共查询到20条相似文献，搜索用时 31 毫秒
1.
Delayed transneuronal death of substantia nigra neurons prevented by gamma-aminobutyric acid agonist 总被引：7，自引：0，他引：7
In an investigation of the mechanism by which brain lesions result in delayed degeneration of neurons remote from the site of injury, neurons within the caudate nucleus of rats were destroyed by local injection of the excitotoxin ibotenic acid. Treatment resulted in the rapid degeneration of the striatonigral pathway including projections containing the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and delayed transneuronal death of neurons in the substantia nigra pars reticulata. The distribution of nigral cell loss corresponded to the loss of GABAergic terminals. Neuronal death was prevented by long-term intraventricular infusion of the GABA agonist muscimol. Delayed transneuronal degeneration may be produced by neuronal disinhibition consequent to loss of inhibitory inputs. Replacement of inhibitory transmitters by suitable drugs may prevent some forms of delayed neuronal death. 相似文献
2.
Gamma-aminobutyric acid: role in primary afferent depolarization 总被引：4，自引：0，他引：4
The effects of putative transmitters on the primary afferent terminals were studied in the magnesium-treated, isolated spinal cord of the frog. Gamma-aminobutyric acid and glutamic acid reversibly depolarized primary afferent terminals and increased their excitability, whereas glycine produced weak and variable effects. Bicuculline and picrotoxin, which reduce primary afferent depolarization, reversibly antagonized the gamma-aminobutyric acid-mediated responses but had little effect on those produced by either glutamic acid or glycine. The glutamic acid- and the gamma-aminobutyric acid-induced depolarizations remained in the absence of external chloride but disappeared in the absence of external sodium. These results support the hypotheses that gamma-aminobutyric acid is the transmitter mediating the synaptic depolarization of primary afferent terminals and that sodium is the predominant ion involved. 相似文献
3.
(-)Pentobarbital opens ion channels of long duration in cultured mouse spinal neurons 总被引：6，自引：0，他引：6
Intracellular recordings from voltage-clamped mouse spinal neurons in tissue culture were used to study the membrane mechanisms underlying inhibitory responses to gamma-aminobutyric acid and the (-) isomer of pentobarbital. Fluctuation analysis suggested that both substances activated ion channels in the membranes. However, the channels activated by pentobarbital remained open five times longer than those activated by gamma-aminobutyric acid. 相似文献
4.
Gamma-aminobutyric acid antagonism and presynaptic inhibition in the frog spinal cord 总被引：11，自引：0，他引：11
R A Davidoff 《Science (New York, N.Y.)》1972,175(19):331-333
The convulsant alkaloid bicuculline blocked presynaptic inhibition, dorsal root potentials, primary afferent depolarization, and depolarizing effects of gamma-aminobutyric acid on dorsal root terminals of the amphibian spinal cord, but did not block effects of other putative amino acid transmitters. These actions of bicuculline suggest that gamma-aminobutyric acid may be the transmitter involved in spinal presynaptic inhibition. 相似文献
5.
The localization of brain succinic semialdehyde dehydrogenase, a specific gamma-aminobutyric acid degradative enzyme, could potentially yield valuable information concerning the function of the enzyme. Application of a new histochemical technique for this enzyme has revealed characteristic patterns of neuronal staining that are contsistent within embryologically and functionally similar nuclei of the brainstem of the rat. 相似文献
6.
Synaptosomes treated with radioactive gamma-aminobutyric acid can be stimulated to release this substance. The release is maximal within 40 seconds after stimulation and is dependent on calcium. Magnesium and manganese ions, known to block stimulus-secretion coupling processes, depress calcium-dependent release. This release is specific to synaptosomes because microsomal or myelin fractions do not release accumulated gamma-aminobutyric acid. The data illustrate a simple in vitro system suitable for analysis of secretion of gamma-aminobutyric acid in brain and in addition describe several new aspects of uptake and secretion of this compound at brain nerve endings. 相似文献
7.
