dopamine secretion

Definition

Target type: biologicalprocess

The regulated release of dopamine by a cell. Dopamine is a catecholamine and a precursor of adrenaline and noradrenaline. It acts as a neurotransmitter in the central nervous system but it is also produced peripherally and acts as a hormone. [GOC:ef]

Dopamine secretion is a complex process that involves the synthesis, packaging, and release of dopamine, a neurotransmitter that plays a crucial role in various functions, including movement, reward, motivation, and cognition. The process begins in dopamine-producing neurons, known as dopaminergic neurons, which are located in specific areas of the brain, such as the substantia nigra and ventral tegmental area. Here's a detailed breakdown of the process:

1. **Synthesis:** The precursor molecule for dopamine is L-tyrosine, an amino acid that is obtained from the diet or synthesized from phenylalanine. L-tyrosine is transported into the dopaminergic neuron and converted into L-DOPA (L-dihydroxyphenylalanine) by the enzyme tyrosine hydroxylase. L-DOPA is then converted into dopamine by the enzyme aromatic L-amino acid decarboxylase (DOPA decarboxylase).

2. **Packaging:** Once synthesized, dopamine molecules are packaged into small, membrane-bound vesicles within the neuron. These vesicles act as storage containers for dopamine, preventing its premature release and degradation. The packaging process is facilitated by the vesicular monoamine transporter (VMAT2), which transports dopamine from the cytoplasm into the vesicles.

3. **Release:** When a neuron receives an electrical signal, it triggers the release of dopamine from the synaptic vesicles into the synaptic cleft, the small space between the presynaptic neuron and the postsynaptic neuron. This release occurs through a process called exocytosis, where the vesicles fuse with the presynaptic membrane, releasing dopamine into the synaptic cleft. The release of dopamine is regulated by calcium ions, which enter the neuron through voltage-gated calcium channels when the neuron is stimulated.

4. **Reuptake and Degradation:** After dopamine is released, it binds to dopamine receptors on the postsynaptic neuron, triggering various cellular responses. However, dopamine's action in the synaptic cleft is short-lived due to two main processes: reuptake and degradation. Dopamine is reabsorbed back into the presynaptic neuron by a specific transporter protein called the dopamine transporter (DAT), which then repackages it into vesicles for future release. Some dopamine is also broken down by the enzyme monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT), which convert dopamine into inactive metabolites.

5. **Regulation:** The secretion of dopamine is tightly regulated by various factors, including the activity of the dopaminergic neurons themselves, the availability of precursors, the activity of enzymes involved in synthesis and degradation, and the presence of neurotransmitters and hormones that modulate dopamine signaling.

The precise balance of dopamine in the brain is crucial for normal functioning, and disruptions in dopamine secretion can lead to a range of neurological and psychiatric disorders, including Parkinson's disease, schizophrenia, and addiction. Understanding the intricate process of dopamine secretion is essential for developing therapies that target dopamine pathways to treat these conditions.'
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Proteins (2)

Compounds (24)