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 selective destruction of neuronal perikarya via intracerebral injections of kainic acid was used to elucidate the cellular location of four neurotransmitter-related enzymes in the substantia nigra (SN). Two weeks after intranigral injections of kainic acid, dopamine-sensitive adenylate cyclase, glutamic acid decarboxylase (GAD), choline acetyltransferase (CAT) and acetylcholinesterase (AChE) were measured in the SN. Histological examination of the SN, and a reduction of striatal tyrosine hydroxylase (TH) activity by 94%, confirmed the extensive loss of neuronal cell bodies in the SN. Dopamine stimulation of adenylate cyclase was not reduced in the lesioned SN, supporting the view that dendritically-released dopamine can regulate cyclic AMP synthesis in afferent terminals to these dendrites. Nigral GAD activity was significantly reduced by the lesions, suggesting that there are GAD-containing perikarya in the SN. CAT activity was not affected by the kainic injections, indicating the absence of cholinergic perikarya in the SN. Nigral AChE activity was significantly decreased after kainic injections, thus confirming the presence of AChE within the nigral perikarya. The results suggest that dopamine-sensitive adenylate cyclase and CAT are located within afferents to the SN, while GAD and AChE are found, to some extent at least, in neuronal soma of the SN. The differentail effects of kainic acid on these enzymes suggest that this compound may be a useful neurochemical tool with which to determine the cellular distribution of enzyme systems in the central nervous system.
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PMID:The use of kainic acid in the localization of enzymes in the substantia nigra. 2 84

The effects of pyridostigmine pretreatment on the neuromuscular blockade produced by soman in anaesthetized, atropinized animals have been studied on the soleus and anterior tibialis muscle (rhesus monkeys, cats and rabbits) and the gastrocnemius muscle (guinea-pigs and rats). Pyridostigmine pretreatment produced a complete recovery of neuromuscular function following blockade by soman; the rate of recovery was similar in all the species, suggesting a common mechanism of action. In the absence of pyridostigmine or if pyridostigmine was delayed until after blockade by soman, there was no recovery of neuromuscular function. Detailed studies in the guinea-pig showed that the recovery of neuromuscular function was related to the dose of soman and to the degree of carbamoylation of blood cholinesterase at the time of nerve agent challenge, i.e. to the dose of pyridostigmine and the time interval between the administration of pyridostigmine and soman. It is suggested that the effectiveness of pyridostigmine pretreatment is due to the carbamoylation of a portion of the tissue acetylcholinesterase, which protects it against irreversible inhibition by soman: after poisoning spontaneous decarbamoylation produces sufficient free acetylcholinesterase to restore normal function.
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PMID:Effectiveness of pyridostigmine in reversing neuromuscular blockade produced by soman. 2 7

The effect of physostigmine has been studied on cholinesterase in homogenates of chick biventer cervicis muscles and on the contractile responses of the intact muscles to acetylcholine and carbachol. The concentration of physostigmine required to produce the maximum increase in sensitivity to acetylcholine almost completely inhibited the cholinesterase in muscle homogenates. This concentration of physostigmine had no effect on muscle contractures elicited by carbachol. By taking account of the combined effects of acetylcholine diffusion and enzymic hydrolysis, a quantitative theoretical relationship has been derived between the level of cholinesterase activity in cylindrical muscles and the fractional occupancy of the acetylcholine receptors in these muscles in the presence of different concentrations of exogenous acetylcholine. This theory attributes the thousand-fold increase in sensitivity to exogenous acetylcholine produced by anticholinesterases in chick biventer cervicis muscles largely to an alteration in acetylcholine concentration gradient within the muscle and accounts satisfactorily for the shift in the dose-response curve for acetylcholine which occurs after treatment of the muscles with various concentrations of physostigmine.
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PMID:The relationship between cholinesterase inhibition in the chick biventer cervicis muscle and its sensitivity to exogenous acetylcholine. 2 8

Acetic acid was found to repress cholinesterase synthesis in the cells of Arthrobacter simplex var. cholinesterasus even at very low concentrations (0.1%). The repression is very stable. It is not eliminated by glucose or an organic acid of the Krebs cycle being added to the medium with acetic acid. The combination of acetic and butyric acids decreases the repression but does not eliminate it. The kinetics of cholinesterase synthesis was different in the cells grown on the medium with acetic acid and the cells cultivated on the medium with acetic acid and glucose, then washed and transferred to a fresh growth medium with glucose and acetylcholine as the sources of carbon.
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PMID:[Acetic acid, a catabolite repressor of cholinesterase synthesis by an Arthrobacter simplex culture]. 2 5

