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Angoa-Perez M, Kuhn DM. The pharmacology and neurotoxicology of synthetic cathinones. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2023; 99:61-82. [PMID: 38467489 DOI: 10.1016/bs.apha.2023.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
The synthetic cathinones are man-made compounds derived from the naturally occurring drug cathinone, which is found in the khat plant. The drugs in this pharmacological class that will be the focus of this chapter include mephedrone, MDPV, methcathinone and methylone. These drugs are colloquially known as "bath salts". This misnomer suggests that these drugs are used for health improvement or that they have legitimate medical uses. The synthetic cathinones are dangerous drugs with powerful pharmacological effects that include high abuse potential, hyperthermia and hyperlocomotion. These drugs also share many of the pharmacological effects of the amphetamine class of drugs including methamphetamine, amphetamine and MDMA and therefore have high potential to cause damage to the central nervous system. The synthetic cathinones are frequently taken in combination with other psychoactive drugs such as alcohol, marijuana and the amphetamine-like stimulants, creating a situation where heightened pharmacological and neurotoxicological effects are likely to occur. Despite the structural features shared by the synthetic cathinones and amphetamine-like stimulants, including their actions at monoamine transporters and receptors, the effects of the synthetic cathinones do not always match those of the amphetamines. In particular, the synthetic cathinones are far less neurotoxic than their amphetamine counterparts, they produce a weaker hyperthermia, and they cause less glial activation. This chapter will briefly review the pharmacology and neurotoxicology of selected synthetic cathinones with the aim of delineating key areas of agreement and disagreement in the literature particularly as it relates to neurotoxicological outcomes.
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Affiliation(s)
- Mariana Angoa-Perez
- Research and Development Service, John D. Dingell VA Medical Center, Detroit, MI, United States; Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Donald M Kuhn
- Research and Development Service, John D. Dingell VA Medical Center, Detroit, MI, United States; Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI, United States.
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Zhou J, Deng W, Chen C, Kang J, Yang X, Dou Z, Wu J, Li Q, Jiang M, Liang M, Han Y. Methcathinone Increases Visually-evoked Neuronal Activity and Enhances Sensory Processing Efficiency in Mice. Neurosci Bull 2023; 39:602-616. [PMID: 36449230 PMCID: PMC10073404 DOI: 10.1007/s12264-022-00965-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 07/18/2022] [Indexed: 12/02/2022] Open
Abstract
Methcathinone (MCAT) belongs to the designer drugs called synthetic cathinones, which are abused worldwide for recreational purposes. It has strong stimulant effects, including enhanced euphoria, sensation, alertness, and empathy. However, little is known about how MCAT modulates neuronal activity in vivo. Here, we evaluated the effect of MCAT on neuronal activity with a series of functional approaches. C-Fos immunostaining showed that MCAT increased the number of activated neurons by 6-fold, especially in sensory and motor cortices, striatum, and midbrain motor nuclei. In vivo single-unit recording and two-photon Ca2+ imaging revealed that a large proportion of neurons increased spiking activity upon MCAT administration. Notably, MCAT induced a strong de-correlation of population activity and increased trial-to-trial reliability, specifically during a natural movie stimulus. It improved the information-processing efficiency by enhancing the single-neuron coding capacity, suggesting a cortical network mechanism of the enhanced perception produced by psychoactive stimulants.
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Affiliation(s)
- Jun Zhou
- Department of Neurobiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Wen Deng
- Department of Neurobiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Chen Chen
- Department of Neurobiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Junya Kang
- Department of Neurobiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Xiaodan Yang
- Department of Neurobiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Zhaojuan Dou
- Department of Neurobiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Jiancheng Wu
- Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Quancong Li
- Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Man Jiang
- Department of Physiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Man Liang
- Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
- Key Laboratory of Forensic Toxicology, Ministry of Public Security, Beijing, 100192, China.
| | - Yunyun Han
- Department of Neurobiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
- Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, 430030, China.
- Key Laboratory of Forensic Toxicology, Ministry of Public Security, Beijing, 100192, China.
