Ramelteon primarily targets which receptors?

• A. GABA-A receptors
• B. Melatonin receptors MT1 and MT2
• C. Dopamine D2 receptors
• D. Histamine H1 receptors

Answer: (B)

Ramelteon selectively activates melatonin receptors MT1 and MT2. By binding these receptors in the brain, especially the suprachiasmatic nucleus, it mimics natural melatonin to promote sleep onset and help regulate circadian rhythms. This mechanism distinguishes it from drugs that mainly target GABA-A receptors (like many traditional hypnotics), dopamine D2 receptors, or histamine H1 receptors. The MT1 receptor is linked to initiating sleep, while MT2 helps adjust the internal clock, making ramelteon effective for sleep-onset insomnia without relying on GABAergic or antihistaminic pathways.