Which mechanism involves substance P in antiemetic therapy?

In antiemetic therapy, substance P is a neuropeptide that plays a significant role in the process of emesis (vomiting). It primarily interacts with the neurokinin-1 (NK1) receptor in the central nervous system, particularly in the area of the brain known as the chemoreceptor trigger zone (CTZ). The CTZ is crucial in signaling nausea and vomiting.

When substance P binds to the NK1 receptors in the CTZ, it can activate this area and trigger the vomiting reflex. Therefore, antagonists that block these receptors, such as aprepitant, work effectively in preventing nausea and vomiting, especially those related to chemotherapy-induced emesis. The role of substance P in this context underlines the importance of targeting the NK1 pathway in antiemetic therapy to mitigate the effects of substances that induce vomiting.

Other mechanisms listed do not specifically involve substance P and its interaction with the NK1 receptors, which is why they do not apply to this context of antiemetic action.