RESUMO
Fluorine-18 radiolabeling typically includes several conserved steps including elution of the [18F]fluoride from an anion exchange cartridge with a basic solution of K2CO3 or KHCO3 and Kryptofix 2.2.2. in mixture of acetonitrile and water followed by rigorous azeotropic drying to remove the water. In this work we describe an alternative "non-anhydrous, minimally basic" ("NAMB") technique that simplifies the process and avoids the basic conditions that can sometimes limit the scope and efficiency of [18F]fluoride incorporation chemistry. In this approach, [18F]F- is eluted from small (10-12 mg) anion-exchange cartridges with solutions of tetraethylammonium bicarbonate, perchlorate or tosylate in polar aprotic solvents containing 10-50% water. After dilution with additional aprotic solvent, these solutions are used directly in nucleophilic aromatic and aliphatic 18F-fluorination reactions, obviating the need for azeotropic drying. Perchlorate and tosylate are minimally basic anions that are nevertheless suitable for removal of [18F]F- from the anion-exchange cartridge. As proof-of-principle, "NAMB" chemistry was utilized for the synthesis of the dopamine D2/D3 antagonist [18F]fallypride.
Assuntos
Radioisótopos de Flúor/química , Halogenação , Resinas de Troca Aniônica/química , Benzaldeídos/síntese química , Benzaldeídos/química , Cromatografia Líquida de Alta Pressão , Compostos de Amônio Quaternário/química , SolventesRESUMO
Previous studies have demonstrated that kappa opioid receptor (KOR) antagonists reduce stress- and depression-like behaviors. We hypothesized that administration of a novel opioid mixed agonist/antagonist capable of antagonist activity at the KOR would attenuate forced-swim stress (FSS)-induced immobility, an animal model of depression-like behavior. C57Bl/6J mice were exposed to antinociceptive and repeated FSS testing after pretreatment with a graded dose of a novel bivalent morphinan compound, bis(N-cyclobutylmethylmorphinan-3-yl) sebacoylate dihydrochloride (MCL-144B). MCL-144B demonstrated dose- and time-dependent antinociception and KOR-mediated antagonism. In support of the hypothesis, pretreatment with MCL-144B dose-dependently attenuated stress-induced antinociception and immobility in the forced-swim test.
Assuntos
Alcanos/farmacologia , Antidepressivos/farmacologia , Depressão/tratamento farmacológico , Morfinanos/farmacologia , Receptores Opioides kappa/antagonistas & inibidores , Estresse Psicológico/tratamento farmacológico , Alcanos/administração & dosagem , Animais , Antidepressivos/administração & dosagem , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Imobilização , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Morfinanos/administração & dosagem , Natação , Fatores de TempoRESUMO
The in vivo kinetics of the dopamine (DA) transporter probe 123I-labeled 2 beta-carboxymethoxy-3 beta-(4-iodophenyl) tropane ([123I] beta-CIT) in striatum was investigated with single-photon emission computerized tomography (SPECT) in five healthy human subjects. The aim of this study was to derive an adequate measure of the DA transporter density that would not be affected by regional cerebral blood flow or peripheral clearance of the tracer. SPECT data were acquired on the day of injection (day 1) from 0 to 7 h and on the following day (day 2) from 19 to 25 h. Arterial sampling on day 1 was used to measure the input function. Graphical, kinetic, and equilibrium analyses were evaluated. Graphical analysis of day 1 data, with the assumption of negligible dissociation of the tracer-receptor complex (k4 = 0), was found to be blood flow-dependent. A three-compartment kinetic analysis of day 1 data were performed using a three (k4 = 0)- and a four (k4 > 0)-parameter model. The three-parameter model estimated the konBmax product at 0.886 +/- 0.087 min-1. The four-parameter model gave a binding potential (BP) of 476 ml g-1, a value consistent with in vitro measurements. The stability of the regional uptake on day 2 allowed direct measurement of the specific to nonspecific equilibrium partition coefficient (V3" = k3/k4 = 6.66 +/- 1.54). Results of day 1 kinetic analysis and day 2 equilibrium analysis were well correlated among subjects. Simulations indicated that the error associated with the day 2 equilibrium analysis was acceptable for plasma tracer terminal half-lives > 10 h. We propose the equilibrium analysis on day 2 as the method of choice for clinical studies since it does not require multiple scans or the measurement of the arterial plasma tracer concentrations.
