Synthetic cathinones constitute a major class of New Psychoactive Substances (NPS) with significant abuse potential. Within this class, 3F-N-ethylbuphedrone (3F-NEB or 2-(ethylamino)-1-(3-fluorophenyl)butan-1-one), a novel N-ethyl buphedrone derivative, has recently emerged in recreational drug markets. However, its pharmacological properties and abuse liability remain uncharacterized. The present study aimed to evaluate the neurochemical mechanisms and behavioral effects of 3F-NEB to assess its potential for abuse and addiction. To this end, we conducted in vitro monoamine uptake inhibition assays and in mice we performed locomotor activity and conditioned place preference tests. In rats, we conducted in vivo microdialysis in the nucleus accumbens, intravenous self-administration, and assessed neuroadaptive changes by ΔFosB immunohistochemistry following chronic self-administration. Our results demonstrate that 3F-NEB acts as a potent dopamine transporter (DAT) inhibitor, with more than 100-fold selectivity over the serotonin transporter (SERT). Acute administration (3 mg/kg) rapidly increased extracellular dopamine levels in the nucleus accumbens of rats. At the behavioral level, 3F-NEB induced dose-dependent locomotor increases (10-30 mg/kg), with anxiety-like effects at the highest doses, and conditioned place preference at all tested doses (3-30 mg/kg) in mice. 3F-NEB was readily self-administered by rats under both fixed-ratio and progressive-ratio schedules. Furthermore, chronic self-administration significantly increased ΔFosB expression in dorsomedial and dorsolateral striatum, mirroring patterns observed with methamphetamine. Taken together, these results demonstrate that 3F-NEB exhibits potent dopaminergic activity and high abuse liability through selective dopamine transporter inhibition. The compound's robust reinforcing properties and induction of addiction-related molecular adaptations suggest significant public health risks warranting immediate regulatory control.

Synthetic cathinones represent the main group of emerging psychostimulants consumed worldwide. Structural modifications of these compounds have led to pyrovalerones, potent dopamine transporter (DAT) inhibitors associated with high abuse liability. Among them, α-pyrrolidinoisohexanophenone (α-PiHP) became the most seized pyrovalerone in the European Union in 2023. Novel analogues have rapidly appeared, yet their neuropharmacological and toxicological properties remain unknown. This study aimed to characterize α-PiHP and five structurally related derivatives (3-Me-α-PiHP, 4-Me-α-PiHP, 3-F-α-PiHP, 4-F-α-PiHP, and MDPiHP). Monoamine transporter activity was evaluated using HEK293 cells expressing human norepinephrine (hNET), hDAT, or serotonin (hSERT) transporters through uptake inhibition and binding assays. Molecular docking was performed to model interactions at hDAT. Psychostimulant, thigmotactic, and rewarding effects were evaluated in male Swiss CD-1 mice using horizontal locomotor activity, open field, and conditioned place preference paradigms. Lethality after drug administration was also assessed. All compounds potently inhibited hDAT and hNET, while displaying limited activity at hSERT. This resulted in high hDAT/hSERT ratios indicative of a stimulant-like profile and elevated abuse liability, confirmed in vivo by pronounced psychostimulant and rewarding effects. All molecules interacted with the orthosteric binding site at hDAT and displayed higher binding affinity than cocaine in in vitro and in silico studies. Meta-substituted analogues showed greater hDAT affinity and behavioural responses than para-isomers. Notably, MDPiHP exhibited the highest potency and affinity, strongest psychostimulant effects and significant lethality. These findings demonstrate that minor structural modifications markedly influence pharmacological activity of pyrovalerone derivatives, highlighting the high abuse potential and health risks associated with emerging α-PiHP analogues.

