Behavioral effects of four novel synthetic cathinone analogs in rodents

Locomotor and discriminative stimulus effects of NBOH hallucinogens in rodents

Despite the efforts of the Drug Enforcement Administration to safeguard the public from hazardous analogs of synthetic hallucinogens, these compounds have increasingly been observed in the illicit drug market. Four novel compounds were found to be similar in structure to the previously described 25X-NBOMe synthetic hallucinogens. These four compounds, 25B-NBOH, 25C-NBOH, 25E-NBOH, and 25I-NBOH were evaluated for their ability to modify spontaneous locomotor activity in mice to obtain dose range and time-course information and were then tested for discriminative stimulus effects similar to the prototypical hallucinogen (-)-2,5-dimethoxy-4-methylamphetamine (DOM). All four test compounds decreased locomotor activity. The locomotor depressant effects were similar in magnitude and potency to DOM, but less potent than the 25X-NBOMe compounds in previous reports. 25B-NBOH, 25C-NBOH, and 25E-NBOH fully substituted (≥80%) in DOM-trained rats, whereas 25I-NBOH failed to fully substitute for DOM even at doses that suppressed responding. The discriminative stimulus effects were more potent than those of DOM and the 25X-NBOMe compounds. These findings suggest that three of the four test compounds are most likely to be used as recreational hallucinogens in a similar manner to DOM and the 25X-NBOMe compounds, whereas 25I-NBOH may be less liable to illicit use.

Toxicological evaluation, postmortem case descriptions, and pharmacological activity of N,N-dimethylpentylone and related analogs

Identification of N,N-dimethylpentylone (DMP) in counterfeit "Ecstasy" and "Molly" tablets poses risk to public health due to its adverse effects. Little information is available regarding the pharmacological activity or relevant blood or tissue concentrations of DMP, and even less is known about other structurally related beta-keto methylenedioxyamphetamine analogs on recreational drug markets, such as N-propyl butylone. Here, a novel toxicological assay utilizing liquid chromatography-tandem quadrupole mass spectrometry was developed and validated for the quantitation of DMP and five related synthetic cathinones [eutylone, pentylone, N-ethyl pentylone (NEP), N-propyl butylone, and N-cyclohexyl butylone], with chromatographic resolution from isomeric variants and quantitation performed by standard addition. A forensic series of 125 cases is presented for DMP and related analogs, along with pharmacological activity assessments using monoamine transporter and mouse behavioral assays. The blood concentration range for DMP in postmortem forensic cases was 3.3-4600 ng/mL (mean: 320 ± 570 ng/mL, median: 150 ng/mL), whereas pentylone, the primary N-desmethyl metabolite of DMP, was identified in 98% of cases with a concentration range 1.3-710 ng/mL (mean ± SD: 105 ± 120 ng/mL, median: 71 ng/mL). N-Propyl butylone, a newly identified synthetic cathinone, was quantitated in seven cases (mean ± SD: 82 ± 75 ng/mL, median: 50 ng/mL, range: 1.7-200 ng/mL). DMP displayed potent uptake inhibition at the dopamine transporter [half maximal inhibitory concentration (IC50) of 49 nM], with 100-fold weaker potency at the serotonin transporter (IC50 = 4990 nM). DMP was a locomotor stimulant in mice [medium effective dose (ED50) of 3.5 mg/kg] exhibiting potency relatively similar to eutylone, NEP, and pentylone. Our results show that DMP is a psychomotor stimulant associated with adverse clinical outcomes leading to death. Forensic laboratories must continue to update testing methods to capture emerging drugs, with specific emphasis on resolution and identification of isomeric species. Following the scheduling of DMP in early 2024, there could be an anticipated market shift toward a new unregulated synthetic stimulant to replace DMP.

