Reinforcing Effects of the Synthetic Cathinone α-Pyrrolidinopropiophenone (α-PPP) in a Repeated Extended Access Binge Paradigm

From Psychoactivity to Antimicrobial Agents: Multifaceted Applications of Synthetic Cathinones and Catha edulis Extracts

The emergence of new psychoactive substances (NPS) in the global drug market since the 2000s has posed major challenges for regulators and law enforcement agencies. Among these, synthetic cathinones have gained prominence due to their stimulant effects on the central nervous system, leading to widespread recreational use. These compounds, often marketed as alternatives to illicit stimulants such as amphetamines and cocaine, have been linked to numerous cases of intoxication, addiction and death. The structural diversity and enantiomeric forms of synthetic cathinones further complicate their detection and regulation and pose challenges to forensic toxicology. In addition to their psychoactive and toxicological effects, new research suggests that cathinones may have antimicrobial properties. Compounds derived from Catha edulis (khat), including cathinone, have shown antimicrobial activity against multidrug-resistant bacteria such as Staphylococcus aureus and Escherichia coli, highlighting their potential role in the fight against antibiotic resistance. This article provides an overview of the chemistry, pharmacokinetics, pharmacodynamics, toxicological effects and potential antimicrobial applications of synthetic cathinones. The potential therapeutic use of cathinone-derived compounds to combat antimicrobial resistance represents an exciting new frontier in drug development, although further research is needed to balance these benefits with the psychoactive risks.

EMCDDA framework and practical guidance for naming cathinones

Cathinones are often sold as "legal" alternatives to controlled stimulants such as amphetamine, MDMA and cocaine. Cathinones are the second largest group of new psychoactive substances (NPS), with close to 170 monitored by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA). Although all cathinones are related to the parent compound cathinone, one of the psychoactive principles in khat, assigning consistent, informative and user-friendly common names to these substances is challenging. Over time different naming approaches have been applied, leading to cathinones being known by several names. This work provides a framework and practical examples for the consistent naming of cathinones which is easy to understand and can be applied by the forensic community, researchers, clinical practitioners, and policy makers. The scope of the issue and rationale for earlier naming approaches are also discussed. The new naming framework has been developed based on established naming approaches and centered around the common "cathinone," and "phenone" motifs/scaffolds. The proposed framework establishes clear rules to derive the EMCDDA framework names for cathinones. Each name is, in turn, composed by a principal name containing a parent letter, derived after the "cathinone" or the "phenone" scaffold. Additional substitutions are prepended to the principal name. The framework also provides for exceptions for several cathinones and structural analogs scheduled under UN and EU legislation.

Methamphetamine and the Synthetic Cathinone 3,4-Methylenedioxypyrovalerone (MDPV) Produce Persistent Effects on Prefrontal and Striatal Microglial Morphology and Neuroimmune Signaling Following Repeated Binge-like Intake in Male and Female Rats

Psychostimulants alter cellular morphology and activate neuroimmune signaling in a number of brain regions, yet few prior studies have investigated their persistence beyond acute abstinence or following high levels of voluntary drug intake. In this study, we examined the effects of the repeated binge-like self-administration (96 h/week for 3 weeks) of methamphetamine (METH) and 21 days of abstinence in female and male rats on changes in cell density, morphology, and cytokine levels in two addiction-related brain regions-the prefrontal cortex (PFC) and dorsal striatum (DStr). We also examined the effects of similar patterns of intake of the cocaine-like synthetic cathinone derivative 3,4-methylenedioxypyrovalerone (MDPV) or saline as a control. Robust levels of METH and MDPV intake (~500-1000 infusions per 96 h period) were observed in both sexes. We observed no changes in astrocyte or neuron density in either region, but decreases in dendritic spine densities were observed in PFC pyramidal and DStr medium spiny neurons. The microglial cell density was decreased in the PFC of METH self-administering animals, accompanied by evidence of microglial apoptosis. Changes in microglial morphology (e.g., decreased territorial volume and ramification and increased cell soma volume) were also observed, indicative of an inflammatory-like state. Multiplex analyses of PFC and DStr cytokine content revealed elevated levels of various interleukins and chemokines only in METH self-administering animals, with region- and sex-dependent effects. Our findings suggest that voluntary binge-like METH or MDPV intake induces similar cellular perturbations in the brain, but they are divergent neuroimmune responses that persist beyond the initial abstinence phase.

