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

OSWALDO TOVAR; ALEJANDRO S. MECHALY; MARIANO ELISIO; TOMÁS CHALDE; LUIS F. CANOSA; LEANDRO A. MIRANDA; GUSTAVO M. SOMOZA

Gothenburg

Congreso; 8th International Symposium on Fish Endocrinology; 2016

The brain-pituitary-gonadal (BPG) axis is implicated in the regulation of vertebrate reproduction, and kisspeptin has emerged as a key player of this axis. Two ligands, kiss1 and kiss2 and receptors, kissr2 and kissr3, were characterized in Odontesthes bonariensis, and changes in the expression profile of these transcripts were analyzed at the BPG axis during female and male gametogenesis. Adult fish were collected every month from the wild, and the relative abundance of these transcripts was measured by real-time PCR. In females, brain kiss1 levels were higher at final maturation (FM); meanwhile kiss2 levels were high at primary growth 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. Finally, there was an increase of kiss1, kissr2 and kissr3 in the ovary during the Ca stage and kissr2 and kissr3 at FM. These results showed that these genes were differentially expressed at the three levels of the BPG axis throughout oogenesis. Changes of brain kiss1 expression levels suggested that it could be related to FM, in relation with the rise of gnrh1 observed at the same stage. Meanwhile kiss2 seemed to be associated with initial stages of gametogenesis.In males, the four genes were highly expressed in 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 spermiogenic stage (SP). In testes, kiss1 and kiss2 significantly increased during the SG and SC stages; meanwhile, kissr2 increases at SG and SC, whereas kissr3 levels were significantly high at SC and SP stages.Taken together, these results suggested that kisspeptin ligands and receptors are involved in the regulation of pejerrey gonadal development at the three levels of the BPG axis, showing differential expression profiles in both sexes, suggesting different roles in female and male gametogenesis.