RESUMO
The normalization of excessive glutamatergic neurotransmission through the activation of metabotropic glutamate 2 (mGlu2) receptors may have therapeutic potential in a variety of psychiatric disorders, including anxiety/depression and schizophrenia. Here, we characterize the pharmacological properties of N-(4-((2-(trifluoromethyl)-3-hydroxy-4-(isobutyryl)phenoxy)methyl)benzyl)-1-methyl-1H-imidazole-4-carboxamide (THIIC), a structurally novel, potent, and selective allosteric potentiator of human and rat mGlu2 receptors (EC(50) = 23 and 13 nM, respectively). THIIC produced anxiolytic-like efficacy in the rat stress-induced hyperthermia assay and the mouse stress-induced elevation of cerebellar cGMP and marble-burying assays. THIIC also produced robust activity in three assays that detect antidepressant-like activity, including the mouse forced-swim test, the rat differential reinforcement of low rate 72-s assay, and the rat dominant-submissive test, with a maximal response similar to that of imipramine. Effects of THIIC in the forced-swim test and marble burying were deleted in mGlu2 receptor null mice. Analysis of sleep electroencephalogram (EEG) showed that THIIC had a sleep-promoting profile with increased non-rapid eye movement (REM) and decreased REM sleep. THIIC also decreased the dark phase increase in extracellular histamine in the medial prefrontal cortex and decreased levels of the histamine metabolite tele-methylhistamine (t-MeHA) in rat cerebrospinal fluid. Collectively, these results indicate that the novel mGlu2-positive allosteric modulator THIIC has robust activity in models used to predict anxiolytic/antidepressant efficacy, substantiating, at least with this molecule, differentiation in the biological impact of mGlu2 potentiation versus mGlu2/3 orthosteric agonism. In addition, we provide evidence that sleep EEG and CSF t-MeHA might function as viable biomarker approaches to facilitate the translational development of THIIC and other mGlu2 potentiators.
Assuntos
Ansiolíticos/farmacologia , Antidepressivos/farmacologia , Compostos de Benzil/farmacologia , Sistema Nervoso Central/efeitos dos fármacos , Sistema Nervoso Central/metabolismo , Agonistas de Aminoácidos Excitatórios/farmacologia , Imidazóis/farmacologia , Receptores de Glutamato Metabotrópico/agonistas , Animais , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Linhagem Celular , Sistema Nervoso Central/química , Cerebelo/química , Cerebelo/efeitos dos fármacos , Cerebelo/metabolismo , Sinergismo Farmacológico , Humanos , Masculino , Camundongos , Camundongos Knockout , Ratos , Ratos Endogâmicos F344 , Ratos Sprague-Dawley , Ratos Wistar , Receptores de Glutamato Metabotrópico/fisiologiaRESUMO
Neuropeptide Y (NPY) is an important central regulator of food consumption and energy expenditure via the hypothalamus. NPY containing neurons have a broad central distribution and are often colocalized with norepinephrine (NE). However, NPY deficient mice do not exhibit any substantial changes in food consumption, body weight or body composition when compared to wild type mice. Since NE and serotonin (5HT) are also important regulators of appetite and metabolism, we evaluated these systems in NPY deficient mice. Brain sections from NPY deficient and wild type mice were labeled with either (3)H-nisoxetine for the NE transporter (NET) or (3)H-citalopram for the 5HT transporter (SERT). Tyrosine hydroxylase expression was evaluated by radioimmunohistochemistry. Brain monoamines and metabolites were evaluated using HPLC. NPY deficient mice exhibited a substantial decrease in NET binding in most brain regions examined. NET binding was less than 50% of control binding in the cerebral cortex and subregions of the thalamus with the greatest decrease seen in the hypothalamus. In contrast, more modest and regionally variable changes were observed in the SERT binding with decreases in regions such as the accessory olfactory nucleus, glomerular layer of the olfactory bulb and the CA1 region of the hippocampus. Measurement of NE and 5HT content as well as the primary metabolites revealed increased NE turnover and decreased 5HT content in the hypothalamus. Therefore, developmental compensation by the NE and 5HT systems may contribute to the absence of a body weight phenotype in NPY deficient mice.
