Researchers from the University of Guelph along with the University of Toronto with the help of studies on rat discovered that serotonin release in the visceral insular cortex in the brain may be responsible for the sensation of nausea.
The insular cortex is a site of taste and illness input in the brain.
Based on its cell structure and inputs, the insular cortex can be divided into two regions: the gustatory insular cortex and the visceral insular cortex.
The gustatory insular cortex receives taste input and the visceral insular cortex receives input from regions of the gut that may produce the sensation of nausea.
Researchers first demonstrated that depletion of serotonin in the entire insular cortex prevented the nausea-induced gaping reactions in rats, suggesting that serotonin activation in this region is necessary for the production of nausea.
Next they examined the effects of delivering drugs that either activate serotonin-3 receptors or block serotonin-3 receptors to specific regions of the insular cortex.
In the visceral insular cortex, but not the gustatory insular cortex, activating serotonin caused nausea (produced gaping reactions) and blocking serotonin reduced nausea (eliminated gaping reactions).
The data suggested that the activation of the visceral insular cortex by serotonin may be responsible for the production of the elusive sensation of nausea, which is so difficult to treat, researchers said in a statement.
They hope the work will lead to a better understanding of basic neural processes affected by prescribed drugs, with specific applications to controlling nausea and vomiting caused by cancer chemotherapy.
The study was published in the Journal of Neuroscience.
