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1.
Int J Mol Sci ; 25(4)2024 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-38396814

RESUMO

Methadone is an effective and long-lasting analgesic drug that is also used in medication-assisted treatment for people with opioid use disorders. Although there is evidence that methadone activates µ-opioid and Toll-like-4 receptors (TLR-4s), its effects on distinct immune cells, including mast cells (MCs), are not well characterized. MCs express µ-opioid and Toll-like receptors (TLRs) and constitute an important cell lineage involved in allergy and effective innate immunity responses. In the present study, murine bone-marrow-derived mast cells (BMMCs) were treated with methadone to evaluate cell viability by flow cytometry, cell morphology with immunofluorescence and scanning electron microscopy, reactive oxygen species (ROS) production, and intracellular calcium concentration ([Ca2+]i) increase. We found that exposure of BMMCs to 0.5 mM or 1 mM methadone rapidly induced cell death by forming extracellular DNA traps (ETosis). Methadone-induced cell death depended on ROS formation and [Ca2+]i. Using pharmacological approaches and TLR4-defective BMMC cultures, we found that µ-opioid receptors were necessary for both methadone-induced ROS production and intracellular calcium increase. Remarkably, TLR4 receptors were also involved in methadone-induced ROS production as it did not occur in BMMCs obtained from TLR4-deficient mice. Finally, confocal microscopy images showed a significant co-localization of µ-opioid and TLR4 receptors that increased after methadone treatment. Our results suggest that methadone produces MCETosis by a mechanism requiring a novel crosstalk pathway between µ-opioid and TLR4 receptors.


Assuntos
Analgésicos Opioides , Armadilhas Extracelulares , Humanos , Animais , Camundongos , Analgésicos Opioides/farmacologia , Receptor 4 Toll-Like/metabolismo , Metadona/farmacologia , Mastócitos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Medula Óssea/metabolismo , Cálcio/metabolismo , Armadilhas Extracelulares/metabolismo , Receptor 2 Toll-Like/metabolismo , Receptores Toll-Like/metabolismo
2.
Harm Reduct J ; 20(1): 174, 2023 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-38053148

RESUMO

BACKGROUND: Perception of drug adulteration has increased in Mexico, but there is little research on adulterants and toxicity. The aim of this study was to identify drug composition in an electronic music outdoor festival nearby Mexico City. METHODS: The participants completed a questionnaire with demographic data, harm reduction strategies, drug-use patterns, history, and the drug they expected to find. We took a small sample of each substance and prepared it for drug checking. A two-section drug testing station was placed within the grounds of the festival. Interaction with participants occurred at the front part. Drug checking was conducted at the rear part. The service was free of charge, voluntary and confidential. Forty persons aged 22 to 48 years participated (mode = 28), of which 92.5% were male, most (82.5%) were single. Through the Substance Analysis Program of "ReverdeSer Collective," we conducted the testing with the attendants that provided 51 drug samples, following ethical and biosafety protocols. We used colorimetry, Fourier Transform Infrared Spectroscopy, and fentanyl immunoassay strips for sample analysis. RESULTS: Substances of choice among attendants were psychostimulants (MDMA and other amphetamine-like drugs) and hallucinogens. Most samples contained what the users expected plus adulterants. Main adulterants were methylene-dioxy-ethyl-amphetamine, methylene-dioxy-propyl-amphetamine, hydroxyamphetamine, and the selective serotonin reuptake inhibitor venlafaxine. Fentanyl was present in 2 out of 4 cocaine samples and in 14 of the 22 confirmed MDMA samples. CONCLUSIONS: Some of the adulterants found pose serious health risks, especially fentanyl, amphetamine-like substances, and venlafaxine. Therefore, it is urgent to monitor these adulterants at electronic music festivals and to implement prevention, treatment, and harm reduction public policies. Naloxone distribution and drug-assisted therapies should be part of government programs in Mexico.