Assuntos
Monoaminas Biogênicas/metabolismo , Química Encefálica/genética , Neuropeptídeo Y/deficiência , Animais , Autorradiografia , Cromatografia Líquida de Alta Pressão , Citalopram , Fluoxetina/análogos & derivados , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Knockout , Neuropeptídeo Y/genética , Norepinefrina/metabolismo , Proteínas da Membrana Plasmática de Transporte de Norepinefrina/metabolismo , Serotonina/metabolismo , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Inibidores Seletivos de Recaptação de Serotonina , Tirosina 3-Mono-Oxigenase/biossíntese , Tirosina 3-Mono-Oxigenase/genéticaRESUMO
We have previously shown that the orexin-1 antagonist SB-334867 blocks the electrophysiological effects of haloperidol and olanzapine on the activity of A9 and A10 dopamine neurons. To evaluate if orexin-1 antagonists might block other effects of antipsychotic drugs in animals, we examined the effects of SB-334867 on behavioral, neurochemical, and neuroendocrine effects of antipsychotic drugs. Pretreatment with SB-334867 (0.01-10 mg/kg, intraperitoneal [IP]) significantly decreased the catalepsy produced by the administration of haloperidol (1 mg/kg, subcutaneous [SC]), risperidone (2 mg/kg, SC), and olanzapine (10 mg/kg, SC). Administration of SB-334467 also reversed catalepsy after it had been established in animals pretreated 2 hours earlier with haloperidol. However, pretreatment with SB-334867 (1-10 mg/kg, IP) did not block the decreases in exploratory locomotor activity produced by administration of haloperidol (0.1 mg/kg, SC) or risperidone (0.3 mg/kg, SC). In addition, pretreatment with SB-334867 (1-10 mg/kg, IP) neither blocked the increased levels of dihydroxyphenylacetic acid (DOPAC) in the nucleus accumbens or striatum nor the elevation in serum prolactin produced by administration of haloperidol (0.1 mg/kg, SC) and risperidone (1 mg/kg, SC). Administration of SB-334867 alone neither changed locomotor activity and DOPAC or prolactin levels nor produced catalepsy. These results show that orexin-1 antagonists block the catoleptogenic effects of antipsychotics but do not block other locomotor, neurochemical, or neuroendocrine effects of antipsychotics. Because catalepsy is thought to be a good predictor of extrapyramidal symptoms in humans, treatment with orexin-1 antagonists might decrease the occurrence or severity of antipsychotic treatment-emergent extrapyramidal symptoms in humans.
Assuntos
Antipsicóticos/antagonistas & inibidores , Doenças dos Gânglios da Base/tratamento farmacológico , Benzodiazepinas/antagonistas & inibidores , Benzoxazóis/farmacologia , Benzoxazóis/uso terapêutico , Catalepsia/tratamento farmacológico , Haloperidol/antagonistas & inibidores , Peptídeos e Proteínas de Sinalização Intracelular/antagonistas & inibidores , Neuropeptídeos/antagonistas & inibidores , Risperidona/antagonistas & inibidores , Ureia/análogos & derivados , Animais , Comportamento Animal/efeitos dos fármacos , Locomoção/efeitos dos fármacos , Masculino , Naftiridinas , Olanzapina , Orexinas , Prolactina/metabolismo , Ratos , Ratos Sprague-Dawley , Ureia/farmacologia , Ureia/uso terapêuticoRESUMO
The selective norepinephrine (NE) transporter inhibitor atomoxetine (formerly called tomoxetine or LY139603) has been shown to alleviate symptoms in Attention Deficit/Hyperactivity Disorder (ADHD). We investigated the mechanism of action of atomoxetine in ADHD by evaluating the interaction of atomoxetine with monoamine transporters, the effects on extracellular levels of monoamines, and the expression of the neuronal activity marker Fos in brain regions. Atomoxetine inhibited binding of radioligands to clonal cell lines transfected with human NE, serotonin (5-HT) and dopamine (DA) transporters with dissociation constants (K(i)) values of 5, 77 and 1451 nM, respectively, demonstrating selectivity for NE transporters. In microdialysis studies, atomoxetine increased extracellular (EX) levels of NE in prefrontal cortex (PFC) 3-fold, but did not alter 5-HT(EX) levels. Atomoxetine also increased DA(EX) concentrations in PFC 3-fold, but did not alter DA(EX) in striatum or nucleus accumbens. In contrast, the psychostimulant methylphenidate, which is used in ADHD therapy, increased NE(EX) and DA(EX) equally in PFC, but also increased DA(EX) in the striatum and nucleus accumbens to the same level. The expression of the neuronal activity marker Fos was increased 3.7-fold in PFC by atomoxetine administration, but was not increased in the striatum or nucleus accumbens, consistent with the regional distribution of increased DA(EX). We hypothesize that the atomoxetine-induced increase of catecholamines in PFC, a region involved in attention and memory, mediates the therapeutic effects of atomoxetine in ADHD. In contrast to methylphenidate, atomoxetine did not increase DA in striatum or nucleus accumbens, suggesting it would not have motoric or drug abuse liabilities.