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He T, Han C, Liu C, Chen J, Yang H, Zheng L, Waddington JL, Zhen X. Dopamine D1 receptors mediate methamphetamine-induced dopaminergic damage: involvement of autophagy regulation via the AMPK/FOXO3A pathway. Psychopharmacology (Berl) 2022; 239:951-964. [PMID: 35190859 DOI: 10.1007/s00213-022-06097-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 02/15/2022] [Indexed: 01/17/2023]
Abstract
RATIONALE Clinical studies have revealed that methamphetamine abuse increases risk for developing Parkinson's diseases. It is thus important to elucidate the mechanisms by which methamphetamine damages dopaminergic neurons. OBJECTIVES The present study was designed to elucidate the role of the dopamine D1 receptor in methamphetamine-mediated dopaminergic neuronal damage and its underlying mechanisms. METHODS Mice were treated for 4 days with vehicle, methamphetamine, or the D1 agonist SKF38393 and then assessed for locomotion and performance in the pole and rotarod tests. Cellular indices of autophagy, LC3, P62, and Beclin-1, tyrosine hydroxylase, and the AMPK/FOXO3A pathway were analyzed in striatal tissue from treated mice, in PC12 cells, and in D1 receptor mutant mice. RESULTS Repeated treatment with a relatively high dose of methamphetamine for 4 days induced both loss of dopaminergic neurons and activation of autophagy in the striatum as evidenced by increased expression of LC3 and P62. However, such treatment did not induce either loss of dopaminergic neurons or activation of autophagy in D1 receptor knockout mice. D1 receptor-mediated activation of autophagy was also confirmed in vitro using dopaminergic neuronal PC12 cells. Further studies demonstrated that the AMPK/FOXO3A signaling pathway is responsible for D1 receptor-mediated activation of autophagy. CONCLUSIONS The present data indicate a novel mechanism for methamphetamine-induced dopaminergic neuronal damage and reveal an important role for D1 receptors in the neurotoxicity of this drug.
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Affiliation(s)
- Tao He
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Chaojun Han
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
- College of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, 712046, Shaanxi, China
| | - Chun Liu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Jiaojiao Chen
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Huicui Yang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - Longtai Zheng
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
| | - John L Waddington
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China
- School of Pharmacy and Biomolecular Sciences, RCSI University of Medicine and Health Sciences, Dublin 2, Ireland
| | - Xuechu Zhen
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China.
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Miyata K, Ikoma Y, Murata K, Kusumoto-Yoshida I, Kobayashi K, Kuwaki T, Ootsuka Y. Multifaceted roles of orexin neurons in mediating methamphetamine-induced changes in body temperature and heart rate. IBRO Neurosci Rep 2022; 12:108-120. [PMID: 35128515 PMCID: PMC8804267 DOI: 10.1016/j.ibneur.2022.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 01/12/2022] [Accepted: 01/17/2022] [Indexed: 11/26/2022] Open
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Docherty JR, Alsufyani HA. Pharmacology of Drugs Used as Stimulants. J Clin Pharmacol 2021; 61 Suppl 2:S53-S69. [PMID: 34396557 DOI: 10.1002/jcph.1918] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 05/22/2021] [Indexed: 12/21/2022]
Abstract
Psychostimulant, cardiovascular, and temperature actions of stimulants involve adrenergic (norepinephrine), dopaminergic (dopamine), and serotonergic (serotonin) pathways. Stimulants such as amphetamine, 3,4-methylenedioxymethamphetamine (MDMA), or mephedrone can act on the neuronal membrane monoamine transporters NET, DAT, and SERT and/or the vesicular monoamine transporter 2 to inhibit reuptake of neurotransmitter or cause release by reverse transport. Stimulants may have additional effects involving pre- and postsynaptic/junctional receptors for norepinephrine, dopamine, and serotonin and other receptors. As a result, stimulants may have a wide range of possible actions. Agents with cocaine or MDMA-like actions can induce serious and potentially fatal adverse events via thermodysregulatory, cardiovascular, or other mechanisms. MDMA-like stimulants may cause hyperthermia that can be life threathening. Recreational users of stimulants should be aware of the dangers of hyperthermia in a rave/club environment.
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Affiliation(s)
| | - Hadeel A Alsufyani
- Department of Physiology, King Abdulaziz University, Jeddah, Saudi Arabia
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Magee CP, Le BD, Siripathane YH, Wilkins DG, Hanson GR, Fleckenstein AE. Methcathinone decreases dopamine transporter function: Role of protein kinase C. J Neurochem 2021; 159:116-127. [PMID: 34320222 DOI: 10.1111/jnc.15483] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 07/19/2021] [Accepted: 07/25/2021] [Indexed: 11/28/2022]
Abstract
Methcathinone (MCAT) is a psychostimulant of abuse that can cause both persistent striatal dopaminergic and serotonergic, as well as hippocampal serotonergic, deficits. Evidence suggests that the rapid effects of stimulants that are structurally and mechanistically similar to MCAT on monoamine transporter function may contribute to the abuse liability and/or persistent monoaminergic deficits caused by these agents. Thus, effects of MCAT on 1) striatal dopamine (DA) transporter (DAT); and 2) striatal and hippocampal serotonin transporter (SERT) function, as determined in tissues from adult male rats, were assessed. As reported previously, a single administration of MCAT rapidly (within 1 hr) decreases striatal [3 H]DA uptake. Similarly, incubation of rat synaptosomes with MCAT at 37℃ (but not 4˚C) decreased striatal [3 H]DA uptake. Incubation with MCAT likewise decreased [3 H]5HT but not vesicular [3 H]DA uptake. MCAT incubation in vitro was without effect on [3 H]DA uptake in striatal synaptosomes prepared from MCAT-treated rats. The decrease in [3 H]DA uptake caused by MCAT incubation: (a) reflected a decrease in Vmax , with minimal change in Km , and (b) was attenuated by co-incubation with the cell-permeable calcium chelator, N,N'-[1,2-ethanediylbis(oxy-2,1-phenylene)]bis[N-[2-[(acetyloxy)methoxy]-2-oxoethyl]-1,1'-bis[(acetyloxy)methyl] ester-glycine (BAPTA-AM), as well as the non-selective protein kinase-C (PKC) inhibitors bisindolylmaleimide-1 (BIM-1) and 2-[1-3(Aminopropyl)indol-3-yl]-3(1-methyl-1H-indol-3-yl)maleimide (or Bisindolylmaleimide VIII; Ro-31-7549). Taken together, these results suggest that in vitro MCAT incubation may model important aspects of MCAT administration in vivo, and that calcium and PKC contribute to the in vitro effects of MCAT on DAT.
