Which neurotransmitter system is targeted by benzodiazepines in treating anxiety?

• A. Serotonin.
• B. Dopamine.
• C. Glutamate.
• D. GABA-A receptor activity.

Answer: (D)

GABA is the main inhibitory neurotransmitter in the brain, and anxiety is eased when this inhibitory control is strengthened. Benzodiazepines treat anxiety by binding to a specific site on the GABA-A receptor and acting as positive allosteric modulators. They don’t directly activate the receptor themselves; instead, they increase how effectively GABA can open the receptor’s chloride channel. This leads to greater chloride influx, hyperpolarization, and reduced neuronal excitability in circuits that drive anxiety. That enhancement of GABA-A–mediated inhibition is why benzodiazepines are effective anxiolytics. While other systems like serotonin, dopamine, and glutamate play roles in anxiety, the pharmacologic action of benzodiazepines centers on amplifying GABA-A receptor activity.