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1.
Neurosci Lett ; 756: 135952, 2021 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-33979702

RESUMO

Natural rewards, such as food and social interaction, as well as drugs of abuse elicit increased mesolimbic dopamine release in the nucleus accumbens (NAc). Drugs of abuse, however, increase NAc dopamine release to a greater extent and are known to induce lasting changes on the functioning of the mesolimbic dopamine pathway. Less is known about the long-term effects of diet composition on this reward pathway. In the present study, two diets were compared: a higher-fat diet (Western Diet: WD) and a control diet (standard lab chow) on their effect on the mesolimbic dopamine system. Twenty male C57BL/6 J mice were placed on one of these diets at 7 weeks old. After twelve weeks on the diet, in vivo fixed potential amperometry was used to measure real-time stimulation-evoked dopamine release in the NAc of anesthetized mice before and after an i.p. injection of the dopamine transporter (DAT) inhibitor nomifensine. Results indicated that diet altered mesolimbic dopamine functioning. Mice that consumed the WD demonstrated a hypodopaminergic profile, specifically reduced baseline dopamine release and an attenuated dopaminergic response to DAT inhibition compared to the control diet group. Thus, diet may play a role in mediating dopamine-related behavior, disorders associated with dopamine dysfunction, and pharmacological treatments aimed at altering dopamine transmission.


Assuntos
Dieta Hiperlipídica , Dieta Ocidental , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Dopamina/metabolismo , Núcleo Accumbens/metabolismo , Recompensa , Animais , Peso Corporal/efeitos dos fármacos , Inibidores da Captação de Dopamina/farmacologia , Masculino , Camundongos , Nomifensina/farmacologia , Núcleo Accumbens/efeitos dos fármacos
2.
PLoS One ; 16(2): e0245663, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33534843

RESUMO

Parkinson's disease is associated with the loss of dopamine (DA) neurons in ventral mesencephalon. We have previously reported that no single neurotrophic factor we tested protected DA neurons from the dopaminergic toxin 1-methyl-4-phenylpyridinium (MPP+) in dissociated cultures isolated from the P0 rat substantia nigra, but that a combination of five neurotrophic factors was protective. We now report that cerebral DA neurotrophic factor (CDNF) and a variant of neurturin (NRTN), N4, were also not protective when provided alone but were protective when added together. In cultures isolated from the substantia nigra, MPP+ (10 µM) decreased tyrosine hydroxylase-positive cells to 41.7 ± 5.4% of vehicle control. Although treatment of cultures with 100 ng/ml of either CDNF or N4 individually before and after toxin exposure did not significantly increase survival in MPP+-treated cultures, when the two trophic factors were added together at 100 ng/ml each, survival of cells was increased 28.2 ± 6.1% above the effect of MPP+ alone. In cultures isolated from the ventral tegmental area, another DA rich area, a higher dose of MPP+ (1 mM) was required to produce an EC50 in TH-positive cells but, as in the substantia nigra, only the combination of CDNF and N4 (100 ng/ml each) was successful at increasing the survival of these cells compared to MPP+ alone (by 22.5 ± 3.5%). These data support previous findings that CDNF and N4 may be of therapeutic value for treatment of PD, but suggest that they may need to be administered together.


Assuntos
Neurônios Dopaminérgicos/metabolismo , Mesencéfalo/metabolismo , Fatores de Crescimento Neural/farmacologia , Fármacos Neuroprotetores/farmacologia , Neurturina/farmacologia , 1-Metil-4-fenilpiridínio , Animais , Células CHO , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Cricetulus , Dopamina/metabolismo , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Neurônios Dopaminérgicos/efeitos dos fármacos , Humanos , Nomifensina/farmacologia , Ratos Sprague-Dawley , Substância Negra/citologia , Trítio/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Área Tegmentar Ventral/citologia
3.
Artigo em Inglês | MEDLINE | ID: mdl-32474007

RESUMO

Clinical studies have shown the therapeutic efficacy of an increase in dopamine (DA) transmission in treatment of major depressive disorder (MDD). In the present study, we investigated whether blockade of DA transporters in addition to serotonin (5-HT) and norepinephrine (NE) produced additional adaptations of monoaminergic systems. In vivo electrophysiological recordings were carried out in male anesthetized rats. Vehicle, the 5-HT reuptake inhibitor escitalopram, the NE/DA reuptake blocker nomifensine and their combination (triple reuptake inhibition; TRI) were delivered for 2 or 14 days. Firing activity of NE, 5-HT and DA neurons was assessed. Tonic activation of 5-HT1A receptors and α1- and α2-adrenoceptors was determined in the hippocampus and extracellular DA levels in the nucleus accumbens (NAc). Unlike escitalopram, nomifensine and TRI administration increased the tonic activation of α2-adrenoceptors in the hippocampus despite decreasing NE neuronal firing activity after 2 and 14 days of administration. The firing activity of 5-HT neurons was increased after prolonged nomifensine and TRI regimens, while addition of nomifensine to escitalopram prevented the early 2-day suppression of firing by 5-HT reuptake inhibition. The tonic activation of 5-HT1A receptors was enhanced only with escitalopram. Whereas escitalopram and nomifensine decreased firing activity of DA neurons after a 2-day administration, their combination normalized it to baseline level after 14 days; this was accompanied by a robust increase in extracellular DA levels in the NAc. In summary, these results indicate that TRI increases NE and DA but not 5-HT transmission, suggesting a differential efficacy profile in MDD patients.


Assuntos
Inibidores da Captação Adrenérgica/farmacologia , Inibidores da Captação de Dopamina/farmacologia , Dopamina/metabolismo , Hipocampo/efeitos dos fármacos , Núcleo Accumbens/metabolismo , Receptores Adrenérgicos alfa 2/efeitos dos fármacos , Inibidores de Captação de Serotonina/farmacologia , Animais , Região CA3 Hipocampal/efeitos dos fármacos , Região CA3 Hipocampal/metabolismo , Citalopram/farmacologia , Neurônios Dopaminérgicos/efeitos dos fármacos , Masculino , Nomifensina/farmacologia , Núcleo Accumbens/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Neurônios Serotoninérgicos/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos
4.
Neuroscience ; 408: 226-238, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30981861

RESUMO

Growing research indicates oxytocin may be involved in relieving anxiety and attenuating the rewarding effects of psychostimulants. This study investigated the effects of subchronic oxytocin treatments on mesolimbic dopamine transmission in areas associated with anxiety and addiction, the amygdala and the nucleus accumbens (NAc), respectively. Using in vivo fixed potential amperometry, stimulation-evoked dopamine release was recorded in anesthetized mice pretreated with subchronic oxytocin (four i.p. injections of 1 mg/kg oxytocin or saline with 48 h between injections). During dopamine recordings, mice received an i.p. drug challenge of either oxytocin (1 mg/kg), the dopamine reuptake blocker nomifensine (10 mg/kg), or saline. Overall, subchronic oxytocin pretreatment did alter properties of dopamine release in these limbic structures. In the amygdala, dopamine release was decreased following the oxytocin challenge but only in oxytocin pretreated mice. In the NAc, baseline dopamine release was attenuated in oxytocin pretreated mice relative to saline pretreated mice. Furthermore, oxytocin pretreated mice displayed a reduced dopaminergic response to the drug challenge of nomifensine relative to control mice. Together these results suggest that oxytocin may be useful at treating aspects of anxiety and drug abuse. Elucidating the neural effects of oxytocin is critical given the multitude of potential therapeutic uses for this drug.


Assuntos
Tonsila do Cerebelo/efeitos dos fármacos , Dopamina/metabolismo , Núcleo Accumbens/efeitos dos fármacos , Ocitocina/farmacologia , Tonsila do Cerebelo/metabolismo , Animais , Inibidores da Captação de Dopamina/farmacologia , Masculino , Camundongos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Nomifensina/farmacologia , Núcleo Accumbens/metabolismo
5.
Neuroscience ; 396: 154-165, 2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30447392

RESUMO

Extracellular levels of dopamine (DA) and other monoamines in the brain depend not only on the classic transporters encoded by SLC6A gene family such as DAT, NET and SERT, but also a more recently identified group of low-affinity/high-capacity 'Uptake-2' transporters, mainly OCT3 and PMAT. The most frequently used pharmacological tool in functional studies of Uptake-2 is decynium-22 (D-22) known to block these transporters. However, the effectiveness of this drug in enhancing extracellular DA remains uncertain. Our aim was to test the hypothesis that D-22 increases extracellular levels of DA released from the somatodendritic region of dopaminergic neurons in the substantia nigra pars compacta (SNc) by reducing the OCT3/PMAT-dependent component of DA uptake. Extracellular DA was assessed indirectly, by evoking D2-IPSCs in SNc neurons following stimulated release of this neurotransmitter in midbrain slices obtained from mice. Recordings were conducted after partial inhibition of DAT with nomifensine, and after application of L-DOPA which increased the releasable DA pool. Contrary to our expectations, D-22 reduced, rather than increased, the amplitude of D2-IPSCs. Other effects included inhibition of GABAB-IPSCs and Ih current, and a reduction in firing frequency of nigral neurons. These results show that in addition to the previously known non-specific inhibitory action on α1 adrenoceptors, D-22 exerts additional off-target effects by inhibiting dopaminergic and GABAergic synaptic transmission in the SNc and the spontaneous (pacemaker) activity of nigral neurons. It remains to be established if these novel effects contribute to a reduction in spontaneous locomotor activity reported in previous studies after systemic drug administration.


