Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 4 de 4
Filtrar
Mais filtros

Base de dados
Tipo de estudo
Tipo de documento
Intervalo de ano de publicação
2.
Mol Pharmacol ; 42(4): 656-65, 1992 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-1331757

RESUMO

Protein kinase C (PKC) activation was examined for its role in delta-opioid receptor down-regulation in the neuroblastoma X glioma hybrid cell line NG108-15. Incubation of NG108-15 cells for 2 hr at 37 degrees with up to 1 microM 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA), a phorbol ester that activates PKC, had no effect on opioid binding to membranes prepared from these cells. However, as little as 3 nM PMA incubated with an opioid agonist and NG108-15 cells potentiated the decrease and the rate of decrease of opioid binding, compared with agonist alone. Scatchard analysis of [3H][D-Ala2,D-Leu5]enkephalin (DADLE) binding revealed that NG108-15 cells incubated for 3 hr with 1 nM DADLE and 30 nM PMA displayed a > 50% reduction in the number of [3H]DADLE binding sites with no affinity change at the remaining sites, compared with cells treated with DADLE alone. The antagonist naloxone blocked both DADLE-induced and PMA-enhanced DADLE-induced down-regulation. The agonists morphine and cyclazocine, which alone were unable to induce delta receptor down-regulation, did so in the presence of PMA. The PKC inhibitor staurosporine and down-regulation of PKC by chronic PMA treatment blocked PMA potentiation of DADLE-induced down-regulation, but not "normal" DADLE-induced down-regulation. The enhancement of down-regulation by PMA was unaffected by either metabolic inhibitor or incubations at 20 degrees, conditions that blocked down-regulation by DADLE alone. NG108-15 cells incubated with [3H]DADLE and PMA retained more [3H]DADLE than cells incubated with [3H]DADLE alone, suggesting that PMA enhanced receptor internalization instead of merely inhibiting membrane binding. The diacylglycerol 1-oleoyl-2-acetyl-glycerol and bradykinin substituted for PMA but not carbachol, indicating that PKC activated physiologically may play a role in delta receptor down-regulation.


Assuntos
Neurônios/fisiologia , Proteína Quinase C/metabolismo , Receptores Opioides delta/metabolismo , Alcaloides/farmacologia , Membrana Celular/metabolismo , Células Cultivadas , Cloroquina/farmacologia , Regulação para Baixo , Leucina Encefalina-2-Alanina/metabolismo , Ativação Enzimática , Etorfina/farmacologia , Técnicas In Vitro , Naloxona/farmacologia , Entorpecentes/farmacologia , Estaurosporina , Acetato de Tetradecanoilforbol/farmacologia
3.
Ann Neurol ; 17(1): 46-8, 1985 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-3985585

RESUMO

Acetylcholinesterase (AChE) activity was measured in cerebrospinal fluid (CSF) samples from 36 individuals, including 12 persons with Alzheimer's disease, 12 normal controls, and 12 patients with other dementias. AChE activity also was measured in 47 normal subjects whose ages ranged from 20 to 84 to evaluate the effect of age on AChE activity. CSF from patients with senile dementia of the Alzheimer type showed significantly lower mean AChE activity than in age-matched controls and patients with other dementia syndromes. No correlation was found between duration of illness, age, or severity of illness (as measured by the Mini-Mental State Examination score) and CSF AChE activity in Alzheimer's disease. AChE increased significantly over the age range of 20 to 84. CSF AChE activity may prove to be a useful diagnostic test to confirm the clinical diagnosis of moderate to severe Alzheimer's disease.


Assuntos
Acetilcolinesterase/líquido cefalorraquidiano , Doença de Alzheimer/líquido cefalorraquidiano , Idoso , Envelhecimento , Humanos , Pessoa de Meia-Idade , Estatística como Assunto
4.
J Pharmacol Exp Ther ; 274(3): 1513-23, 1995 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-7562528

RESUMO

Opioid binding sites were found in nuclear matrix preparations from NG108-15 neurohybrid cells. Binding parameters of delta-specific radioligands indicated that high-affinity binding sites discovered in purified nuclei were present in nuclear membranes and nuclear matrix fractions. Agonists bind with low affinity, if at all, to nuclear matrix preparations. Neither sensitivity of agonist binding to the GTP analog 5-guanylylimidodiphosphate nor adenylyl cyclase activity were detected in this fraction, suggesting the presence of guanine nucleotide binding regulatory protein/effector uncoupled sites. Opioid inhibition of basal and forskolin-stimulated adenylyl cyclase activity was found in nuclear membrane preparations. Cycloheximide treatment of cells inhibited opioid binding to nuclear membrane fractions to a greater extent than that associated with membranes sedimenting at 20,000 x g (P20) or nuclear matrix. Colchicine, a microtubule disrupter and inhibitor of receptor internalization, caused up-regulation of nuclear membrane and P20 opioid receptors and a loss in nuclear matrix associated sites. Taxol, a microtubule stabilizing agent, prevented the effect of colchicine. Etorphine-elicited down-regulation increased nuclear matrix associated binding while diminishing that in nuclear membranes and P20 fractions. Agonist-induced desensitization completely abolished nuclear matrix binding. In vitro preincubation of nuclear matrix preparations with protein kinase A catalytic subunit mimicked the desensitization effect. Forskolin treatment of cells potentiated nuclear matrix and P20 binding. These data suggest that nuclear membrane opioid receptors represent newly synthesized molecules en route to the cell surface, whereas nuclear matrix contains internalized delta sites.


Assuntos
Entorpecentes/metabolismo , Membrana Nuclear/metabolismo , Matriz Nuclear/metabolismo , Receptores Opioides delta/metabolismo , Analgésicos/metabolismo , Linhagem Celular , Colforsina/farmacologia , Proteínas Quinases Dependentes de AMP Cíclico/química , Proteínas Quinases Dependentes de AMP Cíclico/farmacologia , Etorfina/farmacologia , Microscopia Eletrônica , Antagonistas de Entorpecentes/metabolismo , Matriz Nuclear/ultraestrutura , Receptores Opioides delta/agonistas , Receptores Opioides delta/antagonistas & inibidores , Frações Subcelulares/efeitos dos fármacos , Frações Subcelulares/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA