Phoenixin-20 is a small peptide that has been detected in mammals, birds, amphibians and fish. Studies have shown that it can modify reproductive processes in female mammals and fish. In addition, it has been shown in mammalian studies to act as a pain reducer and modulator of food intake.
In a new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, researchers explored whether phoenixin-20 has a biological role in zebrafish, Danio rerio. The peptide sequence for phoenixin-20 in zebrafish is most similar to that of alligators (70% sequence identity), followed by 65% shared identity with mice, chickens and humans and only 50% shared identity with frogs. When administered phoenixin-20, both male and female fish ate less and had increases genes responsible for suppressing appetite along with decreases in genes responsible for stimulating hunger. The researchers also found that the peptide increased the expression of genes responsible for metabolizing glucose (glycolysis) in liver cell cultures.
Given these findings, you may be wondering whether phoenixin-20 could be a new candidate for weight loss in mammals. Unfortunately, the effects of phoenixin-20 zebrafish appetite are opposite to what has been observed in mammals.
JJ Rajeswari, AM Blanco, S Unniappan. Phoenixin-20 suppresses food intake, modulates glucoregulatory enzymes, and enhances glycolysis in zebrafish. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. 318(5): R917-R928, 2020.