Assuntos
Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/fisiologia , Quinolinas/farmacologia , Substância Negra/citologia , Animais , Potenciais Pós-Sinápticos Inibidores/efeitos dos fármacos , Potenciais Pós-Sinápticos Inibidores/fisiologia , Levodopa/farmacologia , Potenciais da Membrana/efeitos dos fármacos , Camundongos , Nomifensina/farmacologia , Substância Negra/efeitos dos fármacos , Substância Negra/fisiologia
6.
Sci Rep ; 8(1): 16277, 2018 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-30389979

RESUMO

In Drosophila melanogaster, aversive (electric shock) stimuli have been shown to activate subpopulations of dopaminergic neurons with terminals in the mushroom bodies (MBs) of the brain. While there is compelling evidence that dopamine (DA)-induced synaptic plasticity underpins the formation of aversive memories in insects, the mechanisms involved have yet to be fully resolved. Here we take advantage of the accessibility of MBs in the brain of the honey bee to examine, using fast scan cyclic voltammetry, the kinetics of DA release and reuptake in vivo in response to electric shock, and to investigate factors that modulate the release of this amine. DA increased transiently in the MBs in response to electric shock stimuli. The magnitude of release varied depending on stimulus duration and intensity, and a strong correlation was identified between DA release and the intensity of behavioural responses to shock. With repeated stimulation, peak DA levels increased. However, the amount of DA released on the first stimulation pulse typically exceeded that evoked by subsequent pulses. No signal was detected in response to odour alone. Interestingly, however, if odour presentation was paired with electric shock, DA release was enhanced. These results set the stage for analysing the mechanisms that modulate DA release in the MBs of the bee.


Assuntos
Abelhas/fisiologia , Condicionamento Psicológico/fisiologia , Dopamina/metabolismo , Neurônios Dopaminérgicos/metabolismo , Corpos Pedunculados/metabolismo , Animais , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Condicionamento Psicológico/efeitos dos fármacos , Inibidores da Captação de Dopamina/farmacologia , Neurônios Dopaminérgicos/efeitos dos fármacos , Eletrodos , Eletrochoque/instrumentação , Eletrochoque/métodos , Masculino , Corpos Pedunculados/citologia , Corpos Pedunculados/efeitos dos fármacos , Plasticidade Neuronal/efeitos dos fármacos , Plasticidade Neuronal/fisiologia , Nomifensina/farmacologia , Odorantes
7.
Exp Anim ; 67(2): 147-153, 2018 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-29176298

RESUMO

Volatile anesthetics accelerate dopamine turnover in the brain, especially when used in conjunction with psychotropic agents such as methamphetamine and nomifensine. The effect of intravenous propofol anesthesia on the extracellular dopamine concentrations is unclear. The aim of this study was to compare the effect of two anesthetics on the extracellular concentrations of dopamine and metabolites using an in vivo microdialysis model. Male Sprague Dawley rats were implanted with a microdialysis probe into the right striatum. The probe was perfused with modified Ringer's solution, and the dialysate was directly injected into a high-performance liquid chromatography system every 20 min. The rats were intraperitoneally administered saline, methamphetamine at 2 mg/kg, or nomifensine at 10 mg/kg. After treatment, the rats were anesthetized with intravenous propofol (20 mg/kg followed by 25 or 50 mg/kg/h) or inhalational sevoflurane (2.5%) for 1 h. Propofol showed no effect on the extracellular concentration of dopamine during anesthesia; however, propofol decreased the dopamine concentration after anesthesia in the high-dose group. Sevoflurane anesthesia increased the concentration of metabolites. Systemic administration of methamphetamine and nomifensine increased the extracellular concentration of dopamine. Sevoflurane anesthesia significantly enhanced the increase in the dopamine concentration induced by both methamphetamine and nomifensine, whereas propofol anesthesia showed no effect on the methamphetamine- and nomifensine-induced dopamine increase during anesthesia. The enhancing effect of psychotropic agent-induced acceleration of dopamine turnover was smaller for propofol anesthesia than for sevoflurane anesthesia.


