RESUMO
The M1 muscarinic agonist CI-1017 was administered intravenously to aging rabbits on a daily basis before and during hippocampally dependent trace eyeblink conditioning sessions. Circulating levels of CI-1017 were significantly related to the drug dose. The drug was found to significantly increase the rate and amount of learning in a dose-dependent manner with no significant effects on the amplitude, area, or latency of conditioned responses. There was no evidence of pseudoconditioning at the highest drug concentration, and the minimally effective dose produced only mild and temporary hypersalivation as a side effect. CI-1017 (10 microM) was also found to increase the excitability of CA1 pyramidal neurons recorded from hippocampal slices from young and aging naive rabbits as measured by changes in spike-frequency adaptation and the postburst afterhyperpolarization. These biophysical changes were reversed with either atropine (1 microM) or pirenzepine (1 microM). These results suggest that M1 agonists ameliorate age-related learning and memory impairments at least in part by reducing the afterhyperpolarization and spike-frequency adaptation of hippocampal pyramidal neurons and that M1 agonists may be an effective therapy for reducing the cognitive deficits that accompany normal aging and/or Alzheimer's disease.
Assuntos
Piscadela/efeitos dos fármacos , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Hipocampo/fisiologia , Agonistas Muscarínicos/farmacologia , Oximas/farmacologia , Células Piramidais/fisiologia , Receptores Muscarínicos/fisiologia , Estimulação Acústica , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Envelhecimento/fisiologia , Animais , Piscadela/fisiologia , Condicionamento Clássico , Feminino , Hipocampo/efeitos dos fármacos , Hipocampo/crescimento & desenvolvimento , Pirenzepina/farmacologia , Células Piramidais/efeitos dos fármacos , Coelhos , Receptor Muscarínico M1 , Fatores de TempoRESUMO
Many neurodegenerative diseases are associated with the abnormal sequestration of disease-specific proteins in the brain, but the events that initiate this process remain unclear. To determine whether the deposition of the beta-amyloid peptide (Abeta), a key pathological feature of Alzheimer's disease (AD), can be induced in vivo, we infused dilute supernatants of autopsy-derived neocortical homogenates from Alzheimer's patients unilaterally into the hippocampus and neocortex of 3-month-old beta-amyloid precursor protein (betaAPP)-transgenic mice. Up to 4 weeks after the infusion there was no Abeta-deposition in the brain; however, after 5 months, the AD-tissue-injected hemisphere of the transgenic mice had developed profuse Abeta-immunoreactive senile plaques and vascular deposits, some of which were birefringent with Congo Red. There was limited deposition of diffuse Abeta also in the brains of betaAPP-transgenic mice infused with tissue from an age-matched, non-AD brain with mild beta-amyloidosis, but none in mice receiving extract from a young control case. Abeta deposits also were not found in either vehicle-injected or uninjected transgenic mice or in any nontransgenic mice. The results show that cerebral beta-amyloid can be seeded in vivo by a single inoculation of dilute AD brain extract, demonstrating a key pathogenic commonality between beta-amyloidosis and other neurodegenerative diseases involving abnormal protein polymerization. The paradigm can be used to clarify the conditions that initiate in vivo beta-amyloidogenesis in the brain and may yield a more authentic animal model of Alzheimer's disease and other neurodegenerative disorders.
Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/farmacologia , Precursor de Proteína beta-Amiloide/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Peptídeos beta-Amiloides/imunologia , Animais , Reações Antígeno-Anticorpo , Artérias Cerebrais/patologia , Corantes , Vermelho Congo , Modelos Animais de Doenças , Encefalite/metabolismo , Encefalite/patologia , Feminino , Hipocampo/patologia , Humanos , Injeções Intraventriculares , Masculino , Camundongos , Camundongos Transgênicos , Degeneração Neural/metabolismo , Degeneração Neural/patologiaRESUMO
INTRODUCTION: Endoscopic techniques are becoming increasingly accepted for treatment of vesicoureteric reflux as alternatives to open surgical reimplantation. However, there is some debate about the ideal injectable material. Since we have accumulated experience with several substances, an opportunity existed to compare them. MATERIALS AND METHODS: From 1991 to 2003, 101 children with vesicoureteric reflux were treated by endoscopic subureteric injection either once (74) or twice (27) by either of two pediatric urologists. There were a total of 165 ureteral injections, 83 with polytetrafluoroethylene (Teflon), 73 with polydimethylsiloxane (Macroplastique), and 9 with collagen. Each child was evaluated pre-operatively and 3 months post-operatively with a nuclear cystogram and renal ultrasonography. RESULTS: The polytetrafluoroethylene and polydimethylsiloxane groups were not significantly different with respect to sex, age, indication for surgery, severity of reflux or prior surgeries. The collagen group overall did very poorly with only 3 of 9 refluxing ureters cured. The other two substances had much more success with 61% of ureters in the polytetrafluoroethylene group cured on first injection and 75% with polydimethylsiloxane, plus another 19% and 11% cured on second attempt, respectively (total 80% and 86%). CONCLUSIONS: Subureteric injections of polytetrafluoroethylene and polydimethylsiloxane are very effective at curing vesicoureteric reflux in children with little morbidity. When comparing individual cases, ureters, and all grades of reflux, polytetrafluoroethylene and polydimethylsiloxane have similar success rates. Collagen injections were less successful, and patients with neurogenic bladders had poor results.
Assuntos
Colágeno/administração & dosagem , Endoscopia , Injeções/métodos , Politetrafluoretileno/administração & dosagem , Refluxo Vesicoureteral/tratamento farmacológico , Criança , Feminino , Humanos , Masculino , UreterRESUMO
Inhibition of brain acetylcholinesterase (AChE) can provide relief from the cognitive loss associated with Alzheimer's disease (AD). However, unwanted peripheral side effects often limit the usefulness of the available anticholinesterases. Recently, we identified a dihydroquinazoline compound, PD 142676 (CI 1002) that is a potent anticholinesterase and a functional muscarinic antagonist at higher concentrations. Peripherally, PD 142676, unlike other anticholinesterases, inhibits gastrointestinal motility in rats, an effect consistent with its muscarinic antagonist properties. Centrally, the compound acts as a cholinomimetic. In rats, PD 142676 decreases core body temperature. It also increases neocortical arousal, as measured by quantitative electroencephalography, and cortical acetylcholine levels, measured by in vivo microdialysis. The compound improves the performance of C57/B10j mice in a water maze task and of aged rhesus monkeys in a delayed match-to-sample task involving short-term memory. The combined effect of AChE inhibition and muscarinic antagonism distinguishes PD 142676 from other anticholinesterases, and may be useful in treating the cognitive dysfunction of AD and produce fewer peripheral side effects.
Assuntos
Inibidores da Colinesterase/farmacologia , Antagonistas Muscarínicos/farmacologia , Quinazolinas/farmacologia , Animais , Células CHO , Cognição/efeitos dos fármacos , Cricetinae , Cricetulus , Eletroencefalografia/efeitos dos fármacos , Feminino , Motilidade Gastrointestinal/efeitos dos fármacos , Humanos , Técnicas In Vitro , Cinética , Macaca mulatta , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fosfatidilinositóis/metabolismo , Ensaio Radioligante , Ratos , Receptores Muscarínicos/metabolismoRESUMO
A structure-activity relationship study of a series of novel Na(+) channel blockers, structurally related to N-[3-(2,6-dimethyl-1-piperidinyl)propyl]-alpha-phenylbenzeneacetamide (1, PD85639) is described. The diphenylacetic acid portion of the molecule was left unchanged throughout the study, while structural features in the amine portion and the amide alkyl linkage of the molecule were modified. The compounds were tested for inhibition of veratridine-stimulated Na(+) influx in CHO cells expressing type IIA Na(+) channels. Several derivatives show a trend toward more potent Na+ channel blockade activity with increasing lipophilicity of the amine portion of the molecule. The presence of a phenyl ring near the amine increases inhibitory potency. A three-carbon spacer between the amide and amine is optimal, and a secondary amide linkage is preferred.
