Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The localization of cholinergic, aminergic and amino acid-ergic neurones in the mediobasal hypothalamus has been studied in normal rat brain and in brains where neurones in nucleus arcuatus were destroyed by repeated administration of 2 mg/g body weight monosodium glutamate to newborn animals. In normal animals acetylcholinesterase staining, choline acetyltransferase and aromatic L-amino acid decarboxylase were concentrated in the median eminence and the arcuate nucleus. Glutamate decarboxylase was concentrated at the boundary between the ventromedial and the arcuate nuclei, with lower activity in the arcuate nucleus and very low activity in the median eminence. Nucleus arcuatus contained an intermediate level of high affinity glutamate uptake. In the lesioned animals, there were significant decreases in choline acetyltransferase, acetylcholinesterase staining and glutamate decarboxylase in the median eminence, whereas choline acetyltransferase activity and acetylcholinesterase staining, but not glutamate decarboxylase activity, were decreased in nucleus arcuatus. Aromatic L-amino acid decarboxylase was unchanged in all regions studied. The high affinity uptakes of glutamate, dopamine and noradrenaline, and the endogenous amino acid levels were also unchanged in the treated animals. The results indicate the existence of acetylcholine- and GABA-containing elements in the tuberoinfundibular tract. They further indicate that the dopamine cells in the arcuate nucleus are less sensitive to the toxic effect of glutamate than other cell types, possibly because they contain less glutamate receptors.
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PMID:The effect of parenteral glutamate treatment on the localization of neurotransmitters in the mediobasal hypothalamus. 2 95

Bilateral occlusion of common carotid arteries in Mongolian gerbils was produced for the periods (up to 15 min) which were shown to be totally reversible. There was an initial increase of cyclic AMP and GABA levels and enhanced activities of adenylate cyclase and glutamate decarboxylase, as well as the reduction of norepinephrine level and decreased activities of monoamine oxidase, GABA-transaminase and Na+-K+-ATPase. Following these changes, decreased concentration of dopamine, serotinin and glutamate were found. The activities of total protein kinase and acetylcholinesterase were found to be reduced after longer periods of short-term ischemia. The data are consistent with the concept of increased non-controled release of putative neurotransmitters in ischemia.
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PMID:Alterations of putative neurotransmitters and enzymes during ischemia in gerbil cerebral cortex. 3 75

Molecular layer, granular layer and white matter are dissected from bovine cerebellum under optical microscope and without freezing under conditions which preserve their main anatomical features. Polyacrylamide gel electrophoresis in sodium dodecyl sulphate of the isolated layers reveal that the P400 protein characteristic of the Purkinje cells is found in the isolated molecular layer and in the molecular layer free from Purkinje cell soma, but not in the granular layer or white matter. The histones (F1, F2A1,2, F2B, F3) are abundant in the granular layer and myelin proteins in the white matter. The DNA content per wet weight is 10 times greater in the isolated granular layer than in the other layers and the RNA content twice as great in the granular layer than in any other layer. The specific activity of acetylcholinesterase is 4 times greater in the granular layer than in the other layers. Homogenates of the isolated layers take up labeled amino-acids and the velocity of glutamate incorporation is 9 times greater in the molecular layer than in the granular layer, while GABA incorporation is about twice as great in the granular layer than in the molecular layer. Homogenates of isolated molecular layer are centrifuged on discontinuous Ficoll gradient after incubation with L[3H]glutamate and [14C]GABA. The analysis of the distribution of glutamate and GABA after centrifugation reveals that the particles which incorporate glutamate can be separated from those which take up GABA.
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PMID:Morphological and biochemical studies on isolated molecular and granular layers from bovine cerebellum. 63 47

Picrotoxin, 2 mg/kg i.p., a GABA receptor blocking agent, increased rat striatal acetylcholine content by approximately 70% without altering the levels of this amine in the cerebral hemispheres, mesencephalon, diencephalon, hippocampus and cerebellum. Striatal choline levels were concomitantly decreased by about 25%. This dose of picrotoxin also increased striatal homovanillic acid levels by about 30%, an effect which was not antagonized by pretreatment with the dopamine receptor stimulating agent, piribedil. Picrotoxin did not affect striatal choline-O-acetyltransferase or cholinesterase activity after in vitro incubation. The action of picrotoxin on striatal acetylcholine levels was partially antagonized by pimozide and completely blocked by alpha-methyl-para-tyrosine pretreatment while the intraventricular injection of 6-hydroxydopamine was without effect. Convulsions were not prevented by any of these treatments. The results are interpreted as follows: picrotoxin released dopamine through disinhibition of the dopaminergic neurons as a result of blockade of gabergic receptors. The increased dopaminergic activity inhibited cholinergic neurons and lead to an increase in acetylcholine content. The data thus provide evidence for a possible gabergic (inhibitory)--dopaminergic (inhibitory)-cholinergic link terminating in the striatum.
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PMID:Increase in striatal acetylcholine by picrotoxin in the rat: evidence for a gabergic-dopaminergic-cholinergic link. 94 12