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Affiliation(s)
- Charlotte P Magee
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, USA.,School of Dentistry, University of Utah, Salt Lake City, UT, USA
| | - BaoMinh D Le
- School of Dentistry, University of Utah, Salt Lake City, UT, USA
| | | | - Diana G Wilkins
- Department of Pathology, University of Utah, Salt Lake City, UT, USA
| | - Glen R Hanson
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, USA.,School of Dentistry, University of Utah, Salt Lake City, UT, USA
| | - Annette E Fleckenstein
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, USA.,School of Dentistry, University of Utah, Salt Lake City, UT, USA
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Chen L, Ru Q, Xiong Q, Zhou M, Yue K, Wu Y. The Role of Chinese Herbal Therapy in Methamphetamine Abuse and its Induced Psychiatric Symptoms. Front Pharmacol 2021; 12:679905. [PMID: 34040537 PMCID: PMC8143530 DOI: 10.3389/fphar.2021.679905] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 04/16/2021] [Indexed: 01/21/2023] Open
Abstract
Repeated intake of methamphetamine (METH) leads to drug addiction, the inability to control intake, and strong drug cravings. It is also likely to cause psychiatric impairments, such as cognitive impairment, depression, and anxiety. Because the specific neurobiological mechanisms involved are complex and have not been fully and systematically elucidated, there is no established pharmacotherapy for METH abuse. Studies have found that a variety of Chinese herbal medicines have significant therapeutic effects on neuropsychiatric symptoms and have the advantage of multitarget comprehensive treatment. We conducted a systematic review, from neurobiological mechanisms to candidate Chinese herbal medicines, hoping to provide new perspectives and ideas for the prevention and treatment of METH abuse.
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Affiliation(s)
- Lin Chen
- Department of Health and Physical Education, Jianghan University, Wuhan, China
| | - Qin Ru
- Wuhan Institutes of Biomedical Sciences, Jianghan University, Wuhan, China
| | - Qi Xiong
- Wuhan Institutes of Biomedical Sciences, Jianghan University, Wuhan, China
| | - Mei Zhou
- Wuhan Institutes of Biomedical Sciences, Jianghan University, Wuhan, China
| | - Kai Yue
- Wuhan Institutes of Biomedical Sciences, Jianghan University, Wuhan, China
| | - Yuxiang Wu
- Department of Health and Physical Education, Jianghan University, Wuhan, China
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8
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Docherty JR, Alsufyani HA. Cardiovascular and temperature adverse actions of stimulants. Br J Pharmacol 2021; 178:2551-2568. [PMID: 33786822 DOI: 10.1111/bph.15465] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 02/22/2021] [Accepted: 03/10/2021] [Indexed: 12/11/2022] Open
Abstract
The vast majority of illicit stimulants act at monoaminergic systems, causing both psychostimulant and adverse effects. Stimulants can interact as substrates or antagonists at the nerve terminal monoamine transporter that mediates the reuptake of monoamines across the nerve synaptic membrane and at the vesicular monoamine transporter (VMAT-2) that mediates storage of monoamines in vesicles. Stimulants can act directly at presynaptic or postsynaptic receptors for monoamines or have indirect monoamine-mimetic actions due to the release of monoamines. Cocaine and other stimulants can acutely increase the risk of sudden cardiac death. Stimulants, particularly MDMA, in hot conditions, such as that occurring at a "rave," have caused fatalities from the consequences of hyperthermia, often compounding cardiac adverse actions. This review examines the pharmacology of the cardiovascular and temperature adverse actions of stimulants.
