Dynamins and myosin-II regulate the distinct modes of synaptic vesicle exocytosis in mature cerebrocortical nerve terminals and this involves calcium dependent phosphorylations.
type: CreativeWork
description: Synaptic vesicle (SV) exocytosis is vital to maintaining neuronal transmission at chemical synapses and defects in this processes has been linked to various psychiatric and neuronal disorders. Further, distinct modes of exocytosis have been implicated in post-synaptic plasticity and these latter processes maybe compromised in many neurodegenerative disorders. Therefore, it is vitally important to elucidate the machinery involved in SV exocytosis and decode the regulatory pathways for distinct modes of SV exocytosis. Herein, synaptosomes, pinched off nerve terminals, prepared from cerebral cortex of adult male Wistar rats were used as a model system to investigate these processes. Especially, A. Ashton had previously demonstrated the existence of KR mode of exocytosis in these synaptosomes and determined that the distinct modes can be regulated by adjusting the activity of various kinases and phosphatases. Synaptosomes were maximally labelled with 100 µM FM2-10 dye such that all the releasable vesicles, from readily releasable pool (RRP) and reserve pool (RP), were loaded with the dye. The exocytosis of the dye was then studied by employing various secretagogues (high K+ {HK}, 4-aminopyridine {4AP} or ionomycin {ION}) in the presence of 5 mM [Ca2+]e; these stimuli only induced a single round of release. This dye release was then directly compared to Glu release from terminals treated identically (more than 80% of these synaptosomes are glutamatergic), and differences between dye and Glu release were studied following various drug treatments. The results show that the inhibition of dynamins can increase the FM2-10 dye release during certain stimulation conditions (4AP5C and ION5C; where 5C represents 5 mM [Ca2+]e) without changing the Glu released indicating that dynamin(s) are required for the closure of the fusion pore (and therefore KR) during the employment of these stimuli. However experiments involving blockade of the ATPase activity of non-muscle myosin-II sugg…
abstract: Synaptic vesicle (SV) exocytosis is vital to maintaining neuronal transmission at chemical synapses and defects in this processes has been linked to various psychiatric and neuronal disorders. Further, distinct modes of exocytosis have been implicated in post-synaptic plasticity and these latter processes maybe compromised in many neurodegenerative disorders. Therefore, it is vitally important to elucidate the machinery involved in SV exocytosis and decode the regulatory pathways for distinct modes of SV exocytosis. Herein, synaptosomes, pinched off nerve terminals, prepared from cerebral cortex of adult male Wistar rats were used as a model system to investigate these processes. Especially, A. Ashton had previously demonstrated the existence of KR mode of exocytosis in these synaptosomes and determined that the distinct modes can be regulated by adjusting the activity of various kinases and phosphatases. Synaptosomes were maximally labelled with 100 µM FM2-10 dye such that all the releasable vesicles, from readily releasable pool (RRP) and reserve pool (RP), were loaded with the dye. The exocytosis of the dye was then studied by employing various secretagogues (high K+ {HK}, 4-aminopyridine {4AP} or ionomycin {ION}) in the presence of 5 mM [Ca2+]e; these stimuli only induced a single round of release. This dye release was then directly compared to Glu release from terminals treated identically (more than 80% of these synaptosomes are glutamatergic), and differences between dye and Glu release were studied following various drug treatments. The results show that the inhibition of dynamins can increase the FM2-10 dye release during certain stimulation conditions (4AP5C and ION5C; where 5C represents 5 mM [Ca2+]e) without changing the Glu released indicating that dynamin(s) are required for the closure of the fusion pore (and therefore KR) during the employment of these stimuli. However experiments involving blockade of the ATPase activity of non-muscle myosin-II sugg…
author: Bhuva, Dilip
language: en
date published: 2015-01
date modified: 2026-07-24T01:35:49Z
provider: University of Central Lancashire
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Central Lancashire