Where is the principal site of action of the serotonin receptor antagonist ondansetron?
- Area postrema
- Basal ganglia
- GI tract
- Hypothalamus
- Vestibular system
Answer : Area postrema.
The serotonin receptor antagonists such as ondansetron, granisetron, and tropisetron are a class of agents that have generated much interest secondary to their effect on chemotherapy induced emesis. Their principal site of action is the area postrema, which is located in the lateral reticular formation of the medulla. They also exert some effect on receptors of the GI tract; however, this is secondary to their effect in the area postrema.