Bioactivity of a peptide derived from acetylcholinesterase in hippocampal organotypic cultures.

Abstract

While the molecular basis underlying the non-classical actions of acetylcholinesterase (AChE) is presently unknown, a candidate peptide sequence located at the C-terminus of AChE (AChE-peptide) has recently been identified. This study explored the bioactivity of synthetic AChE-peptide using in vitro organotypic cultures of rat hippocampus. Neurotrophic effects, detected as increased neurite outgrowth from MAP-immunopositive neurones, were apparent using 1 h exposure to 1-10 nM AChE-peptide. As exposure time increased, cell death occurred as indicated by TdT-mediated dUTP biotin nick-end labelling (TUNEL). This process was accelerated at higher AChE-peptide concentrations, with lactate dehydrogenase (LDH) efflux observed following prolonged exposure to 1-10 microM AChE-peptide. Apoptotic cells were detected by Hoechst 33342 staining following 24 h application of 10 nM AChE-peptide. However, propidium iodide reactivity revealed a simultaneous loss of membrane integrity indicative of necrosis, suggesting that AChE-peptide induces cell death via a continuum of apoptotic and necrotic processes. Prolonged exposure to AChE-peptide also resulted in a concentration-dependent reduction in neurite outgrowth from MAP2-positive neurons, although immunohistochemical studies provided some evidence of differential responsiveness in GABAergic, cholinergic and somatostatin neurones. In addition, bioactivity was sequence specific since a scrambled AChE-peptide analogue, as well as the corresponding BuChE-peptide, was ineffective. In conclusion, the bioactivity associated with the AChE-peptide sequence may account for the non-cholinergic actions of AChE, whilst its neurotrophic-apoptotic-necrotic spectrum of action may be involved in the aetiology of neurodegenerative disorders such as Alzheimer's disease.

• Authors: T Day, S A Greenfield
• Journal: Experimental brain research (Exp Brain Res) Vol. 155 Issue 4 Pg. 500-8 (Apr 2004) ISSN: 0014-4819 [Print] Germany
• PMID: 14685807 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Enzyme Inhibitors
• Microtubule-Associated Proteins
• Nerve Growth Factors
• Neuropeptides
• Neurotoxins
• L-Lactate Dehydrogenase
• Acetylcholinesterase

Topics

• Acetylcholinesterase (metabolism)
• Alzheimer Disease (enzymology, physiopathology)
• Animals
• Animals, Newborn
• Apoptosis (drug effects, physiology)
• Base Sequence (physiology)
• Cell Communication (physiology)
• Cell Death (drug effects, physiology)
• Dose-Response Relationship, Drug
• Enzyme Inhibitors (pharmacology)
• Hippocampus (cytology, drug effects, enzymology)
• L-Lactate Dehydrogenase (metabolism)
• Microtubule-Associated Proteins (metabolism)
• Necrosis
• Nerve Growth Factors (metabolism, pharmacology)
• Neurites (drug effects, pathology)
• Neurons (cytology, drug effects, enzymology)
• Neuropeptides (metabolism, pharmacology)
• Neurotoxins (metabolism, pharmacology)
• Organ Culture Techniques
• Rats
• Rats, Wistar
• Reaction Time (drug effects, physiology)