共查询到20条相似文献，搜索用时 62 毫秒
1.
Spinal sympathetic neurons: possible sites of opiate-withdrawal suppression by clonidine 总被引：2，自引：0，他引：2
Morphine, methadone, meperidine, fentanyl, and clonidine rapidly depressed transmission through sympathetic preganglionic neurons in cats with the spinal cord transected. Naloxone promptly antagonized this effect of the opiates but not that of clonidine which was reversed by alpha 2-adrenergic receptor antagonists. The independent depression of preganglionic neurons by clonidine may contribute to the ability of this drug to depress the symptoms of opiate withdrawal that are characterized by sympathetic hyperactivity. 相似文献
2.
Parasympathetic ganglia: activation of an adrenergic inhibitory mechanism by cholinomimetic agents 总被引：1，自引：0，他引：1
Electrical stimulation of the sympathetic nerves to the urinary bladder or the intraarterial administration of the cholinomimetic substances acetylcholine or methacholine produced adrenergic inhibition in parasympathetic ganglia on the surface of the bladder. The inhibition appeared to be mediated, at least in part, via adrenergic inhibitory neurons located in the pelvic plexus. Atropine blocked the inhibitory response to injected cholinomimetic agents but did not alter the response to stimulation of the sympathetic nerves. Thus, the inhibitory neurons can be activated via both muscarinic and nonmuscarinic receptors, the latter being of primary physiological importance. 相似文献
3.
T Scheuer V J Auld S Boyd J Offord R Dunn W A Catterall 《Science (New York, N.Y.)》1990,247(4944):854-858
Transfection of Chinese hamster ovary cells with complementary DNA encoding the RIIA sodium channel alpha subunit from rat brain led to expression of functional sodium channels with the rapid, voltage-dependent activation and inactivation characteristic of sodium channels in brain neurons. The sodium currents mediated by these transfected channels were inhibited by tetrodotoxin, persistently activated by veratridine, and prolonged by Leiurus alpha-scorpion toxin, indicating that neurotoxin receptor sites 1 through 3 were present in functional form. The RIIA sodium channel alpha subunit cDNA alone is sufficient for stable expression of functional sodium channels with the expected kinetic and pharmacological properties in mammalian somatic cells. 相似文献
4.
The normal function of neural networks depends on a delicate balance between excitatory and inhibitory synaptic inputs. Synapse formation is thought to be regulated by bidirectional signaling between pre- and postsynaptic cells. We demonstrate that members of the Neuroligin family promote postsynaptic differentiation in cultured rat hippocampal neurons. Down-regulation of neuroligin isoform expression by RNA interference results in a loss of excitatory and inhibitory synapses. Electrophysiological analysis revealed a predominant reduction of inhibitory synaptic function. Thus, neuroligins control the formation and functional balance of excitatory and inhibitory synapses in hippocampal neurons. 相似文献
5.
CORRELL JW 《Science (New York, N.Y.)》1963,140(3565):387-388
Electrical stimulation of nerves to isolated rat and rabbit adipose tissue in vitro causes production of free fatty acids. Starvation increases the response. The response of white (epididymal) fat is prevented by sympathetic denervation. Direct evidence is provided showing that adipose tissue has the capacity to be an effector organ responsive to the nervous system. 相似文献
6.
ADP-ribosyltransferase activity of pertussis toxin and immunomodulation by Bordetella pertussis 总被引：22，自引：0，他引：22
W J Black J J Munoz M G Peacock P A Schad J L Cowell J J Burchall M Lim A Kent L Steinman S Falkow 《Science (New York, N.Y.)》1988,240(4852):656-659
Pertussis toxin is produced by the causative agent of whooping cough, Bordetella pertussis, and is an adenosine diphosphate (ADP)-ribosyltransferase capable of covalently modifying and thereby inactivating many eukaryotic G proteins involved in cellular metabolism. The toxin is a principal determinant of virulence in whooping cough and is a primary candidate for an acellular pertussis vaccine, yet it is unclear whether the ADP-ribosyltransferase activity is required for both pathogenic and immunoprotective activities. A B. pertussis strain that produced an assembled pertussis holotoxin with only 1 percent of the ADP-ribosyltransferase activity of the native toxin was constructed and was found to be deficient in pathogenic activities associated with B. pertussis including induction of leukocytosis, potentiation of anaphylaxis, and stimulation of histamine sensitivity. Moreover, this mutant strain failed to function as an adjuvant and was less effective in protecting mice from intracerebral challenge infection. These data suggest that the ADP-ribosyltransferase activity is necessary for both pathogenicity and optimum immunoprotection. These findings bear directly on the design of a nontoxic pertussis vaccine. 相似文献
7.
The second messenger cyclic adenosine monophosphate (cAMP) is the most important modulator of sympathetic control over cardiac contractility. In cardiac myocytes and many other cell types, however, cAMP transduces the signal generated upon stimulation of various receptors and activates different cellular functions, raising the issue of how specificity can be achieved. In the general field of signal transduction, the view is emerging that specificity is guaranteed by tight localization of signaling events. Here, we show that in neonatal rat cardiac myocytes, beta-adrenergic stimulation generates multiple microdomains with increased concentration of cAMP in correspondence with the region of the transverse tubule/junctional sarcoplasmic reticulum membrane. The restricted pools of cAMP show a range of action as small as approximately 1 micrometer, and free diffusion of the second messenger is limited by the activity of phosphodiesterases. Furthermore, we demonstrate that such gradients of cAMP specifically activate a subset of protein kinase A molecules anchored in proximity to the T tubule. 相似文献
8.
Ahumada A Slusarski DC Liu X Moon RT Malbon CC Wang HY 《Science (New York, N.Y.)》2002,298(5600):2006-2010
The Frizzled-2 receptor (Rfz2) from rat binds Wnt proteins and can signal by activating calcium release from intracellular stores. We show that wild-type Rfz2 and a chimeric receptor consisting of the extracellular and transmembrane portions of the beta2-adrenergic receptor with cytoplasmic domains of Rfz2 also signaled through modulation of cyclic guanosine 3',5'-monophosphate (cGMP). Activation of either receptor led to a decline in the intracellular concentration of cGMP, a process that was inhibited in cells treated with pertussis toxin, reduced by suppression of the expression of the heterotrimeric GTP-binding protein (G protein) transducin, and suppressed through inhibition of cGMP-specific phosphodiesterase (PDE) activity. Moreover, PDE inhibitors blocked Rfz2-induced calcium transients in zebrafish embryos. Thus, Frizzled-2 appears to couple to PDEs and calcium transients through G proteins. 相似文献
9.
Liu T DeCostanzo AJ Liu X Wang Hy Hallagan S Moon RT Malbon CC 《Science (New York, N.Y.)》2001,292(5522):1718-1722
The frizzled receptors, which mediate development and display seven hydrophobic, membrane-spanning segments, are cell membrane-localized. We constructed a chimeric receptor with the ligand-binding and transmembrane segments from the beta2-adrenergic receptor (beta2AR) and the cytoplasmic domains from rat Frizzled-1 (Rfz1). Stimulation of mouse F9 clones expressing the chimera (beta2AR-Rfz1) with the beta-adrenergic agonist isoproterenol stimulated stabilization of beta-catenin, activation of a beta-catenin-sensitive promoter, and formation of primitive endoderm. The response was blocked by inactivation of pertussis toxin-sensitive, heterotrimeric guanine nucleotide-binding proteins (G proteins) and by depletion of Galphaq and Galphao. Thus, G proteins are elements of Wnt/Frizzled-1 signaling to the beta-catenin-lymphoid-enhancer factor (LEF)-T cell factor (Tcf) pathway. 相似文献
10.
Dominant role of N-type Ca2+ channels in evoked release of norepinephrine from sympathetic neurons 总被引：41，自引：0，他引：41
L D Hirning A P Fox E W McCleskey B M Olivera S A Thayer R J Miller R W Tsien 《Science (New York, N.Y.)》1988,239(4835):57-61
Multiple types of calcium channels have been found in neurons, but uncertainty remains about which ones are involved in stimulus-secretion coupling. Two types of calcium channels in rat sympathetic neurons were described, and their relative importance in controlling norepinephrine release was analyzed. N-type and L-type calcium channels differed in voltage dependence, unitary barium conductance, and pharmacology. Nitrendipine inhibited activity of L-type channels but not N-type channels. Potassium-evoked norepinephrine release was markedly reduced by cadmium and the conesnail peptide toxin omega-Conus geographus toxin VIA, agents that block both N- and L-type channels, but was little affected by nitrendipine at concentrations that strongly reduce calcium influx, as measured by fura-2. Thus N-type calcium channels play a dominant role in the depolarization-evoked release of norepinephrine. 相似文献
11.
Mutants of pertussis toxin suitable for vaccine development 总被引：53，自引：0，他引：53
M Pizza A Covacci A Bartoloni M Perugini L Nencioni M T De Magistris L Villa D Nucci R Manetti M Bugnoli 《Science (New York, N.Y.)》1989,246(4929):497-500
Immunization with chemically detoxified pertussis toxin can prevent severe whooping cough with an efficacy similar to that of the cellular pertussis vaccine, which normally gives unwanted side effects. To avoid the reversion to toxicity and the loss of immunogenicity that may follow chemical treatment of pertussis toxin, inactive toxins were constructed by genetic manipulation. A number of genetically engineered alleles of the pertussis toxin genes, constructed by replacing either one or two key amino acids within the enzymatically active S1 subunit, were introduced into the chromosome of strains of Bordetella pertussis, B. parapertussis, and B. bronchiseptica. These strains produce mutant pertussis toxin molecules that are nontoxic and immunogenic and that protect mice from the intracerebral challenge with virulent Bordetella pertussis. Such molecules are ideal for the development of new and safer vaccines against whooping cough. 相似文献
12.
Modulation of calcium channels in cardiac and neuronal cells by an endogenous peptide 总被引：8，自引：0，他引：8
Calcium channels mediate the generation of action potentials, pacemaking, excitation-contraction coupling, and secretion and signal integration in muscle, secretory, and neuronal cells. The physiological regulation of the L-type calcium channel is thought to be mediated primarily by guanine nucleotide-binding proteins (G proteins). A low molecular weight endogenous peptide has been isolated and purified from rat brain. This peptide regulates up and down the cardiac and neuronal calcium channels, respectively. In cardiac myocytes, the peptide-induced enhancement of the L-type calcium current had a slow onset (half-time approximately 75 seconds), occurred via a G protein-independent mechanism, and could not be inhibited by alpha 1-adrenergic, beta-adrenergic, or angiotensin II blockers. In neuronal cells, on the other hand, the negative effect had a rapid onset (half-time less than 500 milliseconds) and was observed on both T-type and L-type calcium channels. 相似文献
13.
The proto-oncogene c-fos is expressed in neurons in response to direct stimulation by growth factors and neurotransmitters. In order to determine whether the c-fos protein (Fos) and Fos-related proteins can be induced in response to polysynaptic activation, rat hindlimb motor/sensory cortex was stimulated electrically and Fos expression examined immunohistochemically. Three hours after the onset of stimulation, focal nuclear Fos staining was seen in motor and sensory thalamus, pontine nuclei, globus pallidus, and cerebellum. Moreover, 24-hour water deprivation resulted in Fos expression in paraventricular and supraoptic nuclei. Fos immunohistochemistry therefore provides a cellular method to label polysynaptically activated neurons and thereby map functional pathways. 相似文献
14.
Noradrenergic stimulation of cyclic adenosine monophosphate in rat Purkinje neurons: an immunocytochemical study 总被引：4，自引：0，他引：4
G R Siggins E F Battenberg B J Hoffer F E Bloom A L Steiner 《Science (New York, N.Y.)》1973,179(73):585-588
A specific immunofluorescent histochemical method for cyclic adenosine monophosphate was used to study rat cerebellum. After topical treatment with norepinephrine or stimulation of norepinephrine-containing afferents from locus coeruleus, there was a striking increase in the number of Purkinje cells with strong cyclic adenosine monophosphate reactivity. Other putative inhibitory transmitters had no significant effect on staining of Purkinje cells. The results provide the first histochemical support for the hypothesis that cyclic adenosine monophosphate can be generated postsynaptically in central neurons in response to noradrenergic stimuli. 相似文献
15.
