The pathophysiology of post-operative nausea and vomiting (PONV) involves a complex interaction of specific receptors and neural pathways critical to the initiation of the nausea and vomiting reflex. Research has identified five neurotransmitters involved in mediating nausea and vomiting: muscarinic acetylcholine/cholinergic M3/M5 receptor, dopamine-2 (D2) and dopamine-3 (D3) receptor, histamine/H1 receptor, serotonin/5-HT3 receptor, and substance P/neurokinin-1 (NK-1) receptor. Nausea and vomiting are modulated through these diverse receptors, leading to various treatment options that target these mechanisms.
Furthermore, the neural mechanisms responsible for PONV can be categorized based on the origin of the stimuli: central and peripheral. Central stimuli, such as those from the vestibular system related to motion, directly activate the central pattern generator in the medulla, which coordinates the vomiting response. Conversely, peripheral stimuli, which might come from gastrointestinal irritation or distention, are initially processed by the nucleus tractus solitarius, located near the chemoreceptor trigger zone (CTZ) in the medulla. This intricate network of neural communication between the CTZ and the central pattern generator is crucial in triggering the vomiting reflex, underscoring the sophisticated neural network involved in the manifestation of PONV. Understanding these mechanisms is vital for the development of targeted interventions to mitigate PONV.
