α-PVP (“flakka”): a new synthetic cathinone invades the drug arena

α-Pyrrolidinononanophenone derivatives induce differentiated SH-SY5Y neuroblastoma cell apoptosis via reduction of antioxidant capacity: Involvement of NO depletion and inactivation of Nrf2/HO1 signaling pathway

α-Pyrrolidinononanophenone (α-PNP) derivatives are known to be one of the hazardous new psychoactive substances due to the most extended hydrocarbon chains of any pyrrolidinophenones on the illicit drug market. Our previous report showed that 4'-iodo-α-PNP (I-α-PNP) is the most potent cytotoxic compound among α-PNP derivatives and induces apoptosis due to mitochondrial dysfunction and suppression of nitric oxide (NO) production in differentiated human neuronal SH-SY5Y cells. In this study, to clarify the detailed action mechanisms by I-α-PNP, we investigated the mechanism of reactive oxygen species (ROS) -dependent apoptosis by I-α-PNP in differentiated SH-SY5Y with a focus on the antioxidant activities. Treatment with I-α-PNP elicits overproduction of ROS such as H2O2, hydroxyl radical, and 4-hydroxy-2-nonenal, and pretreatment with antioxidant N-acetyl-L-cysteine is attenuated the SH-SY5Y cells apoptosis by I-α-PNP. These results suggested that the overproduction of ROS is related to SH-SY5Y cell apoptosis by I-α-PNP. In addition, I-α-PNP markedly decreased antioxidant capacity in differentiated cells than in undifferentiated cells and inhibited the upregulation of hemeoxygenase 1 (HO1) and glutathione peroxidase 4 (GPX4) expression caused by induction of differentiation. Furthermore, the treatment with I-α-PNP increased the nuclear expression level of BTB Domain And CNC Homolog 1 (Bach1), a transcriptional repressor of Nrf2, only in differentiated cells, suggesting that the marked decrease in antioxidant capacity in differentiated cells was due to suppression of Nrf2/HO1 signaling by Bach1. Additionally, pretreatment with an NO donor suppresses the I-α-PNP-evoked ROS overproduction, HO1 down-regulation, increased nuclear Bach1 expression and reduced antioxidant activity in the differentiated cells. These findings suggest that the ROS-dependent apoptosis by I-α-PNP in differentiated cells is attributed to the inactivation of the Nrf2/HO1 signaling pathway triggered by NO depletion.

A review of synthetic cathinones emerging in recent years (2019-2022)

Purpose

The emergence of novel psychoactive substances (NPS) has been being a continuous and evolving problem for more than a decade. Every year, dozens of new, previously unknown drugs appear on the illegal market, posing a significant threat to the health and lives of their users. Synthetic cathinones are one of the most numerous and widespread groups among NPS. The purpose of this work was to identify and summarize available data on newly emerging cathinones in very recent years.

Methods

Various online databases such as PubMed, Google Scholar, but also databases of government agencies including those involved in early warning systems, were used in search of reports on the identification of newly emerging synthetic cathinones. In addition, threads on various forums created by users of these drugs were searched for reports on the effects of these new substances.

Results

We have identified 29 synthetic cathinones that have been detected for the first time from early 2019 to mid-2022. We described their structures, known intoxication symptoms, detected concentrations in biological material in poisoning cases, as well as the countries and dates of their first appearance. Due to the lack of studies on the properties of the novel compounds, we compared data on the pharmacological profiles of the better-known synthetic cathinones with available information on the newly emerged ones. Some of these new agents already posed a threat, as the first cases of poisonings, including fatal ones, have been reported.

Conclusions

Most of the newly developed synthetic cathinones can be seen as analogs and replacements for once-popular compounds that have been declining in popularity as a result of legislative efforts. Although it appears that some of the newly emerging cathinones are not widely used, they may become more popular in the future and could become a significant threat to health and life. Therefore, it is important to continue developing early warning systems and identifying new compounds so that their widespread can be prevented.