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/metabolismo , Dopamina/metabolismo , Norepinefrina/metabolismo , Córtex Pré-Frontal/efeitos dos fármacos , Propilaminas/farmacologia , Animais , Cloridrato de Atomoxetina , Transtorno do Deficit de Atenção com Hiperatividade/tratamento farmacológico , Sinergismo Farmacológico , Humanos , Masculino , Córtex Pré-Frontal/metabolismo , Ratos , Ratos Sprague-DawleyRESUMO
Direct-acting serotonin (5-HT) receptor agonists increase serum corticosterone in rats by activating receptors of the 5-HT(1A) or the 5-HT(2A/2C) subtypes. While involvement of 5-HT(1A) receptors in activation of the hypothalamic-pituitary-adrenocortical (HPA) axis is clear, the 5-HT(2) receptor subtype--5-HT(2A) or 5-HT(2C)--responsible for activation of the HPA axis by direct-acting 5-HT(2) receptor agonists has been difficult to determine due to the lack of selective pharmacologic agents. Recently, however, 5-HT(2) receptor antagonists with high selectivity for 5-HT(2A) and 5-HT(2C) receptor subtypes have been discovered. The selective 5-HT(2A) receptor antagonist MDL 100,907 and the selective 5-HT(2C) receptor antagonist SB 242084 were used to block the increases in rat serum corticosterone elicited by 5-HT(2) receptor agonists with varying degrees of affinity for 5-HT(2A) and 5-HT(2C) receptors. MDL 100,907 was fully effective in blocking the increases in corticosterone concentrations produced by quipazine, DOI, m-CPP and Ro 60-0175, whereas SB 242084 was ineffective or was only marginally effective. Our findings implicate 5-HT(2A) receptors rather than 5-HT(2C) receptors in mediating increases in rat serum corticosterone produced by direct-acting 5-HT(2) receptor agonists in vivo.
Assuntos
Aminopiridinas/farmacologia , Corticosterona/sangue , Fluorbenzenos/farmacologia , Sistema Hipotálamo-Hipofisário/efeitos dos fármacos , Indóis/farmacologia , Piperidinas/farmacologia , Receptores de Serotonina/efeitos dos fármacos , Antagonistas da Serotonina/farmacologia , Agonistas do Receptor de Serotonina/farmacologia , Anfetaminas/farmacologia , Animais , Relação Dose-Resposta a Droga , Etilaminas/farmacologia , Masculino , Piperazinas/farmacologia , Quipazina/farmacologia , Ratos , Ratos Sprague-Dawley , Receptor 5-HT2A de SerotoninaRESUMO
Compounds that block both serotonin (5-HT) and norepinephrine (NE) transporters have been proposed to have improved antidepressant efficacy. We compared the ability of four dual transporter inhibitors-chlorimipramine, duloxetine, milnacipran and venlafaxine-to block monoamine transporters in vitro and in vivo and increase extracellular monoamines in rat brain. Inhibition of radioligand binding to clonal human monoamine transporters in vitro and in vivo in rats was determined. Extracellular concentrations of 5-HT and NE in rat prefrontal cortex (PFC) were quantified using the microdialysis technique. All compounds blocked binding to human 5-HT and NE transporters, although chlorimipramine and venlafaxine had markedly greater affinity for 5-HT than NE transporters. In vivo, chlorimipramine and duloxetine potently blocked both transporters, milnacipran blocked both with lower potency and venlafaxine only blocked the 5-HT transporter. Chlorimipramine and duloxetine increased robustly and approximately equally monoamine extracellular concentrations. Milnacipran produced only small increases in NE, whereas venlafaxine increased 5-HT markedly at the lower doses and both monoamines at high doses. Thus, the dual transporter inhibitors blocked 5-HT and NE transporters in vitro and in vivo with varying potency. Chlorimipramine, duloxetine, and high dose venlafaxine acted as dual transporter inhibitors in rat PFC and increased extracellular concentrations of the monoamines, indicating functional dual transporter inhibition.