N-Ethylhexedrone: A very long and bad trip! A case series

N-ethylhexedrone (NEH) is a new cathinone derivative with, currently, low toxicokinetic and toxicodynamic knowledge. We present three documented clinical cases of NEH intoxication with plasma and urine concentrations. A thorough search for metabolites was performed. The three patients were admitted to the emergency department, and two out of the three were hospitalized for an extended period. While recovering from the drug effects, 12-24 h after nasal intake of New Psychoactive Substance (NPS), the patients described the following disorders: anxiety, feelings of persecution, asthenia, anhedonia, abulia, psychomotor slowing and loss of consciousness. NEH was identified in all samples by liquid chromatography-high resolution mass spectrometry (LC-HRMS), and quantified by liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS). Quantitative analysis showed decreasing concentrations over time: for Case 1, from 97.2 (Day 1, D1) to 0.7 (Day 7, D7) µg/L for plasma, and from 724 (D1) to 0.5 (D7) µg/L for urine. NEH concentration of 7.9 µg/L was found in the plasma collected at admission for Case 2. For Case 3, concentrations ranging from 49 (D1) to 1.8 (D7) µg/L in plasma, and from 327.3 (Day 6, D6) to 116.8 (D7) µg/L in urine were found. NEH was no longer detected in the urine sample at Day 10. Elimination half-life was estimated at 19, and 28 hours in Patients 1 and 3, respectively. Four metabolites were identified in blood and urine: reduced NEH, dealkyl-NEH, reduced dealkyl-NEH and hydroxy-NEH. The cases presented highlight the long detectable lifetime of NEH. Characterization of the metabolites will allow better identification of the consumption of this drug. Serious adverse events can be observed after NEH consumption, as two out of the three patients required intubation and ventilation. A syndrome of inappropriate antidiuretic hormone secretion (SIADH) was also diagnosed. Two out of the three cases are notable because of the number of samples collected and because NEH was the only drug of abuse detected.

N,N-dimethylpentylone poisoning: Clinical manifestations, analytical detection, and metabolic characterization

INTRODUCTION

The proliferation of new psychoactive substances (NPS) poses a significant challenge to clinical and forensic toxicology laboratories. N,N-dimethylpentylone, a novel synthetic cathinone, has emerged as a public health concern. The aims of this study are to describe the clinical presentation of N,N-dimethylpentylone poisoning, to describe detection methods, and to deduce its metabolic pathways.

METHODS

Clinical data was collected and reviewed retrospectively from patients with confirmed N,N-dimethylpentylone exposure. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify N,N-dimethylpentylone and its metabolites in urine samples. The metabolic pathway was characterised by comparison of the detected substances with reference standards.

RESULTS

Eight cases were included in the case series. Seven different metabolites of N,N-dimethylpentylone were identified in in vivo patient urine samples, where the two major metabolic pathways were proposed to be opening of the 5-membered ring and reduction of carboxide. All patients presented with neuropsychiatric and/or cardiovascular symptoms. Co-ingestion with other substances was reported in all cases. One patient requiring intensive care was described in detail. All patients eventually recovered. The analytical method allowed the simultaneous identification of N,N-dimethylpentylone, pentylone and bisdesmethyl-N,N-dimethylpentylone, as well as other drugs of abuse in patient samples.

CONCLUSION

N,N-dimethylpentylone appears to be less potent than its metabolite pentylone. Co-ingestion with other drugs of abuse is common. Poisoning cases have neuropsychiatric and cardiovascular manifestations. An updated and comprehensive laboratory method is needed for its detection.

Detection of the synthetic cathinone N,N-dimethylpentylone in seized samples from prisons

Drug use is prevalent in prisons with drugs associated with depressant effects found to be more prevalent than stimulants. Synthetic cathinones (SCats; often sold as "bath salts", "ecstasy", "molly", and "monkey dust") are the second largest category of new psychoactive substances (NPS) currently monitored by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) and are commonly used as substitutes for regulated stimulants, such as amphetamine, cocaine, and MDMA. N,N-dimethylpentylone (also known as dimethylpentylone, dipentylone, and bk-DMBDP) was detected for the first time in the Scottish prisons in seven powder samples seized between January and July 2023. Samples were analyzed using gas chromatography-mass spectrometry (GC-MS), ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-QToF-MS), and nuclear magnetic resonance imaging (NMR). Dimethylpentylone was detected alongside other drugs in four samples, including the novel benzodiazepine desalkylgidazepam (bromonordiazepam) and the synthetic cannabinoid receptor agonists (SCRAs) MDMB-INACA and MDMB-4en-PINACA.