BACKGROUND:The continual emergence of novel synthetic cathinones poses significant public health concerns due to their unpredictable pharmacological profiles and potential for abuse. Among these, 4-F-3-Me-α-PVP-a newly identified analogue of α-PVP-has recently surfaced on the illicit drug market, yet its biological effects remain uncharacterized. AIM:To provide the first comprehensive pharmacological evaluation of 4-F-3-Me-α-PVP. METHODS:In vitro transporter inhibition was assessed using HEK293 cells expressing human dopamine (DA), norepinephrine, and serotonin transporter (DAT, NET, or SERT). In male rodents, locomotor activity was measured after i.p. (mice) or s.c. (rats) administration. In vivo microdialysis in rats quantified extracellular DA in the nucleus accumbens. Rewarding and reinforcing effects were evaluated using conditioned place preference (CPP) in mice and intravenous self-administration (IVSA) in rats under fixed-ratio and progressive-ratio schedules. RESULTS:In vitro assays revealed that 4-F-3-Me-α-PVP acts as a potent DAT and NET inhibitor, with additional, though weaker, activity at SERT. In vivo, 4-F-3-Me-α-PVP significantly increased locomotor activity in male rodents (10 and 30 mg/kg in mice; 3 mg/kg in rats). Importantly, 4-F-3-Me-α-PVP also increased extracellular DA levels in the rat nucleus accumbens (3 mg/kg, s.c.), pointing to its potential for abuse. Behavioral assays further demonstrated rewarding and reinforcing effects in rodents, with significant CPP in mice at all doses tested and dose-dependent IVSA in rats observed under both fixed-ratio and progressive-ratio schedules. CONCLUSIONS:Collectively, these findings indicate that 4-F-3-Me-α-PVP possesses substantial psychostimulant and abuse-related effects in rodents, underscoring the need for regulatory vigilance and continued investigation into emerging synthetic cathinones.

Synthetic cathinones are emerging psychoactive substances designed to mimic the effects of classical psychostimulants. Among them, α-D2PV, a novel pyrrolidine-containing cathinone characterized by a phenyl group on the α-carbon atom, has gained significant attention. This study investigates the in vitro and in silico mechanism of action as well as the abuse liability of α-D2PV using rodent models. Dopamine (DA), noradrenaline (NE), and serotonin (5-HT) uptake inhibition assays were conducted in HEK293 cells expressing the corresponding human monoamine transporter, complemented by molecular docking studies at the DA transporter (DAT). Behavioral studies in male Swiss CD-1 mice assessed locomotor activity and conditioned place preference, while microdialysis and self-administration experiments were performed in male Sprague-Dawley rats. The findings reveal that α-D2PV is a potent DA and NE uptake inhibitor, with minimal activity at the 5-HT transporter (SERT). Docking studies showed that the benzene rings of α-PVP and α-D2PV align precisely in their most stable conformations at DAT. In vivo, α-D2PV elicited dose-dependent hyperlocomotion, thigmotaxis, and rewarding effects in mice, alongside increased extracellular DA levels in the nucleus accumbens of awake rats. Self-administration experiments confirmed α-D2PV's high reinforcing efficacy, indicating a significant risk of abuse in humans. Finally, these results underscore the necessity for continued surveillance of α-D2PV within the illicit drug market. Furthermore, novel synthetic cathinones incorporating a phenyl ring at the α-carbon side chain warrant proactive monitoring due to their potential to retain dopaminergic activity and evade initial legal controls.

