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Altered levels of acetylcholinesterase in Alzheimer plasma.

García-Ayllón MS, Riba-Llena I, Serra-Basante C, Alom J, Boopathy R, Sáez-Valero J - PLoS ONE (2010)

Bottom Line: Conventional assays using selective cholinesterase inhibitors have not been particularly successful as excess amounts of butyrylcholinesterase (BuChE) pose a major problem.The levels and pattern of the molecular forms are similar to that observed in individuals with silent BuChE.We have also compared plasma AChE with the enzyme pattern obtained from human liver, red blood cells, cerebrospinal fluid (CSF) and brain, by sedimentation analysis, Western blotting and lectin-binding analysis.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, San Juan de Alicante, Spain.

ABSTRACT

Background: Many studies have been conducted in an extensive effort to identify alterations in blood cholinesterase levels as a consequence of disease, including the analysis of acetylcholinesterase (AChE) in plasma. Conventional assays using selective cholinesterase inhibitors have not been particularly successful as excess amounts of butyrylcholinesterase (BuChE) pose a major problem.

Principal findings: Here we have estimated the levels of AChE activity in human plasma by first immunoprecipitating BuChE and measuring AChE activity in the immunodepleted plasma. Human plasma AChE activity levels were approximately 20 nmol/min/mL, about 160 times lower than BuChE. The majority of AChE species are the light G(1)+G(2) forms and not G(4) tetramers. The levels and pattern of the molecular forms are similar to that observed in individuals with silent BuChE. We have also compared plasma AChE with the enzyme pattern obtained from human liver, red blood cells, cerebrospinal fluid (CSF) and brain, by sedimentation analysis, Western blotting and lectin-binding analysis. Finally, a selective increase of AChE activity was detected in plasma from Alzheimer's disease (AD) patients compared to age and gender-matched controls. This increase correlates with an increase in the G(1)+G(2) forms, the subset of AChE species which are increased in Alzheimer's brain. Western blot analysis demonstrated that a 78 kDa immunoreactive AChE protein band was also increased in Alzheimer's plasma, attributed in part to AChE-T subunits common in brain and CSF.

Conclusion: Plasma AChE might have potential as an indicator of disease progress and prognosis in AD and warrants further investigation.

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Related in: MedlinePlus

AChE levels and molecular form pattern are altered in plasma samples from non-demented controls (ND) and Alzheimer's patients (AD).(A) Box plot comparing total plasma-AChE activity from 15 ND and 14 AD cases, AChE activity was calculated after BuChE depletion. AChE molecular forms were separated, identified by sedimentation analysis (representative profiles; left panel), and a G4/(G1+G2) ratio calculated (n = 6 for each group). * p<0.05 significantly different from NDs, as assessed by Student's t-test. (B) Total BuChE and molecular form pattern was also calculated, prior to immunoprecipitation, with no statistically significant differences between groups.
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pone-0008701-g004: AChE levels and molecular form pattern are altered in plasma samples from non-demented controls (ND) and Alzheimer's patients (AD).(A) Box plot comparing total plasma-AChE activity from 15 ND and 14 AD cases, AChE activity was calculated after BuChE depletion. AChE molecular forms were separated, identified by sedimentation analysis (representative profiles; left panel), and a G4/(G1+G2) ratio calculated (n = 6 for each group). * p<0.05 significantly different from NDs, as assessed by Student's t-test. (B) Total BuChE and molecular form pattern was also calculated, prior to immunoprecipitation, with no statistically significant differences between groups.

Mentions: The level of plasma AChE in BuChE immunodepleted samples obtained from AD patients were screened for activity. The AChE assay revealed that AD-plasma samples had higher activity, (20% increase; p = 0.01), in comparison to age and gender-matched controls, while no change was found in BuChE levels (Fig 4A). To determine if the AChE molecular pattern is altered in AD plasma, the supernatants of BuChE immunoprecipitated samples were fractionated on sucrose density gradients. In AD plasma, a slight decrease was observed in the minor G4 peak, and an increase in the G1+G2 species, resulting in a significant decrease in the G4/(G1+G2) ratio (p = 0.006) (Fig 4B). The BuChE levels and G4/(G2+G1) ratio of the AD group were indistinguishable from the control group (Fig 4B).


