Ghrelin is an appetite stimulatory peptide that regulates reproduction in vertebrates. The acylation of ghrelin by ghrelin-O-acyltransferase (Goat) is essential for most of its functions. The ghrelinergic system (ghrelin, ghrelin receptor [Ghsr] and Goat) is present in teleost fish ovary and testis. In this research, we determined the abundance of the ghrelinergic system mRNAs in different stages of follicle (oocyte) development in zebrafish ovary. The highest levels of preproghrelin mRNA were observed in the first stage of follicular development (previtellogenesis). Significantly low levels of preproghrelin mRNA were observed in stages 3II, 4 and 5 of the follicle development. Ghsr mRNA abundance remained unchanged at early stages of follicle development and decreased in stage 5 compared to other developmental stages. A significant decrease in preproghrelin and Ghsr mRNAs in the testis, and ghsr mRNA in the ovary of zebrafish deprived of food for 3 days were found. At 7 days food deprivation, preproghrelin, ghsr and goat mRNA in the ovary and preproghrelin and goat in the testis of zebrafish were significantly reduced. These results show that metabolic status modulates gonadal ghrelinergic system in zebrafish and provide support for a role for ghrelin in fish reproduction.
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