Allopregnanolone is?

• A. A neurotransmitter
• B. A protein
• C. A neurosteroid derived from pregnanolone
• D. A vitamin

Answer: (C)

Allopregnanolone is a neurosteroid—steroids synthesized in the brain that directly influence neuronal activity rather than acting as classic neurotransmitters. It is formed from pregnanolone through enzymatic steps, so it is a derivative of pregnanolone. Its key action is to positively modulate GABA-A receptors, meaning it enhances the receptor’s response to the inhibitory neurotransmitter GABA. This increases chloride ion influx into neurons, boosting inhibitory signaling and producing calming, anticonvulsant, and anxiolytic effects. Because of this mechanism, it’s not a neurotransmitter, a protein, or a vitamin, but a brain-derived steroid that modulates neuronal Inhibition. Its pharmacological relevance is tied to its strong GABA-A modulation, which underpins its potential therapeutic uses.