucrose renewal and contextual memory reconsolidation in rats.

Metaplastic effects of the NMDARs blocker ketamine at the neural and behavioural levels have been described as potential mechanisms underlying the beneficial effects in treatment-resistant depression. However, ketamine effects on addictive behaviours are still unexplored. In the present study, we investigated the effects of ketamine given under a "metaplasticity-inducing dose regimen" on sucrose-related renewal and contextual memory reconsolidation in rats. After a molecular analysis of ketamine modulation of GluN2B, GluA1 and mGluR5 receptors levels in nucleus accumbens, hippocampus and amygdala, two behavioural models were used to investigate ketamine effects: i) context-induced renewal of sucrose-seeking, and ii) sucrose memory reconsolidation. Ketamine was administrated 24 h before the renewal test or the retrieval. At the molecular level, ketamine i) decreased GluN2B, GluA1 and mGluR5 receptors in hippocampus, ii) decreased GluA1 and mGluR5 but increased GluN2B in nucleus accumbens and iii) increased GluN2B and mGluR5 in amygdala. At the behavioural level, ketamine given prior to renewal significantly inhibited responding compared to vehicle, while no significant effects were observed on reconsolidation of contextual memory. In conclusion, the molecular analysis of ketamine metaplastic effects in key brain areas suggest a possible involvement of glutamatergic receptors in the inhibition of sucrose renewal but not of contextual memory reconsolidation. The inhibition of renewal could be correlated to hippocampal and accumbal decreased levels of GluA1 and mGluR5, whereas, the lack of effect on contextual memory reconsolidation could be correlated to decreased GluN2B expression in hippocampus, landmark of destabilization-insensitive state.

The novel psychoactive substance methoxetamine induces persistent behavioral abnormalities and neurotoxicity in rats.

Methoxetamine (MXE) is a novel psychoactive substance that can induce several short-term effects on emotional states and behavior. However, little is known about the persistent emotional and behavioral effects of MXE. Moreover, neurotoxic effects of MXE have been hypothesized, but never demonstrated in vivo. To clarify these issues, rats received repeated treatment with MXE every other day (0.1-0.5 mg/kg, i.p., × 5), and 7 days later they were challenged with MXE (0.1-0.5 mg/kg, i.p.). Behavioral effects of MXE were first evaluated by measuring emission of ultrasonic vocalizations and locomotor activity after each administration. Thereafter, persistent behavioral effects of MXE were evaluated, starting 8 days after challenge, through elevated plus maze, spontaneous alternation, novel object recognition, and marble burying tests. After completion of behavioral analysis, neurotoxic effects of MXE were evaluated by measuring densities of dopamine transporter, tyrosine hydroxylase, and serotonin transporter in various brain regions. Repeated treatment and challenge with MXE affected neither calling behavior nor locomotor activity of rats. Conversely, rats previously treated with MXE exhibited behavioral alterations in the elevated plus maze, marble burying and novel object recognition tests, suggestive of increased anxiety and impaired non-spatial memory. Noteworthy, the same rats displayed dopaminergic damage in the medial prefrontal cortex, nucleus accumbens, caudate-putamen, substantia nigra pars compacta, and ventral tegmental area, along with accumbal serotonergic damage. Our findings show for the first time that repeated administration of MXE induces persistent behavioral abnormalities and neurotoxicity in rats, which can help elucidating the risks associated with human MXE consumption.

Neurochemical and Behavioral Profiling in Male and Female Rats of the Psychedelic Agent 25I-NBOMe.

4-Iodo-2,5-dimethoxy-N-(2-methoxybenzyl)phenethylamine (25I-NBOMe), commonly called "N-Bomb," is a synthetic phenethylamine with psychedelic and entactogenic effects; it was available on the Internet both as a legal alternative to lysergic acid diethylamide (LSD) and as a surrogate of 3,4-methylenedioxy-methamphetamine (MDMA), but now it has been scheduled among controlled substances. 25I-NBOMe acts as full agonist on serotonergic 5-HT2A receptors. Users are often unaware of ingesting fake LSD, and several cases of intoxication and fatalities have been reported. In humans, overdoses of "N-Bomb" can cause tachycardia, hypertension, seizures, and agitation. Preclinical studies have not yet widely investigated the rewarding properties and behavioral effects of this compound in both sexes. Therefore, by in vivo microdialysis, we evaluated the effects of 25I-NBOMe on dopaminergic (DA) and serotonergic (5-HT) transmissions in the nucleus accumbens (NAc) shell and core, and the medial prefrontal cortex (mPFC) of male and female rats. Moreover, we investigated the effect of 25I-NBOMe on sensorimotor modifications as well as body temperature, nociception, and startle/prepulse inhibition (PPI). We showed that administration of 25I-NBOMe affects DA transmission in the NAc shell in both sexes, although showing different patterns; moreover, this compound causes impaired visual responses in both sexes, whereas core temperature is heavily affected in females, and the highest dose tested exerts an analgesic effect prominent in male rats. Indeed, this drug is able to impair the startle amplitude with the same extent in both sexes and inhibits the PPI in male and female rats. Our study fills the gap of knowledge on the behavioral effects of 25I-NBOMe and the risks associated with its ingestion; it focuses the attention on sex differences that might be useful to understand the trend of consumption as well as to recognize and treat intoxication and overdose symptoms.