Medial hypothalamic tissue of 1 to 4 days old rats was dissociated and cultured in vitro for 8--10 days. Neuronal perikarya were demonstrated by supravital methylene blue staining and electron microscopy. Synapses with typical vesicles and subsynaptic thickening were also observed. 3H-GABA was taken up into a small percentage of the cells in the cultures. Neuron-like perikarya and long processes accumulated the label while many neurons contained much less activity. Some astroglial and oligodendroglial cells and processes also accumulated GABA. A few neurons in these cultures contained acetylcholinesterase. It is concluded that neurons concentrating GABA and containing acetylcholinesterase are present in the hypothalamus of rats of 1 to 4 days of age and can be maintained in dissociated cell culture.
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PMID:3H-GABA uptake and acetylcholinesterase activity in dissociated cell cultures of the medial hypothalamus. 103

Following the implantation of cobalt-gelatine pellets into the frontal cortex, epileptiform spikes in both primary and secondary foci developed and reached a peak between 7-12 days post implantation. Histological examination showed a necrotic lesion with terminal and fibre degeneration in brain areas connected with the frontal cortex. Golgi staining at 60 days showed a loss of pyramidal cells in the primary focal area. In the lesion and primary focal areas GABA, glutamate and aspartate were significantly reduced between 5--10 days post implantation. No changes in glutamine and glycine were found in either the lesion or pulmonary focus. No changes in amino acid content were found in the secondary focus or in glass implanted controls at any time. In cobalt-treated rats there were significant reductions in the transmitter related enzymes, glutamate decarboxylase, acetylcholinesterase, choline acetyltransferase and aromatic amino acid decarboxylase in the lesion area and primary and secondary foci at 4--8 days post implantation. Levels of these enzymes had recovered to normal by 24 days. Lactate dehydrogenase was reduced only in the lesion area. Beta-Galactosidase was reduced in the lesion area at 4 days but subsequent rose rapidly paralleling increasing gliosis around the lesion. It is concluded that cobalt-induced epilepsy is associated with relatively selective loss of neuronal tissue and provides a useful model for further investigation relevant to clinical epilepsy.
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PMID:Neurochemical and morphological changes during the development of cobalt-induced epilepsy in the rat. 113 20

Bicuculline and 3 chemical derivatives were assayed on a variety of biological systems. Consistent with reports of studies on other animals, some of these compounds caused convulsions in insects and blocked inhibitory postsynaptic potentials in insect muscle. They all potently inhibited mouse brain acetylcholinesterase. Bicuculline and its analogs inhibited the binding of GABA in vitro to sites in crayfish muscle membranes which have properties of receptor sites; this site of action could explain the activity of bicuculline at arthropod neuromuscular junctions. These compounds, at high concentrations (over 100 muM), also inhibited GABA uptake by mouse brain homogenates at 0 degrees C apparently non-competitively. Bicucine methyl ester inhibited GABA transport by brain at 37 degrees C, consistent with non-specific membrane effects at high concentrations of drug. These and other observations cast doubt upon the specificity of bicuculline-like compounds for action on GABA synapses, especially for in vitro studies at high drug concentrations (over 10 muM). The neuroactivity of low doses of bicuculline is apparently not explained by these in vitro effects, and could very well be due to inhibition of GABA synapses at either receptor or ionophore sites. At physiological conditions of pH and temperature, bicuculline is hydrolyzed at its lactone moiety to the less active compound bicucine; this could lead to underestimates of the biological activity of bicuculline. More stable analogs studied so far are not more potent, however.
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PMID:Studies on the neuropharmacological activity of bicuculline and related compounds. 124 86

1. Intracellular recordings were made from CA1 pyramidal cells in the rat hippocampal slice to study the cholinergic modulation of GABAergic inhibition. The cholinergic receptor agonist, carbamylcholine (carbachol), depressed evoked excitatory postsynaptic potentials (EPSPs) and evoked inhibitory postsynaptic potentials (IPSPs), but enhanced small spontaneously occurring membrane potential fluctuations that resembled IPSPs. Both atropine (1 microM) and picrotoxin (25-60 microM) abolished the small fluctuations. 2. Recording from cells with potassium or caesium chloride (KCl or CsCl)-filled microelectrodes enhanced and inverted spontaneous Cl(-)-dependent GABAA-mediated IPSPs. These events appeared to result from the spontaneous firing of GABAergic interneurons since they could be inhibited by picrotoxin or bicuculline and nearly eliminated by tetrodotoxin. 3. Muscarinic acetylcholine (ACh) receptor activation significantly increased the frequency of spontaneous-activity-dependent IPSPs from 1.7 +/- 0.4 s (mean +/- S.E.M.) in control saline to 7.0 +/- 1.1 s in carbachol (10-50 microM)-containing saline, although evoked IPSPs were inhibited. All effects of carbachol were completely reversed by atropine. 4. The increase in frequency of spontaneous IPSPs observed in carbachol was not secondary to changes in the postsynaptic cell and was not blocked by high doses of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5-10 microM) and 2-amino-5-phosphonovaleric acid (APV, 10-20 microM), which abolished evoked excitatory transmission. Amplitude histograms showed an increase in mean size as well as of frequency of spontaneous IPSCs in carbachol. 5. Stimulation of cholinergic afferents in stratum oriens in the presence of the acetylcholinesterase inhibitor eserine (1 microM) also increased spontaneous IPSP frequency, and the time course of this response was similar to that of the muscarinic slow EPSP. Postsynaptic factors or the activation of glutamatergic excitatory pathways could not account for this effect. 6. Evoked monosynaptic IPSCs in CNQX and APV were diminished by carbachol. 7. We conclude that GABAergic inhibitory interneurons possess muscarinic receptors, that activation of these receptors increases the excitability of the interneurons and that synaptically released ACh increases interneuronal activity. Cholinergic reduction of the monosynaptic IPSC may point to additional complexity in cholinergic regulation of the GABA system.
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PMID:Cholinergic excitation of GABAergic interneurons in the rat hippocampal slice. 135 21

