γ-Aminobutyric Acid (GABA)

γ-Aminobutyric Acid (GABA) is the main inhibitory neurotransmitter in the CNS, reducing neuronal excitability and promoting relaxation.

Function of γ-Aminobutyric Acid (GABA):

• Primary inhibitory neurotransmitter in the CNS.
• Reduces neuronal excitability and prevents overstimulation.
• Maintains balance with excitatory glutamate.

Receptors:

• GABA-A (ionotropic): Ligand-gated Cl⁻ channels → fast inhibition.
• GABA-B (metabotropic): G-protein-coupled → opens K⁺ channels, inhibits Ca²⁺ channels → slow inhibition.

Synthesis Pathway:

1. Glucose (via Krebs cycle) → α-Ketoglutarate
2. α-Ketoglutarate → Glutamate
3. Glutamate → GABA
   • Enzyme: Glutamic Acid Decarboxylase (GAD)
   • Cofactor: Pyridoxal phosphate (Vitamin B6)

Drug examples:

• Tiagabine (blocks GAT‑1 re‑uptake).
• Vigabatrin (irreversible GABA‑transaminase inhibitor).
• Propofol and etomidate (direct gating in β subunits of GABA‑A).

Clinical Uses of γ-Aminobutyric Acid:

• Anxiety disorders
• Epilepsy
• Insomnia
• Muscle spasms

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