Effects of cholesterol oxidase on neurotransmission and acetylcholine levels at the mice neuromuscular junctions

Guzalia F Zakirjanova; Arthur R Giniatullin; Chulpan R Gafurova; Artem I Malomouzh; Nikita S Fedorov; Arthur N Khaziev; Andrei N Tsentsevitsky; Alexey M Petrov

doi:10.1016/j.abb.2023.109803

Effects of cholesterol oxidase on neurotransmission and acetylcholine levels at the mice neuromuscular junctions

Arch Biochem Biophys. 2023 Nov:749:109803. doi: 10.1016/j.abb.2023.109803. Epub 2023 Oct 28.

Authors

Guzalia F Zakirjanova¹, Arthur R Giniatullin¹, Chulpan R Gafurova¹, Artem I Malomouzh², Nikita S Fedorov³, Arthur N Khaziev³, Andrei N Tsentsevitsky³, Alexey M Petrov⁴

Affiliations

¹ Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia; Kazan State Medical University, 49 Butlerova St., Kazan, 420012, RT, Russia.
² Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia; Kazan National Research Technical University, 10, K. Marx Street, Kazan, 420111, Russia.
³ Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia.
⁴ Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky St, Kazan, 420111, RT, Russia; Kazan State Medical University, 49 Butlerova St., Kazan, 420012, RT, Russia; Kazan Federal University, 18 Kremlyovskaya Street, Kazan, 420008, Russia. Electronic address: alexey.petrov@kazangmu.ru.

PMID: 37955112
DOI: 10.1016/j.abb.2023.109803

Abstract

Membrane cholesterol oxidation is a hallmark of redox and metabolic imbalance, and it may accompany neurodegenerative disorders. Using microelectrode recordings of postsynaptic responses as well as fluorescent dyes for monitoring synaptic vesicle cycling and membrane properties, the action of enzymatic cholesterol oxidation on neuromuscular transmission was studied in the mice diaphragms. Cholesterol oxidase (ChO) at low concentration disturbed lipid-ordering specifically in the synaptic membranes, but it did not change markedly spontaneous exocytosis and evoked release in response to single stimuli. At low external Ca²⁺ conditions, analysis of single exocytotic events revealed a decrease in minimal synaptic delay and the probability of exocytosis upon plasmalemmal cholesterol oxidation. At moderate- and high-frequency activity, ChO treatment enhanced both neurotransmitter and FM-dye release. Furthermore, it precluded a change in exocytotic mode from full-fusion to kiss-and-run during high-frequency stimulation. Accumulation of extracellular acetylcholine (without stimulation) dependent on vesamicol-sensitive transporters was suppressed by ChO. The effects of plasmalemmal cholesterol oxidation on both neurotransmitter/dye release at intense activity and external acetylcholine levels were reversed when synaptic vesicle membranes were also exposed to ChO (i.e., the enzyme treatment was combined with induction of exo-endocytotic cycling). Thus, we suggest that plasmalemmal cholesterol oxidation affects exocytotic machinery functioning, enhances synaptic vesicle recruitment to the exocytosis and decreases extracellular neurotransmitter levels at rest, whereas ChO acting on synaptic vesicle membranes suppresses the participation of the vesicles in the subsequent exocytosis and increases the neurotransmitter leakage. The mechanisms underlying ChO action can be related to the lipid raft disruption.

Keywords: Acetylcholine; Cholesterol; Exocytosis; Lipid raft; Mobilization; Neuromuscular junction; Oxysterol; Synaptic vesicle.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Acetylcholine* / metabolism
Acetylcholine* / pharmacology
Animals
Cholesterol / metabolism
Cholesterol Oxidase* / metabolism
Cholesterol Oxidase* / pharmacology
Mice
Neuromuscular Junction / metabolism
Neurotransmitter Agents / metabolism
Neurotransmitter Agents / pharmacology
Synaptic Transmission / physiology

Substances

Cholesterol Oxidase
Acetylcholine
Cholesterol
Neurotransmitter Agents