Lowering of brain endothelial cell barrier function by exposure to 4'-iodo-α-pyrrolidinononanophenone

Overuse of pyrrolidinophenones (PPs) is known to cause damage to vascular and central nervous systems, but little is known about its effect on brain endothelial barrier function. In this study, we found that exposure to 4'-iodo-α-pyrrolidinononanophenone (I-α-PNP), one of the most potently cytotoxic PPs, at sublethal concentrations decreases trans-endothelial electrical resistance and increases paracellular permeability across a monolayer of human brain microvascular endothelial cells. Treatment with I-α-PNP also elevated the production of superoxide anion. Furthermore, the treatment reduced the expression and plasma membrane localization of a tight junction protein claudin-5 (CLDN5), which was almost restored by pretreatment with an antioxidant N-acetyl-l-cysteine. These results indicate that I-α-PNP treatment may down-regulate the plasma membrane-localized CLDN5 by elevating the production of reactive oxygen species (ROS). The treatment with I-α-PNP increased the nuclear translocation of Forkhead box protein O1 (FoxO1), an oxidative stress-responsive transcription factor, and pretreating with a FoxO1 inhibitor ameliorated the decrease in CLDN5 mRNA. In addition, I-α-PNP treatment up-regulated the expression and secretion of matrix metalloproteinase-2 (MMP2) and MMP9, and the addition of an MMP inhibitor reversed the degradation of CLDN5 by I-α-PNP. Moreover, I-α-PNP treatment facilitated the activation of 26S proteasome-based proteolytic activity and pretreatment with an inhibitor of 26S proteasome, but not autophagy, suppressed the CLDN5 degradation by I-α-PNP. Accordingly, it is suggested that the down-regulation of CLDN5 by exposure to I-α-PNP is ascribable to suppression of the gene transcription due to FoxO1 nuclear translocation through ROS production and to acceleration both of the MMPs (MMP2 and MMP9)- and 26S proteasome-based proteolysis.

4'-Iodo-α-Pyrrolidinononanophenone Provokes Differentiated SH-SY5Y Cell Apoptosis Through Downregulating Nitric Oxide Production and Bcl-2 Expression

Abuse of pyrrolidinophenone derivatives (PPs) is known to cause severe damage to the central nervous system due to their high lipophilicity. In this study, we compared sensitivity to toxicity elicited by 4'-iodo-α-pyrrolidinononanophenone (I-α-PNP), one of the most potent cytotoxic derivatives among PPs synthesized previously, between SH-SY5Y cells differentiated by all-trans-retinoic acid (ATRA) and the undifferentiated cells, and found that the differentiated cells are more sensitive to I-α-PNP toxicity than the undifferentiated cells. Treatment with I-α-PNP elicited some apoptotic alterations (Bax expression, loss of mitrochondrial membrane potential, and activation of caspases) in the differentiated cells, whose patterns were similar to those in the undifferentiated cells. I-α-PNP treatment resulted in no significant alteration in Bcl-2 expression in the undifferentiated cells, whereas it considerably downregulated the protein expression in the differentiated cells, suggesting that the high I-α-PNP sensitivity of the differentiated cells is mainly due to downregulation of Bcl-2 expression. I-α-PNP treatment decreased nitric oxide (NO) production and neuronal NOS (nNOS) expression in the differentiated cells, and the patterns of I-α-PNP-evoked alterations in phosphorylation of cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) expression were almost the same as that in nNOS expression. Additionally, the addition of an NO donor restored the I-α-PNP-evoked alterations in expressions of Bcl-2, BDNF, and nNOS in the differentiated cells. These findings suggest that the downregulation of Bcl-2 expression by I-α-PNP in differentiated cells is attributed to the acceleration of two negative feedback loops (nNOS/NO/CREB loop and CREB/BDNF loop) triggered by decreased NO production.