The cholinergic neuronal differentiation factor from heart cells is identical to leukemia inhibitory factor 总被引：46，自引：0，他引：46
T Yamamori K Fukada R Aebersold S Korsching M J Fann P H Patterson 《Science (New York, N.Y.)》1989,246(4936):1412-1416
A protein secreted by cultured rat heart cells can direct the choice of neurotransmitter phenotype made by cultured rat sympathetic neurons. Structural analysis and biological assays demonstrated that this protein is identical to a protein that regulates the growth and differentiation of embryonic stem cells and myeloid cells, and that stimulates bone remodeling and acute-phase protein synthesis in hepatocytes. This protein has been termed D factor, DIA, DIF, DRF, HSFIII, and LIF. Thus, this cytokine, like IL-6 and TGF beta, regulates growth and differentiation in the embryo and in the adult in many tissues, now including the nervous system. 相似文献
16.
Sequence of the alpha subunit of photoreceptor G protein: homologies between transducin, ras, and elongation factors 总被引：40，自引：0，他引：40
A bovine retinal complementary DNA clone encoding the alpha subunit of transducin (T alpha) was isolated with the use of synthetic oligodeoxynucleotides as probes, and the complete nucleotide sequence of the insert was determined. THe predicted protein sequence of 354 amino acids includes the known sequences of four tryptic peptides and sequences adjacent to the residues that undergo adenosine diphosphate ribosylation by cholera toxin and pertussis toxin. On the basis of homologies to other proteins, such as the elongation factors of protein synthesis and the ras oncogene proteins, regions are identified that are predicted to be acylated and involved in guanine nucleotide binding and hydrolysis. Amino acid sequence similarity between T alpha and ras is confined to these regions of the molecules. 相似文献
17.
M D Majewska N L Harrison R D Schwartz J L Barker S M Paul 《Science (New York, N.Y.)》1986,232(4753):1004-1007
Two metabolites of the steroid hormones progesterone and deoxycorticosterone, 3 alpha-hydroxy-5 alpha-dihydroprogesterone and 3 alpha, 5 alpha-tetrahydrodeoxycorticosterone, are potent barbiturate-like ligands of the gamma-aminobutyric acid (GABA) receptor-chloride ion channel complex. At concentrations between 10(-7) and 10(-5)M both steroids inhibited binding of the convulsant t-butylbicyclophosphorothionate to the GABA-receptor complex and increased the binding of the benzodiazepine flunitrazepam; they also stimulated chloride uptake (as measured by uptake of 36Cl-) into isolated brain vesicles, and potentiated the inhibitory actions of GABA in cultured rat hippocampal and spinal cord neurons. These data may explain the ability of certain steroid hormones to rapidly alter neuronal excitability and may provide a mechanism for the anesthetic and hypnotic actions of naturally occurring and synthetic anesthetic steroids. 相似文献
18.
An M2 muscarinic receptor subtype coupled to both adenylyl cyclase and phosphoinositide turnover 总被引：20，自引：0，他引：20
A Ashkenazi J W Winslow E G Peralta G L Peterson M I Schimerlik D J Capon J Ramachandran 《Science (New York, N.Y.)》1987,238(4827):672-675
To investigate whether a particular receptor subtype can be coupled to multiple effector systems, recombinant M2 muscarinic receptors were expressed in cells lacking endogenous receptor. The muscarinic agonist carbachol both inhibited adenylyl cyclase and stimulated phosphoinositide hydrolysis. The stimulation of phosphoinositide hydrolysis was significantly less efficient and more dependent on receptor levels than the inhibition of adenylyl cyclase. Both responses were mediated by guanine nucleotide binding proteins, as evidenced by their inhibition by pertussis toxin; the more efficiently coupled adenylyl cyclase response was significantly more sensitive. Thus, individual subtypes of a given receptor are capable of regulating multiple effector pathways. 相似文献
19.
Spinal sympathetic pathway: an enkephalin ladder 总被引：3，自引：0，他引：3
20.
实验尝试在旋转生物反应器(RCCS)中采用微载体培养技术对心肌细胞进行快速培养。采用顺序消化和差速贴壁法分离纯化1~2日龄新生大鼠的心肌细胞,并将其在RCCS内应用Cytodex-3微载体进行培养,于倒置显微镜和扫描电镜下对微载体表面的细胞进行动态观察,同时测定细胞的代谢活性。结果表明,心肌细胞可快速贴附于微载体表面,细胞伸展后生长加速,并可形成心肌细胞-微载体团块,细胞代谢旺盛,说明在RCCS内应用微载体培养技术可简便、快速地在体外培养心肌细胞,是心肌细胞培养的一条可行途径。 相似文献