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Affiliation(s)
- James R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Hadeel A Alsufyani
- Department of Physiology, King Abdulaziz University, Jeddah, Saudi Arabia
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Grotell M, den Hollander B, Jalkanen A, Törrönen E, Ihalainen J, de Miguel E, Dudek M, Kettunen MI, Hyytiä P, Forsberg MM, Kankuri E, Korpi ER. Alcohol Co-Administration Changes Mephedrone-Induced Alterations of Neuronal Activity. Front Pharmacol 2021; 12:679759. [PMID: 33995109 PMCID: PMC8115874 DOI: 10.3389/fphar.2021.679759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 04/12/2021] [Indexed: 11/13/2022] Open
Abstract
Mephedrone (4-MMC), despite its illegal status, is still a widely used psychoactive substance. Its effects closely mimic those of the classical stimulant drug methamphetamine (METH). Recent research suggests that unlike METH, 4-MMC is not neurotoxic on its own. However, the neurotoxic effects of 4-MMC may be precipitated under certain circumstances, such as administration at high ambient temperatures. Common use of 4-MMC in conjunction with alcohol raises the question whether this co-consumption could also precipitate neurotoxicity. A total of six groups of adolescent rats were treated twice daily for four consecutive days with vehicle, METH (5 mg/kg) or 4-MMC (30 mg/kg), with or without ethanol (1.5 g/kg). To investigate persistent delayed effects of the administrations at two weeks after the final treatments, manganese-enhanced magnetic resonance imaging brain scans were performed. Following the scans, brains were collected for Golgi staining and spine analysis. 4-MMC alone had only subtle effects on neuronal activity. When administered with ethanol, it produced a widespread pattern of deactivation, similar to what was seen with METH-treated rats. These effects were most profound in brain regions which are known to have high dopamine and serotonin activities including hippocampus, nucleus accumbens and caudate-putamen. In the regions showing the strongest activation changes, no morphological changes were observed in spine analysis. By itself 4-MMC showed few long-term effects. However, when co-administered with ethanol, the apparent functional adaptations were profound and comparable to those of neurotoxic METH.
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Affiliation(s)
- Milo Grotell
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Bjørnar den Hollander
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Aaro Jalkanen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Essi Törrönen
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Jouni Ihalainen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Elena de Miguel
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Mateusz Dudek
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Mikko I Kettunen
- Kuopio Biomedical Imaging Unit, A.I. Virtanen Institute for Molecular Sciences, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Petri Hyytiä
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Markus M Forsberg
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Esko Kankuri
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Esa R Korpi
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
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Jîtcă G, Ősz BE, Tero-Vescan A, Vari CE. Psychoactive Drugs-From Chemical Structure to Oxidative Stress Related to Dopaminergic Neurotransmission. A Review. Antioxidants (Basel) 2021; 10:381. [PMID: 33806320 PMCID: PMC8000782 DOI: 10.3390/antiox10030381] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/24/2021] [Accepted: 03/01/2021] [Indexed: 12/26/2022] Open
Abstract
Nowadays, more and more young people want to experience illegal, psychoactive substances, without knowing the risks of exposure. Besides affecting social life, psychoactive substances also have an important effect on consumer health. We summarized and analyzed the published literature data with reference to the mechanism of free radical generation and the link between chemical structure and oxidative stress related to dopaminergic neurotransmission. This review presents data on the physicochemical properties, on the ability to cross the blood brain barrier, the chemical structure activity relationship (SAR), and possible mechanisms by which neuronal injuries occur due to oxidative stress as a result of drug abuse such as "bath salts", amphetamines, or cocaine. The mechanisms of action of ingested compounds or their metabolites involve intermediate steps in which free radicals are generated. The brain is strongly affected by the consumption of such substances, facilitating the induction of neurodegenerative diseases. It can be concluded that neurotoxicity is associated with drug abuse. Dependence and oxidative stress are linked to inhibition of neurogenesis and the onset of neuronal death. Understanding the pathological mechanisms following oxidative attack can be a starting point in the development of new therapeutic targets.
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Affiliation(s)
- George Jîtcă
- Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, George Emil Palade University of Medicine, Pharmacy, Science and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (G.J.); (C.E.V.)
| | - Bianca E. Ősz
- Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, George Emil Palade University of Medicine, Pharmacy, Science and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (G.J.); (C.E.V.)
| | - Amelia Tero-Vescan
- Department of Biochemistry, Faculty of Pharmacy, George Emil Palade University of Medicine, Pharmacy, Science and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania;
| | - Camil E. Vari
- Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, George Emil Palade University of Medicine, Pharmacy, Science and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (G.J.); (C.E.V.)
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Buzhdygan TP, Rodrigues CR, McGary HM, Khan JA, Andrews AM, Rawls SM, Ramirez SH. The psychoactive drug of abuse mephedrone differentially disrupts blood-brain barrier properties. J Neuroinflammation 2021; 18:63. [PMID: 33648543 PMCID: PMC7923670 DOI: 10.1186/s12974-021-02116-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 02/19/2021] [Indexed: 12/13/2022] Open
Abstract
Background Synthetic cathinones are a category of psychostimulants belonging to the growing number of designer drugs also known as “Novel Psychoactive Substances” (NPS). In recent years, NPS have gained popularity in the recreational drug market due to their amphetamine-like stimulant effects, low cost, ease of availability, and lack of detection by conventional toxicology screening. All these factors have led to an increase in NPS substance abuse among the young adults, followed by spike of overdose-related fatalities and adverse effects, severe neurotoxicity, and cerebral vascular complications. Much remains unknown about how synthetic cathinones negatively affect the CNS and the status of the blood-brain barrier (BBB). Methods We used in vitro models of the BBB and primary human brain microvascular endothelial cells (hBMVEC) to investigate the effects of the synthetic cathinone, 4-methyl methcathinone (mephedrone), on BBB properties. Results We showed that mephedrone exposure resulted in the loss of barrier properties and endothelial dysfunction of primary hBMVEC. Increased permeability and decreased transendothelial electrical resistance of the endothelial barrier were attributed to changes in key proteins involved in the tight junction formation. Elevated expression of matrix metalloproteinases, angiogenic growth factors, and inflammatory cytokines can be explained by TLR-4-dependent activation of NF-κB signaling. Conclusions In this first characterization of the effects of a synthetic cathinone on human brain endothelial cells, it appears clear that mephedrone-induced damage of the BBB is not limited by the disruption of the barrier properties but also include endothelial activation and inflammation. This may especially be important in comorbid situations of mephedrone abuse and HIV-1 infections. In this context, mephedrone could negatively affect HIV-1 neuroinvasion and NeuroAIDS progression.
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Affiliation(s)
- Tetyana P Buzhdygan
- Department of Pathology and Laboratory Medicine, The Lewis Katz School of Medicine at Temple University, 3500 N Broad St, Philadelphia, PA, 19140, USA.,Center for Substance Abuse Research, The Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Cassidy R Rodrigues
- Center for Substance Abuse Research, The Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Hannah M McGary
- Department of Pathology and Laboratory Medicine, The Lewis Katz School of Medicine at Temple University, 3500 N Broad St, Philadelphia, PA, 19140, USA
| | - Jana A Khan
- Department of Pathology and Laboratory Medicine, The Lewis Katz School of Medicine at Temple University, 3500 N Broad St, Philadelphia, PA, 19140, USA
| | - Allison M Andrews
- Department of Pathology and Laboratory Medicine, The Lewis Katz School of Medicine at Temple University, 3500 N Broad St, Philadelphia, PA, 19140, USA
| | - Scott M Rawls
- Center for Substance Abuse Research, The Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Servio H Ramirez
- Department of Pathology and Laboratory Medicine, The Lewis Katz School of Medicine at Temple University, 3500 N Broad St, Philadelphia, PA, 19140, USA. .,Center for Substance Abuse Research, The Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA. .,Shriners Hospital Pediatric Research Center, The Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA.
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12
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Soares J, Costa VM, Gaspar H, Santos S, Bastos MDL, Carvalho F, Capela JP. Adverse outcome pathways induced by 3,4-dimethylmethcathinone and 4-methylmethcathinone in differentiated human SH-SY5Y neuronal cells. Arch Toxicol 2020; 94:2481-2503. [PMID: 32382956 DOI: 10.1007/s00204-020-02761-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 04/22/2020] [Indexed: 12/27/2022]
Abstract
Cathinones (β-keto amphetamines), widely abused in recreational settings, have been shown similar or even worse toxicological profile than classical amphetamines. In the present study, the cytotoxicity of two β-keto amphetamines [3,4-dimethylmethcathinone (3,4-DMMC) and 4-methylmethcathinone (4-MMC)], was evaluated in differentiated dopaminergic SH-SY5Y cells in comparison to methamphetamine (METH). MTT reduction and NR uptake assays revealed that both cathinones and METH induced cytotoxicity in a concentration- and time-dependent manner. Pre-treatment with trolox (antioxidant) partially prevented the cytotoxicity induced by all tested drugs, while N-acetyl-L-cysteine (NAC; antioxidant and glutathione precursor) and GBR 12909 (dopamine transporter inhibitor) partially prevented the cytotoxicity induced by cathinones, as evaluated by the MTT reduction assay. Unlike METH, cathinones induced oxidative stress evidenced by the increase on intracellular levels of reactive oxygen species (ROS), and also by the decrease of intracellular glutathione levels. Trolox prevented, partially but significantly, the ROS generation elicited by cathinones, while NAC inhibited it completely. All tested drugs induced mitochondrial dysfunction, since they led to mitochondrial membrane depolarization and to intracellular ATP depletion. Activation of caspase-3, indicative of apoptosis, was seen both for cathinones and METH, and confirmed by annexin V and propidium iodide positive staining. Autophagy was also activated by all drugs tested. Pre-incubation with bafilomycin A1, an inhibitor of the vacuolar H+-ATPase, only protected against the cytotoxicity induced by METH, which indicates dissimilar toxicological pathways for the tested drugs. In conclusion, the mitochondrial impairment and oxidative stress observed for the tested cathinones may be key factors for their neurotoxicity, but different outcome pathways seem to be involved in the adverse effects, when compared to METH.
