✍️ Author: Dr Eleni Christoforidou
🕒 Approximate reading time: 4 minutes
Neurotransmitter release is the fundamental process by which neurons communicate with each other. Understanding this process at the molecular level provides key insights into how our brain functions and what might go wrong in neurological disorders. This post will delve into the molecular mechanisms underlying neurotransmitter release.
Neurons communicate with each other through synapses, which are specialised structures where two neurons come into close contact. The neuron sending the signal, known as the presynaptic neuron, releases neurotransmitters that are detected by the receiving neuron, or postsynaptic neuron. Neurotransmitters are stored in synaptic vesicles in the presynaptic neuron, waiting for a signal to be released.
The release of neurotransmitters is triggered by an electrical signal known as an action potential. When an action potential reaches the presynaptic neuron's terminal, voltage-gated calcium channels open, allowing calcium ions to flood into the neuron. This sudden increase in calcium ions prompts synaptic vesicles to fuse with the neuron's membrane, releasing their neurotransmitter contents into the synaptic cleft.
This process of vesicle fusion is mediated by a complex of proteins known as SNAREs. SNARE proteins on the vesicle (v-SNAREs) interact with those on the neuron membrane (t-SNAREs), pulling the two membranes together. This interaction is facilitated by additional proteins, including synaptotagmin, which acts as a calcium sensor and triggers vesicle fusion in response to the influx of calcium ions.
Once released, neurotransmitters don't linger in the synaptic cleft. They quickly bind to receptors on the postsynaptic neuron, triggering an electrical response. Any neurotransmitters that are not taken up by receptors are typically reabsorbed by the presynaptic neuron in a process known as reuptake, which involves transport proteins in the presynaptic neuron's membrane.
In conclusion, neurotransmitter release is a complex, finely-tuned process that underlies neuronal communication. Dysregulation of any component of this process can lead to neurological disorders, making it a crucial area of research for advancing our understanding and treatment of these conditions.