Synaptic transmission between dissociated adult mammalian neurons and attached synaptic boutons 总被引：5，自引：0，他引：5
In most studies of synaptic currents in mammalian central neurons, preparations have been used in which synaptic currents are recorded at some distance from the synapse itself. This procedure introduces problems in interpretation of the kinetics and voltage-dependent properties of the synaptic current. These problems have now been overcome by the development of a preparation in which presynaptic vesicle-containing boutons have been coisolated with the soma of individual neurons, thus providing the opportunity to study synaptic currents under conditions of both adequate voltage control and internal ionic perfusion. Spontaneous synaptic currents mediated by gamma-aminobutyric acid and excitatory amino acids were recorded from neurons isolated from a mammalian medial solitary tract nucleus. Calcium- and depolarization-dependent spontaneous currents of several to hundreds of picoamperes occurred with rapid rise times of 0.8 to 3 milliseconds and decays at least ten times as long. 相似文献
8.
Decreased hippocampal inhibition and a selective loss of interneurons in experimental epilepsy 总被引：46，自引：0，他引：46
R S Sloviter 《Science (New York, N.Y.)》1987,235(4784):73-76
The occurrence of seizure activity in human temporal lobe epilepsy or status epilepticus is often associated with a characteristic pattern of cell loss in the hippocampus. An experimental model that replicates this pattern of damage in normal animals by electrical stimulation of the afferent pathway to the hippocampus was developed to study changes in structure and function that occur as a result of repetitive seizures. Hippocampal granule cell seizure activity caused a persistent loss of recurrent inhibition and irreversibly damaged adjacent interneurons. Immunocytochemical staining revealed unexpectedly that gamma-aminobutyric acid (GABA)-containing neurons, thought to mediate inhibition in this region and predicted to be damaged by seizures, had survived. In contrast, there was a nearly complete loss of adjacent somatostatin-containing interneurons and mossy cells that may normally activate inhibitory neurons. These results suggest that the seizure-induced loss of a basket cell-activating system, rather than a loss of inhibitory basket cells themselves, may cause disinhibition and thereby play a role in the pathophysiology and pathology of the epileptic state. 相似文献
9.
疣枝卫矛根皮中麻醉成分F对昆虫作用的研究 总被引：4，自引：0，他引：4
以疣枝卫矛根皮中分离到的麻醉成分Ｆ对粘虫、菜青虫和小地老虎进行选择性试验,发现无选择麻醉作用,化合物使粘虫心搏速率降低,呼吸耗氧量降低,并使试虫体内谷氨酸及γ－氨基丁酸含量显著增加,分别增加７３．７％、１９２．３％,化合物Ｆ可能影响γ－氨基丁酸为递质的突触神经兴奋传导。 相似文献
10.
Glycine in the spinal cord of cats with local tetanus rigidity 总被引：2，自引：0，他引：2
In cats, significant loss of glycine occurred in spinal grey matter on the side of local tetanus, whereas the gamma-aminobutyric acid concentration remained unaltered. These findings suggest that tetanus rigidity is due to the blocking of the spinal inhibitory transmission by decrease of inhibitory transmitter and that glycine is an effective inhibitory transmitter in cat spinal cord. 相似文献
11.
A major direct GABAergic pathway from zona incerta to neocortex 总被引：4，自引：0，他引：4
Retrograde fluorescent tracers were used to demonstrate a previously unknown but sizable direct gamma-aminobutyric acid (GABA)-containing neuronal pathway from the zona incerta to the neocortex in rats. This incertocortical pathway was found to project bilaterally to the entire neocortex and exhibited a rough corticotopic organization. Many of the zona incerta neurons projecting to the parietal and occipital cortices could also be immunohistochemically stained with antibodies to glutamic acid decarboxylase and GABA. Few of these neurons were immunoreactive to tyrosine hydroxylase antibodies, which identify dopamine-containing neurons. Injections in the frontal and entorhinal cortices labeled many neurons near or within the dopaminergic A13 subdivision of the zona incerta. In addition, the incertocortical system was found to be significantly larger during early postnatal (2 to 3 weeks) development. The projection pattern of this newly discovered pathway resembles that of the monoaminergic and cholinergic systems, arising from the brainstem and forebrain, suggesting possible similarities of function. 相似文献
12.