The psychomotor, reinforcing, and discriminative stimulus effects of synthetic cathinone mexedrone in male mice and rats

The chronic use of the novel synthetic cathinone mexedrone, like other psychoactive drugs, can be considered addictive, with a high potential for abuse and the ability to cause psychological dependence in certain users. However, little is known about the neurobehavioral effects of mexedrone in association with its potential for abuse. We investigated the abuse potential for mexedrone abuse through multiple behavioral tests. In addition, serotonin transporter (SERT) levels were measured in the synaptosome of the dorsal striatum, and serotonin (5-HT) levels were measured in the dorsal striatum of acute mexedreone (50 mg/kg)-treated mice. To clarify the neuropharmacological mechanisms underlying the locomotor response of mexedrone, the 5-HT2A receptor antagonist M100907 (0.5 or 1.0 mg/kg) was administered prior to the acute injection of mexedrone in the locomotor activity experiment in mice. Mexedrone (10-50 mg/kg) produced a significant place preference in mice and mexedrone (0.1-0.5 mg/kg/infusion) maintained self-administration behavior in rats in a dose-dependent manner. In the drug discrimination experiment, mexedrone (5.6-32 mg/kg) was fully substituted for the discriminative stimulus effects of cocaine in rats. Mexedrone increased locomotor activity, and these effects were reversed by pretreatment with M100907. Acute mexedrone significantly increased c-Fos expression in the dorsal striatum and decreased SERT levels in the synaptosome of the dorsal striatum of mice, resulting in an elevation of 5-HT levels. Taken together, our results provide the possibility that mexedrone has abuse potential, which might be mediated, at least in part, by the activation of the serotonergic system in the dorsal striatum.

Synthetic Cathinones: Epidemiology, Toxicity, Potential for Abuse, and Current Public Health Perspective

Synthetic cathinones, derived from cathinone found in the plant Catha edulis, represent the second largest and most frequently seized group of new psychoactive substances. They are considered as β-keto analogs of amphetamine, sharing pharmacological effects with amphetamine and cocaine. This review describes the neurotoxic properties of synthetic cathinones, encompassing their capacity to induce neuroinflammation, dysregulate neurotransmitter systems, and alter monoamine transporters and receptors. Additionally, it discusses the rewarding and abuse potential of synthetic cathinones drawing from findings obtained through various preclinical animal models, contextualized with other classical psychostimulants. The review also offers an overview of current abuse trends of synthetic cathinones on the illicit drug market, specifying the aspects covered, and underscores the risks they pose to public health. Finally, the review discusses public health initiatives and efforts to reduce the hazards of synthetic cathinones, including harm reduction methods, education, and current clinical management strategies.

Structure-activity relationships for locomotor stimulant effects and monoamine transporter interactions of substituted amphetamines and cathinones

Substitutions to the phenethylamine structure give rise to numerous amphetamines and cathinones, contributing to an ever-growing number of abused novel psychoactive substances. Understanding how various substitutions affect the pharmacology of phenethylamines may help lawmakers and scientists predict the effects of newly emerging drugs. Here, we established structure-activity relationships for locomotor stimulant and monoamine transporter effects of 12 phenethylamines with combinations of para-chloro, β-keto, N-methyl, or N-ethyl additions. Automated photobeam analysis was used to evaluate effects of drugs on ambulatory activity in mice, whereas in vitro assays were used to determine activities at transporters for dopamine (DAT), norepinephrine (NET), and 5-HT (SERT) in rat brain synaptosomes. In mouse studies, all compounds stimulated locomotion, except for 4-chloro-N-ethylcathinone. Amphetamines were more potent stimulants than their β-keto counterparts, while para-chloro amphetamines tended to be more efficacious than unsubstituted amphetamines. Para-chloro compounds also produced lethality at doses on the ascending limbs of their locomotor dose-effect functions. The in vitro assays showed that all compounds inhibited uptake at DAT, NET, and SERT, with most compounds also acting as substrates (i.e., releasers) at these sites. Unsubstituted compounds displayed better potency at DAT and NET relative to SERT. Para-chloro substitution or increased N-alkyl chain length augmented relative potency at SERT, while combined para-chloro and N-ethyl substitutions reduced releasing effects at NET and DAT. These results demonstrate orderly SAR for locomotor stimulant effects, monoamine transporter activities, and lethality induced by phenethylamines. Importantly, 4-chloro compounds produce toxicity in mice that suggests serious risk to humans using these drugs in recreational contexts.

