LPXRFa down-regulates brain reproductive genes in yellowtail kingfish (Seriola lalandi)

Abstract Gonadotropin-inhibitory hormone (GnIH) is a hypothalamic peptide that inhibits the reproductive axis of mammals and birds. Little information is available in teleosts regarding its actions on the brain neuroendocrine systems controlling reproduction. Here, we analyzed the effects of intraperitoneal injection of the piscine GnIH ortholog LPXRFa peptides (LPXRFa-1, LPXRFa-2, and LPXRFa-3) on the expression of reproduction-related genes in the brain of yellowtail kingfish. Our results revealed an inhibitory effect of the three LPXRFa peptides on gnrh1, lpxrfa, kiss1r, kiss2r, and lpxrfa-r mRNA levels. Both LPXRFa-1 and LPXRFa-2 were found to suppress kiss2 expression, and LPXRFa-1 reduced gnrh2 expression. Moreover, LPXRFa-3 induced a decrease in kiss1 and gnrh2 expression. Overall, these data suggest the inhibitory actions of each LPXRFa peptide encoded by the same precursor on the brain reproductive genes in yellowtail kingfish.