The behavioral effects of GABAergic manipulation of the basal forebrain were investigated using two behavioral tasks, which previous studies have shown to yield dissociable effects following quisqualate-induced lesions of the basal forebrain: a five-choice serial reaction time task, involving approaching the location of a brief visual stimulus that is associated with reward; and a conditional visual discrimination task, requiring retrieval of information about a discriminative stimulus that stays constant over time. Following acquisition of the tasks, chronic guide cannulae were stereotaxically implanted into the basal forebrain. Those animals trained on the conditional visual discrimination task showed a dose-dependent reduction in choice accuracy and a lengthening of latency to respond correctly to the visual stimulus following administration of the GABA-A agonist, muscimol (1, 2, 3 ng/microliters/hem). While certain of these deficits, for example response latency, could be restored to control levels by co-administration of the GABA-A antagonist, bicuculline, none of the behavioural impairments could be significantly attenuated by systemic by systemic co-administration of the cholinesterase inhibitor, physostigmine (0.05, 0.1, 0.2 mg/kg, IP). Similarly, a dose dependent effect of muscimol (1, 1.5, 2 ng/microliters/hem) on choice accuracy and correct response latency was observed on performance of the five-choice attentional task. However, in contrast to the conditional task, significant attenuation of the impairment in choice accuracy was obtained following administration of physostigmine (0.05 and 0.1 mg/kg). Attenuation of muscimol-induced deficits by administration of bicuculline was also observed. It is therefore evident that although manipulation of GABAergic activity in the region of the basal forebrain produces profound deficits in different tasks of cognitive function, only some of these may be due to modulation of the magnocellular cholinergic projection to the neocortex.
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PMID:Disruptive effects of muscimol infused into the basal forebrain on conditional discrimination and visual attention: differential interactions with cholinergic mechanisms. 160 98

A detailed neurochemical analysis of the distribution of markers for the most relevant neurotransmitter systems within the rat hippocampal formation has been performed. The hippocampi, obtained from unfrozen brains of male Sprague-Dawley rats were subdissected into tissue parts containing mainly CA1, CA3 or the dentate gyrus, respectively. Each part was further divided into ventral and dorsal halves. In these six hippocampal subregions the concentrations of noradrenaline, dopamine, serotonin, 3-methoxy-4-hydroxyphenylglycol, 5-hydroxyindoleacetic acid and the putative neurotransmitter amino acids glutamate, aspartate, GABA, glycine and taurine, and the levels of somatostatin and neuropeptide Y and the activities of choline acetyltransferase, acetylcholinesterase and glutamate decarboxylase were measured. A marked heterogeneity in the subregional distribution of markers for various neurotransmitter systems within the hippocampal formation was observed. Each neuronal marker was characterized by an individual pattern of distribution. Most of the markers showed a concentration-gradient, increasing from dorsal to ventral; only taurine was more abundant in the dorsal than in the ventral parts and no dorsoventral difference was seen for aspartate, glycine and neuropeptide Y. The highest molar ratios of total 3-methoxy-4-hydroxyphenylglycol to noradrenaline and 5-hydroxyindoleacetic acid to serotonin were found in the dorsal hippocampus. The levels of noradrenaline, GABA and glutamate decarboxylase activity were highest in the dentate gyrus and lowest in CA1. The concentrations of somatostatin were highest in CA1; those of serotonin were highest in CA3. Highest activities of choline acetyltransferase and acetylcholinesterase were found in the dentate gyrus; lowest activities were found in CA3. In CA3 the lowest values of glutamate, aspartate, taurine and somatostatin were also found. The heterogeneity in the distribution of individual neurochemical markers allows insights into possible functional differences of hippocampal subregions and provides a relevant basis for future neurochemical investigations in this brain area.
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PMID:Regional heterogeneity in the distribution of neurotransmitter markers in the rat hippocampus. 168 35


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