Neuropsychopharmacology of Emerging Drugs of Abuse: meta- and para-Halogen-Ring-Substituted α-PVP (“flakka”) Derivatives

Changes in the molecular structure of synthetic cathinones has led to an increase in the number of novel emerging drugs in the illicit drug market at an unprecedented rate. Unfortunately, little is known about the neuropsychopharmacology of recently emerged halogen-substituted α-PVP derivatives. Thus, the aim of this study was to investigate the role of para- and meta-halogen (F-, Cl-, and Br-) substitutions on the in vitro, in silico, and in vivo effects of α-pyrrolidinopentiophenone (α-PVP) derivatives. HEK293 cells expressing the human dopamine or serotonin transporter (hDAT and hSERT) were used for the uptake inhibition and transporter affinity assays. Molecular docking was used to model the interaction mechanism against DAT. Swiss CD-1 mice were used for the horizontal locomotor activity, open field test, and conditioned place preference paradigm. All compounds demonstrated potent DA uptake inhibition and higher DAT selectivity than cocaine. Meta-substituted cathinones showed higher DAT/SERT ratios than their para- analogs, which correlates with an increased psychostimulant effect in vivo and with different meta- and para-in silico interactions at DAT. Moreover, all compounds induced rewarding and acute anxiogenic effects in mice. In conclusion, the present study demonstrates the role of meta- and para-halogen substitutions in the mechanism of action and provides the first evidence of the rewarding and anxiety-like properties of halogenated α-PVP derivatives.

Apoptotic mechanism in human brain microvascular endothelial cells triggered by 4'-iodo-α-pyrrolidinononanophenone: Contribution of decrease in antioxidant properties

In this study, we newly synthesized four α-pyrrolidinononanophenone (α-PNP) derivatives [4'-halogenated derivatives and α-pyrrolidinodecanophenone (α-PDP)], and then performed the structure-cytotoxicity relationship analyses. The results showed the rank order for the cytotoxic effects, α-PNP < α-PDP < 4'-fluoro-α-PNP < 4'-chrolo-α-PNP < 4'-bromo-α-PNP < 4'-iodo-α-PNP (I-α-PNP), and suggest that cytotoxicities of 4'-halogenated derivatives were more intensive than that of elongation of the hydrocarbon chain (α-PDP). We also surveyed the apoptotic mechanism of I-α-PNP in brain microvascular endothelial (HBME) cells that are utilized as the in vitro model of the blood-brain barrier. HBME cell treatment with I-α-PNP facilitated the apoptotic events (caspase-3 activation, externalization of phosphatidylserine, and DNA fragmentation), which were almost completely abolished by pretreating with antioxidants. In addition, the immunofluorescent staining revealed the enhanced production of hydroxyl radical in mitochondria by the I-α-PNP treatment, inferring that the I-α-PNP treatment triggers the apoptotic mechanism dependent on the enhanced ROS production in mitochondria. The treatment with I-α-PNP increased the production of cytotoxic aldehyde 4-hydroxy-2-nonenal and decreased the amount of reduced glutathione. Additionally, the treatment decreased the 26S proteasome-based proteolytic activities and aggresome formation. These results suggest that decrease in the antioxidant properties is also ascribable to HBME cell apoptosis elicited by I-α-PNP.

Analysis of Google Trends to monitor new psychoactive substance. Is there an added value?

The past decade has seen an increase in the development and availability of a broad category of drugs, known as new psychoactive substances (NPS). NPS are challenging for public health authorities, therefore the two major drug monitoring bodies - the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) and the United Nations Office on Drugs and Crime (UNODC) - have implemented the EU Early Warning System (EWS) and Early Warning Advisory (EWA), respectively. While these monitoring systems are informative, it is difficult to keep up with the constant and rapid developmental rate of NPS. The EMCDDA has recognised the need for an alternative and technologically derived early warning system. The aim of this research is to determine whether Google Trends and drug discussion forum data can be used to complement early warning systems for NPS. Forty-eight substances were used in this study and classed into groups based on their chemical structure, following the UNODC classification system. Google Trends data (time range: 2004-2019) and drug forum data (time range: 2003-2018) were extracted for each substance and visual trend profiles were created for class groups as well as individual substances. Analysis was conducted to determine when a substance first appeared on Google Trends and a drug discussion forum as well as their trends over time. This date of first appearance was then compared to the date the substance was first reported to UNODC. Of the three data sources utilised, substances were most likely to appear on Google Trends first. Amongst the different classes of NPS, discernible trends ('block', 'successive', and 'generational' trends) were observed. These trends reflect the evolution of the manufacture of substances or generations of substances that has been observed in the literature. For example, in the synthetic cannabinoids' category, a generational trend is observed that corresponds to the different generations of synthetic cannabinoids. When comparing Google Trends and Drugs-Forum directly, the order of appearance and duration of presence for substances aligns accurately for most classes. Google Trends showed the emergence, persistence, or transient nature of substances, which could direct the focus of law enforcement, health organisation and laboratory resources towards a limited number of substances. When one considers the reliance of individual information seeking on the Web as well as the prominence of NPS on the Web, it becomes clear that Google Trends and drug discussion forums could be used as a complement to current early warning systems.

