Poster Presentation 2014 International Biophysics Congress

Choline activates and modulates low-sensitivity α4β2neuronal nicotinic acetylcholine receptors (#281)

Ladislas Bizimana 1 , Nathan Absalom 1 , Philip K. Ahring 1 , Mary Collins Chebib 1 , Thomas Balle 1
  1. Faculty of Pharmacy, The University of Sydney, Sydney, NSW, Australia

Neuronal nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels situated on post synaptic neurons in cholinergic synapses where they mediate the response of acetylcholine (ACh). In the synapse, ACh esterase (AChE) is responsible for rapid termination of signaling by degradation of ACh to choline[1]. Choline has previously, dependent on concentration, been reported to potentiate and/or inhibit α7 and α4β4 receptors[2, 3]. In the present study we investigated its interaction with α4β2 nAChRs. The α4β2 nAChR is the most abundant nAChR in the human brain and it is known to exist in two distinct stoichiometries. (α4)32)2 receptors expressed in Xenopus oocytes were studied using two electrodes voltage clamp electrophysiology recordings. The results show a low degree of activation by choline with a response of around 10% of the ACh response. This is comparable to that found on α4β4[3]. When co-applied with ACh (10µM fixed concentration) choline potentiated the response and maximum potentiation was observed at 1mM after which inhibition of the ACh response was apparent. Our results show that the (α4)32)2 nAChR is also modulated by high concentrations of choline.

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  2. Manickavasagom Alkondon, E.F.R.P., Wellington S. Cartes, Alfred Maelicke, Edson X. A l buquerque, Choline is a Selective Agonist of a7 nAChR in rat brain neurons. European Journal of Neuroscience, 1997. 9: p. 2734-2742.
  3. Ruud Zwart, H.P.M.V., Potentiation and inhibition of neuronal α4β4 nicotinic acetylcholine receptors by choline. 2000. 393: p. 209–214.