Assuntos
Acetamidas/síntese química , Acetamidas/farmacologia , Benzenoacetamidas , Piperidinas/farmacologia , Bloqueadores dos Canais de Sódio , Acetamidas/química , Animais , Células CHO , Cricetinae , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Piperidinas/química , Sódio/metabolismo , Canais de Sódio/metabolismo , Relação Estrutura-Atividade , Veratridina/farmacologiaRESUMO
The introduction of lipophilic groups onto the ring nitrogen of nipecotic acid and guvacine, two known GABA uptake inhibitors, afforded potent, orally-active anticonvulsant drugs. A series of compounds is reported which explores the structure-activity relationships (SAR) in this series. Among the areas explored: side-chain SAR (aromatic-, heterocyclic-, and tricyclic-containing side chains) and modifications to the tetrahydropyridine ring. The benzhydrol ether-containing side chains afforded the most potent compounds with several exhibiting in vitro IC50 values for GABA uptake of < 1 microM (including 5, Table I; 37, 43, Table IV; and 44, Table V). Compound 44 was selected for extensive evaluation and subsequently progressed to Phase 1 clinical trials with severe adverse effects seen after single dose administration to humans.
Assuntos
Anticonvulsivantes/síntese química , Inibidores da Captação de Neurotransmissores/síntese química , Ácidos Nicotínicos/síntese química , Ácidos Nipecóticos/síntese química , Prolina/análogos & derivados , Ácido gama-Aminobutírico/metabolismo , Administração Oral , Animais , Anticonvulsivantes/farmacologia , Compostos Benzidrílicos/síntese química , Compostos Benzidrílicos/farmacologia , Barreira Hematoencefálica , Humanos , Técnicas In Vitro , Camundongos , Inibidores da Captação de Neurotransmissores/farmacologia , Ácidos Nicotínicos/farmacologia , Ácidos Nipecóticos/farmacologia , Ratos , Relação Estrutura-AtividadeRESUMO
The synthesis and structure-activity relationships of a series of phenylacetamides related to N-[3-(2,6-dimethyl-1-piperidinyl)propyl]-alpha-phenylbenzeneacetamide (1) (PD85639) acting at the voltage-dependent Na+ channel are described. All structural variations for this study were made in the phenylacetic acid portion of these molecules, and the compounds were synthesized by coupling the appropriately substituted phenylacetic acid derivative with 3-[1-(2,6-dimethyl)piperidinyl]-propanamine using standard methods of amide formation. Compounds were tested as inhibitors of [3H]batrachtoxinin binding in rat neocortical membranes and also as inhibitors of veratridine-induced Na+ influx in Chinese hamster ovary cells expressing type IIA Na+ channels. Diphenylacetic acid derivatives with halogenated aromatic rings (12-15) were very potent in both assays, while alkoxy and alkyl substitution did not affect activity (16 and 17). Selected compounds were tested as potential neuroprotective agents in two cell culture assays involving inhibition of veratridine-induced and hypoxia-induced lactate dehydrogenase release. Compound 15 was equipotent with flunarizine, a reference compound in both neuroprotection assays.
