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)

Electroretinographic changes induced by organophosphorus pesticides (OPs) were studied in rats. Male Wistar rats were intraperitoneally injected with fenthion, chlorpyrifos, fenitrothion, dichlorvos or chlorfenvinphos at doses of 0.01 mmol/kg and/or 0.05 mmol/kg. The electroretinogram (ERG) was recorded at 5 hours and 2 days after the administration, and brain and retinochoroid cholinesterase (ChE) activities was assayed at 3 days after the injections. The brain and retinochoroid ChE activities were reduced in rats treated with the OPs. Notably, the reduction of ChE activities by fenthion, chlorpyrifos and dichlorvos were similar. The administration of OPs induced a change in the ERG, characterized by alteration of the amplitudes of a- and b-waves. Nevertheless the ChE activities in the brain and retinochoroid were inhibited by all of the OPs, the OPs affected the amplitude of ERG differently. Fenthion and chlorpyrifos decreased the amplitudes; dichlorvos and chlorfenvinphos increased; and fenitrothion transiently decreased at 5 hours but increased 2 days after the injection. These results indicate that a factor or factors other than inhibition of ChE activities contributes to the alteration of ERG induced by OPs.
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PMID:Electroretinographic changes induced by organophosphorus pesticides in rats. 169 27

Fenthion, an irreversible cholinesterase inhibitor, was used to study the role of the cholinergic system on the development of gizzard erosion. Fenthion increases the gizzard erosion score in a dose-dependent manner and this effect became significant at levels higher than .1 ppm (p less than .05). An inverse relationship between plasma cholinesterase activity and pesticide concentration was also observed at doses higher than 1 ppm (P less than .05). These results show the necessity to evaluate organophosphate pesticide levels during the selection of fish meals in poultry.
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PMID:Research note: ability of fenthion to increase gizzard erosion in broiler chicks. 188 75

To assess the utility of phosphinates as pretreatments against nerve agents, experiments were conducted to determine whether oximes can reactivate phosphinate-inhibited guinea pig acetylcholinesterase (AChE) and whether the toxicity of phosphinates is reduced by treatment with atropine and/or oxime. Three phosphinates, 4-nitrophenyl methyl(phenyl) phosphinate (MPP), 4-nitrophenyl chloromethyl(phenyl) phosphinate (CMPP), and 4-nitrophenyl 2-methoxyphenyl(methyl) phosphinate (MPMP), were used in these experiments. In the first group of experiments, 2-PAM or HI-6 was administered, im, 2 min after peak inhibition of whole blood AChE activity by the phosphinates. Both oximes significantly reactivated MPP- or CMPP-inhibited AChE; however, HI-6 was the better reactivator in both cases. Oximes were ineffective against MPMP. Efficacy studies revealed that neither HI-6 nor 2-PAM potentiated the toxic effects of MPP or CMPP and that atropine/oxime therapy provided greater protection (up to 100 LD50s) against either phosphinate than any single therapy. The reactivation and efficacy data, especially for CMPP, support the concept that oxime sensitive phosphinates may be useful as pretreatments against nerve agent intoxication.
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PMID:Evaluation of phosphinates as potential pretreatments for nerve agents. 204 71

An organophosphorus pesticide (OP) inhibits acetylcholinesterase (AChE) of various organs, especially in cholinergically innervated organs. Pupil constriction is a major sign of an ocular symptom in the patient with acute OP intoxication, but the etiology is unknown. The present experiments were intended to elucidate a central mechanism of pupil size in which AChE and OP are involved. Fenthion (dimethyl 4-methylthion-m-tolyl phosphorothionate) of 5mg/day body weight) was subcutaneously administered dorsally in Wistar rats for 14 days consecutively in the longest group. Histochemical staining and microspectrophotometry were used to analyze the intensity of the AChE activity in the iris, the pretectal nucleus and Edinger-Westphal (EW) nucleus on the 2nd, 4th, 6th, 10th and 14th day of administration. The pupil was measured after 20 minutes of dark adaptation. The pupil constricted on the 6th day and most remarkably on the 10th day. The AChE activity in the iris decreased remarkably on the 4th day. Miosis was not seen on the 4th day. The AChE activity in the pretectal nucleus decreased remarkably on the 6th day. The AChE activity in the EW nucleus reduced gradually from the 6th day and 62% reduction of initial value was seen on the 14th day. Intense miosis was seen on the 10th day. In conclusion inhibition of AChE activity was detected first in the iris, thereafter in the pretectal nucleus and the EW nucleus in close correlation with the miotic pupil. Therefore, miosis associated with OP intoxicated patients may parallel the central inhibition of AChE in pupil-related centers.
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PMID:[Inhibition of acetylcholinesterase at pupil-related central nuclei by organophosphorus pesticide (fenthion)--an experimental study]. 277 98

