Activation of Neuronal Nicotinic Receptors Inhibits Acetylcholine Release in the Neuromuscular Junction by Increasing Ca²⁺ Flux through Ca_v1 Channels

• Main Authors: Nikita Zhilyakov, Arsenii Arkhipov, Artem Malomouzh, Dmitry Samigullin
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: International Journal of Molecular Sciences
• Subjects: neuromuscular junction; neurotransmitter release; acetylcholine; nicotinic receptor; calcium channel; calcium transient
• Online Access: https://www.mdpi.com/1422-0067/22/16/9031

Cholinergic neurotransmission is a key signal pathway in the peripheral nervous system and in several branches of the central nervous system. Despite the fact that it has been studied extensively for a long period of time, some aspects of its regulation still have not yet been established. One is the relationship between the nicotine-induced autoregulation of acetylcholine (ACh) release with changes in the concentration of presynaptic calcium levels. The mouse neuromuscular junction of m. Levator Auris Longus was chosen as the model of the cholinergic synapse. ACh release was assessed by electrophysiological methods. Changes in calcium transients were recorded using a calcium-sensitive dye. Nicotine hydrogen tartrate salt application (10 μM) decreased the amount of evoked ACh release, while the calcium transient increased in the motor nerve terminal. Both of these effects of nicotine were abolished by the neuronal ACh receptor antagonist dihydro-beta-erythroidine and Ca_v1 blockers, verapamil, and nitrendipine. These data allow us to suggest that neuronal nicotinic ACh receptor activation decreases the number of ACh quanta released by boosting calcium influx through Ca_v1 channels.