Assuntos
Anestesia por Inalação , Anestesia Intravenosa , Corpo Estriado/metabolismo , Dopamina/metabolismo , Metanfetamina/farmacologia , Éteres Metílicos , Nomifensina/farmacologia , Propofol , Psicotrópicos/farmacologia , Animais , Infusões Parenterais , Masculino , Metanfetamina/administração & dosagem , Éteres Metílicos/farmacologia , Microdiálise , Modelos Animais , Nomifensina/administração & dosagem , Propofol/farmacologia , Ratos , Ratos Sprague-Dawley , Sevoflurano
8.
ACS Chem Neurosci ; 8(2): 329-338, 2017 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-28094974

RESUMO

Recently, our laboratory has demonstrated the technical feasibility of monitoring dopamine at 1 min temporal resolution with microdialysis and online liquid chromatography. Here, we monitor dopamine in the rat striatum during local delivery of high potassium/low sodium or nomifensine in awake-behaving rats. Microdialysis probes were implanted and perfused continuously with or without dexamethasone in the perfusion fluid for 4 days. Dexamethasone is an anti-inflammatory agent that exhibits several positive effects on the apparent health of the brain tissue surrounding microdialysis probes. Dopamine was monitored 1 or 4 days after implantation under basal conditions, during 10 min applications of 60 mM or 100 mM K+, and during 15 min applications of 10 µM nomifensine. High K+ and nomifensine were delivered locally by adding them to the microdialysis perfusion fluid using a computer-controlled, low-dead-volume six-port valve. Each day/K+/dexamethasone combination elicited specific dopamine responses. Dexamethasone treatment increased dopamine levels in basal dialysates (i.e., in the absence of K+ or nomifensine). Applications of 60 mM K+ evoked distinct responses on days one and four after probe implantation, depending upon the presence or absence of dexamethasone, consistent with dexamethasone's ability to mitigate the traumatic effect of probe implantation. Applications of 100 mM K+ evoked dramatic oscillations in dopamine levels that correlated with changes in the field potential at a metal electrode implanted adjacent to the microdialysis probe. This combination of results indicates the role of spreading depolarization in response to 100 mM K+. With 1 min temporal resolution, we find that it is possible to characterize the pharmacokinetics of the response to the local delivery of nomifensine. Overall, the findings reported here confirm the benefits arising from the ability to monitor dopamine via microdialysis at high sensitivity and at high temporal resolution.


Assuntos
Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Inibidores da Captação de Dopamina/farmacologia , Dopamina/metabolismo , Nomifensina/farmacologia , Potássio/farmacologia , Animais , Cromatografia Líquida , Estimulação Elétrica , Potenciais Evocados/efeitos dos fármacos , Potenciais Evocados/fisiologia , Masculino , Microdiálise , Sistemas On-Line , Ratos , Ratos Sprague-Dawley , Vigília
9.
J Pharm Biomed Anal ; 129: 482-491, 2016 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-27497649

RESUMO

The use of liquid chromatography (LC) coupled with triple quadrupole linear ion trap (Qtrap) mass spectrometry (MS) for both quantitative and qualitative analysis in drug metabolism and pharmacokinetic studies is of great interest. Here, a new Qtrap-based analytical methodology for simultaneous detection, structural characterization and semi-quantitation of in vitro oxidative metabolites and glutathione trapped reactive metabolites was reported. In the current study, combined multiple ion monitoring and multiple reaction monitoring were served as surveying scans to trigger product ion spectral acquisition of oxidative metabolites and glutathione adduct, respectively. Then, detection of metabolites and recovery of their MS/MS spectra were accomplished using multiple data mining approaches. Additionally, on-line ultraviolet (UV) detection was employed to determine relative concentrations of major metabolites. Analyses of metabolites of clozapine and nomifensine in rat liver microsomes not only revealed multiple oxidative metabolites and glutathione adducts, but also identified their major oxidative metabolism and bioactivation pathways. The results demonstrated that the LC/UV/MS method enabled Qtrap to perform the comprehensive profiling of oxidative metabolites and glutathione adducts in vitro.


