Question

Vigabatrin produces anti-epileptic activity through

• A. Potentiating GABA mediated neuronal inhibition by depressing GABA transporters
• B. Modifying synaptic release of glutamate/GABA by binding to a specific synaptic protein
• C. Inhibiting GABA transaminase enzyme which degrades GABA
• D. Potentiating post synaptic GABA receptor effect

Answer 1

The Correct Option is C

Vigabatrin is an antiepileptic medication that is used to treat seizures by increasing levels of gamma-aminobutyric acid (GABA) in the brain, which is an inhibitory neurotransmitter. The mechanism by which vigabatrin exerts its antiepileptic activity is through the inhibition of the enzyme GABA transaminase. GABA transaminase is responsible for the breakdown of GABA in the central nervous system.

Here is the step-by-step explanation for why vigabatrin works through this mechanism:

1. Concept Understanding: GABA is a major inhibitory neurotransmitter in the brain. Increasing GABA activity generally helps to control excessive neuronal firing and reduce seizure activity.
2. Mechanism of Vigabatrin: Vigabatrin irreversibly inhibits GABA transaminase, which is the enzyme that degrades GABA. By inhibiting this enzyme, vigabatrin prevents the breakdown of GABA, thereby increasing its concentration in the brain.
3. Increase in GABA Concentration: With higher levels of GABA, there is enhanced neuronal inhibition, which is beneficial in reducing the occurrence and severity of seizures.

Ruling Out Other Options:

• Potentiating GABA mediated neuronal inhibition by depressing GABA transporters: This involves mechanisms that increase GABA levels differently, often through interfering with GABA reuptake, which vigabatrin does not target.
• Modifying synaptic release of glutamate/GABA by binding to a specific synaptic protein: This describes a mechanism involving the direct modulation of neurotransmitter release, which is not the action of vigabatrin.
• Potentiating post synaptic GABA receptor effect: This option suggests enhancing the action of GABA at the receptor level, generally through receptor modulation or allosteric activation, which is not the specific mechanism of vigabatrin.

Therefore, the correct answer is that vigabatrin produces its anti-epileptic activity by inhibiting GABA transaminase enzyme which degrades GABA. This mechanism increases GABA concentrations and enhances its inhibitory effects in the brain, helping to control seizures.