Assuntos
Encéfalo/metabolismo , Proteínas de Transporte/metabolismo , Cocaína/análogos & derivados , Glicoproteínas de Membrana , Proteínas de Membrana Transportadoras , Adulto , Encéfalo/diagnóstico por imagem , Cocaína/sangue , Cocaína/metabolismo , Simulação por Computador , Corpo Estriado/metabolismo , Proteínas da Membrana Plasmática de Transporte de Dopamina , Feminino , Humanos , Radioisótopos do Iodo , Cinética , Masculino , Modelos Biológicos , Proteínas do Tecido Nervoso/metabolismo , Valores de Referência , Fatores de Tempo , Tomografia Computadorizada de Emissão de Fóton ÚnicoRESUMO
Changes in D2-like dopamine (DA) receptor binding in rat brain regions were compared by quantitative in vitro receptor autoradiography after 21-d treatment with a typical (fluphenazine), atypical (clozapine), or candidate atypical antipsychotic (S[+]-N-n-propylnorapomorphine, [+]-NPA). Fluphenazine treatment significantly increased binding of the D2,3,4 radioligands [3H]nemonapride and [3H]spiperone in caudate-putamen (CPu: 22%, 32%), nucleus accumbens (ACC: 67%, 52%), olfactory tubercle (OT: 53%, 43%), and medial prefrontal cerebral cortex (MPC: 46%, 47%) but not dorsolateral frontal cortex (DFC). D2-like binding in MPC was also increased by (+)-NPA (49%, 39%) and clozapine (60%, 40%), but not in DFC, CPu, ACC, or OT. Binding of D2,3-selective [3H]raclopride increased less after fluphenazine in ACC (27%) and CPu (16%) than with the nonselective radioligands, and not after clozapine or (+)-NPA. D3-selective binding of [3H]R (+)-7-OH-DPAT was not changed with any treatment or region including islands of Calleja. Binding of [3H]nemonapride or [3H]spiperone under D4-selective conditions (with 300 nM S[-]-raclopride and other masking agents, at sites occluded by D4 ligand L-745,870), was increased by fluphenazine, (+)-NPA, clozapine in ACC (120%, 76%, 70%, respectively), and CPu (54%, 37%, 35%), but not in OT, DFC or MPC. These results support the hypothesis that cerebrocortical D2-like and striatolimbic D4-like receptors contribute to antipsychotic actions of both typical and atypical drugs and encourage further consideration of S(+)aporphines as potential atypical antipsychotics.
Assuntos
Antipsicóticos/farmacologia , Apomorfina/análogos & derivados , Córtex Cerebral/efeitos dos fármacos , Clozapina/farmacologia , Agonistas de Dopamina/farmacologia , Flufenazina/farmacologia , Sistema Límbico/efeitos dos fármacos , Receptores de Dopamina D2/metabolismo , Animais , Apomorfina/farmacologia , Autorradiografia , Linhagem Celular , Córtex Cerebral/metabolismo , Desenho de Fármacos , Sistema Límbico/metabolismo , Masculino , Ratos , Ratos Sprague-Dawley , Receptores de Dopamina D4RESUMO
Two aporphine analogues to the potent and selective serotonin (5-HT) agonist, 8-hydroxy-2-di-n-propylaminotetralin (8-OH-DPAT) were studied with regard to their actions upon central monoaminergic systems. The biochemical and behavioural findings indicate that 8-hydroxy-N-methyl-aporphine (8-OH aporphine) and its N-n-propyl analogue (8-OH PNA) possess weak dopamine/noradrenaline antagonist- and agonist-like properties, respectively. In addition, both aporphines seemed to only weakly influence serotoninergic transmission. The latter findings are compared to those of known serotonin agonists (e.g. 8-OH-DPAT), and are discussed with particular reference to the structural requirements for activation of central 5-HT receptors.