Assuntos
Drogas Ilícitas , N-Metil-3,4-Metilenodioxianfetamina , Humanos , Masculino , Feminino , Drogas Ilícitas/análise , Fentanila/análise , Férias e Feriados , México , Cloridrato de Venlafaxina , Anfetamina
3.
Drug Alcohol Depend ; 253: 110993, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37883846

RESUMO

BACKGROUND: Fentanyl is commonly laced with xylazine. People who use this combination report heightened effects, but it also increases death risk. Although no medication has been approved to counteract overdoses produced by fentanyl and xylazine, naloxone is frequently used. This paper studies the preclinical rewarding and lethal effects of fentanyl combined with xylazine and the efficacy of yohimbine or naloxone to prevent death. METHODS: Male Swiss Webster mice were treated with (in mg/kg, i.p.) xylazine (0.3, 1, 3, or 5.6), fentanyl (0.01, 0.3, or 0.1), or 1 xylazine plus 0.01 (non-effective) or 0.1 (effective) fentanyl doses during the conditioned-place preference (CPP) test. In addition, independent groups received (in mg/kg, i.p.): xylazine (31.6, 60, 74.2, or 100), fentanyl (3.1 or 10), or both substances at two doses: 31.6 xylazine + 3.1 fentanyl, or 60 xylazine + 10 fentanyl to analyze lethal effects. We determined whether yohimbine or naloxone (each medication tested at 10 or 30mg/kg) could prevent the lethality produced by fentanyl/xylazine combinations. Female mice were also tested in key experiments. RESULTS: Xylazine neither induced CPP nor altered fentanyl's rewarding effects. In contrast, lethality was potentiated when fentanyl was combined with xylazine. Naloxone, but not yohimbine, effectively prevented the lethality of the fentanyl/xylazine combinations. CONCLUSIONS: At the doses tested, xylazine does not increase the rewarding effect of fentanyl on the CPP in male mice but potentiates the risk of fatal overdose in male and female mice. A high naloxone dose prevents death induced by coadministration of fentanyl and xylazine in both sexes.


Assuntos
Overdose de Drogas , Xilazina , Humanos , Masculino , Feminino , Camundongos , Animais , Xilazina/farmacologia , Fentanila/farmacologia , Ioimbina/farmacologia , Naloxona/farmacologia , Analgésicos Opioides
4.
Rev Invest Clin ; 75(3): 169-178, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37441761

RESUMO

Since the dawn of civilization, ancient cultures have utilized hallucinogens from plants and fungi in the context of religious and healing practices. Recently, their use has expanded to other cultures. Hallucinogens are natural or synthetic substances that alter the perception of reality at nontoxic doses, producing intense psychological and physiological effects. The initial research on hallucinogens began in the 1950s. However, their non-medical use, studies without proper controls, and negative social opinion resulted in legal restrictions that limited their use for clinical and preclinical research for more than two decades. A renewed interest in studying hallucinogens as potential therapeutic agents for treating different psychiatric conditions has recently re-emerged. This review summarizes the effects of main hallucinogen drugs and their therapeutic potential. Classic hallucinogens such as LSD, dimethyltryptamine, psilocin, and mescaline have chemical structures similar to serotonin and directly activate 5-hydroxy-tryptamine (5-HT2A) receptors. Ketamine is a dissociative anesthetic with antagonist effects at the glutamatergic N-methyl-D-aspartate receptor, indirectly activating 5-HT2A receptors. Ketamine has rapid antidepressant effects and reduces suicidal ideation, but its effects are short-lasting. Other hallucinogens are under study. It is necessary to continue this research with a more rigorous methodology and include studying the long-term effects of psychedelics use.


Assuntos
Alucinógenos , Ketamina , Humanos , Alucinógenos/farmacologia , Alucinógenos/química , Ketamina/farmacologia , Serotonina , Mescalina/farmacologia , N,N-Dimetiltriptamina
6.
Rev Invest Clin ; 75(3): 143-157, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37441770