Assuntos
Glutationa/química , Glutationa/metabolismo , Animais , Cromatografia Líquida/métodos , Clozapina/química , Clozapina/metabolismo , Microssomos Hepáticos/metabolismo , Nomifensina/química , Nomifensina/metabolismo , Oxirredução , Ratos , Espectrofotometria Ultravioleta/métodos , Espectrometria de Massas em Tandem/métodos
10.
ACS Chem Neurosci ; 7(6): 700-9, 2016 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-27018734

RESUMO

Fast-scan cyclic voltammetry (FSCV) using carbon fiber electrodes is widely used to rapidly monitor changes in dopamine (DA) levels in vitro and in vivo. Current analytical approaches utilize parameters such as peak oxidation current amplitude and decay times to estimate release and uptake processes, respectively. However, peak amplitude changes are often observed with uptake inhibitors, thereby confounding the interpretation of these parameters. To overcome this limitation, we demonstrate that a simple five-parameter, two-compartment model mathematically describes DA signals as a balance of release (r/ke) and uptake (ku), summed with adsorption (kads and kdes) of DA to the carbon electrode surface. Using nonlinear regression, we demonstrate that our model precisely describes measured DA signals obtained in brain slice recordings. The parameters extracted from these curves were then validated using pharmacological manipulations that selectively alter vesicular release or DA transporter (DAT)-mediated uptake. Manipulation of DA release through altering the Ca(2+)/Mg(2+) ratio or adding tetrodotoxin reduced the release parameter with no effect on the uptake parameter. DAT inhibitors methylenedioxypyrovalerone, cocaine, and nomifensine significantly reduced uptake and increased vesicular DA release. In contrast, a low concentration of amphetamine reduced uptake but had no effect on DA release. Finally, the kappa opioid receptor agonist U50,488 significantly reduced vesicular DA release but had no effect on uptake. Together, these data demonstrate a novel analytical approach to distinguish the effects of manipulations on DA release or uptake that can be used to interpret FSCV data.


Assuntos
Cocaína/farmacologia , Corpo Estriado/efeitos dos fármacos , Proteínas da Membrana Plasmática de Transporte de Dopamina/efeitos dos fármacos , Inibidores da Captação de Dopamina/farmacologia , Dopamina/metabolismo , Animais , Transporte Biológico/efeitos dos fármacos , Corpo Estriado/metabolismo , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Estimulação Elétrica/métodos , Técnicas Eletroquímicas , Masculino , Nomifensina/farmacologia , Ratos Sprague-Dawley
11.
Expert Rev Neurother ; 16(2): 131-44, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26693882

RESUMO

Adult Attention Deficit Hyperactivity Disorder (ADHD) is a prevalent psychiatric condition associated with high disability and frequent comorbidity. Current standard pharmacotherapy (methylphenidate and atomoxetine) improves ADHD symptoms in the short-term, but poor data were published about long-term treatment. In addition a number of patients present partial or no response to methylphenidate and atomoxetine. Research into the main database sources has been conducted to obtain an overview of alternative pharmacological approaches in adult ADHD patients. Among alternative compounds, amphetamines (mixed amphetamine salts and lisdexamfetamine) have the most robust evidence of efficacy, but they may be associated with serious side effects (e.g. psychotic symptoms or hypertension). Antidepressants, particularly those acting as noradrenaline or dopamine enhancers, have evidence of efficacy, but they should be avoided in patients with comorbid bipolar disorder. Finally metadoxine and lithium may be particularly suitable in case of comorbid alcohol misuse or bipolar disorder.


Assuntos
Antidepressivos/uso terapêutico , Transtorno do Deficit de Atenção com Hiperatividade/tratamento farmacológico , Estimulantes do Sistema Nervoso Central/uso terapêutico , Dopaminérgicos/uso terapêutico , Agonistas Nicotínicos/uso terapêutico , Agonistas alfa-Adrenérgicos/uso terapêutico , Adulto , Anfetaminas/uso terapêutico , Compostos Benzidrílicos/uso terapêutico , Compostos Bicíclicos Heterocíclicos com Pontes/uso terapêutico , Bupropiona/uso terapêutico , Desipramina/uso terapêutico , Droxidopa/uso terapêutico , Combinação de Medicamentos , Cloridrato de Duloxetina/uso terapêutico , Guanfacina/uso terapêutico , Histamínicos/uso terapêutico , Humanos , Dimesilato de Lisdexanfetamina/uso terapêutico , Compostos de Lítio/uso terapêutico , Lobelina/uso terapêutico , Mecamilamina/uso terapêutico , Memantina/uso terapêutico , Modafinila , Morfolinas/uso terapêutico , Antagonistas Nicotínicos/uso terapêutico , Nomifensina/uso terapêutico , Paroxetina/uso terapêutico , Piridinas/uso terapêutico , Piridoxina/uso terapêutico , Ácido Pirrolidonocarboxílico/uso terapêutico , Quinazolinonas/uso terapêutico , Reboxetina , Cloridrato de Venlafaxina/uso terapêutico , Promotores da Vigília/uso terapêutico
12.
ACS Chem Neurosci ; 6(8): 1468-75, 2015 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-26083009

