In mammals, several hormones interact to regulate fertility and reproduction. Gonadotrophin releasing hormone (GnRH) is released by neurons (pink) in an area of the brain called the median eminence (ME; peach oval), which is part of the hypothalamus. This triggers the release of gonadotrophin and other hormones from the pituitary gland, which leads to the production of sex cells and sex (gonadal) hormones in the gonads. In turn, the gonads provide feedback to the system by regulating the release of GnRH (not shown) and gonadotrophin. Qiu et al. found that kisspeptin neurons in the hypothalamus synchronize their activity and drive GnRH neuronal activity. Kisspeptin neurons in the arcuate nucleus of the hypothalamus (KissARH neurons; blue) activate other KissARH neurons by releasing two neurotransmitters called neurokinin B (NkB) and dynorphin (Dyn). These neurons also activate kisspeptin neurons in the anteroventral periventricular nucleus and the periventricular preoptic nucleus (Kiss1AVPV/PeN neurons; green) in a pathway that involves another neurotransmitter called glutamate (Glu). In turn, the Kiss1AVPV/PeN neurons contact the cell body of GnRH neurons to stimulate the release of GnRH (Glanowska and Moenter, 2015). KissARH neurons can also directly contact the fibers of GnRH neurons in the arcuate nucleus (Ciofi et al., 2006), which has been proposed to stimulate GnRH release without involving the cell body of GnRH neurons.