RESUMO

This review focuses on the effects and mechanisms of action of amphetamine-type stimulants (ATS) and their adverse effects on the cardiovascular, nervous, and immune systems. ATS include amphetamine (AMPH), methamphetamine (METH, "crystalmeth," or "ice"), methylenedioxymethamphetamine (MDMA, "ecstasy," or "Molly"), MDMA derivatives (e.g., methylenedioxyamphetamine [MDA] and methylenedioxy-N-ethylamphetamine [MDEA]), khat, and synthetic cathinones. The first section of this paper presents an overview of the historical aspects of ATS use, their initial clinical use, and regulations. The second part reviews the acute and chronic impact and the most salient clinical effects of ATS on the central nervous and cardiovascular systems, skin, and mouth. The chemical structure, pharmacokinetics, and classic and non-canonical pharmacological actions are covered in the third section, briefly explaining the mechanisms involved. In addition, the interactions of ATS with the central and peripheral immune systems are reviewed. The last section presents data about the syndemic of ATS and opioid use in the North American region, focusing on the increasing adulteration of METH with fentanyl.


Assuntos
3,4-Metilenodioxianfetamina , Estimulantes do Sistema Nervoso Central , Metanfetamina , N-Metil-3,4-Metilenodioxianfetamina , Humanos , Anfetamina/efeitos adversos , N-Metil-3,4-Metilenodioxianfetamina/farmacologia , Estimulantes do Sistema Nervoso Central/efeitos adversos , Metanfetamina/efeitos adversos
7.
Rev Invest Clin ; 75(3): 93-104, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37441771

RESUMO

Synthetic opioids have played a significant role in the current opioid crisis in the United States (U.S.) and Canada and are a matter of concern worldwide. New psychoactive opioids (NPOs) are classified in the internationally recognized new psychoactive substances (NPSs) category. This group comprises compounds that may have been synthesized decades ago but appeared only recently in the illicit drug market. Such is the case of fentanyl, fentanyl analogs, and non-fentanyl opioids. Most NPOs have effects similar to morphine, including euphoria and analgesia, and can produce fatal respiratory depression. Here, we present an overview of the systemic and molecular effects of main NPOs, their classification, and their pharmacological properties. We first review the fentanyl group of NPOs, including the four compounds of clinical use (fentanyl, alfentanil, sufentanil, and remifentanil) and the veterinary drug carfentanil. We also provide essential information on non-medical fentanyl analogs and other synthetic opioids such as brorphine, etonitazene, and MT-45, used as adulterants in commonly misused drugs. This paper also summarizes the scarce literature on the use of NPOs in Mexico. It concludes with a brief review of the challenges to prevention and treatment posed by NPOs and some recommendations to face them.


Assuntos
Analgésicos Opioides , Humanos , Estados Unidos , Analgésicos Opioides/efeitos adversos , Remifentanil , Canadá , México
8.
Rev. invest. clín ; Rev. invest. clín;75(3): 91-92, May.-Jun. 2023.
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1515313
9.
Rev. invest. clín ; Rev. invest. clín;75(3): 93-104, May.-Jun. 2023. tab, graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1515314

RESUMO

ABSTRACT Synthetic opioids have played a significant role in the current opioid crisis in the United States (U.S.) and Canada and are a matter of concern worldwide. New psychoactive opioids (NPOs) are classified in the internationally recognized new psychoactive substances (NPSs) category. This group comprises compounds that may have been synthesized decades ago but appeared only recently in the illicit drug market. Such is the case of fentanyl, fentanyl analogs, and non-fentanyl opioids. Most NPOs have effects similar to morphine, including euphoria and analgesia, and can produce fatal respiratory depression. Here, we present an overview of the systemic and molecular effects of main NPOs, their classification, and their pharmacological properties. We first review the fentanyl group of NPOs, including the four compounds of clinical use (fentanyl, alfentanil, sufentanil, and remifentanil) and the veterinary drug carfentanil. We also provide essential information on non-medical fentanyl analogs and other synthetic opioids such as brorphine, etonitazene, and MT-45, used as adulterants in commonly misused drugs. This paper also summarizes the scarce literature on the use of NPOs in Mexico. It concludes with a brief review of the challenges to prevention and treatment posed by NPOs and some recommendations to face them.