The authors studied the changes of erythrocyte acetylcholinesterase (AChE) activity in rabbits respectively subjected to bleeding, hypobaric hypoxia and CoCl2 treatment; in such conditions a rise of the enzyme activity was observed. Similar increases take place also as a consequence of intravenous infusions carried out by using lactic or hydrochloric acid. The authors suggest that these increases in the erythrocyte AChE activity are connected with the decrease of the pCO2 that occurs in the various experimental conditions achieved.
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PMID:Erythrocyte acetylcholinesterase activity changes in the early stages of anemic and hypobaric hypoxia or after CoCl2 treatment in rabbits. 2 34

Experiments were conducted on rabbits with tetanus intoxication induced by the intravenous injection of a lethal dose of the toxin; a study was made of the therapeutic efficacy of the acetylcholinesterase reactivators--dipyroxim and isonitrosine, and also of the central cholinolytics--amizyl and diphacyl. In dose of 25 mg/kg dipyroxim produced no therapeutic effect, and in doses of 30--40 mg/kg caused the animal death. Amizyl and diphacil in a dose of 3--4 mg/kg caused elimination of tonic convulsions for 1 1/2--2 hours. As to isonitrosin--it produced the same effect for 4--5 hours. In case of combined administration of reactivators and cholinolytics convulsions were eliminated for 4--5 hours.
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PMID:[Use of acetylcholinesterase reactivators and central cholinolytics in the treatment of experimental tetanus poisoning]. 2 62

The total and free acetylcholine (Ach) and cholinesterase (CHE) content of adult Setaria cervi were estimated. The Ach was estimated by bioassay on rectus abdominis muscle of frog and the CHE by measuring the drop in pH following incubation of worm homogenate with Ach chloride. The free and total Ach contents (4.0 +/- 0.57 and 6.0 +/- 0.48 microgram/g wet weight of worms respectively) were as high as found in mammalian brain cortex. The cholinesterase activity was found to be 5.57 +/- 0.6 units/g wet weight of worms. It is possible that there may exist a well developed system responsible for the synthesis, storage, release and destruction of Ach and that Ach may be acting as an excitatory neurohormone in S. cervi.
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PMID:Acetylcholine: a possible neurotransmitter in Setaria cervi. 2 90

Kinetic studies were made with 2 forms of immobilized acetylcholinesterase: enzyme trapped in polyacrylamide gel which was cut into slices; and enzyme attached to the inner surface of nylon tubing. Rates were measured at substrate concentrations which were low and high with reference to the Michaelis constant, and over the temperature range 16-40 degrees C. Low activation energies (1.7-2.7 kcal mol-1) were obtained at low substrate concentrations, indicating diffusion control. At high substrate concentrations the Arrhenius plots were non-linear and the activation energies substantially higher, and there is less diffusion control. With enzyme-polyacrylamide slices, there was a continuous increase in rate with increasing pH, in contrast to the bell-shaped behavior with free enzyme. A theoretical treatment suggests that this is due to the lowering of local pH as a result of the acid released in the hydrolysis.
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PMID:Temperature and pH effects with immobilized electric eel acetylcholinesterase. 2 73

1. In the posterior half of the pulvinar of cats anaesthetized with halothane and nitrous oxide, the majority of neurons were fired by ACh released with small electrophoretic currents. In the anterior part of that nucleus, ACh had more variable effects: excitation, depression or none. 2. In comparison with L-glutamate, DL-homocysteic acid and DL-aspartic acid, ACh appeared to be the most potent excitant. 3. ACh-induced discharges were easily and reversibly blocked by low doses of atropine. In most cases, ACh effects could not be blocked selectively by mecamylamine or dihydro-beta-erythroidine. 4. Nicotine failed to mimic ACh, whereas carbachol was a potent excitant and was readily blocked by low doses of atropine. 5. The histochemical reaction to acetylcholinesterase was moderate in the pulvinar. 6. These observations support the view that pulvinar cells differ from other thalamic cells.
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PMID:Micro-electrophoretic studies in the cat pulvinar region: effect of acetylcholine. 2 59

The in vitro effect of ten benzodiazepine derivatives on the cholinesterases of human plasma and red cells was determined. Flurazepam, temazepam, lorazepam, flunitrazepam and diazepam had an inhibitory effect on plasma cholinesterase of 60--90 per cent and, with the exception of lorazepam, an inhibitory effect of 40--50 per cent on red cell cholinesterase. Clonazepam, oxazepam, chlordiazepoxide, nitrazepam and bromazepam had comparatively minor effects on both enzymes
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PMID:Effect of benzodiazepine derivatives on human blood cholinesterase in vitro. 2 27


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