To study the effect of occupational organophosphate exposure on neuromuscular function, 24 workers exposed to fenthion [0,0-dimethyl-0(4-methyl mercapto-3 methyl phenyl)phosphorothioate], whose mean age was 31.7 years (range 22-50) and mean duration of exposure to fenthion 8.5 years (range 1-19) were subjected to detailed clinical and neurophysiological evaluation after spraying. The neurophysiological tests included motor and sensory nerve conduction velocity; F response, H reflex and electromyographic neuromuscular synapse testing. Fenthion exposure was monitored by serum acetyl cholinesterase (AchE) levels. The observations were repeated after withdrawing the workers from fenthion exposure for 3 weeks to study the reversibility of the observed changes. There was no clinical evidence of peripheral neuropathy or muscle weakness. However, peroneal motor conduction velocity (p less than 0.05) terminal motor latency of median (p less than 0.1), and peroneal nerve (p less than 0.05); F minimal latency and H reflex latency (p less than 0.01) were significantly affected. Twenty-nine per cent of workers had repetitive muscle activity. Serum AchE levels also showed significant changes (p less than 0.01). The clinical significance of these subtle neurophysiological changes requires further investigation and follow-up.
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PMID:A study of nerve conduction velocity, late responses and neuromuscular synapse functions in organophosphate workers in India. 319 Apr 48

1. Adult black ducks (Anas rubripes) were given freshwater or saltwater (1.5% NaCl) for 11 days and half of each group was also given an organophosphate (17 p.p.m. fenthion) in the diet on days 6-11. 2. After 11 days, ducks drinking saltwater had lost more weight and had higher plasma Na and uric acid concentrations and osmolalities than birds drinking freshwater. 3. Saltwater treatment stimulated the salt gland to increased weight and Na, K-ATPase activity. 4. Fenthion generally reduced plasma and brain cholinesterase activity and depressed cholinesterase and Na, K-ATPase activities in salt glands of birds drinking saltwater.
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PMID:Organophosphate inhibition of avian salt gland Na, K-ATPase activity. 612 65

Brain and plasma cholinesterase (ChE) activities were determined for mallard ducklings (Anas platyrhynchos) exposed to dicrotophos and fenthion. Recovery rates of brain ChE did not differ between ducklings administered a single oral dose vs. a 2-week dietary dose of these organophosphates. Exposure to the organophosphates, followed by recovery of brain ChE, did not significantly affect the degree of brain ChE inhibition or the recovery of ChE activity at a subsequent exposure. Recovery of brain ChE activity followed the general model Y = a + b(logX) with rapid recovery to about 50% of normal, followed by a slower rate of recovery until normal ChE activity levels were attained. Fenthion and dicrotophos-inhibited brain ChE were only slightly reactivated in vitro by pyridine-2-aldoxime methiodide, which suggested that spontaneous reactivation was not a primary method of recovery of ChE activity. Recovery of brain ChE activity can be modeled for interpretation of sublethal inhibition of brain ChE activities in wild birds following environmental applications of organophosphates. Plasma ChE activity is inferior to brain ChE activity for environmental monitoring, because of its rapid recovery and large degree of variation among individuals.
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PMID:Recovery of brain and plasma cholinesterase activities in ducklings exposed to organophosphorus pesticides. 722 73

