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)

Ethylcholine aziridinium ion (AF64A), a putative cholinotoxin, was administered into the cerebroventricles of rats, and the effects on learning behaviors were observed. AF64A caused the impairment of learning acquisition in both passive and active avoidance responses. Physostigmine, a cholinesterase inhibitor, antagonized these changes at the doses of 0.03 to 0.1 mg/kg. Our behavioral study may indicate that the central cholinergic system might play a role in AF64A-induced impairment.
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PMID:Effects of physostigmine on AF64A-induced impairment of learning acquisition in rats. 368 13

The acute effects of atropine (0.01-1.0 mg/kg) on pigeons' key-pecking maintained under a variable-interval (VI) 60-sec schedule of food reinforcement were determined. Atropine decreased key-peck rates in a dose-dependent manner. A rate-decreasing dose of physostigmine, an acetylcholinesterase inhibitor, was studied in combination with the range of atropine doses. The rate reduction produced by physostigmine was attenuated by some doses of atropine. An atropine dose which decreased key-peck rates was then administered to the pigeons every day after their experimental sessions (chronic post-session phase). During this regimen, the dose-effect curves for atropine and the combination of atropine and physostigmine were redetermined. Atropine was then given chronically prior to experimental sessions (chronic pre-session phase), and the dose-effect curves for atropine and the combinations of atropine and physostigmine were determined again. The pigeons became tolerant to the rate-reducing effects of atropine following chronic post-session administration. Physostigmine's effect alone was unchanged following chronic atropine administration for two pigeons, and was slightly greater for a third. The rate reduction caused by physostigmine was attenuated across a wider range of atropine doses in the two pigeons for which the effect of physostigmine alone was unchanged. The atropine/physostigmine interaction curve for the third pigeon was shifted to the right following chronic post-session atropine administration. No further changes in effects of either atropine alone or in combination with physostigmine were seen following chronic pre-session atropine administration.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Alterations in the effects of atropine on the behavior of pigeons following chronic administration. 368 73

The effectiveness of physostigmine and atropine pretreatment against the lethal effects of sarin was studied in rats given lethal subcutaneous injections (130 micrograms/kg) of the organophosphate. Pretreatment of these animals with physostigmine 30 min prior to injection of sarin reduced mortality to 28% and when the drug coadministered with atropine only 4% of the animals died. The latter treatment also reduced significantly the extent and duration of symptoms due to sarin; however, atropine, pyridostigmine, and neostigmine injected alone did not protect animals against the lethal effects of sarin. Physostigmine caused only slight inhibition of cholinesterase in blood and skeletal muscle. Cholinesterase activity in blood and muscle of rats pretreated with physostigmine before sarin administration was significantly higher than in tissues from rats injected with sarin alone. In rats receiving sarin following pretreatment with physostigmine, twitch potentiation of extensor muscles and maintenance of tension during tetanic stimulation of the nerve recovered to near control levels. Muscle function recovered despite significant inhibition of cholinesterase. Effective protection against lethality by physostigmine could be related to protection of cerebral cholinesterase since inhibition of this enzyme by sarin was lowered significantly after pretreatment with physostigmine. Alternatively, physostigmine may also interact with the nicotinic acetylcholine receptor ion-channel complex directly.
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PMID:Effectiveness of physostigmine as a pretreatment drug for protection of rats from organophosphate poisoning. 369 40

The relationship between physostigmine (Phy) concentration, acetylcholine (ACh), choline (Ch) and cholinesterase (ChE) activity was examined in whole rat brain after the administration of [3H]Phy (650 microgram/kg i.m.). Cholinesterase inhibition was found to be inversely related to Phy levels. Maximal inhibition (80%) was seen at 5 min and by 2 hrs ChE activity had returned to control levels. Acetylcholine levels in whole brain peaked at 30 min at a concentration (80 nmol/g) 2.3 times higher than controls (33 nmol/g). Choline levels were not significantly altered. The regional distribution of Phy concentration and ChE activity was studied in six areas of the brain following i.m. administration of three different dosages of ( 3H]Phy. Physostigmine concentration and ChE activity showed a dose dependency in each area examined except in SP (medial septum). Striatum (ST) showed the greatest relative increase of ACh up to 30 min, when compared to other areas. Choline levels were not changed in any area with the exception of ST at 5 min where a decrease was seen. There was a relationship between ChE activity, Phy concentration and ACh levels in all areas examined with exception of the medulla oblongata (MO). Our results indicate that even though ChE was inhibited practically uniformly in all brain areas, the percent increase with respect to control animals and the relative increase of ACh varied widely from area to area. This finding has clinical implications in cases in which cholinomimetic therapy is used to elevate ACh levels in specific brain areas which show a cholinergic deficit.
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PMID:Relation of brain regional physostigmine concentration to cholinesterase activity and acetylcholine and choline levels in rat. 374 73

Cerebral cortical ischemia was induced in anesthetized rats by occlusion of the middle cerebral artery (MCA). Cerebral blood flow (CBF) was measured with the H2 clearance technique in the center and periphery of the ischemic territory. A decrease of CBF to about 50% of pre-occlusion values was observed in both areas. Administration of Physostigmine, a cholinesterase inhibitor, at a dose of 0.15 mg/Kg by intravenous route, induced an increase of CBF in the ischemic cortex. This change in CBF reached 120% of pre-occlusion level in the periphery and 80% of pre-occlusion value in the center of the area of distribution of the occluded artery. Although Physostigmine induced an increase in arterial blood pressure, the cerebral hyperemia observed both in normal and ischemic cortex could still be demonstrated after blockade of the pressor effect by bleeding or Phentolamine administration.
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PMID:Physostigmine induced reversal of ischemia following acute middle cerebral artery occlusion in the rat. 376 45