RESUMO

Dopamine is an important neurotransmitter that exhibits numerous functions in the healthy, injured, and diseased brain. Fast scan cyclic voltammetry paired with electrical stimulation of dopamine axons is a popular and powerful method for investigating the dynamics of dopamine in the extracellular space. Evidence now suggests that the heterogeneity of electrically evoked dopamine responses reflects the inherent kinetic diversity of dopamine systems, which might contribute to their diversity of physiological function. Dopamine measurements by fast scan cyclic voltammetry are affected by the adsorption of dopamine to carbon fiber electrodes. The temporal distortion caused by dopamine adsorption is correctable by a straightforward mathematical procedure. The corrected responses exhibit excellent agreement with a dopamine kinetic model cast to provide a generic description of restricted diffusion, short-term plasticity of dopamine release, and first-order dopamine clearance. The new DA kinetic model brings to light the rich kinetic information content of electrically evoked dopamine responses recorded via fast scan cyclic voltammetry in the rat dorsal striatum.


Assuntos
Corpo Estriado/metabolismo , Dopamina/metabolismo , Modelos Moleculares , Modelos Neurológicos , Animais , Calibragem , Carbono , Fibra de Carbono , Corpo Estriado/efeitos dos fármacos , Antagonistas de Dopamina/farmacologia , Inibidores da Captação de Dopamina/farmacologia , Estimulação Elétrica , Neuroestimuladores Implantáveis , Cinética , Masculino , Nomifensina/farmacologia , Racloprida/farmacologia , Ratos Sprague-Dawley
13.
Anal Chem ; 87(12): 6088-94, 2015 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-25970591

RESUMO

Microdialysis is often applied to understanding brain function. Because neurotransmission involves rapid events, increasing the temporal resolution of in vivo measurements is desirable. Here, we demonstrate microdialysis with online capillary liquid chromatography for the analysis of 1 min rat brain dialysate samples at 1 min intervals. Mobile phase optimization involved adjusting the pH, buffer composition, and surfactant concentration to eliminate interferences with the dopamine peak. By analyzing electrically evoked dopamine transients carefully synchronized with the switching of the online LC sample valve, we demonstrate that our system has both 1 min sampling capabilities and bona fide 1 min temporal resolution. Evoked DA transients were confined to single, 1 min brain dialysate samples. After uptake inhibition with nomifensine (20 mg/kg i.p.), responses to electrical stimuli of 1 s duration were detected.


Assuntos
Dopamina/análise , Técnicas Eletroquímicas , Microdiálise , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/cirurgia , Eletroforese Capilar , Masculino , Nomifensina/administração & dosagem , Nomifensina/farmacologia , Ratos , Ratos Sprague-Dawley , Fatores de Tempo
14.
ACS Chem Neurosci ; 6(1): 163-73, 2015 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-25491242

RESUMO

The power of microdialysis for in vivo neurochemical monitoring is a result of intense efforts to enhance microdialysis procedures, the probes themselves, and the analytical systems used for the analysis of dialysate samples. Our goal is to refine microdialysis further by focusing attention on what happens when the probes are implanted into brain tissue. It is broadly acknowledged that some tissue damage occurs, such that the tissue nearest the probes is disrupted from its normal state. We hypothesize that mitigating such disruption would refine microdialysis. Herein, we show that the addition of dexamethasone, an anti-inflammatory drug, to the perfusion fluid protects evoked dopamine responses as measured by fast-scan cyclic voltammetry next to the probes after 24 h. We also show that dexamethasone stabilizes evoked dopamine responses measured at the probe outlet over a 4-24 h postimplantation interval. The effects of dexamethasone are attributable to its anti-inflammatory actions, as dexamethasone had no significant effect on two histochemical markers for dopamine terminals, tyrosine hydroxylase and the dopamine transporter. Using histochemical assays, we confirmed that the actions of dexamethasone are tightly confined to the immediate, local vicinity of the probe.


Assuntos
Anti-Inflamatórios/administração & dosagem , Lesões Encefálicas , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Dexametasona/administração & dosagem , Dopamina/metabolismo , Análise de Variância , Animais , Lesões Encefálicas/tratamento farmacológico , Lesões Encefálicas/metabolismo , Lesões Encefálicas/patologia , Óxidos N-Cíclicos/administração & dosagem , Modelos Animais de Doenças , Inibidores da Captação de Dopamina/farmacologia , Técnicas Eletroquímicas , Lateralidade Funcional , Microdiálise , Nomifensina/farmacologia , Ratos , Fatores de Tempo , Tirosina 3-Mono-Oxigenase/metabolismo
15.
Immunohematology ; 30(2): 80-4, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25247617

RESUMO

Immune hemolytic anemia (IHA) is a rare complication of drug administration. However, its true incidence remains obscure, as there are a number of factors that may lead to misdiagnosis. The clinical and serologic pictures are variable, and there is a great deal of unawareness that certain drugs can cause IHA. Furthermore, serologic results can be easily misinterpreted, resulting in a wrong diagnosis.


