gamma-aminobutyric acid catabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the breakdown of gamma-aminobutyric acid (GABA, 4-aminobutyrate), an amino acid which acts as a neurotransmitter in some organisms. [GOC:ai]

Gamma-aminobutyric acid (GABA) catabolism is a crucial biological process in the nervous system, primarily occurring in glial cells, particularly astrocytes. It involves the breakdown of GABA into succinate, a key intermediate in the citric acid cycle. This process is catalyzed by two major enzymes:

1. **GABA transaminase (GABA-T):** This enzyme catalyzes the first step in GABA catabolism, transferring the amino group of GABA to α-ketoglutarate, forming succinic semialdehyde and glutamate.

2. **Succinic semialdehyde dehydrogenase (SSADH):** This enzyme catalyzes the second step, oxidizing succinic semialdehyde to succinate. The cofactor NAD+ is reduced to NADH in this step, providing reducing equivalents for other metabolic processes.

The breakdown of GABA in this pathway serves several important functions:

* **Regulation of GABA levels:** Catabolism ensures that GABA levels in the brain are maintained within a specific range, preventing excessive GABA accumulation, which could lead to neuronal inhibition.
* **Energy production:** Succinate produced by GABA catabolism enters the citric acid cycle, providing energy to the cell through ATP production.
* **Neurotransmitter recycling:** The glutamate produced by GABA-T can be used for the synthesis of other neurotransmitters, including glutamine and GABA itself.

The GABA catabolic process is tightly regulated by various factors, including:

* **Enzyme activity:** The activity of GABA-T and SSADH is regulated by factors such as substrate availability, cofactor levels, and feedback inhibition.
* **Hormonal control:** Hormones like thyroid hormones can influence the activity of GABA-T.
* **Glial cell function:** Glial cells play a crucial role in regulating GABA catabolism, ensuring efficient removal of GABA from the synaptic cleft and maintaining neuronal activity.

Disruption of GABA catabolism can lead to various neurological disorders, including:

* **GABA-T deficiency:** This genetic disorder results in accumulation of GABA and succinic semialdehyde in the brain, causing neurological symptoms like seizures, developmental delay, and mental retardation.
* **SSADH deficiency:** This genetic disorder affects the breakdown of succinic semialdehyde, leading to its accumulation in the brain, causing neurological symptoms such as seizures, cognitive impairment, and ataxia.

In conclusion, the GABA catabolic process is an essential mechanism in the nervous system, regulating GABA levels, contributing to energy production, and participating in neurotransmitter recycling. Its proper functioning is critical for maintaining brain health and preventing neurological disorders.'
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Proteins (2)

Compounds (17)