Methylenedioxypyrovalerone (MDPV) mimics cocaine in its physiological and behavioral effects but induces distinct changes in NAc glucose

Cocaine hydrochloride, cocaine methiodide and methylenedioxypyrovalerone (MDPV) cause distinct alterations in the structure and composition of the gut microbiota

Cocaine is a highly addictive psychostimulant drug of abuse that constitutes an ongoing public health threat. Emerging research is revealing that numerous peripheral effects of this drug may serve as conditioned stimuli for its central reinforcing properties. The gut microbiota is emerging as one of these peripheral sources of input to cocaine reward. The primary objective of the present study was to determine how cocaine HCl and methylenedioxypyrovalerone, both of which powerfully activate central reward pathways, alter the gut microbiota. Cocaine methiodide, a quaternary derivative of cocaine that does not enter the brain, was included to assess peripheral influences on the gut microbiota. Both cocaine congeners caused significant and similar alterations of the gut microbiota after a 10-day course of treatment. Contrary to expectations, the effects of cocaine HCl and MDPV on the gut microbiota were most dissimilar. Functional predictions of metabolic alterations caused by the treatment drugs reaffirmed that the cocaine congeners were similar whereas MDPV was most dissimilar from the other two drugs and controls. It appears that the monoamine transporters in the gut mediate the effects of the treatment drugs. The effects of the cocaine congeners and MDPV on the gut microbiome may form the basis of interoceptive cues that can influence their abuse properties.

Contrasting dose-dependent effects of acute intravenous methamphetamine on lateral hypothalamic extracellular glucose dynamics in male and female rats

Glucose is the brain's primary energetic resource. The brain's use of glucose is dynamic, balancing delivery from the neurovasculature with local metabolism. Although glucose metabolism is known to differ in humans with and without methamphetamine use disorder (MUD), it is unknown how central glucose regulation changes with acute methamphetamine experience. Here, we determined how intravenous methamphetamine regulates extracellular glucose levels in a brain region implicated in MUD-like behavior, the lateral hypothalamus (LH). We measured extracellular LH glucose in awake adult male and female drug-naive Wistar rats using enzyme-linked amperometric glucose biosensors. Changes in LH glucose were monitored during a single session after: 1) natural nondrug stimuli (novel object presentation and a tail-touch), 2) increasing cumulative doses of intravenous methamphetamine (0.025, 0.05, 0.1, and 0.2 mg/kg), and 3) an injection of 60 mg of glucose. We found second-scale fluctuations in LH glucose in response to natural stimuli that differed by both stimulus type and sex. Although rapid, second-scale changes in LH glucose during methamphetamine injections were variable, slow, minute-scale changes following most injections were robust and resulted in a reduction in LH glucose levels. Dose and sex differences at this timescale indicated that female rats may be more sensitive to the impact of methamphetamine on central glucose regulation. These findings suggest that the effects of MUD on healthy brain function may be linked to how methamphetamine alters extracellular glucose regulation in the LH and point to possible mechanisms by which methamphetamine influences central glucose metabolism more broadly.NEW & NOTEWORTHY Enzyme-linked glucose biosensors were used to monitor lateral hypothalamic (LH) extracellular fluctuations during nondrug stimuli and intravenous methamphetamine injections in drug-naive awake male and female rats. Second-scale glucose changes occurred after nondrug stimuli, differing by modality and sex. Robust minute-scale decreases followed most methamphetamine injections. Sex differences at the minute-scale indicate female central glucose regulation is more sensitive to methamphetamine effects. We discuss likely mechanisms underlying these fluctuations, and their implications in methamphetamine use disorder.

Ethanol enhanced MDPV- and cocaine-induced aggressive behavior in mice: Forensic implications

BACKGROUND

Reports concerning the causal link between aggressive behavior and use and abuse of different substances (i.e., alcohol, MDPV) can be found in the literature. Nonetheless, the topic concerning the effects of acute ethanol administration on MDPV and cocaine induced aggressive behavior has yet to be thoroughly investigated. The aim of this study was to investigate such synergistic effects.

MATERIALS AND METHODS

A total of 360 male mice were employed in the study. Ethanol was diluted with saline solution and administered 10 min before MDPV or cocaine injection via oral gavage needles. Similarly, MDPV and cocaine were dissolved in saline solution and administered by intraperitoneal injection. Different associations of specific drug doses were then tested. To investigate the acute effects of MDPV and cocaine and their interaction with ethanol on aggression in mice, a resident-intruder test was used.

