The elusive area postrema
Nausea is a sense of malaise that all of us know. The sensation can be so overpowering that it leads us to wonder how and why this wretched condition happens. Researchers in Stephen Liberles’ lab at Harvard Medical School did more than wonder. They took the time and applied their expertise to study the neurons and circuits in the brain that control nausea, and reported their findings just in time for Thanksgiving. Deep in the brainstem, on the floor of the fourth ventricle lies the area postrema. A wide variety of evidence suggests that this region of the brain must be involved in nausea. Importantly, there is no blood brain barrier between the cells of the area postrema and the circulating plasma, so these cells are perfectly positioned to sample circulating poisons that most neurons would never encounter. However, the area postrema lies in a very specialized part of the brain which is very difficult to access experimentally.
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IMAGE: GLP1R neurons (red) play a critical role in detecting toxins in blood vessels (green) and initiating the nausea response. view more
Credit: Chuchu Zhang , Stephen Liberles
At some point, everyone experiences nausea. Whether it occurs after unwisely eating a week-old slice of pizza or as an accompaniment to a serious infection, that queasy, unsettling sensation centered around the stomach is a signal that something is amiss within the body and typically portends a bout of vomiting.
Most of the time, nausea is only temporary. But for some people, such as those on certain chemotherapy regimens, it can be severe, chronic and even life-threatening when it prevents patients from adhering to treatment.