Metabolism of dipentylone in zebrafish and human liver microsomes determined by liquid chromatography-high resolution mass spectrometry

The consumption of novel psychoactive substances (NPS) is exceedingly prevalent in society, as these substances are sold and distributed as "legal highs." One novel synthetic cathinone emerging in the market is 1-(1,3-benzodioxol-5-yl)-2-(dimethylamino) pentan-1-one (dipentylone). The goal of this work was to study the in vivo and in vitro metabolism of dipentylone in zebrafish and human liver microsomes (HLMs) by liquid chromatography-high resolution mass spectrometry (LC-HRMS). The zebrafish and HLM samples contained 14 dipentylone metabolites, specifically 12 phase Ⅰ metabolites and 2 phase Ⅱ metabolites. The main metabolic pathways included monohydroxylation (M1 and M2), N-dealkylation (M3), hydroxylation of the aromatic ring and dealkoxylation of M3 (M4), O-dealkylation (M5), N-dealkylation of M5 (M6), reduction of carboxide (M7), monohydroxylation of M5 (M8), dehydrogenation (M9), dealkoxylation (M10), N-dealkylation of M10 (M11), dealkoxylation of M9 (M12), glucuronidation of M5 (M13), and sulfation (M14). The monohydroxylated metabolite (M2) can be recommended as metabolic markers for dipentylone. This study is the first to identify a target compound for monitoring the abuse of dipentylone and to determine the essential chemical structure of the metabolites for further toxicological research.

Locomotor and discriminative stimulus effects of three benzofuran compounds in comparison to abused psychostimulants

Aims

Benzofurans are used recreationally, due their ability to cause psychostimulant and/or entactogenic effects, but unfortunately produce substantial adverse effects, including death. Three benzofurans 5-(2-aminopropyl)-2,3-dihydrobenzofuran (5-APDB), 5-(2-aminopropyl)-2,3-dihydrobenzofuran (5-MAPB) and 6-(2-aminopropyl) benzofuran (6-APB) were tested to determine their behavioral effects in comparison with 2,3-methylenedioxymethamphetamine (MDMA), cocaine, and methamphetamine.

Methods

Locomotor activity was tested in groups of 8 male Swiss-Webster mice in an open-field task to screen for locomotor stimulant or depressant effects and to identify behaviorally active doses and times of peak effect. Discriminative stimulus effects were tested in groups of 6 male Sprague-Dawley rats trained to discriminate MDMA (1.5 mg/kg), cocaine (10 mg/kg), or methamphetamine (1 mg/kg) from saline using a FR 10 for food in a two-lever operant task.

Results

In the locomotor activity test, MDMA (ED50 = 8.34 mg/kg) produced peak stimulant effects 60 to 80 min following injection. 5-MAPB (ED50 = 0.92 mg/kg) produced modest stimulant effects 50 to 80 min after injection, whereas 6-APB (ED50 = 1.96 mg/kg) produced a robust stimulant effect 20 to 50 min after injection. 5-APDB produced an early depressant phase (ED50 = 3.38 mg/kg) followed by a modest stimulant phase (ED50 = 2.57 mg/kg) 20 to 50 min after injection. In the drug discrimination tests, 5-APDB (ED50 = 1.02 mg/kg), 5-MAPB (ED50 = 1.00 mg/kg) and 6-APB (ED50 = 0.32 mg/kg) fully substituted in MDMA-trained rats, whereas only 5-MAPB fully substituted for cocaine, and no compounds fully substituted for methamphetamine.

Conclusions

The synthetic benzofuran compound 5-APDB and 5-MAPB produced weak locomotor effects, whereas 6-APB produced robust locomotor stimulant effects. All compounds were more potent than MDMA. All three compounds fully substituted in MDMA-trained rats suggesting similar subjective effects. Taken together, these results suggest that these benzofuran compounds may have abuse liability as substitutes for MDMA.

