 The major role kisspeptin/GPR54 plays in sexual development was initially found in sexually immature humans and mice who had mutations that blocked the expression of the GPR54 gene.In rats, the initiation of puberty accompanied a greater presence of KISS1 and GPR54 in mRNA.The same events were later observed in mammals, where KISS1 and GPR54 mRNA increased more than twofold in the hypothalamus.