Cloning and expression of a cocaine-sensitive rat dopamine transporter 总被引：33，自引：0，他引：33
The action of dopamine and other monoamine neurotransmitters at synapses is terminated predominantly by high-affinity reuptake into presynaptic terminals by specific sodium-dependent neurotransmitter transport proteins. A complementary DNA encoding a rat dopamine transporter has been isolated that exhibits high sequence similarity with the previously cloned norepinephrine and gamma-aminobutyric acid transporters. Transient expression of the complementary DNA in HeLa cells confirms the cocaine sensitivity of this transporter. 相似文献
13.
14.
A simple quantitative autoradiographic technique for the study of neurotransmitter receptors that includes the use of a tritium-sensitive film permits saturation, kinetic, and competition studies of brain samples as small as 0.01 cubic millimeter. This technique was used to study [3H]muscimol binding in rat brain. Unilateral gamma-aminobutyric acid receptor supersensitivity was observed in the substantia nigra pars reticulata after production of localized lesions of the ipsilateral corpus striatum. 相似文献
15.
一个新的玉米WRKY基因识别及其生物信息学分析 总被引：1，自引：0，他引：1
利用电子克隆技术从玉米EST库中发现了一个新的玉米WRKY基因ZmWRKY。生物信息学分析表明,该基因编码一个由302个氨基酸组成的、相对分子质量为32.5 kD的蛋白,具有一个由60个氨基酸组成的WRKY结构域（155～214）,定位于细胞核,具有转录调控功能。序列分析表明,该蛋白与同科植物水稻OsWRKY76基因具有较高的同源性,推测其可能参与植物病害防御信号的传导过程,在植物生物胁迫防御中发挥作用。 相似文献
16.
17.
Human cerebral cortical function degrades during old age. Much of this change may result from a degradation of intracortical inhibition during senescence. We used multibarreled microelectrodes to study the effects of electrophoretic application of gamma-aminobutyric acid (GABA), the GABA type a (GABAa) receptor agonist muscimol, and the GABAa receptor antagonist bicuculline, respectively, on the properties of individual V1 cells in old monkeys. Bicuculline exerted a much weaker effect on neuronal responses in old than in young animals, confirming a degradation of GABA-mediated inhibition. On the other hand, the administration of GABA and muscimol resulted in improved visual function. Many treated cells in area V1 of old animals displayed responses typical of young cells. The present results have important implications for the treatment of the sensory, motor, and cognitive declines that accompany old age. 相似文献
18.
CLIP identifies Nova-regulated RNA networks in the brain 总被引：1，自引：0，他引：1
19.
NMDA receptor losses in putamen from patients with Huntington's disease 总被引：19，自引：0，他引：19
A B Young J T Greenamyre Z Hollingsworth R Albin C D'Amato I Shoulson J B Penney 《Science (New York, N.Y.)》1988,241(4868):981-983
N-Methyl-D-aspartate (NMDA), phencyclidine (PCP), and quisqualate receptor binding were compared to benzodiazepine, gamma-aminobutyric acid (GABA), and muscarinic cholinergic receptor binding in the putamen and cerebral cortex of individuals with Huntington's disease (HD). NMDA receptor binding was reduced by 93 percent in putamen from HD brains compared to binding in normal brains. Quisqualate and PCP receptor binding were reduced by 67 percent, and the binding to other receptors was reduced by 55 percent or less. Binding to these receptors in the cerebral cortex was unchanged in HD brains. The results support the hypothesis that NMDA receptor-mediated neurotoxicity plays a role in the pathophysiology of Huntington's disease. 相似文献
20.
Striatal nondopaminergic neurons: possible involvement in feeding and drinking behavior 总被引：1，自引：0，他引：1
D J Pettibone N Kaufman M C Scally E Meyer I Ulus L D Lytle 《Science (New York, N.Y.)》1978,200(4346):1175-1177
Intracaudate injections of kainic acid destroy striatal neurons containing acetylcholine and gamma-aminobutyric acid but leave dopaminergic nerve terminals in this brain region intact. Rats injected with the drug are aphagic and adipsic, and have other behavioral abnormalities strikingly similar to those seen in animals with lesions in the dopaminergic nigrostriatal bundle. 相似文献