Blocking the NK1 receptor would primarily block the actions of which molecule?

Blocking the NK1 receptor would primarily block the actions of which molecule?

• A. Substance P
• B. Glutamate
• C. GABA
• D. Dopamine

Answer: (A)

Blocking the NK1 receptor prevents the signaling of substance P, the natural ligand for that receptor. Substance P is a neuropeptide involved in transmitting pain signals and inducing vomiting, among other responses. When the NK1 receptor is blocked, substance P can’t activate its downstream pathways, so its effects are greatly reduced. Glutamate, GABA, and dopamine work through other receptor systems (such as NMDA/AMPA for glutamate, GABA-A/B for GABA, and various dopamine receptors), so blocking NK1 doesn’t primarily affect their actions. This is also why NK1 antagonists are used as antiemetics—to prevent substance P from promoting vomiting.

Blocking the NK1 receptor prevents the signaling of substance P, the natural ligand for that receptor. Substance P is a neuropeptide involved in transmitting pain signals and inducing vomiting, among other responses. When the NK1 receptor is blocked, substance P can’t activate its downstream pathways, so its effects are greatly reduced. Glutamate, GABA, and dopamine work through other receptor systems (such as NMDA/AMPA for glutamate, GABA-A/B for GABA, and various dopamine receptors), so blocking NK1 doesn’t primarily affect their actions. This is also why NK1 antagonists are used as antiemetics—to prevent substance P from promoting vomiting.