Flakka: New Dangerous Synthetic Cathinone on the Drug Scene

New psychoactive substances are being used as drugs and appear to be quite popular nowadays. Thanks to their specific properties, these drugs create inimitable experiences for intoxicated people. Synthetic cathinones are the most common compounds in these new drugs. Among them, α-pyrrolidopentadione (α-PVP), or “Flakka” (street name), is one of the most famous cathinone-designed drugs. Similar to other synthetic cathinone drugs, α-PVP can effectively inhibit norepinephrine and dopamine transmitters. The adverse reactions of α-PVP mainly include mania, tachycardia, and hallucinations. An increasing number of people are being admitted to emergency wards due to the consequences of their use. This work mainly summarizes the history, synthesis, pharmacology, toxicology, structure–activity relationship, metabolism, clinical process and health risks, poisoning and death, forensic toxicology, and legal status of α-PVP. We hope this review will help bring more attention to the exploration of this substance in order to raise awareness of its negative impacts on humans.

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Synthetic cathinones: an evolving class of new psychoactive substances

Synthetic cathinones (SCat) are amphetamine-like psychostimulants that emerged onto drug markets as "legal" alternatives to illicit drugs such as ecstasy, cocaine, and amphetamines. Usually they are sold as "bath salts," "plant food," or "research chemicals," and rapidly gained popularity amongst drugs users due to their potency, low cost, and availability. In addition, internet drug sales have been replacing the old way of supplying drugs of abuse, contributing to their rapid spread. Despite the legislative efforts to control SCat, new derivatives continue to emerge on the recreational drugs market and their abuse still represents a serious public health issue. To date, about 150 SCat have been identified on the clandestine drugs market, which are one of the largest groups of new psychoactive substances (NPS) monitored by the United Nations Office on Drugs and Crime and the European Monitoring Center for Drugs and Drug Addiction. Similar to the classical stimulants, SCat affect the levels of catecholamines in the central nervous system, which results in their psychological, behavioral and toxic effects. Generally, the effects of SCat greatly differ from drug to drug and relatively little information is available about their pharmacology. The present work provides a review on the development of SCat as substances of abuse, current patterns of abuse and their legal status, chemical classification, known mechanisms of action, and their toxicological effects.

α-Pyrrolidinopentiophenone ("Flakka") Catalyzing Catatonia: A Case Report and Literature Review

: Synthetic cathinones are a class of novel psychoactive substances. α-Pyrrolidinopentiophenone (α-PVP), or "Flakka", is one of these substances. Users often present acutely psychotic or agitated. We present the case of a 20-year-old male without prior psychiatric history who was brought to the hospital by his family because of increasingly bizarre and erratic behavior after reported ingestion of Flakka. What ensued was a prolonged course of psychosis and severe catatonia. Synthetic cathinones are thought to cause catatonia in approximately 1% of cases. Awareness of the possible presentations associated with α-PVP intoxication is increasingly important and should be further explored, as they can have important implications in setting expectations for care. Additionally, providers should have a low threshold for asking patients about bath salt ingestion.