Assuntos
Acetamidas/síntese química , Benzenoacetamidas , Piperidinas/química , Bloqueadores dos Canais de Sódio , Acetamidas/farmacologia , Animais , Batraquiotoxinas/metabolismo , Células CHO , Hipóxia Celular , Células Cultivadas , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Cricetinae , L-Lactato Desidrogenase/metabolismo , Masculino , Piperidinas/farmacologia , Ratos , Ratos Sprague-Dawley , Sódio/metabolismo , Relação Estrutura-Atividade , Veratridina/antagonistas & inibidores , Veratridina/farmacologiaRESUMO
PNQX (1,4,7,8,9,10-hexahydro-9-methyl-6-nitropyrido[3, 4-f]quinoxaline-2,3-dione) is a potent AMPA (IC50 = 0.063 microM) and GlyN (IC50 = 0.37 microM) receptor antagonist that was developed in our laboratories. While possessing a desirable in vitro and in vivo activity profile, this compound suffers from low aqueous solubility. In an effort to improve its potency and physical properties, we have designed and synthesized novel ring-opened analogues 4, 6, 9, and 11. Modeling analyses demonstrated that, while the 5-substituent in these analogues was forced to adopt an out-of-plane conformation due to steric contacts with neighboring substituents, the overall structure retained a good fit to a previously described AMPA pharmacophore model. This nonplanar orientation may lessen efficient packing in the solid state, compared to PNQX, leading to increased water solubility. Indeed, several nonplanar analogues containing appropriate functionalities, for example, the sarcosine analogue 9, were found to retain AMPA (IC50 = 0.14 microM) and GlyN (IC50 = 0.47 microM) receptor affinity and possess improved aqueous solubility compared to PNQX. The synthesis and the SAR of these compounds are discussed.
Assuntos
Antagonistas de Aminoácidos Excitatórios/síntese química , Glicina/análogos & derivados , Quinoxalinas/síntese química , Receptores de AMPA/antagonistas & inibidores , Receptores de Glicina/antagonistas & inibidores , Animais , Anticonvulsivantes/síntese química , Anticonvulsivantes/química , Anticonvulsivantes/metabolismo , Anticonvulsivantes/farmacologia , Ligação Competitiva , Córtex Cerebral/metabolismo , Desenho de Fármacos , Antagonistas de Aminoácidos Excitatórios/química , Antagonistas de Aminoácidos Excitatórios/metabolismo , Antagonistas de Aminoácidos Excitatórios/farmacologia , Glicina/síntese química , Glicina/química , Glicina/metabolismo , Glicina/farmacologia , Técnicas In Vitro , Masculino , Camundongos , Modelos Moleculares , Quinoxalinas/química , Quinoxalinas/metabolismo , Quinoxalinas/farmacologia , Ratos , Receptores de AMPA/metabolismo , Receptores de Glicina/metabolismo , Solubilidade , Sinaptossomos/metabolismoRESUMO
A series of esters of 1,4-disubstituted tetrahydropyridine carboxylic acids (I) has been synthesized and characterized as potential m1 selective muscarinic receptor antagonists. The affinity of these compounds for the five human muscarinic receptor subtypes (Hm1-Hm5) was determined by the displacement of [3H]-NMS binding using membranes from transfected Chinese hamster ovarian cells. One of the most potent and selective compounds of this series is an analogue of I [11, R1 = (CH2)5CH3], which has an IC50 value of 27.3 nM at the m1 receptor and possesses 100-fold (m2), 48-fold (m3), 74-fold (m4), and 19-fold (m5) selectivities at the other receptors. Thus, this analogue appears to be more selective on the basis of binding than the prototypical m1 antagonist, pirenzepine. Functional data, such as the inhibition of carbachol-stimulated phosphatidylinositol hydrolysis, on selected analogues confirmed the muscarinic antagonistic properties of this chemical series.
Assuntos
Antagonistas Muscarínicos/química , Animais , Células CHO , Cricetinae , Humanos , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Estrutura Molecular , Antagonistas Muscarínicos/classificação , Antagonistas Muscarínicos/farmacologia , Relação Estrutura-AtividadeRESUMO
The synthesis and SAR of a series of (Z)-(+/-)-1-azabicyclo[2.2. 1]heptan-3-one, O-(3-aryl-2-propynyl)oximes are described. The biochemistry and pharmacology of 24Z (PD 142505) and its enantiomers are highlighted. 24Z is functionally an m1-selective muscarinic agonist. Efficacy and m1 selectivity reside in the R enantiomer, (R)-24Z (CI-1017).
Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/síntese química , Desenho de Fármacos , Agonistas Muscarínicos/síntese química , Oximas/síntese química , Receptores Muscarínicos/efeitos dos fármacos , Células 3T3 , Inibidores de Adenilil Ciclases , Animais , Compostos Bicíclicos Heterocíclicos com Pontes/metabolismo , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Compostos Bicíclicos Heterocíclicos com Pontes/toxicidade , Células CHO , Cricetinae , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/metabolismo , Inibidores Enzimáticos/farmacologia , Inibidores Enzimáticos/toxicidade , Humanos , Fosfatos de Inositol/biossíntese , Masculino , Memória/efeitos dos fármacos , Camundongos , Agonistas Muscarínicos/metabolismo , Agonistas Muscarínicos/farmacologia , Agonistas Muscarínicos/toxicidade , Oximas/metabolismo , Oximas/farmacologia , Oximas/toxicidade , Ratos , Receptor Muscarínico M1 , Receptores Muscarínicos/metabolismo , Estereoisomerismo , Relação Estrutura-Atividade , TransfecçãoRESUMO
The effect of prostaglandins (PG) on amphetamine(AMPH)-induced circling was examined in mice unilaterally lesioned with 6-hydroxy-dopamine. At doses of 0.03-1.0 nmol/g, intraventricularly injected PGD2, PGE2, and PGF2 alpha all inhibited AMP-induced circling, while thromboxane-B2 (TxB2) was inactive at 1.0 nmol/g. The inhibition of circling was not due to alterations in body temperature as measured by rectal temperature changes. When injected intrastriatally, the same major PG inhibited AMP-induced circling at the lower doses of 0.01-0.1 nmol/g, while the PGE2 metabolite 13, 14-dihydro-15-keto-PGE2 was inactive at 0.1 nmol/g. PG administered alone did not procude circling. For both routes of administration, the order of potency was PGE2 greater than PGD2 greater than PGF2 alpha. These results suggest that PG can alter motor function governed by central dopaminergic pathways.
Assuntos
Anfetamina/antagonistas & inibidores , Prostaglandinas/farmacologia , Comportamento Estereotipado/efeitos dos fármacos , Animais , Temperatura Corporal/efeitos dos fármacos , Corpo Estriado , Humanos , Hidroxidopaminas/farmacologia , Injeções , Injeções Intraventriculares , Masculino , Camundongos , OxidopaminaRESUMO
Glutamate treatment of PC12 cells has been shown to result in the accumulation of intracellular inositol phosphates suggesting the presence of glutamate metabotropic receptors (mGluRs) positively coupled to phospholipase C. The present study examined the expression of group I mGluRs (mGluR1 and mGluR5) in PC12 cells. Undifferentiated PC12 cells were found to express both mGluR5 mRNA and receptor protein by reverse transcription polymerase chain reaction (RT-PCR) and western blot techniques. However, mGluR1 mRNA was not detected in these cells and western blot analysis showed only faint mGluR1alpha immunoreactivity suggesting a very low level of mGluR1 expression. Nerve growth factor-induced differentiation of PC12 cells resulted in the induction of mGluR1alpha and mGluR1beta mRNA and mGluR1alpha protein. PC12 cells overexpressing dominant negative ras revealed that NGF-induced mGluR1 induction, but not mGluR5 expression, is dependent on ras pathway activation in these cells. These results suggest PC12 cells may be a useful model for investigating the regulation and expression of group I mGluR isoforms and their role in neuronal processes in vitro.
