Kisspeptins and their receptors are differentially expressed in the brain-pituitary-gonadal axis during gametogenesis in Odontesthes bonariensis.

TOVAR O; MECHALY AS; ELISIO M; CHALDE T; CANOSA LF; MIRANDA LA; SOMOZA GM

GOTHENBURG

Simposio; 8th International Symposium on Fish Endocrinology; 2016

The brain-pituitary-gonadal (BPG) axis is implicatedin the regulation of vertebrate reproduction, and kisspeptin has emerged as akey player of this axis. Two ligands, kiss1and kiss2 and receptors, kissr2 and kissr3, were characterized in Odontesthesbonariensis, and changes in the expression profile of these transcripts wereanalyzed at the BPG axis during female and male gametogenesis. Adult fish werecollected every month from the wild, and the relative abundance of these transcriptswas measured by real-time PCR. In females, brain kiss1 levels were higher at final maturation (FM); meanwhile kiss2 levels were high at primary growth(PG) stage, with no differences in receptors levels. At the pituitary, kiss1 and kiss2 peaked at the cortical alveoli (Ca) stage, and kissr3 at initial vitellogenesis (VgA). Finally,there was an increase of kiss1, kissr2 and kissr3 in the ovary during the Ca stage and kissr2 and kissr3 at FM. Takentogether; these results showed that these genes were differentially expressedat the three levels of the BPG axis throughout oogenesis. Changes of brain kiss1 expression levels suggested thatit could be related with the final maturation  process, and correlated with the rise of gnrh1 at FM. Meanwhile kiss2 would be associated with initialstages of gametogenesis.In males, the four genes were highly expressedin the brain at the arrested stage. In the pituitary, kiss2 peaked at spermatogonial (SG) and spermatocytary (SC) stages;while kissr3 reached a peak at the spermiogenicstage (SP). In testes, kiss1 and kiss2 significantly increased during theSG and SC stages; meanwhile, kissr2 increasesat SG and SC, whereas kissr3 levels weresignificantly high at SC and SP stages.These results suggested that kisspeptin ligandsand receptors are involved in the regulation of pejerrey gonadal development, showingdifferential profiles at the three levels of the BPG axis. Furthermore, the sexuallydimorphic gene expression patterns suggested different roles for these genes infemale and male gametogenesis.