Which receptor primarily mediates the actions of Substance P?

Which receptor primarily mediates the actions of Substance P?

• A. GABA_A receptor
• B. Dopamine D receptor
• C. NK1 receptor
• D. NMDA receptor

Answer: (C)

Substance P mainly acts through the neurokinin-1 receptor (NK1), a G-protein–coupled receptor in the tachykinin family. When Substance P binds NK1, it activates intracellular signaling that enhances excitability of neurons in pain pathways, helping transmit and amplify nociceptive signals in the spinal cord and brain. This direct receptor interaction is what mediates Substance P’s pro-pain and inflammatory effects, making NK1 the best answer. The other receptors listed serve different neurotransmitter systems: GABA_A mediates inhibitory signaling, NMDA receptors respond to glutamate and are involved in synaptic plasticity and excitatory transmission, and dopamine D receptors are part of dopaminergic signaling. They are not the primary receptors through which Substance P exerts its effects.

Substance P mainly acts through the neurokinin-1 receptor (NK1), a G-protein–coupled receptor in the tachykinin family. When Substance P binds NK1, it activates intracellular signaling that enhances excitability of neurons in pain pathways, helping transmit and amplify nociceptive signals in the spinal cord and brain. This direct receptor interaction is what mediates Substance P’s pro-pain and inflammatory effects, making NK1 the best answer.

The other receptors listed serve different neurotransmitter systems: GABA_A mediates inhibitory signaling, NMDA receptors respond to glutamate and are involved in synaptic plasticity and excitatory transmission, and dopamine D receptors are part of dopaminergic signaling. They are not the primary receptors through which Substance P exerts its effects.