Neurotoxicity induced by organophosphorus (OP) compounds such as paraoxon (POX) leads to severe brain damage and cognitive impairments. Although current treatments alleviate acute cholinergic symptoms, they fail to address secondary neurotoxicity. This study investigated the therapeutic potential of N-acetylcysteine-amide (AD4), a blood-brain-barrier permeable antioxidant, in a survival mouse model of acute POX intoxication. Male Swiss CD-1 mice received POX (4 mg/kg) followed by standard emergency therapy (atropine, pralidoxime and diazepam). AD4 (150 mg/kg) was administered 2 and 6 h post-exposure. AD4 treatment effectively prevented oxidative stress by reducing lipid peroxidation and restoring the expression in hippocampus (HP) and/or prefrontal cortex (PFC) of key antioxidant enzymes such as glutathione peroxidase-1 (GPx-1) and catalase (CAT) suppressed by POX acute exposure. Moreover, AD4 attenuated neuroinflammation in specific hippocampal subregions, as evidenced by reduced Glial Fibrillary Acidic Protein (GFAP) and Ionized Calcium Binding Adaptor Molecule 1 (Iba-1) immunoreactivity. Importantly, AD4 also rescued recognition memory deficits, as assessed by the Novel Object Recognition Test (NORT). In summary, these findings demonstrate that AD4 mitigates oxidative stress, neuroinflammation, and cognitive dysfunction following acute POX intoxication, supporting its potential as an adjuvant therapy for mitigating the secondary neurotoxicity derived from organophosphorus poisoning.

Current first-line antidepressants, such as selective serotonin reuptake inhibitors (SSRI), often present a delayed onset of action and fail to effectively treat a large proportion of patients, leaving a gap in the treatment of mood disorders. Psychedelics have recently emerged as promising alternatives due to their ability to produce fast-acting antidepressant effects through neuroplastic adaptations, but their hallucinogenic properties remain a major obstacle to their widespread therapeutic use. In this study, we characterized a novel class of halogenated DMT derivatives—5-F-DMT, 5-Cl-DMT, and 5-Br-DMT—for their pharmacological activity, behavioral effects, and therapeutic potential. Using a combination of in vitro assays, in silico modeling, and in vivo behavioral and gene expression studies, we found that halogen substitution at the 5-position modulates receptor affinity and selectivity across key serotonin (5-HT) receptors (5-HT1A/2 A/2B/2CR) and transporter (SERT). Notably, 5-Br-DMT was found to activate 5-HT2AR but did not induce the head twitch response (HTR) in mice, suggesting non-hallucinogenic activity. Furthermore, 5-Br-DMT upregulated immediate early genes (IEGs) associated with neuroplasticity in the mouse prefrontal cortex and hippocampus (Arc, Egr-1, -2 and -3) and promoted dendritic growth in cortical neurons. In a mouse model of stress-induced depression, a single administration (10 mg/kg, i.p.) of 5-Br-DMT resulted in a significant reduction in depressive-like behavior, reflecting rapid antidepressant effects. Collectively, our results highlight 5-Br-DMT as a non-hallucinogenic psychoplastogen with antidepressant properties, supporting its potential as a prototypical candidate for further study. Moreover, the evaluation and biological characterization of the halogenated DMT derivatives offers valuable information on structure-activity relationships that may guide the design of future therapeutic compounds.

Substance Use Disorder (SUD) is a chronic, relapsing mental health condition characterized by compulsive substance use despite harmful consequences. According to the World Health Organization, in 2021, approximately 39.5 million individuals worldwide suffered from drug use disorders, contributing to an estimated 600,000 deaths annually. Moreover, current pharmacological treatment, such as methadone and buprenorphine, used for opioid use disorder, may pose risks of dependency, overdose, and withdrawal, highlighting the need for innovative therapeutic approaches. Psychedelics, including psilocybin and ibogaine, have gained renewed scientific interest for their therapeutic potential in treating various mental health conditions such as depression and post-traumatic stress disorder. Building on these findings, researchers are exploring their potential in SUD treatment, particularly in facilitating recovery and long-term behavioral change. These compounds may facilitate therapeutic outcomes through mechanisms involving neuroplasticity, altered brain connectivity, and profound psychological experiences that support behavioral modification and emotional resilience. Beyond reducing substance use, psychedelics may enhance psychosocial functioning and overall mental health. This chapter will review their underlying mechanisms, clinical evidence, and future prospects in the treatment of SUD.