Assuntos
Anemia Hemolítica Autoimune/diagnóstico , Idoso , Anemia Hemolítica Autoimune/induzido quimicamente , Anemia Hemolítica Autoimune/imunologia , Complexo Antígeno-Anticorpo/sangue , Anti-Hipertensivos/efeitos adversos , Antimetabólitos Antineoplásicos/efeitos adversos , Antimetabólitos Antineoplásicos/imunologia , Autoanticorpos/sangue , Células Cultivadas , Teste de Coombs , Eritrócitos/efeitos dos fármacos , Eritrócitos/imunologia , Reações Falso-Positivas , Evolução Fatal , Feminino , Fluoruracila/efeitos adversos , Fluoruracila/imunologia , Hemólise/imunologia , Humanos , Hidroclorotiazida/efeitos adversos , Hidroclorotiazida/análogos & derivados , Pessoa de Meia-Idade , Nomifensina/efeitos adversos
16.
ACS Chem Neurosci ; 5(9): 776-83, 2014 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-24983330

RESUMO

In vivo fast-scan cyclic voltammetry provides high-fidelity recordings of electrically evoked dopamine release in the rat striatum. The evoked responses are suitable targets for numerical modeling because the frequency and duration of the stimulus are exactly known. Responses recorded in the dorsal and ventral striatum of the rat do not bear out the predictions of a numerical model that assumes the presence of a diffusion gap interposed between the recording electrode and nearby dopamine terminals. Recent findings, however, suggest that dopamine may be subject to restricted diffusion processes in brain extracellular space. A numerical model cast to account for restricted diffusion produces excellent agreement between simulated and observed responses recorded under a broad range of anatomical, stimulus, and pharmacological conditions. The numerical model requires four, and in some cases only three, adjustable parameters and produces meaningful kinetic parameter values.


Assuntos
Encéfalo/metabolismo , Dopamina/metabolismo , Modelos Biológicos , Animais , Simulação por Computador , Inibidores da Captação de Dopamina/farmacologia , Estimulação Elétrica , Nomifensina/farmacologia , Ratos
17.
Eur J Neurosci ; 40(2): 2320-8, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24766210

RESUMO

The dopamine (DA) terminal fields in the rat dorsal striatum (DS) and nucleus accumbens core (NAcc) are organized as patchworks of domains that exhibit distinct kinetics of DA release and clearance. The present study used fast-scan cyclic voltammetry recordings of electrically evoked DA overflow to test the hypothesis that nomifensine might exhibit domain-dependent actions within the NAcc, as we previously found to be the case within the DS. Within the NAcc, nomifensine preferentially enhanced evoked DA overflow in the slow domains compared with the fast domains. To seek a kinetic explanation for nomifensine's selective actions, we quantified the apparent KM of DA clearance by numerically evaluating the derivative of the descending phase of the DA signal after the end of the stimulus. For comparison, we likewise quantified the apparent KM in the domains of the DS. As expected, because it is a competitive inhibitor, nomifensine significantly increased the apparent KM in both the fast and slow domains of both the NAcc and DS. However, our analysis also led to the novel finding that nomifensine preferentially increases the apparent KM in the NAcc compared with the DS; the apparent KM increased by ~500% in the NAcc and by ~200% in the DS.


Assuntos
Inibidores da Captação de Dopamina/farmacologia , Nomifensina/farmacologia , Núcleo Accumbens/efeitos dos fármacos , Animais , Dopamina/metabolismo , Potenciais Evocados , Masculino , Núcleo Accumbens/metabolismo , Núcleo Accumbens/fisiologia , Especificidade de Órgãos , Ratos , Ratos Sprague-Dawley
18.
PLoS One ; 9(3): e90759, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24614598

RESUMO

Dyskinesia is a major side effect of an otherwise effective L-DOPA treatment in Parkinson's patients. The prevailing view for the underlying presynaptic mechanism of L-DOPA-induced dyskinesia (LID) suggests that surges in dopamine (DA) via uncontrolled release from serotonergic terminals results in abnormally high level of extracellular striatal dopamine. Here we used high-sensitivity online microdialysis and PET imaging techniques to directly investigate DA release properties from serotonergic terminals both in the parkinsonian striatum and after neuronal transplantation in 6-OHDA lesioned rats. Although L-DOPA administration resulted in a drift in extracellular DA levels, we found no evidence for abnormally high striatal DA release from serotonin neurons. The extracellular concentration of DA remained at or below levels detected in the intact striatum. Instead, our results showed that an inefficient release pool of DA associated with low D2 receptor binding remained unchanged. Taken together, these findings suggest that differential DA receptor activation rather than excessive release could be the underlying mechanism explaining LID seen in this model. Our data have important implications for development of drugs targeting the serotonergic system to reduce DA release to manage dyskinesia in patients with Parkinson's disease.