Assuntos
Aporfinas/farmacologia , Aminas Biogênicas/fisiologia , Encéfalo/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Animais , Dopamina/fisiologia , Masculino , Norepinefrina/fisiologia , Ratos , Ratos Endogâmicos , Serotonina/fisiologia , Relação Estrutura-AtividadeRESUMO
Substituted and unsubstituted 10,11-methylenedioxy derivatives of apomorphine (APO) or its N-propyl congener (NPA) were synthesized and evaluated for their ability to alter motor activity or to induce stereotyped behavior in the rat. Of these, (-)10,11-methylenedioxy-N-n-propylnoraporphine hydrochloride (MDO-NPA) was the most active, and the only compound which was found to be active after oral administration. Also, MDO-NPA was more potent than NPA or APO in producing stereotypy, but large doses of these three aporphines were equipotent in stimulating motor activity. The duration of action of MDO-NPA exceeded that of NPA and APO, and increased with increasing doses. The effects of MDO-NPA on general activity were biphasic: larger doses stimulated activity: smaller doses markedly inhibited it and induced catalepsy. Catalepsy did not occur with NPA or APO and their motor-inhibitory effects were apparent only in aroused rats. The stereotypic effects of MDO-NPA were blocked by small doses of haloperidol, but not by large doses of reserpine. The effects due to large or small doses of MDO-NPA were also blocked by a microsomal enzyme inhibitor which did not interfere with the actions of NPA. These results suggest that MDO-NPA is a long-acting, orally effective prodrug of NPA with depot properties and dose-dependent agonistic and antagonistic interactions with central dopamine-mediated systems.
Assuntos
Apomorfina/análogos & derivados , Apomorfina/farmacologia , Comportamento Animal/efeitos dos fármacos , Receptores Dopaminérgicos/efeitos dos fármacos , Administração Oral , Animais , Relação Dose-Resposta a Droga , Humanos , Masculino , Proadifeno/farmacologia , Ratos , Ratos Endogâmicos , Comportamento Estereotipado/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
Dopamine (DA) injected unilaterally into the corpus striatum of the brain of the rat after pretreatment with a monoamine oxidase inhibitor, induced contralateral deviation of the head (ED50 = 23 micrograms). Dopamine, administered similarly into the nucleus accumbens septi, induced strong locomotor arousal effects (ED50 = 32 micrograms), as reported by others. Systemic administration of the S(+) isomers of apomorphine (APO) and its N-n-propyl analog (NPA) had no significant action on the effects on posture of DA given intrastriatally, even in large doses. In striking contrast, both agents selectively inhibited the locomotor-arousal effects of DA injected into the accumbens, but (+)NPA was seven times more potent (ED50 = 0.5 mg/kg vs 16 micrograms of DA) and its effects lasted for about 70 min. The dose-effect curves for (+)NPA against two doses of DA demonstrated parallel, lateral displacement, indicating a competitive interaction. These results support the impression that enantiomers and analogs of apomorphine, and especially S(+)N-propylnorapomorphine, have potent antidopaminergic actions that may be selective for limbic areas of the forebrain.
Assuntos
Apomorfina/farmacologia , Antagonistas de Dopamina , Sistema Límbico/efeitos dos fármacos , Receptores Dopaminérgicos/efeitos dos fármacos , Animais , Apomorfina/análogos & derivados , Corpo Estriado/efeitos dos fármacos , Masculino , Atividade Motora/efeitos dos fármacos , Núcleo Accumbens/efeitos dos fármacos , Postura , Ratos , Ratos EndogâmicosRESUMO
High performance liquid chromatography with electrochemical detection was used to assay N-n-propylnorapomorphine (NPA) and other aporphines. Pretreatment of rats with (-)10,11-methylenedioxy-N-n-propylnoraporphine (MDO-NPA) yielded dose-dependent increases in tissue levels of NPA after oral or parenteral administration. Cerebral levels of NPA significantly paralleled the stereo-typed behavioral effects produced by MDO-NPA at several doses and times. Pretreatment with the microsomal oxidase inhibitor SKF-525A (see Methods) prevented these behavioral effects of MDO-NPA and blocked the formation of NPA in vitro. These results support the suggestion that MDO-NPA is a uniquely orally effective and relatively long-acting aporphine which acts at cerebral dopamine receptors as a prodrug of NPA.
