Nicotinic acetylcholine receptors regulate clustering, fusion and acidification of the rat brain synaptic vesicles

Abstract

The brain nicotinic acetylcholine receptors (nAChRs) expressed in pre-synaptic nerve terminals regulate neurotransmitter release. However, there is no evidence for the expression of nAChRs in synaptic vesicles, which deliver neurotransmitter to synaptic cleft. The aim of this paper was to investigate the presence of nAChRs in synaptic vesicles purified from the rat brain and to study their possible involvement in vesicles life cycle. According to dynamic light scattering analysis, the antibody against extracellular domain (1-208) of α7 nAChR subunit inhibited synaptic vesicles clustering. Sandwich ELISA with nAChR subunit-specific antibodies demonstrated the presence of α4β2, α7 and α7β2nAChR subtypes in synaptic vesicles and showed that α7 and β2 nAChR subunits are co-localized with synaptic vesicle glycoprotein 2A (SV2A). Pre-incubation with either α7selective agonist PNU282987 or nicotine did not affect synaptic vesicles clustering but delayed their Ca 2+dependent fusion with the plasma membranes. In contrast, nicotine but not PNU282987 stimulated acidification of isolated synaptic vesicles, indicating that α4β2 but not α7-containing nAChRs are involved in regulation of proton influx and neurotransmitter refilling. Treatment of rats with levetiracetam, a specific modulator of SV2A, increased the content of α7 nAChRs in synaptic vesicles accompanied by increased clustering but decreased Ca 2+-dependent fusion. These data for the first time demonstrate the presence of nAChRs in synaptic vesicles and suggest an active involvement of cholinergic regulation in neurotransmitter release. Synaptic vesicles may be an additional target of nicotine inhaled upon smoking and of α7-specific drugs widely discussed as antiinflammatory and pro-cognitive tools.

PLEK2 mediates metastasis and invasion via α5‐nAChR activation in nicotine‐induced lung adenocarcinoma

“…ACh receptors are mainly divided into muscarinic receptors (M receptor‐G protein coupled receptor) and nicotine receptors (N receptor‐ion channel receptor). Its main structural feature is the pentamer 33,34 composed of 17 subunits, namely, α1‐10, β1‐4, δ, ε, and γ. Among them, the most common pentamer combinations are α4α5β2, α3α5β4 and homologous α7 pentamers.…”

Nicotine Exposure in a Phencyclidine-Induced Mice Model of Schizophrenia: Sex-Selective Medial Prefrontal Cortex Protein Markers of the Combined Insults in Adolescent Mice

“…Amph is involved in the invagination and fission steps of clathrin-mediated synaptic vesicle endocytosis [68] and, in the interactome map, it was directly linked to Syp, a protein localized in the membrane of synaptic vesicles implicated in the vesicular targeting of the plasma membrane and known to have reduced expression in several brain areas in SCHZ patients [69]. The altered expressions of Amph and Syp are consonant with the known disbalance of presynaptic neurotransmitter release mechanisms in SCHZ [69] and nicotine misuse [70,71]. However, other components of the synapse are also affected.…”