RESULTS

Ethanol alone was ineffective at dosages of 0.05 g/kg and 0.25 g/kg but increased the aggressiveness of the mice at 0.125 g/kg. Similarly, the injection of both cocaine alone and MDPV alone did not significantly increase the aggressiveness of the mice; conversely, the combination of ethanol and cocaine and ethanol and MDPV enhanced aggression at specific ethanol dosages (0.05 g/kg and 0.125 g/kg).

CONCLUSION

This study demonstrated that acute ethanol administration enhances MDPV- and cocaine-induced aggressive behavior in mice. This aggressive response is particularly enhanced when MDVP and cocaine are coupled with specific ethanol dosages, proving that psychostimulant drugs may act synergistically under certain conditions.

Characterization of 3,4-methylenedioxypyrovalerone discrimination in female Sprague-Dawley rats

3,4-Methylenedioxypyrovalerone (MDPV), one of several synthetic cathinones, is a popular constituent of illicit 'bath salts'. In preclinical studies utilizing drug discrimination methods with male rodents, MDPV has been characterized as similar to both cocaine and 3,4-methylenedioxymethamphetamine-hydrochloride (MDMA). Whereas few drug discrimination studies have utilized female rats, the current study evaluated the discriminative stimulus effects of MDPV in 12 adult female Sprague-Dawley rats trained to discriminate 0.5 mg/kg MDPV from saline under a fixed ratio 20 schedule of food reinforcement. Stimulus substitution was assessed with MDPV and its enantiomers, other synthetic cathinones [alpha pyrrolidinopentiophenone-hydrochloride(α-PVP), 4-methylmethcathinone (4-MMC)], other dopamine agonists (cocaine, [+)-methamphetamine] and serotonin agonists [MDMA, lysergic acid diethylamide (LSD)] Stimulus antagonism was assessed with the dopamine D1 receptor antagonist, Sch 23390 and the D2 receptor antagonist, haloperidol. Cocaine and (+)-methamphetamine engendered full stimulus generalization to MDPV with minimal effects on response rate. LSD produced partial substitution, whereas MDMA and 4-MMC produced complete substitution, and all these serotonergic compounds produced dose-dependent response suppression. (S)-MDPV and α-PVP engendered full substitution with similar potency to the racemate, while (R)-MDPV failed to substitute up to 5 mg/kg. Both Sch 23390 and haloperidol attenuated the discrimination of low MDPV doses and essentially shifted the dose-response curve to the right but failed to block discrimination of the training dose. These findings are generally consistent with previous reports based exclusively on male rodents. Moreover, they confirm the contribution of dopaminergic mechanisms but do not rule out the possible contribution of other neurotransmitter actions to the interoceptive stimulus effects of MDPV.

Worsening of the Toxic Effects of (±)Cis-4,4'-DMAR Following Its Co-Administration with (±)Trans-4,4'-DMAR: Neuro-Behavioural, Physiological, Immunohistochemical and Metabolic Studies in Mice

4,4’-Dimethylaminorex (4,4’-DMAR) is a new synthetic stimulant, and only a little information has been made available so far regarding its pharmaco-toxicological effects. The aim of this study was to investigate the effects of the systemic administration of both the single (±)cis (0.1–60 mg/kg) and (±)trans (30 and 60 mg/kg) stereoisomers and their co-administration (e.g., (±)cis at 1, 10 or 60 mg/kg + (±)trans at 30 mg/kg) in mice. Moreover, we investigated the effect of 4,4′-DMAR on the expression of markers of oxidative/nitrosative stress (8-OHdG, iNOS, NT and NOX2), apoptosis (Smac/DIABLO and NF-κB), and heat shock proteins (HSP27, HSP70, HSP90) in the cerebral cortex. Our study demonstrated that the (±)cis stereoisomer dose-dependently induced psychomotor agitation, sweating, salivation, hyperthermia, stimulated aggression, convulsions and death. Conversely, the (±)trans stereoisomer was ineffective whilst the stereoisomers’ co-administration resulted in a worsening of the toxic (±)cis stereoisomer effects. This trend of responses was confirmed by immunohistochemical analysis on the cortex. Finally, we investigated the potentially toxic effects of stereoisomer co-administration by studying urinary excretion. The excretion study showed that the (±)trans stereoisomer reduced the metabolism of the (±)cis form and increased its amount in the urine, possibly reflecting its increased plasma levels and, therefore, the worsening of its toxicity.

