Adenosine receptors and muscarinic receptors cooperate in acetylcholine release modulation in the neuromuscular synapse. (18th May 2015)

• Record Type: Journal Article
• Authors: Santafe, M. M.; Priego, M.; Obis, T.; Garcia, N.; Tomàs, M.; Lanuza, M. A.; Tomàs, J.
• Is Part Of: European journal of neuroscience. Volume 42:Number 2(2015:Jul.)
• Page Start: 1775
• Page End: 1787
• Publication Date: 2015-05-18
• Subjects: Nervous system -- Periodicals; 612.8
• DOI: 10.1111/ejn.12922
• Languages: English
• ISSNs: 0953-816X

Abstract

<abstract abstract-type="main" id="ejn12922-abs-0001"> <title>Abstract</title> <p>Adenosine receptors (ARs) are present in the motor terminals at the mouse neuromuscular junction. ARs and the presynaptic muscarinic acetylcholine receptors (mAChRs) share the functional control of the neuromuscular junction. We analysed their mutual interaction in transmitter release modulation. In electrophysiological experiments with unaltered synaptic transmission (muscles paralysed by blocking the voltage‐dependent sodium channel of the muscle cells with μ‐conotoxin GIIIB), we found that: (i) a collaborative action between different AR subtypes reduced synaptic depression at a moderate activity level (40 Hz); (ii) at high activity levels (100 Hz), endogenous adenosine production in the synaptic cleft was sufficient to reduce depression through A<sub>1</sub>‐type receptors (A<sub>1</sub>Rs) and A<sub>2</sub>A‐type receptors (A<sub>2</sub><sub>A</sub>Rs); (iii) when the non‐metabolizable 2‐chloroadenosine (CADO) agonist was used, both the quantal content and depression were reduced; (iv) the protective effect of CADO on depression was mediated by A<sub>1</sub>Rs, whereas A<sub>2</sub><sub>A</sub>Rs seemed to modulate A<sub>1</sub>Rs; (v) ARs and mAChRs absolutely depended upon each other for the modulation of evoked and spontaneous acetylcholine release in basal conditions and in experimental conditions with CADO stimulation; (vi) the purinergic and muscarinic mechanisms cooperated in the control of depression by sharing a common pathway although the purinergic control was more powerful than the muscarinic control; and (vii) the imbalance of the ARs created by using subtype‐selective and non‐selective inhibitory and stimulatory agents uncoupled protein kinase C from evoked transmitter release. In summary, ARs (A<sub>1</sub>Rs, A<sub>2</sub><sub>A</sub>Rs) and mAChRs (M<sub>1</sub>, M<sub>2</sub>) cooperated in the control of activity‐dependent synaptic depression and may share a common protein kinase C pathway.</p> </abstract>