Liver failure or congenital defects can lead to a build-up of ammonia in the brain of mammals resulting in life-threatening swelling, convulsions and comas. For goldfish (Carassius auratus), environmental exposure to ammonia causes reversible swelling of the brain. In a new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, researchers wanted to explore how the fish were able to accomplish this. They exposed goldfish to high levels of ammonia for 72 hours which, like mammals, caused oxidative stress and swelling of the brain. What they also noticed, however, is that the goldfish increased the activities of several antioxidants in their brains to combat the oxidative stress and reverse some of the swelling. This protective mechanism may help the fish to thrive in otherwise uninhabitable waters for predators or competing fish. I wonder if my mother knew about this when she flushed Goldie my goldfish down the toilet by accident so many years ago…
For humans, this research may lead to new ways to help protect tissues from potential oxidative damage resulting from liver failure or congenital defects.
DFJ Lisser, ZM Lister, PQH Pham-Ho, GR Scott, MP Wilkie. Relationship between oxidative stress and brain swelling in goldfish (Carassius auratus) exposed to high environmental ammonia. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. 312(1): R114-R124, 2017. DOI: 10.1152/ajpregu.00208.2016