Alzheimer patients were treated with lecithin and gradually increasing doses of oral physostigmine during a drug trial to determine if these compounds would improve memory. Memory was measured using a selective reminding task. Of 16 patients, 10 showed improvement in total recall, retrieval from long-term storage and a decrease in intrusions. The optimal dose was 2.0 mg or 2.5 mg of physostigmine per dose for most patients. During a replication study, all 10 patients again responded. During long-term (4 to 20 months) treatment of five patients, most demonstrated continued drug response initially but then lost responsiveness to physostigmine and their dementia progressed. Physostigmine treatment appeared to improve memory with or without concomitant lecithin therapy. However, progressive dementia ensued despite physostigmine therapy. The degree of memory improvement correlated with increasing cerebrospinal fluid cholinesterase inhibition suggesting that memory improvement is associated with entry of physostigmine into the brain.
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PMID:Acute and chronic effects of oral physostigmine and lecithin in Alzheimer's disease. 379 88

Escape from acetylcholine-induced dilatation of gastric submucosal arterioles was studied using in vivo microscopy in rats. Acetylcholine, physostigmine and atropine were applied topically to the submucosa. Experiments were videotaped and diameter changes of the submucosal arterioles were measured with an image splitting technique on playback of the videotapes. Acetylcholine, 10(-6) M and 10(-5) M, caused prompt dilatation of arterioles in a dose-dependent manner, and the dilatation was rapidly followed by escape (return of vessel diameter toward basal diameter in spite of the continued presence of acetylcholine). The escape from acetylcholine-induced dilatation was prevented by physostigmine in a dose-dependent manner, 10(-2) M completely inhibiting the escape. Physostigmine, by itself, 10(-4) M to 10(-2) M, dilated arterioles dose-dependently, and this dilatation was inhibited by atropine. These results indicate that escape of gastric submucosal arterioles from acetylcholine-induced dilatation is mediated by endogenous cholinesterase (catabolism of acetylcholine by endogenous cholinesterase), and basal arteriolar diameter may be determined, in part, by endogenous acetylcholine, this effect being modulated by endogenous cholinesterase.
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PMID:Escape of gastric submucosal arterioles from acetylcholine-induced dilatation. 382 94

Ocular myasthenia is a special form of general myasthenia gravis characterized by unilateral or bilateral ptosis and eye muscle pareses of distinct variability, depending on the time of day and the state of fatigue of the patient. Most important for diagnosis is the Tensilon test, which can, however, produce negative results. In such cases a combination of the Tensilon test with electromyography is indispensable. In ocular myasthenia there is not always an increase in the antibody titer against acetylcholine receptors in the blood. The treatment of ocular myasthenia is based on the application of cholinesterase inhibitors. The drug of choice is Mestinon; however, the reaction of the eye muscles to this drug is often unsatisfactory. Local application of cholinesterase inhibitors in the form of Eserine, Prostigmin etc. is an additional important therapy. Also in ocular myasthenia the modern treatment with Cortisone (alternate-day therapy with 100 mg Prednisone every second day) has proved very useful. Another possible method of interfering with the immunological systems of myasthenia is immunosuppression with Azathioprin or Cyclophosphamide. The pathognomonic significance of the thymus in the autoimmune process of myasthenia gravis is demonstrated by the good results obtained by thymectomy, which can also be performed successfully in ocular myasthenia, not only in young patients in whom the condition is severe, but also in older patients in whom it is chronic. Often, the therapeutic measures mentioned have to be tested one after another or in combination in order to achieve an optimal therapeutic effect.
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PMID:[Ocular myasthenia]. 399 98

The choline uptake system has been characterized in the albino rat iris. The isolated iris of the rat accumulates choline (Ch) by a high affinity (Km = 3.23 microM) and a low affinity (Km = 68.4 microM) process. The uptake of 1 microM Ch at 37 degrees C was inhibited in a dose-dependent manner by hemicholinium (IC50 is 70 microM) and by ouabain (IC50 is 1 mM). The high affinity uptake was temperature and sodium-dependent. At 0 degrees C uptake of Ch was reduced by over 85% and it was not sensitive to hemicholinium. This suggests that choline is taken up by a high affinity active transport into the cholinergic terminals of the iris. The uptake of 1 microM Ch at 37 degrees C was inhibited by 1 mM scopolamine and was reduced in a dose-dependent manner by the irreversible anticholinesterase diisopropylfluorophosphate (DFP). Physostigmine, an anti-cholinesterase lacking agonistic action, decreased the uptake of Ch to 73% of control at 1 mM. The rat iris is a much more homogeneous and readily accessible tissue than the CNS, therefore, it offers several advantages in pharmacological studies of drug action on a selective population of cholinergic terminals.
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PMID:Acute effects of cholinesterase inhibitors on uptake of choline in the rat iris. 400 Apr 6

Physostigmine, a centrally-acting cholinesterase inhibitor, has been shown to have potential as a treatment for primary degenerative dementia. In an experiment to test its effects, i.v. physostigmine caused the onset of unifocal premature contractions and runs of bigeminy in an 85-year-old man.
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PMID:Dose-related physostigmine-induced ventricular arrhythmia: case report. 404 37


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