Forensic Analysis of Synthetic Cathinones on Nanomaterials-Based Platforms: Chemometric-Assisted Voltametric and UPLC-MS/MS Investigation

Synthetic cathinones (SCs) are a group of new psychoactive substances often referred to as "legal highs" or "bath salts", being characterized by a dynamic change, new compounds continuously emerging on the market. This creates a lack of fast screening tests, making SCs a constant concern for law enforcement agencies. Herein, we present a fast and simple method for the detection of four SCs (alpha-pyrrolidinovalerophenone, N-ethylhexedrone, 4-chloroethcathinone, and 3-chloromethcathinone) based on their electrochemical profiles in a decentralized manner. In this regard, the voltametric characterization of the SCs was performed by cyclic and square wave voltammetry. The elucidation of the SCs redox pathways was successfully achieved using liquid chromatography coupled to (tandem) mass spectrometry. For the rational identification of the ideal experimental conditions, chemometric data processing was employed, considering two critical qualitative and quantitative variables: the type of the electrochemical platform and the pH of the electrolyte. The analytical figures of merit were determined on standard working solutions using the optimized method, which exhibited wide linear ranges and LODs suitable for confiscated sample screening. Finally, the performance of the method was evaluated on real confiscated samples, the resulting validation parameters being similar to those obtained with another portable device (i.e., Raman spectrometer).

Neurochemical and Cardiovascular Effects of 4-Chloro Ring-Substituted Synthetic Cathinones in Rats

Synthetic cathinones are a class of new psychoactive substances that display psychomotor stimulant properties, and novel cathinone analogs continue to emerge in illicit drug markets worldwide. The aim of the present study was to characterize the pharmacology of 4-chloro ring-substituted cathinones that are appearing in illicit drug markets compared with the effects of 4-methylmethcathinone (mephedrone). Synaptosomes were prepared from rat caudate for dopamine transporter (DAT) assays or from whole brain minus caudate and cerebellum for norepinephrine transporter (NET) and serotonin transporter (SERT) assays. Findings from transporter uptake inhibition and release assays showed that mephedrone and 4-chloromethcathinone (4-CMC) function as substrates at DAT, NET, and SERT, with similar potency at all three transporters. In contrast, 4-chloro-α-pyrrolidinopropiophenone (4-CαPPP) was an uptake inhibitor at DAT and NET, with similar potency at each site, but had little activity at SERT. 4-Chloroethcathinone (4-CEC) was a low-potency uptake inhibitor at DAT and NET but a substrate at SERT. In rats implanted with telemetry transmitters, mephedrone and 4-CMC increased blood pressure, heart rate, and locomotor activity to a similar extent. 4-CEC and 4-CαPPP were less potent at increasing blood pressure and had modest stimulatory effects on heart rate and activity. 4-CMC also transiently decreased temperature at the highest dose tested. All three 4-chloro ring-substituted cathinones are biologically active, but only 4-CMC has potency comparable to mephedrone. Collectively, our findings suggest that 4-CMC and other 4-chloro cathinones may have abuse potential and adverse effects in humans that are analogous to those associated with mephedrone. SIGNIFICANCE STATEMENT: The 4-chloro ring-substituted cathinones all produced significant cardiovascular stimulation, with 4-chloromethcathinone (4-CMC) showing potency similar to mephedrone. All of the drugs are likely to be abused given their effects at the dopamine transporter, particularly 4-CMC.

Synthetic Cathinones and Neurotoxicity Risks: A Systematic Review

According to the EU Early Warning System (EWS), synthetic cathinones (SCs) are the second largest new psychoactive substances (NPS) class, with 162 synthetic cathinones monitored by the EU EWS. They have a similar structure to cathinone, principally found in Catha Edulis; they have a phenethylamine related structure but also exhibit amphetamine-like stimulant effects. Illegal laboratories regularly develop new substances and place them on the market. For this reason, during the last decade this class of substances has presented a great challenge for public health and forensic toxicologists. Acting on different systems and with various mechanisms of action, the spectrum of side effects caused by the intake of these drugs of abuse is very broad. To date, most studies have focused on the substances’ cardiac effects, and very few on their associated neurotoxicity. Specifically, synthetic cathinones appear to be involved in different neurological events, including increased alertness, mild agitation, severe psychosis, hyperthermia and death. A systematic literature search in PubMed and Scopus databases according to PRISMA guidelines was performed. A total of 515 studies published from 2005 to 2022 (350 articles from PubMed and 165 from Scopus) were initially screened for eligibility. The papers excluded, according to the criteria described in the Method Section (n = 401) and after full text analyses (n = 82), were 483 in total. The remaining 76 were included in the present review, as they met fully the inclusion criteria. The present work provides a comprehensive review on neurotoxic mechanisms of synthetic cathinones highlighting intoxication cases and fatalities in humans, as well as the toxic effects on animals (in particular rats, mice and zebrafish larvae). The reviewed studies showed brain-related adverse effects, including encephalopathy, coma and convulsions, and sympathomimetic and hallucinogenic toxidromes, together with the risk of developing excited/agitated delirium syndrome and serotonin syndrome.