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Affiliation(s)
- Jorge Soares
- UCIBIO, REQUIMTE, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal.
| | - Vera Marisa Costa
- UCIBIO, REQUIMTE, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
| | - Helena Gaspar
- BioISI - Biosystems and Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
- MARE - Marine and Environmental Sciences Centre, Polytechnic of Leiria, Peniche, Portugal
| | - Susana Santos
- Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Maria de Lourdes Bastos
- UCIBIO, REQUIMTE, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
| | - Félix Carvalho
- UCIBIO, REQUIMTE, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
| | - João Paulo Capela
- UCIBIO, REQUIMTE, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal.
- FP-ENAS (Fernando Pessoa Energy, Environment and Health Research Unit), CEBIMED (Biomedical Research Centre), Faculty of Health Sciences, University of Fernando Pessoa, Porto, Portugal.
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Chen Y, Tran HTN, Saber YH, Hall FS. High ambient temperature increases the toxicity and lethality of 3,4-methylenedioxymethamphetamine and methcathinone. Pharmacol Biochem Behav 2020; 192:172912. [PMID: 32201298 DOI: 10.1016/j.pbb.2020.172912] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 03/12/2020] [Accepted: 03/19/2020] [Indexed: 01/09/2023]
Abstract
RATIONALE Methylenedioxymethamphetamine (MDMA) and methcathinone (MCAT) are abused psychostimulant drugs that produce adverse effects in human users that include hepatotoxicity and death. Recent work has suggested a connection between hepatotoxicity, elevations in plasma ammonia, and brain glutamate function for methamphetamine (METH)-induced neurotoxicity. OBJECTIVES These experiments investigated the effect of ambient temperature on the toxicity and lethality produced by MDMA and MCAT in mice, and whether these effects might involve similar mechanisms to those described for METH neurotoxicity. RESULTS Under low (room temperature) ambient temperature conditions, MDMA induced hepatotoxicity, elevated plasma ammonia levels, and induced lethality. Under the same conditions, even a very high dose of MCAT produced limited toxic or lethal effects. High ambient temperature conditions potentiated the toxic and lethal effects of both MDMA and MCAT. CONCLUSION These studies suggest that hepatotoxicity, plasma ammonia, and brain glutamate function are involved in MDMA-induced lethality, as has been shown for METH neurotoxicity. The toxicity and lethality of both MDMA and MCAT were potentiated by high ambient temperatures. Although an initial mouse study reported that several cathinones were much less toxic than METH or MDMA, the present results suggest that it will be essential to assess the potential dangers posed by these drugs under high ambient temperatures.
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Affiliation(s)
- Yu Chen
- Department of Pharmacology & Experimental Therapeutics, College of Pharmacology and Pharmacological Science, University of Toledo, OH, USA
| | - Huyen T N Tran
- Department of Pharmacology & Experimental Therapeutics, College of Pharmacology and Pharmacological Science, University of Toledo, OH, USA
| | - Yasir H Saber
- Department of Pharmacology & Experimental Therapeutics, College of Pharmacology and Pharmacological Science, University of Toledo, OH, USA; Ninevah College of Medicine, Ninevah University, Mosul, Iraq
| | - F Scott Hall
- Department of Pharmacology & Experimental Therapeutics, College of Pharmacology and Pharmacological Science, University of Toledo, OH, USA.
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Youyou Z, Yalei Y, Yanfei D, Shuquan Z, Zhaoyang L, Liang R, Liang L. Effects of Methcathinone Exposure during Prenatal and Lactational Periods on the Development and the Learning and Memory Abilities of Rat Offspring. Neurotox Res 2020; 38:86-95. [PMID: 32140923 DOI: 10.1007/s12640-020-00184-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 02/13/2020] [Accepted: 02/18/2020] [Indexed: 11/30/2022]
Abstract
This study aimed to investigate the effects of prenatal and lactational methcathinone exposure on the development and the learning and memory abilities of rat offspring using a Sprague-Dawley rat model. Pregnant and lactating rats were administered a consecutive daily dose of methcathinone (0.37 mg/kg) or an equivalent volume of saline by injection on gestational days 7-20 and postnatal days 2-15, respectively. The physical development and neurobehavioral test results of rat pups were recorded throughout the lactation period. Morris water maze (MWM) and novel object recognition (NOR) tests were performed from postnatal day 35 to day 42 to assess the learning and memory abilities of rat offspring in adolescence. The occurrence of hair growth and developments in neurological reflexes, such as improvements in limb grasp, righting reflex, and gait, were delayed in pups after perinatal methcathinone exposure compared with that in the control. Results from MWM and NOR tests indicate that perinatal methcathinone exposure induced deficits in spatial memory, learning ability, and novel object exploration in the adolescent offspring compared with that in the control. The impairment of spatial learning and memory was greater in the prenatal exposure group, while the impairment of novel object exploration was greater in the lactational exposure group. These data show that the prenatal and lactational methcathinone exposure induced the delay of physical and neurological reflex development and impaired learning and memory in rat offspring.
