Midbrain regions activated during copper-sulfate induced emesis in felines

The neural pathways that mediate emesis are still poorly defined. Most studies that considered emetic circuitry focused on the brainstem. The goal of this study was to map the distribution of Fos labeling in the feline midbrain following intragastric administration of copper sulfate (CuSO4). In 10 felines (6 male, 4 female), doses of CuSO4 ranging from 83 to 322 mg were administered through an intragastric catheter or gavage, and ~2 hours later animals were euthanized and perfused with paraformaldehyde. The brain was sectioned and processed for Fos labeling as in our prior study (Balaban et al., PLoS ONE 9(1): e86730, 2014). Three additional animals served as controls and did not receive intragastric CuSO4. Animals with emetic responses to CuSO4 exhibited extensive differential labeling in longitudinal columns within central/periaqueductal gray through the entire extent of the aqueduct of Sylvius. Labeling was present in the dorsolateral column of all animals, and differentially in the lateral column, ventrolateral column, ventromedial column, and the ventromedian area that caps the dorsal raphe nucleus. Fos labeling was also heavy in the dorsal tegmental area, superficial to the dorsal tegmental nucleus, locus coeruleus, pontine nuclei including the nucleus reticularis tegmenti pontis, and the dorsal raphe nucleus. Additional labeling was observed in the cuneiform nucleus, raphe centralis superior, and the Edinger-Westphal and anteromedial nuclei. This Fos labeling pattern is less circumscribed that reported for brainstem areas activated during CuSO4-induced vomiting in felines. Only diffuse labeling was noted in control animals. Ongoing studies are correlating physiologic responses to Fos labeling patterns induced by intragastric CuSO4. Midbrain neurons activated during emesis likely mediate affective responses during nausea, and likely also transmit visceral inputs elicited by CuSO4 to higher brain regions. NIH grant R01-DC018229 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.