β-Amyloid Peptide Activates Non-α7 Nicotinic Acetylcholine Receptors in Rat Basal Forebrain Neurons

2003 ◽  
Vol 90 (5) ◽  
pp. 3130-3136 ◽  
Author(s):  
Wen Fu ◽  
Jack H. Jhamandas
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Basal Forebrain ◽  
Single Channel ◽  
Amyloid Peptide ◽  
Nicotinic Acetylcholine ◽  
Whole Cell ◽  
Β Amyloid ◽  
Forebrain Neurons ◽  
Β Amyloid Peptide ◽  
Α7 Nachrs

Alzheimer's disease (AD) is a progressive neurodegenerative condition characterized by profound deficits in memory and cognitive function. Neuropathological hallmarks of the disease include a loss of basal forebrain cholinergic neurons and the deposition of β-amyloid peptide (Aβ) in neuritic plaques. At a cellular level, considerable attention has focused on a study of Aβ interactions with the neuronal nicotinic acetylcholine receptor (nAChR) subtypes. In this study, using cell-attached and outside-out single channel recordings from acutely dissociated rat basal forebrain neurons, we report that Aβ and nicotine activate nAChRs with two distinct levels of single-channel conductance. Whole cell recordings from these neurons reveal Aβ and nicotine, in a concentration-dependent and reversible manner, evoke brisk depolarizing responses and an inward current. The effects of Aβ on both single channel and whole cell are blocked by the noncompetitive nAChR antagonist mecamylamine and competitive nAChR antagonist dihydro-beta-erythroidine, but not the specific α7-selective nAChR antagonist methyllycaconitine, indicating that Aβ activated non-α7 nAChRs on basal forebrain neurons. In addition, the non-α7 nAChR agonists UB-165, epibatidine, and cytisine, but not the selective α7 agonist AR-R17779, induced similar responses as Aβ and nicotine. Thus non-α7 nAChRs may also represent a novel target in mediating the effects of Aβ in AD.

scholarly journals Type I-like behavior of the type II α7 nicotinic acetylcholine receptor positive allosteric modulator A-867744

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7542 ◽  
Author(s):  
Krisztina Pesti ◽  
Peter Lukacs ◽  
Arpad Mike
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Single Channel ◽  
High Temporal Resolution ◽  
Type I ◽  
Type Ii ◽  
Nicotinic Acetylcholine ◽  
Fast Kinetics ◽  
Temporal Precision ◽  
Α7 Nachr ◽  
Α7 Nachrs

Cognitive impairment often involves the decreased expression or hypofunction of alpha 7-type nicotinic acetylcholine receptors (α7 nAChRs). Agonists or positive allosteric modulators (PAMs) of α7 nAChRs are known to be potential treatments for dementias, different neurodegenerative disorders, pain syndromes and conditions involving inflammation. In some of these conditions, it is desirable to maintain the temporal precision of fast cholinergic events, while in others, this temporal precision is unnecessary. For this reason, the optimal therapeutic effect for distinct indications may require PAMs with different mechanisms of action. The two major mechanisms are called “type I”, which are compounds that augment α7 nAChR-mediated currents but maintain their characteristic fast kinetics; and “type II”, which are compounds that produce augmented and prolonged currents. In this study, we performed a kinetic analysis of two type II PAMs of the α7 nAChR: PNU-120596 and A-867744, using a fast perfusion method that allowed high temporal resolution. We characterized the type of modulation produced by the two compounds, the state-dependence of the modulatory action, and the interaction between the two compounds. We found fundamental differences between the modulation mechanisms by PNU-120596 and A-867744. Most importantly, during brief agonist pulses, A-867744 caused a strikingly type I-like modulation, while PNU-120596 caused a type II-like prolonged activation. Our results demonstrate that specific compounds, even though all labeled as type II PAMs, can behave in completely different ways, including their onset and offset kinetics, state preference, and single channel open time. Our results emphasize that subtle details of the mechanism of action may be significant in assessing the therapeutic applicability of α7 nAChR PAM compounds.