The Explosion of a New Designer Drug, Flakka: Implications for Practice

There are many challenges facing healthcare professionals. One such challenge is the continuous introduction of new synthetic drugs. Synthetic drugs pose many difficulties to providers, including identification of the drug ingested, management of symptoms, ensuring safety of the patient and his or her environment, and continual monitoring after the initial symptoms, because synthetic cathinones have many long-term effects on an individual. One such synthetic drug, flakka, is a potent second-generation synthetic cathinone. Because flakka inhibits the reuptake of norepinephrine and dopamine, which are involved in one's perception of pleasure, it causes inflated feelings and also causes signs and symptoms of psychosis. Flakka also induces various exaggerated symptoms, such as feelings of incredible strength, disorientation, aggression, and altered thought processes, and also can cause hyperthermia, coma, and death. Healthcare professionals need to understand the nature of flakka ingestion, the various symptoms a user may exhibit, and the long-term symptoms a person may have once the acute recovery phase has ended. Once the initial phase of ingestion is over and the patient is medically stabilized, the patient may experience signs and symptoms of psychosis or other psychiatric disorders. It is paramount that healthcare professionals are able to recognize the signs and symptoms of flakka ingestion, know the steps to take to ensure safety of the patient and those around him or her, and also know how to facilitate the patient's recovery.

A case of synthetic cannabinoid poisoning in Croatia

The number of new psychoactive substances (NPS), synthetic cannabinoids (SCs) in particular, is growing constantly. Because of the insufficiently explored effects on consumer health, they have become a major problem in the emergency departments. They are difficult to identify, and there are no antidotes that could reverse their detrimental effects. We report a case of poisoning of a young man who used SCs. The patient was admitted to the emergency department of the Clinical Hospital Merkur, Zagreb (Croatia) after sniffing and smoking a herbal product bought on the street. He presented with severe cognitive difficulties and visible eye redness. Other symptoms included somnolence, disorientation, loss of coordination, unsteady gait, hyporeflexia, stiffness, cramps and cold limbs, blurred vision, teeth grinding, dry mouth, tinnitus, fear, suicidal thoughts, impaired focus, memory, and speech, sedation, fatigue, depression, thought blocking, and autistic behaviour. His skin was dry, and his mucosa dry and irritated. Herbal products "Rainbow Special" and "Luminated Aroma" used by the patient were qualitatively analysed with gas chromatography / mass spectrometry (GC/MS) after direct extraction with an organic solvent. Solid-phase extraction method was used to analyse serum and urine samples. Despite the negative findings of biological samples, mostly due to the limitations of GC/MS, the clinical picture infallibly pointed to the poisoning with SCs. This was confirmed by the findings of 5-fluoro AMB (methyl 2-(1-(5-fluoropentyl)-1H-indazole-3-carboxamido)-3-methylbutanoate) in the herbal products.

"Marvin, the Paranoid Android": The Case of an Alpha-PVP User in the Expanding Galaxy of NPS

Alpha-PVP can be defined as a novel psychoactive substance (NPS)-more specifically, a novel synthetic cathinone with unpredictable stimulant effects in humans. "Marvin" arrived at a Dual Diagnosis Unit at Parco dei Tigli, Italy. He underwent a 30-day rehabilitation program to overcome his problematic Alpha-PVP use as a psychonaut. We conducted an online search to understand the properties of Alpha-PVP and its presence in scientific literature, reviewing official reports and the online drug market (e.g., fora, webpages). In the Dual Diagnosis Unit, Marvin completed the 30-day rehabilitation program that included assessments and group and individual cognitive behavioral therapy. Alpha-PVP is a synthetic cathinone with stimulant properties, available in the online market but with unpredictable effects in humans. The present case reports an important risk of psychosis in a psychonaut patient who arrived and declared its intense use before admission to our Unit. This article describes the psychopathological effects of the novel compound Alpha-PVP in a psychonaut patient. Patients attending clinics that have used Alpha-PVP pose a new challenge for traditional services of mental health and addiction.

A two fatal cases of poisoning involving new cathinone derivative PV8

α-Pyrrolidinoheptiophenone (PV8) is a representative of α-pyrrolidinophenone derivatives, a new group of synthetic cathinones. PV8 was first detected in illegal products in Japan in 2013. It is closely related to α-pyrrolidinovalerophenone (α-PVP), which was one of the most popular novel psychoactive substance (NPS) in Poland in years 2013-2015. The article presents two cases of fatal poisonings of 36-year-old man and 37-year-old woman, where a new cathinone derivative - PV8 was detected in biological material collected during medicolegal autopsies. The concentration of PV8, measured with LC-MS method, was in the first case - 0.26 µg/mL in blood and 0.11 µg/mL in urine and in the second - 0.07 µg/mL and 0.13 µg/mL, respectively. In both cases medicolegal experts finally have determined that the cause of death was fatal intoxication with the main role of PV8. This substance is another synthetic cathinone which is dangerous for live of the users and requires constant monitoring and further research.

