Cloning, tissue distribution and effects of fasting on mRNA expression levels of leptin and ghrelin in red-bellied piranha (Pygocentrus nattereri).

cDNAs encoding the appetite regulating peptides leptin and ghrelin were isolated in red-bellied piranha (Characiforme, Serrasalmidae) and their mRNA tissue and brain distributions examined. When compared to other fish, the sequences obtained for all peptides were most similar to that of other Characiforme fish and Siluriformes. All peptides were widely expressed within the brain and in several peripheral tissues, including gastrointestinal tract. In order to better understand the role of these peptides in the regulation of feeding of red-bellied piranha, the mRNA expression levels of leptin and ghrelin were examined in both brain and intestine, in fed and 7-day fasted fish. No significant differences in expression were seen in whole brain for either peptide. Within the intestine, there was a decrease in leptin mRNA expression and an increase in ghrelin mRNA expression in fasted fish, compared to fed fish. The results suggest that leptin and ghrelin might play a major role in the regulation of feeding and energy homeostasis of red-bellied piranha and this role might be more prominent in the intestine than in the brain.