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Affiliation(s)
- Zhang Youyou
- Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Yu Yalei
- Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Deng Yanfei
- Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Chongxin Judicial Expertise Center, Wuhan, 430030, China
| | - Zhao Shuquan
- Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Li Zhaoyang
- Department of Occupational and Environmental Health and State Key Laboratory of Environmental Health for Incubating, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ren Liang
- Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Liu Liang
- Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Synthetic psychoactive cathinones: hypothermia and reduced lethality compared to methamphetamine and methylenedioxymethamphetamine. Pharmacol Biochem Behav 2020; 191:172871. [PMID: 32061662 DOI: 10.1016/j.pbb.2020.172871] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 12/16/2019] [Accepted: 02/11/2020] [Indexed: 12/16/2022]
Abstract
RATIONALE Synthetic psychoactive cathinones (SPCs) are drugs with psychostimulant and entactogenic properties like methamphetamine (MA) and 3,4-methylenedioxymethamphetamine (MDMA). Despite clinical reports of human overdose, it remains to be determined if SPCs have greater propensity for adverse effects than MA or MDMA. OBJECTIVES To determine whether the SPCs cathinone (CAT), methcathinone (MCAT), mephedrone (MMC), and methylenedioxypyrovalerone (MDPV) have lower LD50 values than MA or MDMA. METHODS Male and female C57Bl/6J mice received single injections of one of 6 doses of a test drug (0-160 mg/kg IP). Temperature and behavioral observations were taken every 20 min for 2 h followed by euthanasia of surviving mice. Organs were weighed and evaluated for histopathological changes. RESULTS LD50 values for MA and MDMA, 84.5 and 100.9 mg/kg respectively, were similar to previous observations. The LD50 for MMC was 118.8 mg/kg, but limited lethality was observed for other SPCs (CAT, MCAT, MDPV), so LD50 values could not be calculated. For all drugs, death was associated with seizure, when it was observed. Rather than hyperthermia, dose-dependent hypothermia was observed for MMC, MDPV, CAT, and MCAT. Contrary to initial expectations, none of the SPCs studied here had LD50 values lower than MA or MDMA. CONCLUSIONS These data indicate that, under the conditions studied here: (1) SPCs exhibit less lethality than MA and MDMA; (2) SPCs impair thermoregulation; (3) effects of SPCs on temperature appear to be independent of effects on lethality.
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Nutt D. New psychoactive substances: Pharmacology influencing UK practice, policy and the law. Br J Clin Pharmacol 2020; 86:445-451. [PMID: 31917863 DOI: 10.1111/bcp.14209] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 12/05/2019] [Accepted: 12/17/2019] [Indexed: 12/28/2022] Open
Abstract
This review covers the last 20 years of UK drug control policy leading up to the recent Psychoactive Substances Act. It explores policy decision made in relation to MDMA and mephedrone that not only were associated with increased drug harms overall but also had a significant detrimental effect on the UK research base. The new UK legislation on synthetic cannabinoids and other novel psychoactive substances threatens to do the same, showing that there is still much to learn from the decisions of the past. In future input from academic societies such as the BPS could help improve policy evaluation and policy development and so help avoid such problems in the future.
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Affiliation(s)
- David Nutt
- Department of Brain Sciences, Imperial College, London, W12 0NN, UK
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The Neuroprotective Effect of L-Stepholidine on Methamphetamine-Induced Memory Deficits in Mice. Neurotox Res 2019; 36:376-386. [PMID: 31201732 DOI: 10.1007/s12640-019-00069-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 05/27/2019] [Accepted: 05/28/2019] [Indexed: 10/26/2022]
Abstract
Repeated methamphetamine (METH) exposure can cause severe neurotoxicity to the central nervous system, and lead to memory deficits. L-Stepholidine (L-SPD) is a structurally identified alkaloid extract of the Chinese herb Stephania intermedia, which elicits dopamine (DA) D1-type receptors partial agonistic activity and D2-type receptors antagonistic activity. In this study, we investigated the effect of L-SPD on METH-induced memory deficits in mice and its underlying mechanisms. We found that repeated exposure to METH (10 mg/kg, i.p., once per day for 7 consecutive days) impaired memory functions in the novel object recognition experiment. Pretreatment of L-SPD (10 mg/kg, i.p.) significantly improved METH-induced memory deficits in mice. Meanwhile, the protein expression of dopaminergic D2 receptors in hippocampus area was significantly increased by repeated METH exposure, while the protein expression of dopamine transporter (DAT) was significantly reduced. Additionally, the protein expression of phospho-protein kinase A (p-PKA) was significantly increased by repeated METH exposure. The hyperpolarization-activated cyclic-nucleotide-gated non-selective cation 1 (HCN1) channel, which was a key regulator of memory functions and could be regulated by p-PKA, was also significantly increased by repeated METH exposure. These changes caused by METH could be prevented by L-SPD pretreatment. Therefore, our data firstly showed that pretreatment of L-SPD exhibited the protective effect against METH-induced memory deficits, possibly through reducing METH-induced upregulation of dopaminergic pathway and HCN1 channels.