Cross-reinstatement between 3,4-methylenedioxypyrovalerone (MDPV) and cocaine using conditioned place preference

3,4-Methylenedioxypyrovalerone (MDPV) is a new psychoactive substance (NPS) considered to be a cocaine-like psychostimulant. The substitution of an established illicit drug as cocaine with an NPS is a pattern of use reported among drug users. The aim of this study was to investigate the relationship between cocaine and MDPV in the reinstatement of the conditioned place preference (CPP) paradigm, in order to establish whether there is cross-reinstatement between the two psychostimulants. Four experimental groups of male OF1 mice were subjected to the CPP paradigm: MDPV-MDPV, Cocaine-Cocaine, Cocaine-MDPV, and MDPV-Cocaine. The first drug refers to the substance with which the animals were conditioned (cocaine 10 mg/kg or MDPV 2 mg/kg) and the s to the substance with which preference was reinstated. In parallel, G9a, ΔFosB, CB1 receptor, CDK5, Arc and c-Fos were determined in ventral striatum. MDPV induced CPP at doses from 1 to 4 mg/kg. Although 2 mg/kg MDPV induced a stronger psychostimulant effect than 10 mg/kg cocaine, both doses seemed to be equivalent in their rewarding properties. However, memories associated with MDPV required more time to be extinguished. MDPV and cocaine restore drug-seeking behavior with respect to each other, although relapse into drug-taking is always more pronounced with the conditioning drug. The fact that MDPV-treated mice show increased ΔFosB protein levels correlates with its longer extinction time and points to the activation of neuroplasticity mechanisms that persist for at least 12 days. Moreover, in these animals, a priming-dose of cocaine can trigger significant neuroplasticity, implying a high vulnerability to cocaine abuse.

Brain temperature and its role in physiology and pathophysiology: Lessons from 20 years of thermorecording

It is well known that temperature affects the dynamics of all physicochemical processes governing neural activity. It is also known that the brain has high levels of metabolic activity, and all energy used for brain metabolism is finally transformed into heat. However, the issue of brain temperature as a factor reflecting neural activity and affecting various neural functions remains in the shadow and is usually ignored by most physiologists and neuroscientists. Data presented in this review demonstrate that brain temperature is not stable, showing relatively large fluctuations (2-4°C) within the normal physiological and behavioral continuum. I consider the mechanisms underlying these fluctuations and discuss brain thermorecording as an important tool to assess basic changes in neural activity associated with different natural (sexual, drinking, eating) and drug-induced motivated behaviors. I also consider how naturally occurring changes in brain temperature affect neural activity, various homeostatic parameters, and the structural integrity of brain cells as well as the results of neurochemical evaluations conducted in awake animals. While physiological hyperthermia appears to be adaptive, enhancing the efficiency of neural functions, under specific environmental conditions and following exposure to certain psychoactive drugs, brain temperature could exceed its upper limits, resulting in multiple brain abnormalities and life-threatening health complications.

Acute and repeated administration of MDPV increases aggressive behavior in mice: forensic implications

MDPV is a synthetic cathinone illegally marketed and consumed for its psychostimulant effects, which are similar to those produced by cocaine, amphetamines, and MDMA. Clinical reports indicate that MDPV produces euphoria, increases alertness, and at high doses causes agitation, psychosis, tachycardia and hypertension, hallucinations, delirium, hyperthermia, rhabdomyolysis, and even death. In rodents, MDPV reproduces the typical physiological effects of psychostimulant drugs, demonstrating greater potency than cocaine. Nevertheless, its role in aggressive behavior has been reported but not yet experimentally confirmed. Therefore, the aim of this study was to evaluate the effects of acute and repeated MDPV (0.01-10 mg/kg i.p.) administration on aggressive behavior in mice and to compare them with those of cocaine (0.01-10 mg/kg i.p.) administration. To this purpose, the resident-intruder test in isolated mice and the spontaneous and stimulated aggressiveness tests for group-housed mice were employed. The present study shows for the first time that MDPV enhances aggressive behavior and locomotion in mice with greater potency and efficacy than cocaine treatment. Moreover, the aggressive and locomotor responses are enhanced after repeated administration, indicating that a sensitization mechanism comes into play. These results, although from preclinical investigation, are suggestive that human MDPV intake could be a problem for public health and the criminal justice system. Thus, investigation by police officers and medical staff is needed to prevent interpersonal violence induced by the consumption of synthetic cathinones.