scholarly journals Choline Modulation of the Aβ P1-40 Channel Reconstituted into a Model Lipid Membrane

2010 ◽  
Vol 2010 ◽  
pp. 1-12
Author(s):  
Daniela Meleleo ◽  
Gabriella Notarachille ◽  
Silvia Micelli
Keyword(s):  
Lipid Bilayers ◽  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Lipid Membrane ◽  
Cd Spectroscopy ◽  
Amyloid Peptide ◽  
Random Coil ◽  
Ion Conductance ◽  
Β Amyloid ◽  
Β Amyloid Peptide

Nicotinic acetylcholine receptors (AChRs), implicated in memory and learning, in subjects affected by Alzheimer's disease result altered. Stimulation of α7-nAChRs inhibits amyloid plaques and increases ACh release. β-amyloid peptide (AβP) forms ion channels in the cell and model phospholipid membranes that are retained responsible in Alzheimer disease. We tested if choline, precursor of ACh, could affect the AβP1-40 channels in oxidized cholesterol (OxCh) and in palmitoyl-oleoyl-phosphatidylcholine (POPC):Ch lipid bilayers. Choline concentrations of 5 × 10−11 M–1.5 × 10−8 M added to thecis- ortrans-side of membrane quickly increased AβP1-40 ion channel frequency (events/min) and ion conductance in OxCh membranes, but not in POPC:Ch membranes. Circular Dichroism (CD) spectroscopy shows that after 24 and 48 hours of incubation with AβP1-40, choline stabilizes the random coil conformation of the peptide, making it less prone to fibrillate. These actions seem to be specific in that ACh is ineffective either in solution or on AβP1-40 channel incorporated into PLMs.

scholarly journals Curcumin Potentiates α7 Nicotinic Acetylcholine Receptors and Alleviates Autistic-Like Social Deficits and Brain Oxidative Stress Status in Mice

2021 ◽  
Vol 22 (14) ◽  
pp. 7251
Author(s):  
Petrilla Jayaprakash ◽  
Dmytro Isaev ◽  
Waheed Shabbir ◽  
Dietrich E. Lorke ◽  
Bassem Sadek ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Pathological Condition ◽  
Repetitive Behaviors ◽  
Social Deficits ◽  
Nicotinic Acetylcholine ◽  
Oxidative Stress Status ◽  
Inward Currents ◽  
Α7 Nachrs

Autistic spectrum disorder (ASD) refers to a group of neurodevelopmental disorders characterized by impaired social interaction and cognitive deficit, restricted repetitive behaviors, altered immune responses, and imbalanced oxidative stress status. In recent years, there has been a growing interest in studying the role of nicotinic acetylcholine receptors (nAChRs), specifically α7-nAChRs, in the CNS. Influence of agonists for α7-nAChRs on the cognitive behavior, learning, and memory formation has been demonstrated in neuro-pathological condition such as ASD and attention-deficit hyperactivity disorder (ADHD). Curcumin (CUR), the active compound of the spice turmeric, has been shown to act as a positive allosteric modulator of α7-nAChRs. Here we hypothesize that CUR, acting through α7-nAChRs, influences the neuropathology of ASD. In patch clamp studies, fast inward currents activated by choline, a selective agonist of α7-nAChRs, were significantly potentiated by CUR. Moreover, choline induced enhancement of spontaneous inhibitory postsynaptic currents was markedly increased in the presence of CUR. Furthermore, CUR (25, 50, and 100 mg/kg, i.p.) ameliorated dose-dependent social deficits without affecting locomotor activity or anxiety-like behaviors of tested male Black and Tan BRachyury (BTBR) mice. In addition, CUR (50 and 100 mg/kg, i.p.) mitigated oxidative stress status by restoring the decreased levels of superoxide dismutase (SOD) and catalase (CAT) in the hippocampus and the cerebellum of treated mice. Collectively, the observed results indicate that CUR potentiates α7-nAChRs in native central nervous system neurons, mitigates disturbed oxidative stress, and alleviates ASD-like features in BTBR mice used as an idiopathic rodent model of ASD, and may represent a promising novel pharmacological strategy for ASD treatment.

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