Orexigenic actions of ghrelin in goldfish: novel evidences from preprandial, postprandial and starvation induced changes in its mRNA expression, serum levels and central and peripheral injections

UNNIAPPAN S; CANOSA LF; PETER RE

NEUROENDOCRINOLOGY

Año: 2004 vol. 79 p. 100 - 108

0028-3835

In this study, we examined (i) the preprandial, postprandialand starvation-induced changes in the preproghrelinmRNA expression and serum ghrelin levels, and (ii) theeffects of intracerebroventricular and intraperitoneal administrationof ghrelin on food intake in goldfish. Slotblot analysis revealed a significant postprandial decreasein preproghrelin mRNA expression in the hypothalamus(1 and 3 h after feeding) and gut (3 h after feeding).A similar postprandial decrease (1 and 3 h afterfeeding) in serum ghrelin levels was also detected. In thefish that were unfed at the regular feeding time, thehypothalamic preproghrelin mRNA expression and theserum ghrelin levels remained unchanged, while thepreproghrelin mRNA expression in the gut decreased 3 hafter the regular feeding time. Starvation increased preproghrelinmRNA expression in the hypothalamus andgut on the 7th day. Serum ghrelin levels were significantlyelevated on days 3 and 5 of starvation. Intracerebroventricularinjections of n-octanoylated ghrelin-like peptides(gGRL[1–12]) (10 ng/g body weight) and human ghrelin(1 and 10 ng/g body weight) and intraperitoneal injectionsof n-octanoylated gGRL[1–12] (10 ng/g body weight),gGRL[1–19] (100 ng/g body weight) and human ghrelin (10and 100 ng/g body weight) stimulated food intake ingoldfish. The patterns of synthesis, secretion and actionsindicate that ghrelin is an orexigen in goldfish.