Assuntos
Fatores de Crescimento Neural/farmacologia , Neurônios/química , Receptores de Glutamato Metabotrópico/genética , Proteínas ras/fisiologia , Animais , Western Blotting , Diferenciação Celular/fisiologia , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/fisiologia , Neurônios/citologia , Neurônios/fisiologia , Células PC12 , RNA Mensageiro/metabolismo , Ratos , Receptor de Glutamato Metabotrópico 5 , Receptores de Glutamato Metabotrópico/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/fisiologiaRESUMO
In vitro and in vivo characterization in rodents and monkeys shows that CI-979/RU35926 is a partial muscarinic agonist with equal affinity for the five subtypes of muscarinic receptors. It activates central cholinergic receptors as shown by its ability to decrease body temperature, enhance local cortical blood flow and increase cortical arousal measured by QEEG. Further, it reverses spatial memory deficits in rats with ibotenic acid-induced lesions of forebrain cholinergic neurons. Signs of peripheral cholinergic stimulation appear at doses higher or equal to those necessary to produce central activity. In a single-dose tolerance study in young, healthy human volunteers, CI-979/RU35926 was well tolerated at doses of 0.002-1.0 mg with cholinergic symptoms such as hypersalivation and sweating, observed at 2-4 mg. It demonstrated linear pharmacokinetic behavior over a dose range of 0.1 to 4 mg and elimination half-life varied from 2-5 hours. Measurement of unchanged drug in urine suggests that the drug was extensively metabolized. Thus, the safety profile supported further clinical evaluation and CI-979/RU35926 is currently in Phase II clinical trials.
Assuntos
Doença de Alzheimer/tratamento farmacológico , Di-Hidropiridinas/farmacologia , Agonistas Muscarínicos/farmacologia , Oximas/farmacologia , Adolescente , Adulto , Doença de Alzheimer/metabolismo , Animais , Comportamento Animal/efeitos dos fármacos , Temperatura Corporal/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Células CHO/efeitos dos fármacos , Células CHO/metabolismo , Circulação Cerebrovascular/efeitos dos fármacos , Cricetinae , Estudos Cross-Over , Denervação , Di-Hidropiridinas/farmacocinética , Método Duplo-Cego , Avaliação Pré-Clínica de Medicamentos , Eletroencefalografia , Motilidade Gastrointestinal/efeitos dos fármacos , Humanos , Ácido Ibotênico , Macaca mulatta , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Pessoa de Meia-Idade , Agonistas Muscarínicos/farmacocinética , Oximas/farmacocinética , Ratos , Receptores Muscarínicos/metabolismo , NataçãoRESUMO
Using recombinant CHO cells that express Hm1-Hm5 receptors, reference muscarinic agonists have been characterized with respect to their activity in receptor binding and second messenger assays. In whole cell [3H]-N-methyl scopolamine binding, no agonist was found to be truly subtype selective, although some showed marked differences between several of the subtypes (e.g. m1 vs. m2). As a functional index of receptor activation, phosphatidyl-inositol (PI) turnover was measured for m1, m3, and m5 receptors while inhibition of forskolin-stimulated cAMP accumulation was measured for m2 and m4 receptors. Both full and partial agonists were delineated in PI turnover, but all agonists showed similar responses on cAMP. Alkylation studies with propylbenzylcholine mustard showed that both efficacy and potency were markedly affected in the functional assays by the number of free receptors. Thus, receptor reserve appears to play a major role in the determination of subtype selectivity for agonists using functional measures. Even with these limitations, however, the use of transformed cell lines is playing a pivotal role in the discovery of selective agonists.
Assuntos
Parassimpatomiméticos/metabolismo , Receptores Muscarínicos/metabolismo , Animais , Células CHO , Linhagem Celular Transformada , Colforsina/farmacologia , Cricetinae , AMP Cíclico/metabolismo , N-Metilescopolamina , Parassimpatolíticos/metabolismo , Fosfatidilinositóis/metabolismo , Recombinação Genética , Derivados da Escopolamina/metabolismoRESUMO
The synthesis of a series of potent and efficacious 1-azabicyclo[2.2.1]heptan-3-one oxime muscarinic agonists is described. The oximes have extended appendages designed to span the cavity defined by the seven transmembrane helices of the muscarinic receptor. Some members of the series are selective for receptors of the m1 subtype. One such oxime, 31, shows affinity and functional selectivity for m1 over m2, m3, and m4 muscarinic receptor types.
