Pharmacokinetics of N-ethylpentylone and its effect on increasing levels of dopamine and serotonin in the nucleus accumbens of conscious rats

Sex differences in the effects of N-ethylpentylone in young CD1 mice: Insights on behaviour, thermoregulation and early gene expression

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.

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.

Protective Effect of Aldo-keto Reductase 1B1 Against Neuronal Cell Damage Elicited by 4'-Fluoro-α-pyrrolidinononanophenone

Chronic exposure to cathinone derivatives increases the risk of severe health hazards, whereas little is known about the detailed pathogenic mechanisms triggered by the derivatives. We have recently shown that treatment with α-pyrrolidinononanophenone (α-PNP, a highly lipophilic cathinone derivative possessing a long hydrocarbon main chain) provokes neuronal cell apoptosis and its 4'-fluorinated analog (F-α-PNP) potently augments the apoptotic effect. In this study, we found that neuronal SK-N-SH cell damage elicited by F-α-PNP treatment is augmented most potently by pre-incubation with an AKR1B1 inhibitor tolrestat, among specific inhibitors of four aldo-keto reductase (AKR) family members (1B1, 1C1, 1C2, and 1C3) expressed in the neuronal cells. In addition, forced overexpression of AKR1B1 remarkably lowered the cell sensitivity to F-α-PNP toxicity, clearly indicating that AKR1B1 protects from neurotoxicity of the derivative. Treatment of SK-N-SH cells with F-α-PNP resulted in a dose-dependent up-regulation of AKR1B1 expression and activation of its transcription factor NF-E2-related factor 2. Metabolic analyses using liquid chromatography/mass spectrometry/mass spectrometry revealed that AKR1B1 is hardly involved in the F-α-PNP metabolism. The F-α-PNP treatment resulted in production of reactive oxygen species and lipid peroxidation byproduct 4-hydroxy-2-nonenal (HNE) in the cells. The enhanced HNE level was reduced by overexpression of AKR1B1, which also lessened the cell damage elicited by HNE. These results suggest that the AKR1B1-mediated neuronal cell protection is due to detoxification of HNE formed by F-α-PNP treatment, but not to metabolism of the derivative.

Simultaneous determination of N-ethylpentylone, dopamine, 5-hydroxytryptamine and their metabolites in rat brain microdialysis by liquid chromatography tandem mass spectrometry

N-Ethylpentylone (NEP) is a popular synthetic cathinone abused worldwide. To obtain more information about its pharmacokinetics and pharmacodynamics, a rapid, simple and sensitive liquid chromatography-tandem mass spectrometry method was developed for the determination of NEP, two important neurotransmitters, dopamine and serotonin, and their metabolites, including 3,4-dihydroxyphenylacetic acid, 3-methoxytyramine and 5-hydroxyindole-3-acetic acid, in rat brain microdialysate. The analytes were separated on a Phnomenex Polar C₁₈ column, with a mobile phase of 0.1% formic acid in water (A) and 0.1% formic acid in acetonitrile (B) under gradient elution to shorten the total chromatographic run time. A triple quadruple mass spectrometer coupled with an electrospray ionization source in both positive and negative ion mode was used to detect the analytes. This method showed excellent accuracy (87.4-113.5%) and precision (relative standard deviation <15%) at three quality control levels. The limits of detection were 0.2 ng/mL for NEP and 0.2-50 nm for the others and good linearity was obtained. This study pioneered a method to integrate exogenous drugs and endogenous neurotransmitters as the drugs act on the same determination system, which means that this innovation can provide support for further study of the addictive effects of NEP or other synthetic cathinones on extracellular levels of dopamine and 5-hydroxytryptamine.