Assuntos
Discinesia Induzida por Medicamentos/metabolismo , Levodopa/efeitos adversos , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/metabolismo , Receptores Dopaminérgicos/metabolismo , Animais , Benzamidas , Modelos Animais de Doenças , Dopamina/metabolismo , Discinesia Induzida por Medicamentos/patologia , Espaço Extracelular/metabolismo , Feminino , Levodopa/administração & dosagem , Levodopa/farmacologia , Levodopa/uso terapêutico , Microdiálise , Neostriado/efeitos dos fármacos , Neostriado/metabolismo , Nomifensina/uso terapêutico , Doença de Parkinson/diagnóstico por imagem , Tomografia por Emissão de Pósitrons , Proteínas Proto-Oncogênicas c-fos/metabolismo , Pirrolidinas , Ratos Sprague-Dawley , Serotonina/metabolismo
19.
Anal Chem ; 85(11): 5483-90, 2013 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-23642073

RESUMO

Real-time investigations of neurotransmitter release provide a direct insight on the mechanisms involved in synaptic communication. Carbon fiber microelectrodes are state-of-the-art tools for electrochemical measurements of single vesicle neurotransmitter release. Yet, they lack high-throughput capabilities that are required for collecting robust statistically significant data across multiple samples. Here, we present a chip-based recording system enabling parallel in vitro measurements of individual neurotransmitter release events from cells, cultured directly on planar multielectrode arrays. The applicability of this cell-based platform to pharmacological screening is demonstrated by resolving minute concentration-dependent effects of the dopamine reuptake inhibitor nomifensine on recorded single-vesicle release events from PC12 cells. The experimental results, showing an increased half-time of the recorded events, are complemented by an analytical model for the verification of drug action.


Assuntos
Carbono/química , Dopamina/análise , Dispositivos Lab-On-A-Chip , Microeletrodos , Vesículas Secretórias/metabolismo , Animais , Fibra de Carbono , Simulação por Computador , Dopamina/metabolismo , Inibidores da Captação de Dopamina/farmacologia , Exocitose/efeitos dos fármacos , Nomifensina/farmacologia , Células PC12 , Ratos , Vesículas Secretórias/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos
20.
ACS Chem Neurosci ; 4(5): 870-8, 2013 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-23600442

RESUMO

Recent evidence has shown that the dorsal striatum of the rat is arranged as a patchwork of domains that exhibit distinct dopamine kinetics and concentrations. This raises the pressing question of how these distinct domains are maintained, especially if dopamine is able to diffuse through the extracellular space. Diffusion between the domains would eliminate the concentration differences and, thereby, the domains themselves. The present study is a closer examination of dopamine's ability to diffuse in the extracellular space. We used voltammetry to record dopamine overflow in dorsal striatum while stimulating the medial forebrain bundle over a range of stimulus currents and frequencies. We also examined the effects of drugs that modulated the dopamine release (raclopride and quinpirole) and uptake (nomifensine). Examining the details of the temporal features of the evoked profiles reveals no clear evidence for long-distance diffusion of dopamine between fast and slow domains, even though uptake inhibition by nomifensine clearly prolongs the time that dopamine resides in the extracellular space. Our observations support the conclusion that striatal tissue has the capacity to retain dopamine molecules, thereby limiting its tendency to diffuse through the extracellular space.


Assuntos
Dopamina/metabolismo , Espaço Extracelular/metabolismo , Neostriado/metabolismo , Animais , Difusão/efeitos dos fármacos , Agonistas de Dopamina/farmacologia , Antagonistas de Dopamina/farmacologia , Inibidores da Captação de Dopamina/farmacologia , Estimulação Elétrica , Técnicas Eletroquímicas , Espaço Extracelular/efeitos dos fármacos , Masculino , Feixe Prosencefálico Mediano , Neostriado/efeitos dos fármacos , Nomifensina/farmacologia , Quimpirol/farmacologia , Racloprida/farmacologia , Ratos , Ratos Sprague-Dawley
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