10.
Rev. invest. clín ; Rev. invest. clín;75(3): 143-157, May.-Jun. 2023. tab, graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1515317

RESUMO

ABSTRACT This review focuses on the effects and mechanisms of action of amphetamine-type stimulants (ATS) and their adverse effects on the cardiovascular, nervous, and immune systems. ATS include amphetamine (AMPH), methamphetamine (METH, "crystalmeth," or "ice"), methylenedioxymethamphetamine (MDMA, "ecstasy," or "Molly"), MDMA derivatives (e.g., methylenedioxyamphetamine [MDA] and methylenedioxy-N-ethylamphetamine [MDEA]), khat, and synthetic cathinones. The first section of this paper presents an overview of the historical aspects of ATS use, their initial clinical use, and regulations. The second part reviews the acute and chronic impact and the most salient clinical effects of ATS on the central nervous and cardiovascular systems, skin, and mouth. The chemical structure, pharmacokinetics, and classic and non-canonical pharmacological actions are covered in the third section, briefly explaining the mechanisms involved. In addition, the interactions of ATS with the central and peripheral immune systems are reviewed. The last section presents data about the syndemic of ATS and opioid use in the North American region, focusing on the increasing adulteration of METH with fentanyl.

11.
Rev. invest. clín ; Rev. invest. clín;75(3): 169-178, May.-Jun. 2023. tab, graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1515319

RESUMO

ABSTRACT Since the dawn of civilization, ancient cultures have utilized hallucinogens from plants and fungi in the context of religious and healing practices. Recently, their use has expanded to other cultures. Hallucinogens are natural or synthetic substances that alter the perception of reality at nontoxic doses, producing intense psychological and physiological effects. The initial research on hallucinogens began in the 1950s. However, their non-medical use, studies without proper controls, and negative social opinion resulted in legal restrictions that limited their use for clinical and preclinical research for more than two decades. A renewed interest in studying hallucinogens as potential therapeutic agents for treating different psychiatric conditions has recently re-emerged. This review summarizes the effects of main hallucinogen drugs and their therapeutic potential. Classic hallucinogens such as LSD, dimethyltryptamine, psilocin, and mescaline have chemical structures similar to serotonin and directly activate 5-hydroxy-tryptamine (5-HT2A) receptors. Ketamine is a dissociative anesthetic with antagonist effects at the glutamatergic N-methyl-D-aspartate receptor, indirectly activating 5-HT2A receptors. Ketamine has rapid antidepressant effects and reduces suicidal ideation, but its effects are short-lasting. Other hallucinogens are under study. It is necessary to continue this research with a more rigorous methodology and include studying the long-term effects of psychedelics use.

12.
Eur J Cell Biol ; 102(2): 151324, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37236045

RESUMO

Allergic reactions are highly prevalent pathologies initiated by the production of IgE antibodies against harmless antigens (allergens) and the activation of the high-affinity IgE receptor (FcεRI) expressed in the surface of basophils and mast cells (MCs). Research on the mechanisms of negative control of those exacerbated inflammatory reactions has been intense in recent years. Endocannabinoids (eCBs) show important regulatory effects on MC-mediated immune responses, mainly inhibiting the production of pro-inflammatory mediators. However, the description of the molecular mechanisms involved in eCB control of MC activation is far from complete. In this review, we aim to summarize the available information regarding the role of eCBs in the modulation of FcεRI-dependent activation of that cell type, emphasizing the description of the eCB system and the existence of some of its elements in MCs. Unique characteristics of the eCB system and cannabinoid receptors (CBRs) localization and signaling in MCs are mentioned. The described and putative points of cross-talk between CBRs and FcεRI signaling cascades are also presented. Finally, we discuss some important considerations in the study of the effects of eCBs in MCs and the perspectives in the field.