Acute and chronic neurobehavioral effects of the designer drug and bath salt constituent 3,4-methylenedioxypyrovalerone in the rat

BACKGROUND

The substantial increase in use of 3,4-methylenedioxypyrovalerone (MDPV), a popular recreational synthetic cathinone, has raised legitimate questions about its behavioral consequences and abuse liability.

AIMS

The aim of this study was to study MDPV-induced neurobehavioral effects in the rat, using different paradigms traditionally developed to study drug-attributed addictive properties.

METHODS

Different patterns of intraperitoneal 3 mg/kg MDPV administration were investigated. Consequences on rat horizontal locomotion and behavior of acute, intermittent (once daily dosing over 10 days), and binge (three-time daily dosing for 3 days) MDPV administration as well as challenge after 10 day MDPV withdrawal were studied. The dopamine receptor-D1 antagonist, SCH23390, was bilaterally infused in the nucleus accumbens to determine the role of D1-receptors in MDPV-related effects on the associative memory recall using the conditioned place preference paradigm. In addition, in a separate experience using western blot, we investigated the effects of chronic MDPV administration (four injections during 24 h) on ΔFosB expression in the nucleus accumbens, caudate putamen, and prefrontal cortex.

RESULTS

Acute MDPV administration increased stereotypies and open arm entries in the elevated plus maze while SCH23390 abolished MDPV-induced enhancing effects on memory consolidation. Intermittent MDPV administration resulted in sensitization of MDPV-induced locomotor effects and tolerance during the following challenge. With binge MDPV administration, locomotor activity was not altered despite tolerance onset after challenge. SCH23390 abolished MDPV-induced conditioned place preference. Chronic MDPV administration induced ΔFosB accumulation in the nucleus accumbens, caudate putamen, and prefrontal cortex.

CONCLUSIONS

Our findings clearly show that MDPV produces profound behavioral alterations mediated by the activation of the dopaminergic system similarly to other amphetamines.

Is the 3,4-methylendioxypyrovalerone/mephedrone combination responsible for enhanced stimulant effects? A rat study with investigation of the effect/concentration relationships

RATIONALE

The use of synthetic cathinones as recreational drugs frequently sold in combination has been increasing exponentially. However, the consequences of combining cathinones on the resulting stimulant effects and the pharmacokinetics have been poorly investigated.

OBJECTIVE AND METHODS

To study 3,4-methylenedioxypyrovalerone (MDPV; 3 mg/kg) and mephedrone (4-MMC; 30 mg/kg)-induced effects on rat locomotor activity and pharmacokinetics, administered alone or in combination by the intragastric route. The pharmacokinetic parameters were determined using non-compartmental analysis and the relationships between the locomotor activity and drug concentrations using sigmoidal E_max modeling.

RESULTS

Locomotor activity significantly increased during the first hour post-administration with the MDPV/4-MMC combination in comparison to MDPV (p < 0.001) and 4-MMC (p < 0.01) alone. The pharmacokinetic profile of MDPV, but not 4-MMC, was significantly modified with the combination resulting in decreases in C_max (16.4 ± 5.5 versus 62.2 ± 14.2 μg/L, p < 0.05) and AUC_{0 → ∞} (708 ± 91 versus 3316 ± 682 μg/L/min, p < 0.01) and increases in V/F (582.6 ± 136.8 versus 115.9 ± 42.7 L/kg, p < 0.05) and Cl/F (4.6 ± 0.7 versus 1.2 ± 0.4 L/kg/min, p < 0.01) in comparison to MDPV alone. The sigmoidal E_max model fitted the observed data well; MDPV being markedly more potent than 4-MMC (EC₅₀, 0.043 versus 0.7 μmol/L). The enhancing factor representing the MDPV contribution to the alteration in the relationships between locomotor activity and 4-MMC concentrations was 0.3.

CONCLUSION

An MDPV/4-MMC combination results in enhanced stimulant effects in the rat, despite significant reduction in MDPV bioavailability. Enhanced effects could be explained by increased MDPV distribution and/or possible complementation at the brain dopaminergic targets. However, the exact consequences of the MDPV/4-MMC combination in humans remain to be clarified.

