The effect of dietary fat on the expression of appetite‐regulating hormones in zebrafish, Danio rerio

Abstract

We hypothesized that dietary fat levels during juvenile development affect the central expression of the appetite‐stimulating neurohormone ghrelin. To test this hypothesis, zebrafish were fed high fat (HF) or low fat (LF) diets from 5 weeks to 12 weeks post‐fertilization. Total RNA was extracted from whole heads in fed and fasted conditions, and ghrelin mRNA levels were measured by quantitative PCR (qPCR) of synthesized cDNA, and normalized to GAPDH levels. We found that fish fed a LF diet had higher ghrelin mRNA levels than fish fed a HF diet, in both fed and fasted conditions. Ghrelin expression increased significantly (p<0.05) in LF diet fish after an overnight fast, but did not increase significantly in HF diet fish. To test whether fat levels during development have long‐lasting effects on ghrelin expression, fish reared on high and low fat diets over the same period were all fed a HF diet for an additional 7 weeks, and ghrelin mRNA levels were measured in fed fish. Ghrelin expression did not significantly differ between fish reared on LF and HF diets switched to HF diets as adults (p=0.06). We conclude that dietary fat levels affect central ghrelin expression, but these effects are not permanent. effects. This project was funded by a UMW Undergraduate Research Award to ST.