Assuntos
Hipersensibilidade , Receptores de IgE , Humanos , Receptores de IgE/metabolismo , Imunoglobulina E/metabolismo , Imunoglobulina E/farmacologia , Endocanabinoides/metabolismo , Endocanabinoides/farmacologia , Mastócitos/metabolismo , Hipersensibilidade/metabolismo
13.
Psychopharmacology (Berl) ; 240(4): 797-812, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36745226

RESUMO

RATIONALE: Drug and natural rewarding stimuli activate the mesolimbic dopaminergic system. Both methamphetamine (Meth) and copulation to satiety importantly increase dopamine (DA) release in the nucleus accumbens (NAc), but with differences in magnitude. This paper analyzes the interaction between Meth administration and the intense sexual activity associated with sexual satiety. OBJECTIVES: To evaluate possible changes in Meth-induced behavioral effects and striatal DA-related protein expression due to sexual satiety. METHODS: Meth-induced locomotor activity and conditioned place preference (CPP) were tested in sexually experienced male rats that copulated to satiety (S-S) or ejaculated once (1E) the day before or displayed no sexual activity (control group; C). DA receptors and DA transporter expression were determined by western blot in the striatum of animals of all sexual conditions treated with specific Meth doses. RESULTS: Meth's locomotor and rewarding effects were exacerbated in S-S animals, while in 1E rats, only locomotor effects were enhanced. Sexual activity, by itself, modified DA-related protein expression in the NAc core and in the caudate-putamen (CPu), while Meth treatment alone changed their expression only in the NAc shell. Meth-induced changes in the NAc shell turned in the opposite direction when animals had sexual activity, and additional changes appeared in the NAc core and CPu of S-S rats. CONCLUSION: Sexual satiety sensitizes rats to Meth's behavioral effects and the Meth-induced striatal DA-related protein adaptations are modified by sexual activity, evidencing cross-sensitization between both stimuli.


Assuntos
Metanfetamina , Ratos , Masculino , Animais , Dopamina/metabolismo , Núcleo Accumbens , Corpo Estriado , Neostriado/metabolismo
14.
Addict Biol ; 27(3): e13166, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35470549

RESUMO

Levamisole is a veterinary anthelmintic drug and a common adulterant of misused drugs. This study analyses the lethal, antinociceptive and haematological effects produced by acute or repeated levamisole administration by itself or combined with morphine. Independent groups of male Swiss Webster mice were i.p. injected with 100 mg/kg morphine, 31.6 mg/kg levamisole (lethal doses at 10%, LD10 ) or the same doses combined. Naloxone pretreatment (10 mg/kg, i.p.) prevented morphine-induced death, as did 2.5 mg/kg, i.p. mecamylamine with levamisole. Co-administration of levamisole and morphine (Lvm + Mor) increased lethality from 10% to 80%. This augmented effect was prevented by 30 mg/kg, i.p. naloxone and reduced with 10 mg/kg naloxone plus 2.5 mg/kg, i.p. mecamylamine. In independent groups of mice, 17.7 mg/kg, i.p. levamisole antagonized the acute morphine's antinociceptive effect evaluated in the tail-flick test. Repeated 17.7 mg/kg levamisole administration (2×/day/3 weeks) did not affect tolerance development to morphine (10 mg/kg, 3×/day/1 week). Blood samples obtained from mice repeatedly treated with levamisole showed leukopenia and neutropenia. Morphine also produced neutropenia, increased erythrocyte count and other related parameters (e.g. haemoglobin). Lvm + Mor had similar effects on leukocyte and neutrophil counts to those seen with levamisole only, but no erythrocyte-related alterations were evident. Blood chemistry analysis did not indicate liver damage but suggested some degree of electrolyte balance impairment. In conclusion, Lvm + Mor increased death risk, altered morphine-induced antinociceptive effects and produced haematologic abnormalities. The importance of studying combinations of drugs of abuse lies in the fact that drug users frequently combine drugs, which are commonly adulterated.