Assuntos
Apomorfina/análogos & derivados , Receptores Dopaminérgicos/efeitos dos fármacos , Animais , Apomorfina/metabolismo , Apomorfina/farmacologia , Aporfinas/metabolismo , Cromatografia Líquida de Alta Pressão , Humanos , Ratos , Comportamento Estereotipado/efeitos dos fármacosRESUMO
A series of 2-substituted N-n-propylnorapomorphine (NPA) derivatives were synthesized and compared with other DA agonists for affinity to D1 and D2 dopamine (DA) receptors in rat brain corpus striatum tissue. The 2-substituents tested reduced D1 affinity similarly, but enhanced D2 affinity in the rank order: F greater than OH greater than Br greater than OCH3 greater than H greater than or equal to NH2. The extraordinarily high D2 affinity (Ki = 12 pM) and D2 vs. D1 selectivity (57,500) of 2-F-NPA far-exceeded that of all other DA agonists tested, and it was about 10-times more potent than NPA in vivo.
Assuntos
Apomorfina/análogos & derivados , Corpo Estriado/metabolismo , Dopaminérgicos/farmacologia , Receptores Dopaminérgicos/metabolismo , Animais , Apomorfina/metabolismo , Apomorfina/farmacologia , Membrana Celular/metabolismo , Cinética , Masculino , Ratos , Receptores Dopaminérgicos/efeitos dos fármacos , Receptores de Dopamina D1 , Receptores de Dopamina D2 , Relação Estrutura-AtividadeRESUMO
R(-)11-Hydroxy-N-n-propylnoraporphine (11-OH-NPa) induced stereotyped behavior in the rat as potently (ED50 = 0.80 mg/kg, i.p.) as R(-)apomorphine (APO) and this effect was blocked by haloperidol; the 11-methoxy congener, R(-)11-MeO-NPa, had a weak effect (ED50 greater than 10 mg/kg) and the S(+) isomers had none. The isomer R(-)11-OH-NPa potentiated locomotion stimulated by apomorphine; S(+)11-OH-NPa inhibited it and the isomers of 11-MeO-NPa were inactive. Catecholaporphines usually are inactive orally, but both R(-) and S(+)11-OH-NPa were similarly potent after oral or parenteral administration. The isomer S(+)11-OH-NPa inhibited spontaneous and apomorphine-induced locomotion (ID50 = 1.8-2.7 mg/kg, p.o. and i.p.) and stereotyped behavior (ID50 = 3 mg/kg, p.o. or i.p.), all without inducing catalepsy. While apomorphine was short-acting (1-2 hr), the effects of R(-)11-OH-NPa persisted up to 6-7 hr and those of the S(+) isomer for at least 2.5 hr; moreover, the efficacy of R(-)11-OH-NPa increased markedly up to 3-4 hr, although its ED50 was independent of time (ED50 = 1.7-1.9 mg/kg, i.p. from 1-3 hr). The total effect of R(-)11-OH-NPa (p.o. or i.p.) over time was more than 10-times greater than that of injected apomorphine. These observations accord with the reported high (nM) affinity of 11-OH-NPa at cerebral DA receptor sites (D2 greater than D1) and weak interactions of the 11-methoxy congener. They support the conclusion that the R(-) and S(+) stereoisomers are neuropharmacologically active, respectively, as DA agonist and apparent antagonist, as was found with the enantiomers of N-n-propylnorapomorphine, perhaps due to the low intrinsic postsynaptic agonist activity of the S(+) isomers. Moreover, 11-OH-NPa was highly bioavailable orally and unusually long-acting; it may be absorbed slowly or have active metabolites. Hydroxy-substitution of aporphines at the 11-position, homologous to the 3-OH of DA, evidently is critical for affinity and activity at the DA receptor. These or other monohydroxyaporphines may represent leads to potentially useful DA agonist or antagonist drugs.