Psychedelics have garnered significant interest for their therapeutic potential in mental health conditions such as depression, anxiety, and post-traumatic stress disorder. While research has primarily focused on well-studied psychedelics, phenethylamine derivatives have also gathered interest for their potential therapeutic applications. Thus, this study aims to investigate the pharmacological profile, safety and therapeutic potential of novel N-(2-fluorobenzyl) phenethylamine analogs (NBFs) of the 2C-X series—25C-NBF, 25B-NBF, and 25I-NBF. NBFs displayed high affinity and selectivity for the 5-HT2A receptor and demonstrated bias factors (defined in our study as the preference for Gq over β-arrestin pathways at 5-HT2A receptor) similar to that of 5-HT. Acute administration induced moderate head-twitch responses without affecting locomotion or pre-pulse inhibition. Our studies revealed no rewarding effects in mice nor reinforcing effects or changes in accumbal dopamine levels in rats after NBFs administration. Further characterization of 25C-NBF revealed psychoplastogenic effects (dendritogenesis, spinogenesis and increased Bdnf mRNA levels) both in vitro and in vivo. In addition, 25C-NBF reduced despair-like behavior in response to acute stress and exerted rapid antidepressant effects in a model of anhedonia-like behavior induced by chronic corticosterone administration. Taken together, these findings suggest that 25C-NBF, and further analogs, may hold potential as novel antidepressants with a rapid onset of action and a favorable safety profile in terms of no abuse potential or sensorimotor gating deficits.

The escalating prevalence of new psychoactive substances (NPSs) poses a significant public health challenge, evidenced by the vast chemical diversity, with over 500 substances reported annually to the United Nations Office on Drugs and Crime-Early Warning Advisory (UNODC-EWA) in the past five years. Among NPSs, synthetic cathinones are gaining a lot of popularity among users. Notably, synthetic cathinones accounted for approximately 50% of the total quantity of NPSs reported as seized by EU Member States in 2021. Preliminary data from UNODC indicates that a total of 209 synthetic cathinones have been reported to date. As their popularity grows, studying the structure-activity relationship (SAR) of synthetic cathinones is essential. SAR studies elucidate how structural features impact biological effects, aiding in toxicity prediction, regulatory compliance, and forensic identification. Additionally, SAR studies play a pivotal role in guiding drug policies, aiding authorities in categorizing and regulating newly emerging synthetic cathinones, mitigate public health risks and offer valuable insights into potential therapeutic applications. Thus, our Review consolidates recent findings on the effects of different substitutions in the chemical scaffold of synthetic cathinones on their mechanism of action as well as pharmacological and toxicological effects of synthetic cathinones, thus enhancing understanding of the SAR of synthetic cathinones' pharmacology and potential implications.

The secondary neurotoxicity induced by severe organophosphorus (OP) poisoning, including paraoxon (POX), is associated with cognitive impairments in survivors, who, despite receiving appropriate emergency treatments, may still experience lasting neurological deficits. Thus, the present study provides a survival mouse model of acute and severe POX poisoning to examine secondary neurotoxicity. Swiss CD-1 male mice were injected with POX (4 mg/kg, s.c.) followed by atropine (4 mg/kg, i.p.), pralidoxime (2-PAM; Pyridine-2-aldoxime methochloride) (25 mg/kg, i.p., twice, 1 h apart) and diazepam (5 mg/kg, i.p.), resulting in a survival rate >90% and Racine score of 5-6. Our results demonstrated that the model showed increased lipid peroxidation, downregulation of antioxidant enzymes and astrogliosis in the mouse hippocampus (HP) and prefrontal cortex (PFC), brain areas involved in cognitive functions. Moreover, dopamine (DA) levels were reduced in the hp, but increased in the PFC. Furthermore, the survival mouse model of acute POX intoxication did not exhibit phenotypic manifestations of depression, anxiety or motor incoordination. However, our results demonstrated long-term recognition memory impairments, which are in accordance with the molecular and neurochemical effects observed. In conclusion, this mouse model can aid in researching POX exposure's effects on memory and developing potential countermeasures against the secondary neurotoxicity induced by severe OP poisoning.