Cardiovascular effects of 3,4-methylenedioxypyrovalerone (MDPV) in male and female Sprague-Dawley rats

BACKGROUND

3,4-methylenedioxypyrovalerone (MDPV) toxicity includes intense neurological and cardiovascular events. We examined MDPV-induced cardiovascular, temperature, and locomotor effects following escalating and repeated MDPV administration in adult male and female Sprague-Dawley rats and compared these effects to cocaine in male rats.

METHODS

Telemetry devices were surgically implanted to allow continuous measurement of cardiovascular, temperature, and locomotor activity over a 22 h period after dosing. Rats were administered increasing intraperitoneal (IP) MDPV doses (1-5.6 mg/kg) every other day, followed two days later by a binge regimen of four injections of 3 mg/kg MDPV at 2 h intervals. MDPV serum concentrations were measured by LC-MS/MS. Cocaine (3-30 mg/kg) and four injections of 30 mg/kg IP were administered to male rats for comparison with male MDPV data.

RESULTS

The duration of MDPV cardiovascular effects was significantly greater (p < 0.05) in male rats than female rats at 3-5.6 mg/kg. The ED₅₀ for MDPV-induced locomotor was significantly lower in males (2.4 ± 0.3) than females (3.4 ± 0.2). Males showed significantly greater variability in MDPV serum concentrations than females after binge dosing. MDPV produced five-fold more potent cardiovascular effects than cocaine in male rats. MDPV did not alter thermoregulation in either sex, but cocaine binge administration decreased temperature.

CONCLUSION

Effects of MDPV on temperature were not significantly different between sexes. MDPV-induced cardiovascular and locomotor effects in males lasted significantly longer and were more potent than in females. These differences appeared to be related to pharmacokinetic factors leading to greater variance in MDPV serum concentrations in males.

The Cathinones MDPV and α-PVP Elicit Different Behavioral and Molecular Effects Following Acute Exposure

Since the mid-to-late 2000s, synthetic cathinones have gained popularity among drug users due to their psychostimulant effects greater than those produced by cocaine and amphetamine. Among them, 3,4-methylenedioxypyrovalerone (MDPV) and 1-phenyl-2-(pyrrolidin-1-yl)pentan-1-one (α-PVP) are ones of the most popular cathinones available in the clandestine market as "bath salts" or "fertilizers." Pre-clinical studies indicate that MDPV and α-PVP induced psychomotor stimulation, affected thermoregulation, and promoted reinforcing properties in rodents. However, a direct comparative analysis on the effects caused by MDPV and α-PVP on the behavior and neuronal activation in rodents is still lacking. Behavioral analyses revealed that both MDPV and α-PVP affect spontaneous and stimulated motor responses. In particular, MDPV showed a greater psychomotor effect than α-PVP in line with its higher potency in blocking the dopamine transporter (DAT). Notably, MDPV was found to be more effective than α-PVP in facilitating spontaneous locomotion and it displayed a biphasic effect in contrast to the monophasically stimulated locomotion induced by α-PVP. In addition to the behavioral results, we also found a different modulation of immediate early genes (IEGs) such as Arc/Arg3.1 and c-Fos in the frontal lobe, striatum, and hippocampus, indicating that these drugs do impact brain homeostasis with changes in neuronal activity that depend on the drug, the brain area analyzed, and the timing after the injection. These results provide the first discrimination between MDPV and α-PVP based on behavioral and molecular data that may contribute to explain, at least in part, their toxicity.

The Psychoactive Designer Drug and Bath Salt Constituent MDPV Causes Widespread Disruption of Brain Functional Connectivity

The abuse of 'bath salts' has raised concerns because of their adverse effects, which include delirium, violent behavior, and suicide ideation in severe cases. The bath salt constituent 3,4-methylenedioxypyrovalerone (MDPV) has been closely linked to these and other adverse effects. The abnormal behavioral pattern produced by acute high-dose MDPV intake suggests possible disruptions of neural communication between brain regions. Therefore, we determined if MDPV exerts disruptive effects on brain functional connectivity, particularly in areas of the prefrontal cortex. Male rats were imaged following administration of a single dose of MDPV (0.3, 1.0, or 3.0 mg/kg) or saline. Resting state brain blood oxygenation level-dependent (BOLD) images were acquired at 4.7 T. To determine the role of dopamine transmission in MDPV-induced changes in functional connectivity, a group of rats received the dopamine D1/D2 receptor antagonist cis-flupenthixol (0.5 mg/kg) 30 min before MDPV. MDPV dose-dependently reduced functional connectivity. Detailed analysis of its effects revealed that connectivity between frontal cortical and striatal areas was reduced. This included connectivity between the prelimbic prefrontal cortex and other areas of the frontal cortex and the insular cortex with hypothalamic, ventral, and dorsal striatal areas. Although the reduced connectivity appeared widespread, connectivity between these regions and somatosensory cortex was not as severely affected. Dopamine receptor blockade did not prevent the MDPV-induced decrease in functional connectivity. The results provide a novel signature of MDPV's in vivo mechanism of action. Reduced brain functional connectivity has been reported in patients suffering from psychosis and has been linked to cognitive dysfunction, audiovisual hallucinations, and negative affective states akin to those reported for MDPV-induced intoxication. The present results suggest that disruption of functional connectivity networks involving frontal cortical and striatal regions could contribute to the adverse effects of MDPV.

Methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxypyrovalerone (MDPV) induce differential cytotoxic effects in bovine brain microvessel endothelial cells

Designer drugs such as synthetic psychostimulants are indicative of a worldwide problem of drug abuse and addiction. In addition to methamphetamine (METH), these drugs include 3,4-methylenedioxy-methamphetamine (MDMA) and commercial preparations of synthetic cathinones including 3,4-methylenedioxypyrovalerone (MDPV), typically referred to as "bath salts." These psychostimulants exert neurotoxic effects by altering monoamine systems in the brain. Additionally, METH and MDMA adversely affect the integrity of the blood-brain barrier (BBB): there are no current reports on the effects of MDPV on the BBB. The aim of this study was to compare the effects of METH, MDMA and MDPV on bovine brain microvessel endothelial cells (bBMVECs), an accepted in vitro model of the BBB. Confluent bBMVEC monolayers were treated with METH, MDMA and MDPV (0.5mM-2.5mM) for 24h. METH and MDMA increased lactate dehydrogenase release only at the highest concentration (2.5mM), whereas MDPV induced cytotoxicity at all concentrations. MDMA and METH decreased cellular proliferation only at 2.5mM, with similar effects observed after MDPV exposures starting at 1mM. Only MDPV increased reactive oxygen species production at all concentrations tested whereas all 3 drugs increased nitric oxide production. Morphological analysis revealed different patterns of compound-induced cell damage. METH induced vacuole formation at 1mM and disruption of the monolayer at 2.5mM. MDMA induced disruption of the endothelial monolayer from 1mM without vacuolization. On the other hand, MDPV induced monolayer disruption at doses ≥0.5mM without vacuole formation; at 2.5mM, the few remaining cells lacked endothelial morphology. These data suggest that even though these synthetic psychostimulants alter monoaminergic systems, they each induce BBB toxicity by different mechanisms with MDPV being the most toxic.

Neurobiology of 3,4-methylenedioxypyrovalerone (MDPV) and α-pyrrolidinovalerophenone (α-PVP)

Synthetic cathinones are analogs of cathinone or β-ketoamphetamine - the major psychostimulant component of the shrub Catha edulis or khat. Cathinone analogs - though not termed as such - have been known for >100 years, but confusing chemical nomenclature often made the topic difficult to appreciate. In addition, many of the early analogs were prepared as synthetic precursors for the development of various other agents, and relatively few were pharmacologically evaluated. Cathinone is a close structural relative of amphetamine. Today, certain cathinone derivatives, synthetic cathinones, are known to produce central stimulant actions and represent a "new" class of drugs of abuse. Depending upon the nature of their terminal amine, α substituent, and aryl substituents, they seem to produce their effects via release or reuptake of various neurotansmitters including dopamine norepinephreine and/or serotonin. Two of the newest and most prominent members of the class are MDPV and its parent α-PVP ("flakka"). Both have been encountered on their own and in what might be constituents of what has been termed by a variety of names including psychoactive "bath salts". Here, we describe the nomenclature of synthetic cathinones, the mechanism(s) of action of MDPV and α-PVP, and their structure-activity relationships. In order to assist in forensic studies, and to identify novel substances requiring future pharmacological evaluation, the metabolism of these agents is also described. Finally, the preclinical behavioral actions of these two agents in a variety of behavioral assays, including rodent locomotor assays, self-administration studies, intracranial self-stimulation, conditioned place preference, and drug discrimination, is summarized. The results of these studies with MDPV and α-PVP are consistent with their acting as potent cocaine-like central stimulants with abuse liability.