Assuntos
Aporfinas/farmacologia , Comportamento Animal/efeitos dos fármacos , Receptores Dopaminérgicos/efeitos dos fármacos , Animais , Antipsicóticos/farmacologia , Catalepsia/induzido quimicamente , Relação Dose-Resposta a Droga , Masculino , Atividade Motora/efeitos dos fármacos , Ratos , Ratos Endogâmicos , Estereoisomerismo , Comportamento Estereotipado/efeitos dos fármacosRESUMO
Binding of the tritiated dopamine (DA) agonists, apomorphine (APO) and a dihydroxyaminotetralin (ADTN) to a membrane preparation from the caudate nucleus of calf brain was compared. Binding of [3H]dihydroxyaminotetralin at small (nM) concentrations followed simple, monophasic inhibition (over 80% at less than 500 nM) by concentrations of apomorphine between 50 pM and 1 mM. Inhibition of the binding of [3H]apomorphine by dihydroxyaminotetralin was more complex, and included in component with a low (microM) affinity for dihydroxyaminotetralin accounting for approx. 20% of total binding. The kinetics of binding of the ligands to high-affinity sites were virtually identical (apparent Kd = 0.81 nM; Bmax = 211 fmol/mg protein) and could not be distinguished by curve-fitting techniques adapted to analysis by microcomputer. In contrast, the binding of [3H]apomorphine with a "blank" defined by excess (10 microM) dihydroxyaminotetralin could be resolved into the same high-affinity component and a lower-affinity site (Kd = 124 nM; Bmax = 5740 fmol/mg). The pharmacology of the lower-affinity binding of [3H]apomorphine was evaluated by coincubating with 0.5 microM dihydroxyaminotetralin to "mask" high-affinity sites, and was compared to high-affinity binding of [3H]apomorphine and [3H]dihydroxyaminotetralin. The high-affinity binding was stereoselective for DA receptor agonists and antagonists. The pharmacology of the lower-affinity site resembled no known DA receptor type and showed highest affinities for aporphines but was not stereoselective and reacted weakly and nonspecifically with dihydroxyaminotetralin, DA, other catecholamines and neuroleptics. Thus, [3H]apomorphine, under certain conditions, may detect an aporphine binding site of uncertain pharmacological significance, as well as high-affinity DA agonist (D-3) sites.
Assuntos
Apomorfina/metabolismo , Núcleo Caudado/metabolismo , Receptores Dopaminérgicos/metabolismo , Animais , Sítios de Ligação , Bovinos , Técnicas In Vitro , Cinética , Frações Subcelulares/metabolismoRESUMO
Modern drug discovery demands accurate knowledge of the drug properties of affinity and efficacy at specific receptor proteins. Furthermore, drugs with well defined properties make better tools with which to explore and understand receptor regulation. The use of clonal cell lines stably expressing a given recombinant receptor may provide a highly useful model in which drug effects may be studied on one receptor subtype at a time. The present report was designed to evaluate the utility of a general method in which a clonal cell line stably expressing a recombinant D1A dopamine receptor was used as a model system for studying drug actions by null models. The null model for receptor occlusion (to calculate agonist Ka) and the null model for relative efficacy (to calculate test agonist affinity and epsilon r) were evaluated in these studies. To initiate these studies, rat C6 glioma cells that do not normally express DA receptors have been modified by stable transfection with the primate D1A DA receptor [Machida et al., 1992 (Molec. Pharmacol. 41: 652-659)] to a density of approximately equal to fmol/mg protein. The recombinant receptors show robust stimulation of cAMP in the stably transfected C6 cells. Calculation of agonist Ka from dose-response data requires that a portion of the cell's receptors be occluded in the absence of changes in post-receptor events leading to the response. Receptor reserve is typically reduced by alkylation, thereby lowering maximal response. Unfortunately, most of the currently available alkylating agents are not selective either for a particular receptor or for receptors vs other proteins within a signaling pathway. Short-term agonist treatment offers a possible complement to the use of non-selective or poorly characterized alkylating drugs for reducing maximum response in appropriate cell systems. The null method of receptor occlusion was used to determine the Ka for dopamine when maximum response was decreased by alkylation vs short-term agonist treatment. Direct non-linear curve fitting was used to analyze the data. In addition to DA, two other compounds were used to reduce receptor reserve to validate the method: fenoldopam (relatively high efficacy) and SKF38393 (low efficacy). Analyses indicated that the affinity of DA was similar whether calculated by alkylation (1.1 +/- 0.58 microM), 75 min DA treatment (0.57 +/- 0.16 microM) or 45 min treatment with DA (0.86 +/- 0.11 microM). Short-term agonist treatment experiments using multiple concentrations of DA, fenoldopam, or SKF38393 to decrease receptor reserve provided additional support for the validity of the Ka determinations using this procedure. Other experiments were conducted according to the null model for relative efficacy in which the affinity for DA is calculated by comparing the DA response before and after receptor occlusion, and the affinity and relative intrinsic efficacy of the test agonist are determined as a function of its actions relative to DA. We used the following four test drugs: + Br-APB, a novel agent with potential dopamine agonist properties, and three high-affinity DA agonists, fenoldopam, R-(-)-apomorphine (APO), and SKF38393. Intrinsic efficacy values relative to that of DA (1.0) were as follows: fenoldopam, 0.46 +/- 0.11; APO, 0.19 +/- 0.13; SKF38393, 0.07 +/- 0.01; and +Br-APB, 0.26 +/- 0.40. The agonist affinities (Ka) were: fenoldopam, 0.018 +/- 0.008 microM; APO, 0.80 +/- 0.18 microM; SKF38393, 0.16 +/- 0.04 microM; BR-APB, 0.43 +/- 0.29 microM; and DA, 0.58 +/- 0.17 microM. EC50/Ka ratios were consistent with relative intrinsic efficacies and Ka values were similar to KL values reported for membrane binding studies. Finally, Monte Carlo simulations were conducted to determine the precision of the parameter estimates...