Assuntos
Compostos Bicíclicos com Pontes/síntese química , Compostos Bicíclicos com Pontes/farmacologia , Oximas/síntese química , Oximas/farmacologia , Parassimpatomiméticos/farmacologia , Receptores Muscarínicos/efeitos dos fármacos , Animais , Células CHO , Córtex Cerebral/efeitos dos fármacos , Colforsina/farmacologia , Cricetinae , AMP Cíclico/metabolismo , Dioxolanos/metabolismo , Fosfatos de Inositol/metabolismo , Ligantes , Parassimpatomiméticos/síntese química , Parassimpatomiméticos/metabolismo , Quinuclidinil Benzilato/metabolismo , Ensaio Radioligante , Ratos , Receptores Muscarínicos/metabolismo , Relação Estrutura-AtividadeRESUMO
Aspartate 103 (D103) in the third transmembrane domain of the Hm2 receptor was mutated to glutamate (D103E), asparagine (D103N), or alanine (D103A). As measured by [3H]-NMS, no significant binding was observed in D103A, while a 2-fold decrease in ligand affinity was seen in D103E and a 32-fold decrease in affinity was found in the D103N mutant. Examination of reference agonists showed greater loss of affinity in D103N than in D103E with the rank order of change being: L-607,207>carbachol>arecoline>pilocarpine>oxotremorine>McN-A-343. Of the novel 1-azabicyclo[2.2.1]-heptan-3-one oxime agonists examined, arylacetylene oximes showed little alteration in binding in either the D103E or D103N mutants, while the geometric isomers of several bicyclic aryl-ene-yne oximes showed significant changes in affinity, especially in the D103N mutant. Thus, overall size of the agonist and/or spatial orientation of the molecule within the binding pocket contribute to changes measured in binding.
Assuntos
Ácido Aspártico/genética , Agonistas Muscarínicos/metabolismo , Receptores Muscarínicos/metabolismo , Cloreto de (4-(m-Clorofenilcarbamoiloxi)-2-butinil)trimetilamônio/metabolismo , Cloreto de (4-(m-Clorofenilcarbamoiloxi)-2-butinil)trimetilamônio/farmacologia , Alanina/genética , Substituição de Aminoácidos , Animais , Arecolina/metabolismo , Arecolina/farmacologia , Asparagina/genética , Células COS , Carbacol/metabolismo , Carbacol/farmacologia , Agonistas Muscarínicos/farmacologia , Mutagênese Sítio-Dirigida , Oxotremorina/metabolismo , Oxotremorina/farmacologia , Pilocarpina/metabolismo , Pilocarpina/farmacologia , Receptor Muscarínico M2 , Receptores Muscarínicos/genética , TransfecçãoRESUMO
Thirty-two aryl-substituted 2-benzothiazolamines have been tested for their ability to modulate sodium flux in rat cortical slices. A QSAR analysis, applied to these derivatives, showed a trend toward increasing potency as sodium flux inhibitors with increasing lipophilicity, decreasing size, and increasing electron withdrawal of the benzo ring substituents. Additionally, 4- or 5-substitution of the benzo ring was found to decrease potency. The combination of increased lipophilicity, small size, and electron withdrawal severely limited which groups were tolerated on the benzo ring, thus suggesting that the optimal substitution patterns have been prepared within this series. Nine of these compounds were potent inhibitors of veratridine-induced sodium flux (NaFl). These nine compounds also proved to be anticonvulsant in the maximal electroshock (MES) assay. Fourteen additional 2-benzothiazolamines demonstrated activity in the MES screen, yet exhibited no activity in the NaFl assay. These derivatives may be interacting at the sodium channel in a manner not discernible by the flux paradigm, or they may be acting by an alternative mechanism in vivo.