Assuntos
Inibidores da Captação Adrenérgica/farmacologia , Monoaminas Biogênicas/metabolismo , Proteínas de Transporte/metabolismo , Espaço Extracelular/metabolismo , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , Animais , Química Encefálica/efeitos dos fármacos , Clomipramina/farmacologia , Cicloexanóis/farmacologia , Ciclopropanos/farmacologia , Relação Dose-Resposta a Droga , Cloridrato de Duloxetina , Técnicas In Vitro , Masculino , Microdiálise , Milnaciprano , Norepinefrina/metabolismo , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/metabolismo , Ensaio Radioligante , Ratos , Ratos Sprague-Dawley , Serotonina/metabolismo , Serotoninérgicos/farmacologia , Tiofenos/farmacologia , Cloridrato de Venlafaxina , alfa-Metiltirosina/farmacologia , p-Cloroanfetamina/farmacologiaRESUMO
The objective of the described research effort was to identify a novel serotonin and norepinephrine reuptake inhibitor (SNRI) with improved norepinephrine transporter activity and acceptable metabolic stability and exhibiting minimal drug-drug interaction. We describe herein the discovery of a series of 3-substituted pyrrolidines, exemplified by compound 1. Compound 1 is a selective SNRI in vitro and in vivo, has favorable ADME properties, and retains inhibitory activity in the formalin model of pain behavior. Compound 1 thus represents a potential new probe to explore utility of SNRIs in central nervous system disorders, including chronic pain conditions.
RESUMO
A series of 1-aryloxy-3-piperidinylpropan-2-ols possessing potent dual 5-HT1A receptor antagonism and serotonin reuptake inhibition was discovered. 1-(1H-Indol-4-yloxy)-3-(4-benzo[b]thiophen-2-ylpiperidinyl)propan-2-ols exhibited selective and high affinities at the 5-HT1A receptor and serotonin reuptake site in vitro. In vivo evaluation of this series of compounds demonstrated elevated extracellular serotonin levels from the basal and quick recovery of neuron firing that was presumably suppressed by the initial acute activation of 5-HT1A somatodendritic autoreceptors.
Assuntos
Antidepressivos/farmacologia , Piperidinas/farmacologia , Propanóis/farmacologia , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , Antagonistas do Receptor 5-HT1 de Serotonina , Animais , Antidepressivos/administração & dosagem , Antidepressivos/química , Encéfalo/efeitos dos fármacos , Avaliação Pré-Clínica de Medicamentos , Técnicas In Vitro , Masculino , Conformação Molecular , Piperidinas/administração & dosagem , Piperidinas/química , Propanóis/administração & dosagem , Propanóis/química , Ratos , Ratos Sprague-Dawley , Inibidores Seletivos de Recaptação de Serotonina/administração & dosagem , Inibidores Seletivos de Recaptação de Serotonina/química , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
FMPD [6-fluoro-10-[3-(2-methoxyethyl)-4-methyl-piperazin-1-yl]-2-methyl-4H-3-thia-4,9-diaza-benzo[f]azulene] is a potential novel antipsychotic with high affinity for dopamine D2 (Ki= 6.3 nM), 5-HT(2A) (Ki= 7.3 nM), and 5-HT6 (Ki= 8.0 nM) human recombinant receptors and lower affinity for histamine H1 (Ki= 30 nM) and 5-HT2C (Ki= 102 nM) human recombinant receptors than olanzapine. Oral administration of FMPD increased rat nucleus accumbens 3,4-dihyroxyphenylacetic acid concentrations (ED200 = 6 mg/kg), blocked 5-HT2A agonist-induced increases in rat serum corticosterone levels (ED50= 1.8 mg/kg), and inhibited the ex vivo binding of [125I]SB-258585 [4-iodo-N-[4-methoxy-3-(4-methyl-piperazin-1-yl)-phenyl]-benzenesulfonamide] to striatal 5-HT6 receptors (ED50= 10 mg/kg) but failed to inhibit ex vivo binding of [3H]pyrilamine to hypothalamic histamine H1 receptors at doses of up to 30 mg/kg. In electrophysiology studies, acute administration of FMPD selectively elevated the number of spontaneously active A10 (versus A9) dopamine neurons and chronic administration selectively decreased the number of spontaneously active A10 (versus A9) dopamine neurons. FMPD did not produce catalepsy at doses lower than 25 mg/kg p.o. In Fos-induction studies, FMPD had an atypical antipsychotic profile in the striatum and nucleus accumbens and increased Fos expression in orexin-containing neurons of the hypothalamus. FMPD produced only a transient elevation of prolactin levels. These data indicate that FMPD is an orally available potent antagonist of dopamine D2, 5-HT2A, and 5-HT6 receptors and a weak antagonist of H1 and 5-HT2C receptors. FMPD has the potential to have efficacy in treating schizophrenia and bipolar mania with a low risk of treatment-emergent extrapyramidal symptoms, prolactin elevation, and weight gain. Clinical trials are needed to test these hypotheses.