In Vitro Functional Characterization of GET73 as Possible Negative Allosteric Modulator of Metabotropic Glutamate Receptor 5.

The present study was aimed to further characterize the pharmacological profile of N-[4-(trifluoromethyl) benzyl]-4-methoxybutyramide (GET73), a putative negative allosteric modulator (NAM) of metabotropic glutamate subtype 5 receptor (mGluR5) under development as a novel medication for the treatment of alcohol dependence. This aim has been accomplished by means of a series of in vitro functional assays. These assays include the measure of several down-stream signaling [intracellular Ca++ levels, inositol phosphate (IP) formation and CREB phosphorylation (pCREB)] which are generally affected by mGluR5 ligands. In particular, GET73 (0.1 nM-10 µM) was explored for its ability to displace the concentration-response curve of some mGluR5 agonists/probes (glutamate, L-quisqualate, CHPG) in different native preparations. GET73 produced a rightward shift of concentration-response curves of glutamate- and CHPG-induced intracellular Ca++ levels in primary cultures of rat cortical astrocytes. The compound also induced a rightward shift of concentration response curve of glutamate- and L-quisqualate-induced increase in IP turnover in rat hippocampus slices, along with a reduction of CHPG (10 mM)-induced increase in IP formation. Moreover, GET73 produced a rightward shift of concentration-response curve of glutamate-, CHPG- and L-quisqualate-induced pCREB levels in rat cerebral cortex neurons. Although the engagement of other targets cannot be definitively ruled out, these data support the view that GET73 acts as an mGluR5 NAM and support the significance of further investigating the possible mechanism of action of the compound.

Synthetic cannabinoids: the hidden side of Spice drugs.

Spice drugs are herbal mixtures sprayed with synthetic cannabinoids designed to mimic the psychoactive ingredient in marijuana [Δ-tetrahydrocannabinol (Δ-THC)] and synthesized by introducing modifications to the chemical structure of parental compounds aiming to circumvent legal regulations. Synthetic cannabinoid use/abuse can be devastating as toxicological effects and adverse reactions cannot be entirely predicted and may vary with the dose, route of administration, individual vulnerability and concomitant intake with other drugs. The absence of validated testing procedures in the clinical field makes difficult the adoption of a therapeutic approach effective in coping with the synthetic cannabinoid phenomenon, posing a significant challenge for prevention, treatment and public health in general. The aim of this review is to gain insights into the epidemiological, pharmacological and toxicological properties of synthetic cannabinoids, aiming to provide a reliable background needed for the management of synthetic cannabinoid-related adverse effects. Consumers, competent authorities and medical care professionals should be aware of the risks associated with synthetic cannabinoid use.

4,4'-Dimethylaminorex ("4,4'-DMAR"; "Serotoni") misuse: A Web-based study.

BACKGROUND: 4,4'-DMAR (4,4'-dimethylaminorex; "Serotoni") is a potent stimulant drug that has recently been associated with a number of fatalities in Europe. Over the last few years, online communities have emerged as important resources for disseminating levels of technical knowledge on novel psychoactive substances. OBJECTIVE: Analysing the information provided by the fora communities on 4,4'-DMAR use, additionally critical reviewing the available evidence-based literature on this topic. METHODS: Different website drug fora were identified. A critical review of the existing evidence-based literature was undertaken. Individuation and analysis of qualitative data from the identified website fora were performed. RESULTS: The combined search results identified six website fora from which a range of qualitative data on recurring themes was collected. These themes included routes of administration and doses; desired effects; adverse effects; comparison with other drugs; association with other drugs; medications self-administered to reverse 4,4'-DMAR action; overall impression; and provision of harm-reduction advice. CONCLUSIONS: Although being characterized by a number of methodological limitations, the social networks' Web monitoring approach (netnography) may be helpful to better understand some of the clinical and psychopharmacological issues pertaining to a range of novel psychoactive substances, including 4,4'-DMAR, for which only extremely little, if any, scientific knowledge is available.