Effects of repeated binge intake of the pyrovalerone cathinone derivative 3,4-methylenedioxypyrovalerone on prefrontal cytokine levels in rats - a preliminary study

Drugs of abuse activate neuroimmune signaling in addiction-related regions of the brain, including the prefrontal cortex (PFC) which mediates executive control, attention, and behavioral inhibition. Traditional psychostimulants including methamphetamine and cocaine are known to induce PFC inflammation, yet the effects of synthetic cathinone derivatives are largely unexplored. In this study, we examined the ability of repeated binge-like intake of the pyrovalerone cathinone derivative 3,4-methylenedioxypyrovalerone (MDPV) to alter cytokine profiles in the PFC. Male and female rats were allowed to intravenously self-administer MDPV (0.05 mg/kg/infusion) or saline as a control under conditions of prolonged binge-like access, consisting of three 96 h periods of drug access interspersed with 72 h of forced abstinence. Three weeks following cessation of drug availability, PFC cytokine levels were assessed using antibody arrays. Employing the unsupervised clustering and regression analysis tool CytoMod, a single module of co-signaling cytokines associated with MDPV intake regardless of sex was identified. With regards to specific cytokines, MDPV intake was positively associated with PFC levels of VCAM-1/CD106 and negatively associated with levels of Flt-3 ligand. These findings indicate that prolonged MDPV intake causes changes in PFC cytokine levels that persist into abstinence; however, the functional ramifications of these changes remain to be fully elucidated.

Early Life Stress Promotes Heroin Seeking But Does Not Alter the Excitability of Insular Pyramidal Cells Targeting the Nucleus Accumbens

A number of retrospective studies have demonstrated adverse childhood experiences are associated with increased vulnerability to substance use disorders, including opioid use disorders (OUDs). These adverse childhood experiences, also referred to as early life stress (ELS), can be modeled in laboratory animals by various paradigms including limited bedding and nesting (LBN) procedures. Studies using rodent models of ELS have been shown to recapitulate various aspects of OUDs, including relapse propensity and perseverance of drug-seeking behavior. In the current study, we utilized the LBN paradigm to explore potential effects on heroin self-administration, extinction, and relapse-like behaviors in male and female rats. We also utilized in vitro whole-cell electrophysiology to examine the effects of LBN and repeated heroin administration on the excitability of pyramidal neurons in the anterior insular cortex (AIC) projecting to the nucleus accumbens core (NAc), as recent studies suggest that this circuit may mediate various aspects of OUDs and may be compromised as a result of either ELS or OUDs. We observed that compared to control animals, rats exposed to LBN conditions during postnatal days 2–9 showed increased breakpoints for heroin self-administration under a progressive ratio schedule of reinforcement, impaired extinction of heroin-seeking behavior, and increased reinstatement of heroin-seeking behavior induced by heroin-associated cues. No effect of LBN rearing conditions were observed on the acquisition and maintenance of heroin self-administration, and no sex differences in heroin intake were observed. LBN and control reared animals showed no differences in the excitability of AIC-NAc pyramidal neurons, but animals treated with repeated heroin showed decreased excitability of these neurons through a significant increase in rheobase and reduction in action potentials induced by depolarizing currents. Together, these results suggest that ELS exposure produces exacerbations of heroin seeking behavior without parallel effects on AIC-NAc excitability, although heroin itself reduces the excitability of these neurons.

α-PPP and its derivatives are selective partial releasers at the human norepinephrine transporter: A pharmacological characterization of interactions between pyrrolidinopropiophenones and high and low affinity monoamine transporters

While classical cathinones, such as methcathinone, have been shown to be monoamine releasing agents at human monoamine transporters, the subgroup of α-pyrrolidinophenones has thus far solely been characterized as monoamine transporter reuptake inhibitors. Herein, we report data from previously undescribed α-pyrrolidinopropiophenone (α-PPP) derivatives and compare them with the pharmacologically well-researched α-PVP (α-pyrrolidinovalerophenone). Radiotracer-based in vitro uptake inhibition assays in HEK293 cells show that the investigated α-PPP derivatives inhibit the human high-affinity transporters of dopamine (hDAT) and norepinephrine (hNET) in the low micromolar range, with α-PVP being ten times more potent. Similar to α-PVP, no relevant pharmacological activity was found at the human serotonin transporter (hSERT). Unexpectedly, radiotracer-based in vitro release assays reveal α-PPP, MDPPP and 3Br-PPP, but not α-PVP, to be partial releasing agents at hNET (EC50 values in the low micromolar range). Furthermore, uptake inhibition assays at low-affinity monoamine transporters, i.e., the human organic cation transporters (hOCT) 1-3 and human plasma membrane monoamine transporter (hPMAT), bring to light that all compounds inhibit hOCT1 and 2 (IC50 values in the low micromolar range) while less potently interacting with hPMAT and hOCT3. In conclusion, this study describes (i) three new hybrid compounds that efficaciously block hDAT while being partial releasers at hNET, and (ii) highlights the interactions of α-PPP-derivatives with low-affinity monoamine transporters, giving impetus to further studies investigating the interaction of drugs of abuse with OCT1-3 and PMAT.