Chemoreceptor Trigger Zone - Communication

Communication

One of the ways the chemoreceptor trigger zone implements its effects on the vomiting center is by activation of the opioid mu receptors and delta receptors. The activation of these opioid receptors in the CTZ are especially important for patients who take opioid based pain medications on a regular basis. However, opioids do not play a role in communication to the vomiting center of the brain, they only induce communication. Dopamine and serotonin have been found to play the biggest role in communication from the CTZ to the vomiting center, as well as histamine. Chemoreceptors in the CTZ relay information about there being emetic agents in the blood to the adjacent nucleus tractus solitarius (NTS). The relaying happens by the initiation of an action potential, which is caused by the chemoreceptor causing a change in electric potential in the neuron it is embedded in, which then subsequently causes an action potential. This happens constantly, so the chemoreceptors in the CTZ are continually sending information about how much emetic agents are in the blood, even when emesis is not signaled for. The NTS is organized into subnuclei that direct many different functions relating to swallowing, gastric sensation, laryngeal and pharyngeal sensation, baroreceptor function, and respiration. The NTS directs signals about these functions to a central pattern generator (CPG). This CPG actually coordinates the sequences of physical movements during emesis. The vomiting center of the brain refers to the groups of loosely organized neurons in the medulla that are activated in sequence by the CPG. The main neurotransmitters involved in communication between the CTZ and the vomiting center are serotonin, dopamine, histamine, and endogenous opioids which include endorphins, enkephalins, dynorphin.