Assuntos
Anticonvulsivantes/química , Anticonvulsivantes/farmacologia , Sódio/metabolismo , Tiazóis/química , Tiazóis/farmacologia , Animais , Anticonvulsivantes/síntese química , Ataxia/tratamento farmacológico , Benzotiazóis , Eletrochoque , Masculino , Camundongos , Ratos , Ratos Endogâmicos , Canais de Sódio/efeitos dos fármacos , Canais de Sódio/fisiologia , Relação Estrutura-Atividade , Tiazóis/síntese químicaRESUMO
Arecoline, arecaidine, and a series of derivatives, differing by the presence or absence of methyl groups at positions on the periphery of the molecule, were prepared, and their binding to muscarinic acetylcholine receptors was tested. On the basis of this study, muscarinic agonism for arecoline series is governed by strict structure-activity relationships, as previously observed for other agonist series. Only minor changes in nitrogen substitution were tolerated in the present series of arecoline derivatives.
Assuntos
Arecolina/análogos & derivados , Colina/fisiologia , Receptores Muscarínicos/metabolismo , Animais , Arecolina/metabolismo , Dioxolanos/metabolismo , Dioxolanos/farmacologia , Antagonistas Muscarínicos , Parassimpatomiméticos/metabolismo , Parassimpatomiméticos/farmacologia , Quinuclidinil Benzilato/metabolismo , Quinuclidinil Benzilato/farmacologia , Ratos , Receptores Muscarínicos/fisiologia , Relação Estrutura-Atividade , TrítioRESUMO
A procedure is described for evaluating the effects of drugs on dopaminergic function in the striatum of mice. Mice, anesthetized with chloral hydrate are injected with 6-hydroxydopamine into one striatum to destroy dopamine nerve terminals at this site. Several days later, the mice are anesthetized with halothane, and test drugs or saline are injected into the intact striatum either before or after the systemic administration of amphetamine. The effect of these drugs on amphetamine-induced circling behavior is evaluated. Using this model, we have found that pilocarpine and muscimol can inhibit amphetamine-induced circling and their effects are blocked by the systemic administration of scopolamine and picrotoxin, respectively. In addition, ethyleneglycol-bis-(beta-amino-ethyl ether) N,N'-tetraacetic acid (EGTA), a calcium chelating agent, inhibited amphetamine-induced circling behavior and this effect is prevented by adding calcium to the EGTA solution. Finally, the intrastriatal administration of prostaglandin E2 but not its metabolite, 13,14-dihydro-15-keto-prostaglandin E2 inhibited amphetamine-induced circling suggesting a selective effect of the active prostaglandin. These results suggest that this procedure could be used for evaluating both the mechanism of action of drugs in the striatum as well as screening drugs for their therapeutic potential.
Assuntos
Corpo Estriado/fisiologia , Dopamina/fisiologia , Picrotoxina/farmacologia , Comportamento Estereotipado/efeitos dos fármacos , Animais , Cloreto de Cálcio/farmacologia , Corpo Estriado/efeitos dos fármacos , Dinoprostona , Ácido Egtázico/farmacologia , Humanos , Hidroxidopaminas/farmacologia , Masculino , Camundongos , Muscimol/farmacologia , Oxidopamina , Pilocarpina/farmacologia , Prostaglandinas E/farmacologia , Escopolamina/farmacologiaRESUMO
The effect of prostaglandins (PGs) on apomorphine (apo)-induced circling was examined in unilaterally lesioned mice. Intraventricularly injected PGD2, PGE2, and PGF2 alpha at a dose of 1.0 nmole/g all inhibited apo-induced circling. When injected directly into the striatum, these same PGs also inhibited circling in a dose range of 0.01-0.1 nmole/g, while the PGE2 metabolite, 13,14-dihydro-15-keto-PGE2, was inactive at 0.1 nmole/g. For both routes of administration, PGF2 alpha appeared to be the most potent of the PGs tested. PGs administered alone by either route to unilaterally lesioned mice did not produce circling. Pretreatment with the PG synthetase inhibitor, indomethacin, caused the apo treated mice to circle at significantly higher rates than control animals. These results are the first report suggesting that within dopamine (DA)-mediated pathways PGs act at sites postsynaptic to the dopaminergic synapse.