Assuntos
Antipsicóticos/farmacologia , Piperazinas/farmacologia , Receptores Histamínicos H1/metabolismo , Ácido 3,4-Di-Hidroxifenilacético/análise , Ácido 3,4-Di-Hidroxifenilacético/metabolismo , Animais , Antipsicóticos/metabolismo , Benzodiazepinas/química , Benzodiazepinas/metabolismo , Benzodiazepinas/farmacologia , Benzodiazepinas/uso terapêutico , Peso Corporal/efeitos dos fármacos , Catalepsia/induzido quimicamente , Cocaína/farmacologia , Corticosterona/sangue , Avaliação Pré-Clínica de Medicamentos , Eletroquímica , Eletrofisiologia , Jejum , Feminino , Imuno-Histoquímica , Masculino , Estrutura Molecular , Atividade Motora/efeitos dos fármacos , Núcleo Accumbens/metabolismo , Olanzapina , Piperazinas/química , Piperazinas/metabolismo , Prolactina/sangue , Quipazina/farmacologia , Ensaio Radioligante , Ratos , Ratos Endogâmicos F344 , Ratos Endogâmicos , Ratos Sprague-Dawley , Agonistas do Receptor de Serotonina/farmacologia , Tiofenos/química , Tiofenos/farmacologia , Tiofenos/uso terapêutico , Fatores de TempoRESUMO
5-Hydroxytryptamine (serotonin) (5-HT) and norepinephrine (NE) are implicated in modulating descending inhibitory pain pathways in the central nervous system. Duloxetine is a selective and potent dual 5-HT and NE reuptake inhibitor (SNRI). The ability of duloxetine to antagonize 5-HT depletion in para-chloramphetamine-treated rats was comparable with that of paroxetine, a selective serotonin reuptake inhibitor (SSRI), whereas its ability to antagonize NE depletion in alpha-methyl-m-tyrosine-treated rats was similar to norepinephrine reuptake inhibitors (NRIs), thionisoxetine or desipramine. In this paradigm, duloxetine was also more potent than other SNRIs, including venlafaxine or milnacipran and amitriptyline. Low doses of the SSRI paroxetine or the NRI thionisoxetine alone did not have an effect on late phase paw-licking pain behavior in the formalin model of persistent pain; however, when combined, significantly attenuated this pain behavior. Duloxetine (3-15 mg/kg intraperitoneal) significantly attenuated late phase paw-licking behavior in a dose-dependent manner in the formalin model and was more potent than venlafaxine, milnacipran, and amitriptyline. These effects of duloxetine were evident at doses that did not cause neurologic deficits in the rotorod test. Duloxetine (5-30 mg/kg oral) was also more potent and efficacious than venlafaxine and milnacipran in reversing mechanical allodynia behavior in the L5/L6 spinal nerve ligation model of neuropathic pain. Duloxetine (3-30 mg/kg oral) was minimally efficacious in the tail-flick model of acute nociceptive pain. These data suggest that inhibition of both 5-HT and NE uptake may account for attenuation of persistent pain mechanisms. Thus, duloxetine may have utility in treatment of human persistent and neuropathic pain states.