**4-Aminobutyric Acid (GABA): A Versatile Compound for Industrial and Pharmaceutical Use**  

**Definition**  

4-Aminobutyric acid, commonly known as GABA, is a non-protein amino acid with the chemical formula C?H?NO?. It is a key inhibitory neurotransmitter in the mammalian central nervous system (CNS) and is widely recognized for its role in regulating neuronal excitability.  

**Key Functions**  

- **Neurotransmitter**: GABA is the primary inhibitory neurotransmitter in the CNS, helping to reduce neuronal excitability and promote relaxation.  

- **Metabolic Role**: It plays a crucial role in brain energy metabolism, enhancing glucose metabolism and supporting cellular function.  

- **Antioxidant Properties**: GABA exhibits antioxidant activity, protecting cells from oxidative stress.  

**Applications**  

1. **Pharmaceuticals**: GABA is used in treatments for neurological disorders such as epilepsy, anxiety, and insomnia. It is also studied for its potential in managing metabolic diseases like diabetes.  

2. **Food and Beverage**: As a natural additive, GABA is incorporated into functional foods and beverages for its calming and health-promoting effects.  

3. **Cosmetics**: Due to its antioxidant and soothing properties, GABA is used in skincare products to protect against oxidative damage and improve skin health.