Assuntos
AMP Cíclico/metabolismo , Dopamina/farmacologia , Modelos Biológicos , Receptores de Dopamina D1/efeitos dos fármacos , Animais , Linhagem Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ratos , Recombinação GenéticaRESUMO
The rates and mechanism of solvolysis of (-)-N-(2-chloroethyl)norapomorphine (NCA, 1c) in aqueous solution have been examined by reversed-phase liquid chromatography (HPLC) to follow the levels of starting material and products. The first-order rate constants for aziridinium ion formation at 25 and 37 degrees C at pH 7.0 are 0.024 and 0.096 min-1, respectively. Determination of the first-order rate constant for the disappearance of NCA as a function of pH has allowed the calculation of an approximate pKa of 6.3 for the tertiary amine, while the influence of reaction conditions (e.g., pH, buffer salt and concentration, and added nucleophiles) on product distribution support the view that NCA solvolysis proceeds through an intermediate aziridinium ion. Application of the HPLC procedure allowed us to observe simultaneously the loss of NCA and the appearance of an intermediate and multiple products at trace levels; it also permitted the facile isolation and subsequent identification of small amounts of hydrolysis products. At pH 7, maximum aziridinium concentration is reached only after 10 min at 37 degrees C and at 25 degrees C after 1 h. Increased temperatures and pH facilitate the rate of aziridinium ion formation, as well as of non-dopamine antagonist solvolysis products. The significance of these findings, including the ease with which buffer ions add to the intermediate ion, are discussed in relation to the use of NCA and its tritiated isomer, [3H]NCA, in dopamine receptor studies.
Assuntos
Aporfinas , Receptores Dopaminérgicos/efeitos dos fármacos , Animais , Aporfinas/farmacologia , Cromatografia Líquida de Alta Pressão/métodos , Cinética , Solubilidade , ÁguaRESUMO
The synthesis of a series of benzylisoquinolines 2-9 containing aminoacetamide side chains is described. The method involved reduction of the appropriately substituted nitrobenzylisoquinolines followed by acylation to the chloroacylamide derivatives. Amination with the appropriate amine yielded the desires secondary and tertiary amines. The primary amines were prepared via the phthalimides. Two acetanilides 14 and 15 are also described and compared with the benzylisoquinoline derivatives. All compounds were evaluated for their ability to protect against chloroform-induced ventricular fibrillation in mice. The active compounds 6 and 7 were tested for their effect against ventricular arrhythmias in dogs with myocardial infarction. All compounds with the exception of 5 and 12 exhibited some antiarrhythmic effect. The most potent compound, 1-[2-(2-ethylaminoacetyl)amino-3,4-dimethoxybenzyl]isoquinoline (7), showed greater antiarrhythmic potency, was considerably less toxic than lidocaine, and is a candidate for further evaluation.