Recent studies have sparked renewed interest in the therapeutic potential of psychedelics for treating depression and other mental health conditions. Simultaneously, the novel psychoactive substances (NPS) phenomenon, with a huge number of NPS emerging constantly, has changed remarkably the illicit drug market, being their scientific evaluation an urgent need. Thus, this study aims to elucidate the impact of amino-terminal modifications to the 5-MeO-DMT molecule on its interactions with serotonin receptors and transporters, as well as its psychoactive and thermoregulatory properties. Our findings demonstrated, using radioligand binding methodologies, that all examined 5-MeO-tryptamines exhibited selectivity for 5-HT1AR over 5-HT2AR. In fact, computational docking analyses predicted a better interaction in the 5-HT1AR binding pocket compared to 5-HT2AR. Our investigation also proved the interaction of these compounds with SERT, revealing that the molecular size of the amino group significantly influenced their affinity. Subsequent experiments involving serotonin uptake, electrophysiology, and superfusion release assays confirmed 5-MeO-pyr-T as the most potent partial 5-HT releaser tested. All tested tryptamines elicited, to some degree, the head twitch response (HTR) in mice, indicative of a potential hallucinogenic effect and mainly mediated by 5-HT2AR activation. However, 5-HT1AR was also shown to be implicated in the hallucinogenic effect, and its activation attenuated the HTR. In fact, tryptamines that produced a higher hypothermic response, mediated by 5-HT1AR, tended to exhibit a lower hallucinogenic effect, highlighting the opposite role of both 5-HT receptors. Moreover, although some 5-MeO-tryptamines elicited very low HTR, they still act as potent 5-HT2AR agonists. In summary, this research offers a comprehensive understanding of the psychopharmacological profile of various amino-substituted 5-MeO-tryptamines, keeping structural aspects in focus and accumulating valuable data in the frame of NPS. Moreover, the unique characteristics of some 5-MeO-tryptamines render them intriguing molecules as mixed-action drugs and provide insight within the search of non-hallucinogenic but 5-HT2AR ligands as therapeutical agents.

BACKGROUND AND PURPOSE:New psychoactive substances such as N-ethylpentylone (NEP) are continuously emerging in the illicit drug market, and knowledge of their effects and risks, which may vary between sexes, is scarce. Our present study compares some key effects of NEP in male and female mice. EXPERIMENTAL APPROACH:Psychostimulant, rewarding and reinforcing effects were investigated by tracking locomotor activity, conditioned place preference (CPP) paradigm and through a self-administration (SA) procedure, respectively, in CD1 mice. Moreover, the expression of early genes (C-fos, Arc, Csnk1e, Pdyn, Pp1r1b and Bdnf in addiction-related brain areas) was assessed by qPCR. Finally, serum and brain levels of NEP were determined by UHPLC-MS/MS. KEY RESULTS:NEP-treated males experimented locomotor sensitisation and showed higher and longer increases in locomotion as well as higher hyperthermia after repeated administration than females. Moreover, while preference score in the CPP was similar in both sexes, extinction occurred later, and reinstatement was more easily established for males. Female mice self-administered more NEP than males at a higher dose. Differences in early gene expression (Arc, Bdnf, Csnk1e and Ppp1r1b) were found, but the serum and brain NEP levels did not differ between sexes. CONCLUSION AND IMPLICATIONS:Our results suggest that male mice are more sensitive to NEP psychostimulant and rewarding effects. These differences may be attributed to different early gene expression but not to pharmacokinetic factors. Moreover, males appear to be more vulnerable to the hyperthermic effects of NEP, while females might be more prone to NEP abuse.

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.