Effects of 3-methylmethcathinone on conditioned place preference and anxiety-like behavior: Comparison with methamphetamine

Unveiling the potential abuse liability of α-D2PV: A novel α-carbon phenyl-substituted synthetic cathinone

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.

Safety and cognitive pharmacodynamics following dose escalations with 3-methylmethcathinone (3-MMC): a first in human, designer drug study

3-Methylmethcathinone (3-MMC) is a designer drug that belongs to the group of synthetic cathinones. The compound has been scheduled in many jurisdictions because of public health concerns associated with excessive use. To date, there are no clinical studies that have evaluated the risk profile of 3-MMC in the recreational range of low to moderate doses. The current, first-in-human study (N = 14) assessed the impact of three escalating doses of 3-MMC (25, 50 and 100 mg) on vital signs, neurocognitive function, state of consciousness, appetite and drug desire, in a cross-over, placebo-controlled trial. A battery of neurocognitive tests and questionnaires as well as measures of vital signs were repeatedly administered up to 5 h after dosing. Overall, 3-MMC caused dose-dependent increases in heart rate and blood pressure, though not of clinical significance, and feelings of subjective high. Additionally, 3-MMC induced dose-related enhancement of task performance across several neurocognitive domains, including processing speed, cognitive flexibility, psychomotor function, attention and memory. Impulse control was not affected by 3-MMC. Participants also reported mild increases in dissociative and psychedelic effects, decreased appetite, and gave greater ratings of liking and wanting for 3-MMC that were transient over time. Overall, the cardiovascular, psychostimulant and psychotomimetic profile of 3-MMC appears consistent with that of compounds structurally related to amphetamine. It is concluded that low to moderate doses of 3-MMC were well tolerated and safe and that potential health risks might only occur at high or excessive doses of 3-MMC.

3'-Deoxyadenosin alleviates methamphetamine-induced aberrant synaptic plasticity and seeking behavior by inhibiting the NLRP3 inflammasome

JOURNAL/nrgr/04.03/01300535-202410000-00028/figure1/v/2024-02-06T055622Z/r/image-tiff Methamphetamine addiction is a brain disorder characterized by persistent drug-seeking behavior, which has been linked with aberrant synaptic plasticity. An increasing body of evidence suggests that aberrant synaptic plasticity is associated with the activation of the NOD-like receptor family pyrin domain containing-3 (NLRP3) inflammasome. 3'-Deoxyadenosin, an active component of the Chinese fungus Cordyceps militaris, has strong anti-inflammatory effects. However, whether 3'-deoxyadenosin attenuates methamphetamine-induced aberrant synaptic plasticity via an NLRP3-mediated inflammatory mechanism remains unclear. We first observed that 3'-deoxyadenosin attenuated conditioned place preference scores in methamphetamine-treated mice and decreased the expression of c-fos in hippocampal neurons. Furthermore, we found that 3'-deoxyadenosin reduced the aberrant potentiation of glutamatergic transmission and restored the methamphetamine-induced impairment of synaptic plasticity. We also found that 3'-deoxyadenosin decreased the expression of NLRP3 and neuronal injury. Importantly, a direct NLRP3 deficiency reduced methamphetamine-induced seeking behavior, attenuated the impaired synaptic plasticity, and prevented neuronal damage. Finally, NLRP3 activation reversed the effect of 3'-deoxyadenosin on behavior and synaptic plasticity, suggesting that the anti-neuroinflammatory mechanism of 3'-deoxyadenosin on aberrant synaptic plasticity reduces methamphetamine-induced seeking behavior. Taken together, 3'-deoxyadenosin alleviates methamphetamine-induced aberrant synaptic plasticity and seeking behavior by inhibiting the NLRP3 inflammasome.

Quantifying conditioned place preference: a review of current analyses and a proposal for a novel approach

Conditioned place preference (CPP) is used to measure the conditioned rewarding effects of a stimulus, including food, drugs, and social interaction. Because various analytic approaches can be used to quantify CPP, this can make direct comparisons across studies difficult. Common methods for analyzing CPP involve comparing the time spent in the CS+ compartment (e.g., compartment paired with drug) at posttest to the time spent in the CS+ compartment at pretest or to the CS- compartment (e.g., compartment paired with saline) at posttest. Researchers can analyze the time spent in the compartment(s), or they can calculate a difference score [(CS+post - CS+pre) or (CS+post - CS-post)] or a preference ratio (e.g., CS+post/(CS+post + CS-post)). While each analysis yields results that are, overall, highly correlated, there are situations in which different analyses can lead to discrepant interpretations. The current paper discusses some of the limitations associated with current analytic approaches and proposes a novel method for quantifying CPP, the adjusted CPP score, which can help resolve the limitations associated with current approaches. The adjusted CPP score is applied to both hypothetical and previously published data. Another major topic covered in this paper is methodologies for determining if individual subjects have met criteria for CPP. The paper concludes by highlighting ways in which researchers can increase transparency and replicability in CPP studies.

An orbitofrontal cortex-anterior insular cortex circuit gates compulsive cocaine use

Compulsive drug use, a cardinal symptom of drug addiction, is characterized by persistent substance use despite adverse consequences. However, little is known about the neural circuit mechanisms behind this behavior. Using a footshock-punished cocaine self-administration procedure, we found individual variability of rats in the process of drug addiction, and rats with compulsive cocaine use presented increased neural activity of the anterior insular cortex (aIC) compared with noncompulsive rats. Chemogenetic manipulating activity of aIC neurons, especially aIC glutamatergic neurons, bidirectionally regulated compulsive cocaine intake. Furthermore, the aIC received inputs from the orbitofrontal cortex (OFC), and the OFC-aIC circuit was enhanced in rats with compulsive cocaine use. Suppression of the OFC-aIC circuit switched rats from punishment resistance to sensitivity, while potentiation of this circuit increased compulsive cocaine use. In conclusion, our results found that aIC glutamatergic neurons and the OFC-aIC circuit gated the shift from controlled to compulsive cocaine use, which could serve as potential therapeutic targets for drug addiction.