Organophosphate (OP) poisoning produces various forms of acute, subacute, or delayed neurotoxicity. We investigated in vivo the relationship between clinical, histochemical and electromyographic (EMG) parameters in rats at various stages of poisoning by paraoxon or fenthion. Paraoxon is acutely toxic, whereas fenthion produces more sustained AChE inhibition. Fenthion has been involved in a subacute type of OP-related neurotoxicity in patients, the so-called intermediate syndrome. The animals underwent serial EMGs, with single and repetitive nerve stimulation, and concomitant contralateral muscle biopsies to determine the end-plate acetylcholinesterase (AChE) activity. Repetitive activity (RA) after single nerve stimulation and decrements on repetitive nerve stimulation (RNS) were the major EMG findings in either type of poisoning, occurring in the initial and later stages of the poisoning, respectively. RA was highly correlated to fasciculations in acute, but not in prolonged intoxication. Amplitude decrements provoked by RNS occurred only in weak rats with severe end-plate AChE inhibition. The smallest amplitude occurred either at the second response with gradual improvement in the subsequent responses (decrement-increment phenomenon), or the amplitude decrease progressed up to the last response (decrement phenomenon). The decrement-increment phenomenon preceded the decrement phenomenon and occurred at a slightly less severe degree of AChE inhibition. Various types of impairment of neuromuscular transmission coexist, probably to a different extent at distinct stages of anticholinesterase poisoning.
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PMID:Electromyography in relation to end-plate acetylcholinesterase in rats poisoned by different organophosphates. 799 Dec 22

The intermediate syndrome in organophosphate poisoning is clinically characterized by weakness in the territory of cranial nerves, weakness of respiratory, neck and proximal limb muscles, and depressed deep tendon reflexes. It occurs between the acute cholinergic crisis and the usual onset of organophosphate-induced delayed neurotoxicity. The weakness has been ascribed to muscle fiber necrosis. Fenthion has been the most common cause. This study assesses the occurrence of the necrotizing myopathy in rats in relation to the clinical course and the acetylcholinesterase (AChE) inhibition after poisoning with organophosphates representative for each of the major types of organophosphate-related neurotoxicity. Marked differences are noted in the duration of cholinergic symptoms and of AChE inhibition after either paraoxon and mipafox, or fenthion poisoning. The necrotizing myopathy begins shortly after the initial decline in AChE activity with all organophosphates studied. Maximal muscle involvement occurs within the first 2 days of the poisoning with all organophosphates studied. The myopathy is not aggravated by a further decline in AChE activity in fenthion poisoning. Our data argues against the monophasic necrotizing myopathy being the cause of the intermediate syndrome, and is suggestive of persistent AChE inhibition being involved.
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PMID:Acute and subacute organophosphate poisoning in the rat. 799 Dec 23

Several reports have suggested that exposure to organophosphate pesticides damages the visual system. The prolonged effects of an acute dose of fenthion (dimethyl 3-methyl-4-methylthiophenyl phosphorothionate) were studied on the cholinergic system of the rat retina. Fenthion was administered in a single dose of 0 or 100 mg/kg (sc, in corn oil) to adult, male, Long-Evans rats. The animals were killed 4, 14, or 56 days after treatment and cholinesterase (ChE) activity as well as muscarinic receptor (mChR) function measured in the retina and frontal cortex. Fenthion produced 89% inhibition of ChE activity in both tissues at 4 days, and, although there was recovery, slight (15%) inhibition of the enzyme activity was still observed at 56 days in both tissues. A long-lasting decrease in carbachol-stimulated inositolphosphate (IP) release was observed following fenthion treatment in the retina: IP release was depressed at 4 days and this depression persisted up to 56 days after dosing. The density of mChR in the retina as well as in the cortex was decreased by 14-20% at 4 days and returned to control levels by 56 days. Fenthion had no effect on the metabolism of phospholipids in the retina following intraocular injections of labeled precursors [3H]myo-inositol, [methyl-14C]choline, or [2-3H]glycerol 4 days after fenthion treatment. These prolonged effects of fenthion on mChR function (signal transduction) appear to be specific to the retina as the cortex showed no change in receptor-stimulated IP release even in the presence of significant mChR down-regulation and ChE inhibition. This dose of fenthion did not produce overt morphological changes in the retina or in the cortex, as observed with light microscopy, although an increase in glial fibrillary acidic protein immunoreactivity (GFAP IR) extending from the internal limiting membrane to the external limiting membrane of the retina was noted. This increase in GFAP IR was observed at 14 days and persisted as long as 56 days post-treatment in the retina, but was not noted in the cortex at any of the time points studied. Thus, this long-lasting perturbation in the retinal cholinergic second messenger system induced by fenthion may occur independently of depressed ChE activity and down-regulation of mChR.
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PMID:Fenthion produces a persistent decrease in muscarinic receptor function in the adult rat retina. 817 35


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