Final answer:
Sufentanil is an opioid analgesic that acts through a G-protein-coupled receptor by binding to the mu-opioid receptor, leading to a reduction in cyclic AMP levels and modulation of pain perception.
Step-by-step explanation:
Among the provided options, sufentanil acts via a G-protein-coupled receptor (GPCR). This is because sufentanil is an opioid analgesic that binds to the mu-opioid receptor, which is a type of GPCR, initiating a cascade of intracellular events that lead to its analgesic effects. Opioid receptors are involved in pain modulation and are targeted by various analgesic drugs. When sufentanil binds to the mu-opioid receptor, it activates the G-protein, leading to downstream effects such as the inhibition of adenylyl cyclase and a reduction in cyclic AMP levels. This can ultimately lead to changes in cellular functions such as a decrease in neurotransmitter release and the modulation of pain perception.