Comparison of locomotor stimulant and drug discrimination effects of four synthetic cathinones to commonly abused psychostimulants

BACKGROUND

The underground market is constantly flooded with newer synthetic as alternatives to the older cathinones. Drug Enforcement Administration (DEA) has identified four cathinone compounds of particular concern: 3,4-methylenedioxy-alpha-pyrrolidinohexanophenone (3,4-MD-α-PHP), 4-chloro-α-pyrrolidinopropiophenone (4-Cl-α-PPP), alpha-pyrrolidinoisohexiophenone (α-PiHP) and 4-chloro-pentedrone (4-Cl-pentedrone).

AIMS

The current study aimed to evaluate the behavioral pharmacology of four synthetic cathinones.

METHODS

3,4-MD-α-PHP, 4-Cl-α-PPP, α-PiHP, and 4-CPD were tested for locomotor activity in mice and in a drug discrimination assay with rats trained to discriminate either methamphetamine or cocaine.

RESULTS

Locomotor stimulant effects of 3,4-MD-α-PHP ((effective dose) ED₅₀ = 1.98 mg/kg), α-PiHP (ED₅₀ = 2.46 mg/kg), and 4-Cl-α-PPP (ED₅₀ = 7.18 mg/kg) were observed within 10 min following injection and lasted from 2 to 3.5 h. The stimulant action of 4-CPD (ED₅₀ = 17.24 mg/kg) was delayed, occurring 40-70 min following injection. The maximal motor stimulant actions of 3,4-MD-α-PHP and α-PiHP 1 were equivalent to that of cocaine and methamphetamine, whereas 4-CPD (50% of cocaine) and 4-Cl-α-PPP (73% of cocaine) were less efficacious. All of the test compounds fully substituted for the discriminative stimulus effects of cocaine, 3,4-MD-α-PHP (ED₅₀ = 2.28 mg/kg), α-PiHP (ED₅₀ = 3.84 mg/kg), and 4-Cl-α-PPP (ED₅₀ = 15.56 mg/kg). Only 3,4-MD-α-PHP (ED₅₀ = 1.65 mg/kg), α-PiHP (ED₅₀ = 1.87 mg/kg), and 4-Cl-α-PPP (ED₅₀ = 9.79 mg/kg) fully substituted for the discriminative stimulus effects of methamphetamine. 4-Cl-pentedrone caused 55-70% methamphetamine-appropriate responding at doses that also suppressed responding and produced convulsions.

CONCLUSIONS

These data indicate that 3,4-MD-α-PHP, α-PiHP, and 4-Cl-α-PPP have a potential for abuse similar to that of methamphetamine and cocaine. In contrast, 4-Cl-pentedrone may not be popular for recreational use due to its convulsant effects.

Structure-Activity Relationship of N-Ethyl-Hexedrone Analogues: Role of the α-Carbon Side-Chain Length in the Mechanism of Action, Cytotoxicity, and Behavioral Effects in Mice