The Novel Psychoactive Substances in the UK Project: empirical and conceptual review work to produce research recommendations

Background

Although illegal drug use has largely been declining in the UK over the past decade, this period has witnessed the emergence of a range of novel psychoactive substances (NPS) (‘legal highs’). These are new, mostly synthetic, substances that mimic the effects of existing drugs). Despite there being many causes for concern in relation to NPS, there has been little prior study of the burden associated with their use in public health terms. Clarity is lacking on research priorities in this rapidly developing literature.

Objectives

To inform the development of public health intervention research on NPS by reviewing existing data on their use, associated problems and potential responses to such problems.

Design

A scoping review and narrative synthesis of selected bodies of evidence was undertaken to summarise and evaluate what is known about NPS use and the related harms of, and responses to, such use. Relevant literature was identified from electronic databases (covering January 2006 to June 2016 inclusive), Google (Google Inc., Mountain View, CA, USA), relevant websites and online drug forums and by contacting experts. Articles were included if they were primary studies, secondary studies involving the analysis and interpretation of primary research or discussion papers. A conceptual framework postulating an evidence-informed public health approach to NPS use in the UK was developed through a pragmatic literature review, the iterative development of concepts and finalisation in light of the results from the empirical review work. The process also involved feedback from various stakeholders. Research recommendations were developed from both strands of work.

Results

A total of 995 articles were included in the scoping review, the majority of which related to individual-level health-related adverse effects attributable to NPS use. The prevalence of lifetime NPS use varied widely between (e.g. with higher prevalence in young males) and within population subgroups. The most commonly reported adverse effects were psychiatric/other neurological, cardiovascular, renal and gastrointestinal manifestations, and there is limited evidence available on responses. In these and other respects, available evidence is at an early stage of development. Initial evidence challenges the view that NPS should be treated differently from other illicit drugs. The conceptual framework indicated that much of the evidence that would be useful to inform public health responses does not yet exist. We propose a systems-based prevention approach that develops existing responses, is multilevel and life course informed in character, and emphasises commonalities between NPS and other legal and illegal drug use. We make 20 recommendations for research, including nine key recommendations.

Limitations

Scoping reviews do not interrogate evidence in depth, and the disjunction between the scoping review and the conceptual framework findings is worthy of careful attention.

Conclusions

Key research recommendations build on those that have previously been made and offer more evidence-based justification and detail, as previous recommendations have not yet been acted on. The case for decision-making on commissioning new research based on these recommendations is both strong and urgent.

Future work

The validity of recommendations generated through this project could be enhanced via further work with research commissioners, policy-makers, researchers and the public.

Study registration

The systematic review element of this study is registered as PROSPERO CRD42016026415.

Funding

The National Institute for Health Research Public Health Research programme.

Conditioned taste avoidance, conditioned place preference and hyperthermia induced by the second generation 'bath salt' α-pyrrolidinopentiophenone (α-PVP)

BACKGROUND

α-Pyrrolidinopentiophenone (α-PVP) has been reported to be rewarding in a variety of pre-clinical models. Given that a number of drugs of abuse have both rewarding and aversive effects, the balance of which influences addiction potential, the present study examined the aversive properties of α-PVP by assessing its ability to induce taste avoidance. This assessment was made in a combined taste avoidance/place conditioning design that also allowed an evaluation of the relationship between α-PVP's aversive and rewarding effects.

METHODS

Male Sprague-Dawley rats were exposed to a novel saccharin solution, injected with one of four doses of α-PVP (0, 0.3, 1.0 and 3.0mg/kg) (IP) and placed on one side of a place conditioning apparatus. The next day, they were injected with vehicle, given access to water and placed on the other side. Following four conditioning cycles, saccharin avoidance and place preferences were then assessed. The effects of α-PVP on body temperature were also examined.