Assuntos
Morfina , Neutropenia , Analgésicos , Animais , Levamisol/farmacologia , Masculino , Mecamilamina , Camundongos , Morfina/farmacologia , Naloxona/farmacologia , Neutropenia/induzido quimicamente
15.
Cell Mol Neurobiol ; 42(3): 677-694, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32926257

RESUMO

Morphine promotes neuroinflammation after NOD-like receptor protein 3 (NLRP3) oligomerization in glial cells, but the capacity of other opioids to induce neuroinflammation and its relationship to the development of analgesic tolerance is unknown. We studied the effects of morphine and fentanyl on NLRP3 inflammasome activation in glial and neuronal cells in the dorsal raphe nucleus (DRN), a region involved in pain regulation. Male Wistar rats received i.p. injections of morphine (10 mg/kg) or fentanyl (0.1 mg/kg) 3 × daily for 7 days and were tested for nociception. Two hours after the last (19th) administration, we analyzed NLRP3 oligomerization, caspase-1 activation and gasdermin D-N (GSDMD-N) expression in microglia (CD11b positive cells), astrocytes (GFAP-positive cells) and neurons (NeuN-positive cells). Tolerance developed to both opioids, but only fentanyl produced hyperalgesia. Morphine and fentanyl activated NLRP3 inflammasome in astrocytes and serotonergic (TPH-2-positive) neurons, but fentanyl effects were more pronounced. Both opioids increased GFAP and CD11b immunoreactivity, caspase-1 and GSDMD activation, indicating pyroptotic cell death. The opioid receptor antagonist (-)-naloxone, but not the TLR4 receptor antagonist (+)-naloxone, prevented microglia activation and NLRP3 oligomerization. Only (+)-naloxone prevented astrocytes' activation. The anti-inflammatory agent minocycline and the NLRP3 inhibitor MCC950 delayed tolerance to morphine and fentanyl antinociception and prevented fentanyl-induced hyperalgesia. MCC950 also prevented opioid-induced NLRP3 oligomerization. In conclusion, morphine and fentanyl differentially induce cell-specific activation of NLRP3 inflammasome and pyroptosis in the DRN through TLR4 receptors in astrocytes and through opioid receptors in neurons, indicating that neuroinflammation is involved in opioid-induced analgesia and fentanyl-induced hyperalgesia after repeated administrations.


Assuntos
Fentanila , Morfina , Analgésicos Opioides/farmacologia , Animais , Núcleo Dorsal da Rafe/metabolismo , Fentanila/farmacologia , Masculino , Morfina/farmacologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteínas NLR , Piroptose , Ratos , Ratos Wistar , Receptores Opioides/metabolismo , Receptor 4 Toll-Like/metabolismo
16.
Addiction ; 115(4): 778-781, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31837278

RESUMO

BACKGROUND AND AIMS: Results from a recent study among 750 heroin users in three Mexico's northern border cities revealed an increase in white powder availability (also known as China white) and preference for this product among heroin users, as well as a general perception of increased overdose cases among this population. Here, we questioned whether those findings reflect an increased presence of heroin laced with fentanyl, which is associated with greater risks of overdose but that, until now, has not been described in Mexico. DESIGN: We tested fentanyl using highly sensitive test strips in syringe plungers, metal cookers and drug wrappings associated with heroin use. SETTING: Three injection sites in Tijuana, Baja California, México. PARTICIPANTS: Eighty-nine heroin users who interchanged paraphernalia for new syringes. MEASUREMENTS: We tested 59 residues of 'pure' white powder. The rest were white powder with black tar (n = 5) or white powder with crystal meth (n = 9), black tar with crystal meth (n = 1), black tar only (n = 13) and crystal meth only (n = 2). FINDINGS: Users believed that they consumed either white powder heroin, white powder heroin with crystal meth, white powder with black tar heroin or black tar heroin only. Analyses revealed that 93% (n = 55) of the 'pure' white powder samples had fentanyl. All (n = 9) the white powder samples mixed with crystal meth and 40% (n = 2) of the white powder with black tar were also laced with fentanyl. CONCLUSIONS: In a sample of 89 heroin users in Mexico, most white powder heroin users were unknowingly exposed to fentanyl, with fentanyl detected in 93% of white powder samples.