Assuntos
Antiarrítmicos/síntese química , Isoquinolinas/síntese química , Animais , Arritmias Cardíacas/complicações , Arritmias Cardíacas/prevenção & controle , Clorofórmio , Cães , Feminino , Isoquinolinas/uso terapêutico , Isoquinolinas/toxicidade , Camundongos , Infarto do Miocárdio/complicações , Relação Estrutura-Atividade , Fibrilação Ventricular/induzido quimicamente , Fibrilação Ventricular/prevenção & controleRESUMO
The synthesis of 2-amino- and 2-halo-substituted aporphines is described. The key step is the substitution of a hydroxy group in the 2-position with an amino group effected by a Smiles rearrangement reaction of the 2-methylpropanamide derivative 6. The affinity of the new compounds for the dopamine D-2 receptor in the anterior pituitary gland was evaluated. 2-Fluoroapomorphine was the most potent compound, being 1.5 times more potent than (-)-apomorphine. The structure-activity relationships are discussed in relation to a previously proposed receptor model.
Assuntos
Aporfinas/síntese química , Receptores Dopaminérgicos/metabolismo , Animais , Apomorfina/análogos & derivados , Apomorfina/síntese química , Apomorfina/metabolismo , Aporfinas/metabolismo , Fenômenos Químicos , Química , Estrutura Molecular , Adeno-Hipófise/metabolismo , Receptores de Dopamina D2 , Espiperona/metabolismo , Relação Estrutura-Atividade , SuínosRESUMO
Substituted 1-phenyl-3-benzazepines (e.g., SKF 38393 and fenoldopam) exhibit stereoselectivity in moderately high-affinity binding to and partial agonist activation of D1 dopamine receptors. The 3-allyl (APB) and the 3-allyl-6-chloro (6-Cl-APB) analogues of SKF 38393 are reported to have higher affinity and selectivity for the D1 DA receptor and higher in vivo central neuropharmacologic activity than SKF 38393. We recently reported the corresponding 3-allyl-6-bromo analogue (6-Br-APB) also to be a high-affinity D1 agonist. We now describe the synthesis and characterization of the R-(+) and S-(-) enantiomers of both APB and 6-Br-APB and their comparison with corresponding enantiomers of SKF 38393 with respect to D1 receptor binding affinity and D1 and D2 selectivity. The R-(+) enantiomers of both novel substituted 1-phenyl-3-benzazepines bound to the D1 receptor sites in rat forebrain tissue with much higher affinity and selectivity than their S-(-) antipodes. R-(+)-3-Allyl-6-bromo-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3- benzazepine [(R)-(+)-6-Br-APB, 18] exhibits the highest affinity of the reported 1-phenyl-3-benzazepine D1 agonists.
Assuntos
2,3,4,5-Tetra-Hidro-7,8-Di-Hidroxi-1-Fenil-1H-3-Benzazepina/análogos & derivados , Benzazepinas/síntese química , Receptores Dopaminérgicos/efeitos dos fármacos , 2,3,4,5-Tetra-Hidro-7,8-Di-Hidroxi-1-Fenil-1H-3-Benzazepina/farmacologia , Animais , Benzazepinas/farmacologia , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Ratos , Receptores Dopaminérgicos/metabolismo , Receptores de Dopamina D1 , Receptores de Dopamina D2 , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
Fluorescent probes have been designed and developed for dopamine D-1 and D-2 receptors. Fluorescein and/or NBD (7-nitrobenz-2-oxa-1,3-diazol-4-yl) derivatives of PPHT (D-2 agonist), spiperone (D-2 antagonist), SKF 38393 (D-1 agonist), and SKF 83566 (D-1 antagonist) were synthesized via their amino-functionalized analogues and all ligands were pharmacologically evaluated by measuring their ability to displace [3H]SCH 23390 and [3H]spiperone from D-1 and D-2 receptor sites in caudate putamen of monkeys (Macaca fascicularis). The fluorescein derivatives of PPHT and SKF 83566 and the NBD derivatives of spiperone and SKF 83566 retained the high affinity and selectivity of the parent ligands. The NBD derivatives of PPHT showed higher D-2 receptor affinity and selectivity than their parent ligands. The enantiomers of the fluorescent derivatives of PPHT were also synthesized and were found to exhibit stereoselectivity in binding to the D-2 receptor, with the S enantiomers having a considerably higher affinity than their R analogues. In contrast to these results, the fluorescein derivative of SKF 38393 showed only a low affinity for the D-1 receptor. These fluorescein- and NBD-coupled D-1 and D-2 receptor ligands have considerable significance as potential probes in the study of distribution of the receptors at the cellular/subcellular level and of their mobility in membranes in normal/diseased states by use of fluorescence microscopic and fluorescence photobleaching recovery techniques, respectively. The development of these novel fluorescent probes should also provide new leads for the design and synthesis of additional fluorescent ligands with better fluorescent properties and/or higher affinity/selectivity for the DA receptors.
