acetylcholine uptake

Definition

Target type: biologicalprocess

The directed movement of acetylcholine into a cell, typically presynaptic neurons or glial cells. Acetylcholine is a major neurotransmitter and neuromodulator both in the central and peripheral nervous systems. It also acts as a paracrine signal in various non-neural tissues. [GOC:ai]

Acetylcholine uptake is a crucial process in cholinergic neurotransmission, ensuring the efficient removal of acetylcholine (ACh) from the synaptic cleft. This process is mediated by a high-affinity transporter protein, known as the acetylcholine transporter (AChT), located on the presynaptic membrane. Here's a detailed breakdown of the biological process:

1. **Release of Acetylcholine:** When a nerve impulse arrives at the presynaptic terminal, it triggers the release of ACh into the synaptic cleft. This release occurs through exocytosis, where synaptic vesicles containing ACh fuse with the presynaptic membrane and release their contents.
2. **Binding to Receptors:** Once in the synaptic cleft, ACh diffuses across and binds to its receptors on the postsynaptic membrane. This binding initiates a signal transduction cascade, leading to a postsynaptic response.
3. **Termination of Signal:** The signal needs to be terminated to allow for subsequent neurotransmission. This is where AChT comes into play. AChT actively transports ACh from the synaptic cleft back into the presynaptic terminal.
4. **Mechanism of Transport:** AChT utilizes a coupled transport mechanism. The movement of ACh into the presynaptic terminal is coupled to the movement of sodium ions (Na+) down their electrochemical gradient. This gradient is maintained by the sodium-potassium pump, which actively pumps Na+ out of the cell and potassium ions (K+) into the cell.
5. **Recycling of Acetylcholine:** Once inside the presynaptic terminal, ACh is recycled. It can be repackaged into synaptic vesicles for future release or broken down by the enzyme acetylcholinesterase (AChE).
6. **Regulation of Acetylcholine Uptake:** The rate of ACh uptake is tightly regulated. Factors that influence uptake include:
* **ACh concentration:** Higher concentrations of ACh in the synaptic cleft lead to increased uptake.
* **Presynaptic membrane potential:** Depolarization of the presynaptic membrane can increase uptake.
* **Drugs:** Various drugs can modulate AChT activity. Some drugs, like hemicholinium-3, inhibit ACh uptake, while others, like nicotine, can increase it.
7. **Importance of Acetylcholine Uptake:** Efficient ACh uptake is crucial for normal cholinergic neurotransmission. Its disruption can lead to various neurological disorders. For instance, impaired ACh uptake has been linked to Alzheimer's disease.

This process ensures the precise and efficient regulation of ACh signaling, which is vital for diverse physiological functions, including muscle contraction, memory, and cognition.'
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Proteins (1)

Compounds (5)