Assuntos
Contaminação de Medicamentos , Fentanila/isolamento & purificação , Heroína/química , Humanos , México , Fitas Reagentes , Abuso de Substâncias por Via Intravenosa
17.
Neurotoxicol Teratol ; 73: 9-14, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30826315

RESUMO

Toluene is an organic solvent commonly misused by inhalation among adolescents to experience psychoactive effects. Repeated toluene exposure produces several cognitive deficits, including working memory impairment in which the medial prefrontal cortex (mPFC) plays a central role. Among other effects, toluene antagonizes NMDA receptors, enhance GABAA receptor-mediated responses and increases dopamine release. We have recently reported that animals repeatedly exposed to toluene show increased mPFC excitability; however, alterations in synaptic transmission, including long-term synaptic plasticity of glutamatergic responses have not been studied thus far. Here we used extracellular recordings to determine the effects of repeated toluene exposure (8000 ppm for 30 min, twice a day, for ten days) on the synaptic transmission converging on prelimbic layer 5 pyramidal neurons of the mPFC in adolescent male Wistar rats. Repeated toluene exposure increased mPFC's synaptic strength and reduced the inhibitory transmission assessed by input-output curves and paired-pulse inhibition protocols, respectively. Both toluene and a selective D1 receptor antagonist blocked the ability of exogenous dopamine to induce synaptic potentiation. Repeated toluene exposure also altered the ability of NMDA to induce synaptic depression of excitatory transmission. Taken together, the changes in synaptic strength and impairment of the NMDA-mediated plasticity of the mPFC demonstrate a series of synaptic modifications of the glutamatergic transmission that may underlie the cognitive impairment resulting from repeated toluene exposure.


Assuntos
Córtex Pré-Frontal/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Tolueno/toxicidade , Animais , Dopamina/metabolismo , Ácido Glutâmico/metabolismo , Ácido Cinurênico/farmacologia , Masculino , N-Metilaspartato/metabolismo , Plasticidade Neuronal/efeitos dos fármacos , Picrotoxina/farmacologia , Racloprida/farmacologia , Ratos , Ratos Wistar
18.
Eur J Neurosci ; 50(3): 2113-2123, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-29797469

RESUMO

Inhalant misuse is a worldwide problem, especially among adolescents. Toluene is the most widely misused inhalant. One hallmark of adolescence is the emergence of sexual behaviour, which can be affected by drug use. The aim of this study was to analyse the effects of toluene inhalation on different aspects of male rats' sexual behaviour using a binge pattern of exposure in adolescent rats. Male Wistar rats were individually exposed to air or 6,000 ppm toluene for 30 min (acute exposure; n = 8 each) or twice a day for 12 days (repeated exposure; n = 9 each) in static exposure chambers. Independent groups of sexually experienced, adolescent rats (postnatal day 63, PN63) were tested after acute toluene exposure for copulation, sexual incentive motivation or noncontact erections. Sexually naïve, adolescent rats (PN45-59) were repeatedly exposed to toluene and tested for sexual behaviour after completing the 1st, 3rd, 5th, 7th, 9th, 11th and 13th exposure sessions. Acute toluene exposure impaired copulatory performance, diminished sexual incentive motivation and delayed noncontact erection occurrence in sexually experienced rats. Repeated toluene exposure during adolescence completely inhibited the onset of copulatory behaviours in sexually naïve rats, at the time at which they should have appeared. However, once the inhalant exposure ended, copulatory responses appeared gradually, and animals attained a typical, stable copulatory pattern. In conclusion, acute toluene exposure impairs sexual behaviour in young, sexually experienced animals, while repeated toluene exposure during adolescence prevents the onset of copulatory behaviour, although this effect is transitory.


Assuntos
Comportamento Animal/fisiologia , Motivação/fisiologia , Atividade Motora/fisiologia , Comportamento Sexual/fisiologia , Fatores Etários , Animais , Peso Corporal/fisiologia , Masculino , Atividade Motora/efeitos dos fármacos , Ratos Wistar , Transtornos Relacionados ao Uso de Substâncias/fisiopatologia
19.
Neurotoxicol Teratol ; 68: 27-35, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29715503

