International Journal of Molecular Sciences Review Mechanisms of Nausea and Vomiting: Current Knowledge and Recent Advances in Intracellular Emetic Signaling Systems Weixia Zhong 1, Omar Shahbaz 2, Garrett Teskey 1, Abrianna Beever 3, Nala Kachour 3, Vishwanath Venketaraman 1,3 and Nissar A. Darmani 1,* 1 Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, 309 East Second Street, Pomona, CA 91766, USA;
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[email protected] (N.K.) * Correspondence:
[email protected]; Tel.: +1-909-469-5654 Abstract: Nausea and vomiting are common gastrointestinal complaints that can be triggered by diverse emetic stimuli through central and/or peripheral nervous systems. Both nausea and vomiting are considered as defense mechanisms when threatening toxins/drugs/bacteria/viruses/fungi enter the body either via the enteral (e.g., the gastrointestinal tract) or parenteral routes, including the blood, skin, and respiratory systems. While vomiting is the act of forceful removal of gastrointestinal contents, nausea is believed to be a subjective sensation that is more difficult to study in nonhuman species. In this review, the authors discuss the anatomical structures, neurotransmitters/mediators, Citation: Zhong, W.; Shahbaz, O.; and corresponding receptors, as well as intracellular emetic signaling pathways involved in the Teskey, G.; Beever, A.; Kachour, N.; processes of nausea and vomiting in diverse animal models as well as humans.