Altered levels of acetylcholinesterase in Alzheimer plasma.

García-Ayllón MS, Riba-Llena I, Serra-Basante C, Alom J, Boopathy R, Sáez-Valero J - PLoS ONE (2010)

AChE levels and molecular form pattern are altered in plasma samples from non-demented controls (ND) and Alzheimer's patients (AD).(A) Box plot comparing total plasma-AChE activity from 15 ND and 14 AD cases, AChE activity was calculated after BuChE depletion. AChE molecular forms were separated, identified by sedimentation analysis (representative profiles; left panel), and a G4/(G1+G2) ratio calculated (n = 6 for each group). * p<0.05 significantly different from NDs, as assessed by Student's t-test. (B) Total BuChE and molecular form pattern was also calculated, prior to immunoprecipitation, with no statistically significant differences between groups.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2806824&req=5

pone-0008701-g004: AChE levels and molecular form pattern are altered in plasma samples from non-demented controls (ND) and Alzheimer's patients (AD).(A) Box plot comparing total plasma-AChE activity from 15 ND and 14 AD cases, AChE activity was calculated after BuChE depletion. AChE molecular forms were separated, identified by sedimentation analysis (representative profiles; left panel), and a G4/(G1+G2) ratio calculated (n = 6 for each group). * p<0.05 significantly different from NDs, as assessed by Student's t-test. (B) Total BuChE and molecular form pattern was also calculated, prior to immunoprecipitation, with no statistically significant differences between groups.
Mentions: The level of plasma AChE in BuChE immunodepleted samples obtained from AD patients were screened for activity. The AChE assay revealed that AD-plasma samples had higher activity, (20% increase; p = 0.01), in comparison to age and gender-matched controls, while no change was found in BuChE levels (Fig 4A). To determine if the AChE molecular pattern is altered in AD plasma, the supernatants of BuChE immunoprecipitated samples were fractionated on sucrose density gradients. In AD plasma, a slight decrease was observed in the minor G4 peak, and an increase in the G1+G2 species, resulting in a significant decrease in the G4/(G1+G2) ratio (p = 0.006) (Fig 4B). The BuChE levels and G4/(G2+G1) ratio of the AD group were indistinguishable from the control group (Fig 4B).

Bottom Line: Conventional assays using selective cholinesterase inhibitors have not been particularly successful as excess amounts of butyrylcholinesterase (BuChE) pose a major problem.The levels and pattern of the molecular forms are similar to that observed in individuals with silent BuChE.We have also compared plasma AChE with the enzyme pattern obtained from human liver, red blood cells, cerebrospinal fluid (CSF) and brain, by sedimentation analysis, Western blotting and lectin-binding analysis.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, San Juan de Alicante, Spain.

ABSTRACT

Background: Many studies have been conducted in an extensive effort to identify alterations in blood cholinesterase levels as a consequence of disease, including the analysis of acetylcholinesterase (AChE) in plasma. Conventional assays using selective cholinesterase inhibitors have not been particularly successful as excess amounts of butyrylcholinesterase (BuChE) pose a major problem.

Principal findings: Here we have estimated the levels of AChE activity in human plasma by first immunoprecipitating BuChE and measuring AChE activity in the immunodepleted plasma. Human plasma AChE activity levels were approximately 20 nmol/min/mL, about 160 times lower than BuChE. The majority of AChE species are the light G(1)+G(2) forms and not G(4) tetramers. The levels and pattern of the molecular forms are similar to that observed in individuals with silent BuChE. We have also compared plasma AChE with the enzyme pattern obtained from human liver, red blood cells, cerebrospinal fluid (CSF) and brain, by sedimentation analysis, Western blotting and lectin-binding analysis. Finally, a selective increase of AChE activity was detected in plasma from Alzheimer's disease (AD) patients compared to age and gender-matched controls. This increase correlates with an increase in the G(1)+G(2) forms, the subset of AChE species which are increased in Alzheimer's brain. Western blot analysis demonstrated that a 78 kDa immunoreactive AChE protein band was also increased in Alzheimer's plasma, attributed in part to AChE-T subunits common in brain and CSF.

Conclusion: Plasma AChE might have potential as an indicator of disease progress and prognosis in AD and warrants further investigation.

Show MeSH
Related in: MedlinePlus