RESUMO

Despite serious health effects, volatile industrial products containing toluene are deliberately inhaled for their psychoactive actions, mainly among adolescents and young adults. Chronic toluene inhalation induces multiple alterations at the cellular and behavioral level; however, modifications of neuronal networks associated with the reward system after repeated toluene exposure are not thoroughly characterized. Here we used whole-cell recordings to determine the effects of repeated exposure to toluene (1000, 4000 or 8000 ppm for 30 min, twice a day, for ten days) on the neurophysiological properties of prelimbic layer 5 pyramidal neurons of the medial prefrontal cortex (mPFC) in adolescent male Wistar rats. Neurons from animals repeatedly exposed to toluene showed a concentration-dependent increase in action potential firing discharge. This increase was related to a reduction of the small-conductance calcium-activated potassium current (after-hyperpolarization current, IAHP) that controls the firing frequency of neurons. Likewise, toluene altered the kinetics of the action potential. The hyperexcitability seen in toluene-exposed animals was also associated with an increase in the glutamatergic spontaneous synaptic activity converging on mPFC neurons. In summary, repeated toluene exposure enhances the excitability of prelimbic layer 5 pyramidal neurons of the mPFC in adolescent rats.


Assuntos
Potenciais de Ação/fisiologia , Neurônios/fisiologia , Canais de Potássio Cálcio-Ativados/efeitos dos fármacos , Córtex Pré-Frontal/fisiologia , Células Piramidais/fisiologia , Tolueno/toxicidade , Fatores Etários , Animais , Comportamento Animal/efeitos dos fármacos , Bicuculina/farmacologia , Relação Dose-Resposta a Droga , Potenciais Pós-Sinápticos Excitadores/fisiologia , Ácido Cinurênico/farmacologia , Masculino , Córtex Pré-Frontal/efeitos dos fármacos , Ratos
20.
Psychopharmacology (Berl) ; 232(20): 3797-808, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26255180

RESUMO

RATIONALE: Toluene is a misused inhalant with hallucinogenic properties and complex effects. Toluene blocks N-methyl-D-aspartate (NMDA) receptors, releases dopamine (DA), and modifies several neurotransmitter levels; nonetheless, the mechanism by which it produces hallucinations is not well characterized. OBJECTIVES: This study aims (a) to study toluene's effects on the 5-HT2A-mediated head-twitch response (HTR), dopamine (DA), and serotonin (5-HT) tissue levels in discrete brain regions; (b) to compare the actions of toluene, ketamine, and 1-[2,5-dimethoxy-4-iodophenyl]-2-aminopropane (DOI) on HTR; and (c) to study the pharmacological blockade of toluene's and ketamine's effects by selective drugs. METHODS: Independent groups of rats inhaled toluene (500-12,000 ppm) for 30 min during which the occurrence of serotonergic signs was analyzed. Brains were obtained after exposure to determine DA and 5-HT levels by HPLC. RESULTS: Toluene concentration-dependently induced HTR. Other serotonin syndrome signs were evident at high concentrations. Toluene (4000 and 8000 ppm), and ketamine (3 and 10 mg/kg), significantly increased 5-HT levels in the frontal cortex (FC) striatum, hippocampus, and brain stem, as well as DA levels in the striatum and FC. Pretreatment with ketanserin (5HT2A/2C receptor antagonist), M100907 (selective 5-HT2A receptor antagonist), D-serine (co-agonist of the NMDA receptor glycine site), and haloperidol (D2 receptor antagonist) significantly decreased toluene's and ketamine's actions. The 5HT1A receptor antagonist WAY100635 had no effect. CONCLUSION: Toluene stimulates 5HT2A and 5HT2C receptors, and increases 5-HT and DA levels. These actions are similar to those produced by ketamine and involve activation of a complex neurotransmitter network that includes NMDA receptor antagonism.


Assuntos
Dopamina/metabolismo , Ácido Glutâmico/metabolismo , Alucinógenos/administração & dosagem , Serotonina/metabolismo , Tolueno/administração & dosagem , Administração por Inalação , Animais , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Avaliação Pré-Clínica de Medicamentos/métodos , Masculino , Ratos , Ratos Wistar , Receptor 5-HT2A de Serotonina/metabolismo , Receptor 5-HT2C de Serotonina/metabolismo , Antagonistas do Receptor 5-HT2 de Serotonina/administração & dosagem
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