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Leyrer-Jackson JM, Nagy EK, Olive MF. Cognitive deficits and neurotoxicity induced by synthetic cathinones: is there a role for neuroinflammation? Psychopharmacology (Berl) 2019; 236:1079-1095. [PMID: 30368582 PMCID: PMC6486871 DOI: 10.1007/s00213-018-5067-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 10/03/2018] [Indexed: 02/06/2023]
Abstract
RATIONALE The number of synthetic derivatives of cathinone, the primary psychoactive alkaloid found in Catha edulis (khat), has risen exponentially in the past decade. Synthetic cathinones (frequently referred to as "bath salts") produce adverse cognitive and behavioral sequelae, share similar pharmacological mechanisms of action with traditional psychostimulants, and may therefore trigger similar cellular events that give rise to neuroinflammation and neurotoxicity. OBJECTIVES In this review, we provide a brief overview of synthetic cathinones, followed by a summary of cognitive deficits in animals and humans that have been documented following acute or repeated exposure. We also summarize growing evidence from in vitro and in vivo studies for synthetic cathinone-induced neurotoxicity, and provide a working hypothetic model of potential cellular mechanisms. RESULTS Synthetic cathinones produce varying effects on markers of monoaminergic terminal function and can increase the formation of reactive oxygen and nitrogen species, induce apoptotic signaling, and cause neurodegeneration and cytotoxicity. We hypothesize that these effects result from biochemical events similar to those induced by traditional psychostimulants. However, empirical evidence for the ability of synthetic cathinones to induce neuroinflammatory processes is currently lacking. CONCLUSIONS Like their traditional psychostimulant counterparts, synthetic cathinones appear to induce neurocognitive dysfunction and cytotoxicity, which are dependent on drug type, dose, frequency, and time following exposure. However, additional studies on synthetic cathinone-induced neuroinflammation are clearly needed, as are investigations into the neurochemical and neuroimmune mechanisms underlying their neurotoxic effects. Such endeavors may lead to novel therapeutic avenues to promote recovery in habitual synthetic cathinone users.
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Affiliation(s)
| | | | - M. Foster Olive
- Correspondence to: M. Foster Olive, Ph.D. Department of Psychology, Arizona State University, 950 S. McAllister Ave. Tempe, AZ 85287 USA, Phone 1-480-727-9557, Fax 1-480-965-8544,
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Dissociation between hypothermia and neurotoxicity caused by mephedrone and methcathinone in TPH2 knockout mice. Psychopharmacology (Berl) 2019; 236:1097-1106. [PMID: 30074064 DOI: 10.1007/s00213-018-4991-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 07/30/2018] [Indexed: 01/01/2023]
Abstract
RATIONALE Mephedrone is a commonly abused constituent of "bath salts" and has many pharmacological effects in common with methamphetamine. Despite their structural similarity, mephedrone differs significantly from methamphetamine in its effects on core body temperature and dopamine nerve endings. The reasons for these differences remain unclear. OBJECTIVES Mephedrone elicits a transient hypothermia which may provide intrinsic neuroprotection against methamphetamine-like toxicity to dopamine nerve endings. Furthermore, evidence in the literature suggests that this hypothermia is mediated by serotonin. By utilizing transgenic mice devoid of brain serotonin, we determined the contribution of this neurotransmitter to changes in core body temperature as well as its possible role in protecting against neurotoxicity. The effects of methcathinone and 4-methyl-methamphetamine, two structural analogs of mephedrone and methamphetamine, were also evaluated in these mice. RESULTS The hypothermia induced by mephedrone and methcathinone in wild-type mice was not observed in mice lacking brain serotonin. Despite preventing drug-induced hypothermia, the lack of serotonin did not alter the neurotoxic profiles of the test drugs. CONCLUSIONS Serotonin is a key mediator of pharmacological hypothermia induced by mephedrone and methcathinone, but these body temperature effects do not contribute to dopamine nerve ending damage observed in mice following treatment with mephedrone, methcathinone or 4-methyl-methamphetamine. Thus, the key component of methamphetamine neurotoxicity lacking in mephedrone remains to be elucidated.
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