Synthetic cathinones are β-keto amphetamine derivatives whose appearance has increased dramatically in the past decades. N-Ethyl substituted cathinones have been proven to potently inhibit dopamine (DA) uptake and induce psychostimulant and rewarding effects in mice. However, little is known about the influence of the alpha-carbon side-chain length of N-ethyl cathinones on their pharmacological and toxicological effects. Thus, the aim of this study was to synthesize and investigate the in vitro and in vivo effects of five N-ethyl substituted cathinones: N-ethyl-cathinone (NEC), N-ethyl-buphedrone (NEB), N-ethyl-pentedrone, N-ethyl-hexedrone (NEH), and N-ethyl-heptedrone. HEK293 cells expressing the human DA or serotonin transporter (hDAT and hSERT) were used for uptake inhibition and binding assays. PC12 cells were used for the cytotoxicity assays. Swiss CD-1 mice were used to study the in vivo psychostimulant, anxiogenic, and rewarding properties. Our results show that all tested cathinones are able to inhibit DA uptake and are DAT-selective. The potency of DA uptake inhibitors increases with the elongation of the aliphatic side chain from methyl to propyl and decreases when increasing from butyl to pentyl, which correlates with an inverted U-shape psychostimulant response in mice at the medium dose tested. On the other hand, an increase in the α-carbon side-chain length correlates with an increase in the cytotoxic properties in PC12 cells, probably due to better membrane penetration. Moreover, all the cathinones tested have shown higher cytotoxicity than methamphetamine. Finally, our study not only demonstrated the rewarding properties of NEC and NEB but also the anxiety-like behavior induced at high doses by all the cathinones tested.

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.

Expression of stable and reliable preference and aversion phenotypes following place conditioning with psychostimulants

RATIONALE AND OBJECTIVES

Drug-seeking behavior occurs more readily in some individuals than others. This phenomenon is considered in studies of drug self-administration in which high drug-seeking/taking individuals can be identified. In contrast, studies of conditioned place preference (CPP) often involve a random sample of drug-naïve rodents that includes phenotypes not considered relevant to addiction. The main objective of the current studies was to determine if a priori identification of different conditioning phenotypes could improve the validity and sensitivity of CPP expression as a preclinical test for vulnerability to addiction.

METHODS AND RESULTS

Analysis of cocaine place conditioning data from 443 Swiss-Webster mice revealed a trimodal distribution with peaks corresponding to means of k = 3 clusters. The cluster means occurred at high, low, or negative preference scores, the latter suggesting a phenotype acquiring conditioned place aversion (CPA). The same clusters were identified in mice conditioned with methamphetamine, MDPV, or amphetamine, and these clusters remained stable and reliable during three additional expression tests spaced at 24 h. A meta-analysis of effect sizes obtained from CPP literature revealed a positively skewed distribution affected by sample size, consistent with the existence of a CPA phenotype within the populations tested. A dopamine receptor antagonist, flupentixol, blocked cocaine CPP expression in a group containing all phenotypes, but sensitivity improved markedly when CPA phenotypes were excluded from the dataset.

CONCLUSIONS

These studies suggest that taking phenotype into consideration when designing place conditioning studies will improve their application as a preclinical tool in addiction biology and drug discovery.

Human Neuronal Cell Lines as An In Vitro Toxicological Tool for the Evaluation of Novel Psychoactive Substances

Novel psychoactive substances (NPS) are synthetic substances belonging to diverse groups, designed to mimic the effects of scheduled drugs, resulting in altered toxicity and potency. Up to now, information available on the pharmacology and toxicology of these new substances is very limited, posing a considerable challenge for prevention and treatment. The present in vitro study investigated the possible mechanisms of toxicity of two emerging NPS (i) 4′-methyl-alpha-pyrrolidinoexanophenone (3,4-MDPHP), a synthetic cathinone, and (ii) 2-chloro-4,5-methylenedioxymethamphetamine (2-Cl-4,5-MDMA), a phenethylamine. In addition, to apply our model to the class of synthetic opioids, we evaluated the toxicity of fentanyl, as a reference compound for this group of frequently abused substances. To this aim, the in vitro toxic effects of these three compounds were evaluated in dopaminergic-differentiated SH-SY5Y cells. Following 24 h of exposure, all compounds induced a loss of viability, and oxidative stress in a concentration-dependent manner. 2-Cl-4,5-MDMA activates apoptotic processes, while 3,4-MDPHP elicits cell death by necrosis. Fentanyl triggers cell death through both mechanisms. Increased expression levels of pro-apoptotic Bax and caspase 3 activity were observed following 2-Cl-4,5-MDMA and fentanyl, but not 3,4-MDPHP exposure, confirming the different modes of cell death.