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Title: Nicotinic acetylcholine receptors and their interaction with Aβ₁₋₄₂
Author: Crawford, Nicola
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2006
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Radioligand binding was used to characterise the α4β2 nAChR ([3H]-epibatidine and [3H]-cytisine) and α7 nAChR ([3H]-methyllycaconitine ([3H]-MLA) and [3H]-αBungarotoxin ([3H]-αBgTx)) in rat and mouse brain tissue and in SH-EP1 cell lines overexpressing human forms of the α4β2 or α7 nAChRs. No species difference in ligand affinities were observed for the α4β2 nAChR. In contrast, nicotinic agonists exhibited significantly higher affinity (~100 fold) for human α7 nACRs compared to their rat counterparts with no change in antagonist affinity. Interestingly, evaluation of [3H]-MLA and [3H]-αBgTx binding indicated the latter ligand bound to a restricted number of sites on the α7 nAChR. Furthermore, neither human nor rat Aβ1-42 inhibited [3G[-cytisine or [3H]-MLA binding to nAChRs. In parallel to behavioural studies, these binding assays were also employed to assess nAChR pharmacology in transgenic α7 knockout mice. With no alteration in α4β2 nAChR pharmacology, the deficit in sustained attention exhibited by these α7-KO mice is probably due to loss of the α7 nAChR. Finally, a series of studies were performed to examine the functional interaction between Aβ1-42 and nAChRs. (-)Nicotine evoked changes in calcium flux or membrane potential in SH-EP1-hα4β2 cells were not inhibited by soluble or insoluble human Aβ1-42. Even whole cell patch clamp analysis of single cells showed no direct interaction between the α4β2 nAChR and Aβ1-42. The examination of the functional interaction between α7 nAChRs and Aβ1-42 using whole cell patch clamp or fluorescence based assays was compromised by a lack of consistent expression of functional human α7 nAChRs in the SH-EP1 cell line. In addition, neither human α4β2 or α7 nAChRs co-immunoprecipitated with human Aβ1-42.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available