TAC3 and polycystic ovary syndrome: In PNA PCOS-like rats, the number of kisspeptin- and NKB-positive cells, as well as the expression of Kiss1 (gene for kisspeptin) and Tac2 (gene for NKB), were increased in arcuate nucleus (Yan et al., 2014; Osuka et al., 2017), which possibly increased GnRH-neuron activity.