RESULTS

α-PVP induced dose-dependent taste avoidance as well as significant increases in time spent on the drug-paired side (although this effect was not dependent on dose). α-PVP also induced dose- and time-dependent hyperthermia.

CONCLUSIONS

α-PVP induced significant taste avoidance whose strength relative to the psychostimulants methylenedioxypyrovalerone (MDPV) and cocaine paralleled their relative binding to the dopamine transporter. Similar to other drugs of abuse, α-PVP has both aversive and rewarding effects. It will be important to assess how various experiential and subject variables impact these effects and their balance to predict abuse liability.

Exposure of adolescent mice to 3,4-methylenedioxypyrovalerone increases the psychostimulant, rewarding and reinforcing effects of cocaine in adulthood

BACKGROUND AND PURPOSE

3,4-Methylenedioxypyrovalerone (MDPV) is a synthetic cathinone with powerful psychostimulant effects. It selectively inhibits the dopamine transporter (DAT) and is 10-50-fold more potent as a DAT blocker than cocaine, suggesting a high abuse liability. The main objective of the present study was to assess the consequences of an early (adolescence) MDPV exposure on the psychostimulant, rewarding and reinforcing effects induced by cocaine in adult mice.

EXPERIMENTAL APPROACH

Twenty-one days after MDPV pretreatment (1.5 mg·kg^-1 , s.c., twice daily for 7 days), adult mice were tested with cocaine, using locomotor activity, conditioned place preference and self-administration (SA) paradigms. In parallel, dopamine D₂ receptor density and the expression of c-Fos and ΔFosB in the striatum were determined.

KEY RESULTS

MDPV treatment enhanced the psychostimulant and conditioning effects of cocaine. Acquisition of cocaine SA was unchanged in mice pretreated with MDPV, whereas the breaking point achieved under a progressive ratio programme and reinstatement after extinction were higher in this group of mice. MDPV decreased D₂ receptor density but increased ΔFosB expression three-fold. As expected, acute cocaine increased c-Fos expression, but MDPV pretreatment negatively influenced its expression. ΔFosB accumulation declined during MDPV withdrawal, although it remained elevated in adult mice when tested for cocaine effects.

CONCLUSION AND IMPLICATIONS

MDPV exposure during adolescence induced long-lasting adaptive changes related to enhanced responsiveness to cocaine in the adult mice that seems to lead to a higher vulnerability to cocaine abuse. This particular behaviour correlated with increased expression of ΔFosB.

Chiral enantioresolution of cathinone derivatives present in "legal highs", and enantioselectivity evaluation on cytotoxicity of 3,4-methylenedioxypyrovalerone (MDPV)

Recently, great interest has been focused on synthetic cathinones since their consumption has increased exponentially. All synthetic cathinones exist as chiral molecules; the biological and/or toxicological properties of cathinones generally differ according to the enantiomers in human body. In this study, a chiral liquid chromatography method was developed to separate and determine the enantiomeric ratio of synthetic cathinones present in "legal highs" acquired in old smart shops or over the Internet. All the synthetic cathinones were efficiently enantio-separated with α and Rs ranging from 1.24 to 3.62 and from 1.24 to 10.52, respectively, using polysaccharide-based chiral stationary phases. All synthetic cathinones, with the exception of 4-methylethcathinone (4-MEC), were present in the commercialized "legal highs" in an enantiomeric proportion of 50:50. One of the studied chiral compounds was 3,4-methylenedioxypyrovalerone (MDPV), one of the most consumed cathinone derivative worldwide. Our research group has recently reported its hepatotoxicity in the racemic form. Thus, the analytical enantioresolution of the MDPV was scaled up to multi-milligram using a semi-preparative amylose tris-3,5-dimethylphenylcarbamate column (20 cm × 7.0 mm ID, 7 µm particle size). Both enantiomers were isolated with high enantiomeric purity (enantiomeric excess > 99 %). The toxicity of S-(-)-MDPV and R-(+)-MDPV was evaluated, for the first time, using primary cultures of rat hepatocytes. It was also possible to verify that MDPV enantiomers showed hepatotoxicity in a concentration-dependent manner, but displayed no enantioselective toxicity in this cell culture model.