A unique expression profile of kisspeptin receptor genes during final oocyte maturation in female chub mackerel, Scomber japonicas

Kisspeptin is a key regulator of not only pubertal onset but also the preovulatory luteinizing hormone (LH) surge in mammals. Our previous study demonstrated that both kissl and kiss2 mRNA levels increased during final oocyte maturation (FOM) and ovulation in the spawning cycle, and suggested their possible involvement in the regulation of these two processes. In this paper, we report the expression profiles of kisspeptin receptors (kissrl and kissr2) in the brain of adult female chub mackerel during FOM and ovulation. Contrary to the expression of their ligands, the expression of both receptor genes significantly decreased during FOM. The rhythmic expression of kiss/kissr during the spawning cycle may be involved in regulation of the reproductive axis, especially the LH surge, and could be affected by the circadian clock or the circadian oscillation of an environmental factor.