Assuntos
Corantes Fluorescentes/síntese química , Oxidiazóis/síntese química , Receptores Dopaminérgicos/efeitos dos fármacos , 2,3,4,5-Tetra-Hidro-7,8-Di-Hidroxi-1-Fenil-1H-3-Benzazepina/farmacologia , Animais , Antagonistas de Dopamina , Corantes Fluorescentes/metabolismo , Corantes Fluorescentes/farmacologia , Ligantes , Macaca fascicularis , Oxidiazóis/metabolismo , Oxidiazóis/farmacologia , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
The enantiomers (6aR and 6aS) of 2,10,11-trihydroxyaporphine (THA) were synthesized from thebaine and bulbocapnine and evaluated pharmacologically in vitro in comparison with (-)-apomorphine [(-)-APO] and dopamine by competition with tritiated apomorphine, ADTN, and spiroperidol for binding to a membrane fraction of calf caudate nucleus, as well as for ability to stimulate adenylate cyclase. In all four tests, the rank order of potency was (-)-APO greater than (-)-THA much greater than (+)-THA. Thus, these results extend the impression that the 6aR configuration for hydroxyaporphines is preferred for interactions with putative dopamine receptors and that 2-hydroxylation reduces potency in comparison with 10,11-dihydroxyaporphines.
Assuntos
Apomorfina/análogos & derivados , Receptores Dopaminérgicos/metabolismo , Adenilil Ciclases/metabolismo , Animais , Apomorfina/síntese química , Apomorfina/metabolismo , Apomorfina/farmacologia , Fenômenos Químicos , Química , Corpo Estriado/enzimologia , Ratos , EstereoisomerismoRESUMO
The 7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepines form a series of compounds having a high affinity at the D1 dopamine receptor. The 6-chloro derivative has been previously shown to have enhanced affinity, selectivity, and agonist activity. In an attempt to study the effect of substitution of a 6-bromo group in place of the 6-chloro, we have synthesized a series of compounds and evaluated them for their affinity for the D1 receptor. The results show that the 6-bromo derivatives have virtually identical affinities to their 6-chloro counterparts, a finding similar to that found in the D1 antagonist 7-halo-8-hydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine series. From the present work, 3-allyl-6-bromo-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepi ne (6-Br-APB) has been identified as a suitable candidate for further in vivo studies and resolution into its active and inactive enantiomers.
Assuntos
2,3,4,5-Tetra-Hidro-7,8-Di-Hidroxi-1-Fenil-1H-3-Benzazepina/análogos & derivados , Dopaminérgicos/síntese química , Receptores Dopaminérgicos/efeitos dos fármacos , 2,3,4,5-Tetra-Hidro-7,8-Di-Hidroxi-1-Fenil-1H-3-Benzazepina/síntese química , 2,3,4,5-Tetra-Hidro-7,8-Di-Hidroxi-1-Fenil-1H-3-Benzazepina/farmacologia , Animais , Ligação Competitiva , Cães , Dopaminérgicos/farmacologia , Técnicas In Vitro , Ligantes , Ensaio Radioligante , Receptores Dopaminérgicos/metabolismo , Receptores de Dopamina D1 , Relação Estrutura-AtividadeRESUMO
The R-(-)- and S-(+)-enantiomers of 11-hydroxy-N-allyl (4), and 10,11-dihydroxy-N-allyl (3) congeners of 11-hydroxy-N-n-propylnorapomorphine (11-OH-NPa, 2) or N-n-propylnorapomorphine (NPA, 1) were synthesized. Binding affinity of these compounds at dopamine (DA) receptor sites was evaluated with a membrane preparation of corpus striatum from rat brain. The R/S enantiomeric receptor affinity ratio was enhanced by allylic substitution of 3 and 4 and their R isomers had high DA receptor affinity similar to that of the N-n-propyl congeners. These N-allylnoraporphines are proposed as useful precursors to the preparation of their tritiated N-n-propyl enantiomers.