2-Minute Neuroscience: Neurotransmitter Release

2-Minute Neuroscience: Neurotransmitter Release

Welcome to 2 minute neuroscience, where I
explain neuroscience topics in 2 minutes or less. In this installment I will discuss neurotransmitter
release Neurotransmitters are stored in the axon terminals
of a neuron in small sac-like structures called synaptic vesicles. When an action potential travels down the
neuron and reaches the axon terminal, it causes depolarization of the neuron. This change in membrane potential causes voltage-gated
ion channels, which are ion channels that open in response to changes in membrane potential,
to open and allow calcium to enter the cell. Calcium seems to be involved with mobilizing
vesicles to prepare them for neurotransmitter release. One way this occurs is through an interaction
between calcium and a protein called synapsin, which attaches vesicles to the cytoskeleton
of the cell. Calcium activates an enzyme that causes synapsin
to separate from the vesicles, mobilizing them for release. After mobilization, a family of proteins called
SNARE proteins are involved with getting the vesicle ready to fuse with the cell membrane
of the neuron. Synaptobrevin (also called VAMP) is a SNARE
protein found in the membrane of vesicles, while syntaxin and SNAP-25 are two SNARE proteins
found in the cell membrane. These three proteins are thought to form a
complex, which helps to bring vesicles in contact with the cell membrane, allowing the
two membranes to fuse together. This process is thought to be facilitated
by another protein called munc18. The role of munc18 in vesicle fusion is not
completely understood, but it seems to bind to syntaxin and be necessary for fusion to
occur. Another protein found in synaptic vesicles
known as synaptotagmin is thought to act as a calcium sensor, which aims to promote vesicle
fusion only when calcium levels in the cell are high. When the vesicle fuses with the cell membrane,
it empties its contents into the synaptic cleft. After neurotransmitter release, the SNARE
complex is disassembled with the help of proteins called NSF and SNAP, and the vesicle is recycled
so it can be used again.

7 Replies to “2-Minute Neuroscience: Neurotransmitter Release”

  1. This is really great, thanks for making the video. Would you consider following up someday with what happens after neurotransmitter release (i.e. synaptic cleft, reuptake, etc)?

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